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4646 Dakota Street SE
Prior Lake. MN 55372
CITY COUNCIL AGENDA REPORT
MEETING DATE: January 3, 2012
AGENDA #: 513
PREPARED BY: Ross Bintner P.E. — Water Resources Engineer
PRESENTED BY: Katy Gehler, Public Works and Natural Resources Director
AGENDA ITEM: CONSIDER APPROVAL OF A MAJOR AMENDMENT TO THE LOCAL SUR-
FACE WATER MANGEMENT PLAN.
DISCUSSION: Introduction
The purpose of this agenda item is to consider a major amendment to the
LSWMP.
Hi story
At its October 3, 2011 meeting, Council accepted a request from the Scott Wa-
tershed Management Organization (SWMO) to amend the City of Prior Lake Local
Surface Water Management Plan (LSWMP) and directed staff to prepare an
amendment consistent with the request, the Prior Lake Lakes Advisory Committee
(LAC) to review and Staff to submit the draft amendment for Agency review.
Current Circumstances
The process to consider a plan amendment is spelled out in section 6.11 of the
LSWMP and is summarized as follows:
1. Written request for plan amendment is submitted to and reviewed by City
staff.
2. City staff determines the validity of the request and follows one of three op-
tions: To reject the request, accept the request as a request for minor
amendment or, accept the request as a request for major amendment.
The amendment request and staff recommendation is then forwarded for
City Council consideration. Section 6.11.1 spells out what requests can be
considered minor amendments.
3. Staff recommendations for the amendment request are considered by the
City Council, including the determination of the need for a public hearing.
City Council then decides whether to order the amendment and if and
when a Public Hearing is included in the amendment process.
4. If amendment to the LSWMP is ordered, City staff drafts the proposed
amendment, schedules and holds any necessary Public Hearings and for-
wards the proposed amendment to local watershed organizations, the Met
Council and Board of Water and Soil Resources for their review.
5. Following the review and approval by local agencies, the City Council con-
siders the LSWMP amendment for approval.
This report reviews the result of step 4, and the associated council action fulfills
step 5 of the process detailed above.
City staff prepared a draft amendment consistent with the request and presented it
to the LAC ahead of the October 18 LAC meeting. The LAC reviewed the draft
amendment, and provided feedback to staff. Discussion centered on the unique
challenges and future planning needs in the annexation areas draining to Howard
and Campbell lakes and the unimproved drainage system downstream of these
two lakes. After LAC review, Staff made minor changes and send the draft
amendment to state and local partners for their review.
Correspondence, a draft with changes highlighted and a final draft of the amended
of all modified LSWMP chapters are available on the online document center as
appendix to this agenda report. A description of changes is included in the "issues"
section of this report.
Conclusion
The amendments proposed to the LSWMP update the plan to include current
practices and call for coordinated planning of developing drainage paths in coop-
eration with the SWMO and should be approved.
ISSUES: The request for amendments in the December 28, 2010 SWMO letter detailed six
specific changes.
1. Reference to Municipal Separate Storm Sewer (MS4) Storm Water Pollu-
tion Prevention Program (SWPPP) requirements.
2. Street Sweeping Priorities and Local Governmental Unit (LGU) protocol.
3. Salt and sanding (snow and ice control) best management practice de-
scription.
4. Coordination of drainage networks that overlap jurisdictional boundaries.
5. Coordination strategies for a variety of water resource program elements.
6. Reference to local controls.
Items 1, 2, 3 and 6 were existing processes that need simple changes in plan lan-
guage; items 4 and 5 were the focus of much of the changes.
Changes were made in the following LSWMP sections consistent with the SWMO
request: Executive summary, Section 1 Introduction, Section 3 Goals and Policies,
Section 5 System Assessment and Design, Section 6 Implementation Plan. The
City street maintenance policy, which includes street sweeping and snow and ice
control policies, was also added as a reference document.
Changes made to address item 4 occur in section 3, through additions and modifi-
cations to goals and policies, and in section 5 through added descriptions of coor-
dinating efforts for the Campbell and Howard Lake drainage districts and the
downstream "Louisville Swamp (LSW)" drainage district. Language was added to
describe the ditch drainage path and Picha Creek between these upstream lakes
and Louisville Swamp, and the challenges in this area of annexation and devel-
opment. A planning effort is recommended to be lead by the SWMO and include
the Cities of Prior Lake and Shakopee.
Changes made to address item 5 occur in the executive summary and sections 3
and 5. These coordinating strategies are detailed in the reply memo to the SWMO
and Prior Lake Spring Lake Watershed District ( PLSLWD.) The most notable
coordinating strategy deals with a proposal to find efficient solutions to treat
stormwater for the downtown drainage areas while being sensitive context of the
downtown zone and economic development goals. The proposal to coordinate
with the PLSLWD to plan for a downtown stormwater overlay district and clean wa-
ter practice "bank." This concept would modify development standards in the
downtown area offset by investing in a clean water practice "bank" of more effi-
cient practices in areas in the annexation area or in Spring Lake Township.
FINANCIAL There are no immediate financial impacts associated with this modification. Long
IMPACT: term planning efforts will require continued city involvement and the results may
determine future development and redevelopment standards.
Additional staff effort to finalize the amendment and make the amended LSWMP
available online and in print, and associated costs to copy, mail and make CD
discs to local stakeholders should be minor.
ALTERNATIVES: 1. Approve the LSWMP as amended by Major Amendment 1.
2. Deny the request and provide staff with direction.
RECOMMENDED Alternative 1
MOTION:
PRIO
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4646 Dakota Street SE
Prior Lake, MN 55372
RESOLUTION 12 -xxx
A RESOLUTION APPROVING MAJOR AMENDMENT 1 TO THE LOCAL SURFACE WATER
MANAGEMENT PLAN
Motion By:
Second By:
WHEREAS, On December 28, 2010 The Scott Watershed Management Organization (SWMO)
submitted a valid request an amendment to the Local Surface Water Management Plan
( LSWMP), and;
WHEREAS, On October 3, 2011 City Council accepted the request for amendment and ordered staff
to prepare Major Amendment 1 to the LSWMP and submit it for review from the Lakes
Advisory Committee (LAC) and State Agencies, and;
WHEREAS, After a October 18, 2011 review by the LAC of a draft of Major Amendment 1 to the
LSWMP, Staff sent the draft amendment to local stakeholders and State Agencies for
review, and;
WHEREAS, Comments were received from the SWMO and Prior Lake Spring Lake Watershed District
(PLSLWD) and staff finalized Major Amendment 1 consistent with local stakeholder
comments.
NOW THEREFORE, BE IT HEREBY RESOLVED BY THE CITY COUNCIL OF PRIOR LAKE,
MINNESOTA as follows:
1. The recitals set forth above are incorporated herein.
2. Major Amendment 1 to the Local Surface Water Management Plan is hereby approved.
PASSED AND ADOPTED THIS 3rd DAY OF JANUARY 2012.
YES
NO
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Frank Boyles, City Manager
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952 -49 - %aX 9 52- 496 - 8496
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November t6,2011
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Ross Bintner
City of Prior Lake
4646 Dakota Street SE
Prior Lake, MN 55372
Re: 2011 Amendments to the Local Surface Water Resource Management Plan, City of Prior
Lake, MN
Dear Mr. Bintner:
Thank you for draft amendments to your local water plan dated October 21, 2011 received via
email on October 21, 2011. We appreciate your time and work you put into the amendments,
and have the following comments.
1. One of the items in the WMO memo dated December 28, 2010 asks for a review and
assessment of Coordination Strategies identified in Section 5, Table 5.2 of the WMO
Plan, and a description of the LGU's coordination role with respect to each strategy
where the LGUs are identified as a coordination partner. Your plan does address some of
the coordination strategies listed in this table but a few are not described in your plan.
Please insert a table with the strategies that apply to your city and include the city roles
for those items.
2. I don't see a statement that shows a review of your transportation plan, and the County's
TIP as a means of identifying water quality and flooding retrofit opportunities.
Something to the effect of "As future transportation infrastructure is proposed and
designed, opportunities for water quality and flooding retrofits will be assessed" would
be acceptable to the WMO.
3. Please include a statement in your plan on the schedule for completing amendments to
official controls; i.e. the city will update its official controls within 120 days following
any LSWMP amendments.
4. Page 3 -11. Policy 8.5 could insert a reference here on the Street Sweeping Policy is
included with this plan as Appendix
5. Is the reason why you did not include Chapter 4 because there were no changes?
Page 1 of 2
City of Prior Lake LWP Amendment
November 2011
6. Page 5 -37, third paragraph, include in your implementation section working in
coordination with the WMO on the proposed basin LSW -P9.
7. Page 5 -37, sixth paragraph, include in your implementation plan that the city will
participate in a coordinated planning of LSW 1, 4, 5, 6 and 7 with the WMO and City of
Shakopee.
8. Page 6 -15, 6.5.8, last sentence. Include a reference to the Street Maintenance Policy as
an appendix to the LSWMP. "Appendix ."
9. Page 6 -21, Downtown Redevelopment section: this section should be updated to match
the corrections that were made on page xvii
Thank you for the opportunity to review and comment on the City of Prior Lake amendments.
This review of the proposed amendments does not provide approval or denial, with respect to the
modeling/analysis of the city's fee structure, wetland plan, and piping network.
If the city can make and resubmit these changes by November 23, 2011 to the WMO, we will be
able to consider the amendment by the Watershed Planning Commission at their November 28,
2011 meeting with action by the County Board in early December. If not, we request that the
City Council take action extending the WMO's window for taking action (approval or denial of
the amendments) until January 21, 2012, after the city resubmits.
If you have any questions about the above comments, please contact me at (952) 496 -8887 or
mbokman@co.scott.nui.us We look forward to continue to work with the City as you finalize
your ordinance and start implementation.
Please forward us a copy of the revised ordinance when it has been approved by your City
Council.
Respectfully,
N A , L�It * 6 -'
Melissa A. Bokman
Cc: Paul Nelson, Scott WMO Administrator
Page 2 of 2
City of Prior Lake LWP Amendment
November 2011
November 22, 2011
Mr. Ross Bintner,
I have reviewed the proposed changes to the City of Prior Lake Local Water Management
Plan. It is the understanding of the District that these proposed changes are intended to
address requirements of the Scott Water Management Organization, and that a
subsequent update will address the requirements triggered by the adoption of the 2010
District Comprehensive Water Management Organization.
In general the proposed alterations are acceptable to the District. The following areas
provided some cause for concern:
1. Executive Summary, Page X: The District has not delegated to the City authority for
projects within the Prior Lake Outlet channel, or for municipal or county projects.
2. Executive Summary, Page XVII: While the proposed alternative treatment approach
would not meet current rule requirements, the District is open to discussing a variety of
methods to treat stormwater runoff that would be beneficial to both the quality of
water in the lake and development within the downtown area.
3. Chapter 5, Page 7: The City may wish to consider updating the District Annual Report
references.
Thank you for submitting this update for comment. I look forward to reviewing the
forthcoming update for the District.
Nat Kale
District Technician
14070 Commerce Ave NE, Suite 300, Prior Lake, MN 55372 • (952) 447 -4166 (phone) • (952) 447 -4167
(fax) www.plslwd.org • info @plslwd.org
U trt
Date: November 22, 2011
To: Melissa Bokman (SWMO), Nat Kale (PLSLWD)
From: Ross Bintner, P.E. — Water Resources Engineer
Subject: City of Prior Lake Local Surface Water Management Plan — 2011 Major
Amendment, Response to Comments
Cc: Katy Gehler, P.E. — Public Works and Natural Resources Director
Frank Boyles — City Manager
The Scott Watershed Management Organization (SWMO) has provided comments in a letter
dated November 16, 2011 and the Prior Lake Spring Lake Watershed District (PLSLWD) has
provided comments in a letter dated November 22, 2011.
The following changes were made consistent with each comment letter. Attached you will find
the final amendment that will be forwarded for City Council consideration on December 19,
2011.
Response to SWMO Comments:
1. The following coordinating strategies will be added, or already appear in the text of the
plan:
a. 51.1.5 Assist with wetland banking opportunities
b. 53.2.3 Support wellhead protection
c. 54.3.4 MS4 Maintenance requirements
d. S4.4.1 Promote and facilitate regional stormwater management approaches
e. S4.5.2 Markley Lake outlet
f. S4.7.1 Technical advisory committee input on flood prone areas
g. 56.1.2 Technical advisory committee
h. 56.1.3 Share data and information
2. The following statement will be added to the plan: "As future transportation
infrastructure is proposed and designed, opportunities for water quality and flood control
retrofits will be assessed."
3. The following statement will be added to the plan: "When new LSWMP amendments are
considered, associated official controls should be considered and updated concurrently, or
within 120 days following the approval of the LSWMP amendments."
4. Table 6.0 adds the street maintenance policy, which includes streets sweeping.
5. This is indicated in the cover letter to the amendment. Chapters without changes were
not sent.
6. Changed as indicated.
7. Changed as indicated.
8. Changed as indicated.
9. Changed as indicated.
Memo
Phone 952.447.9800 / Fax 952.447.4245 / www.cityofpriorlake.com
Response to PLSLWD Comments:
1. The following statement will be added to the plan: "The City exercises permitting
authority as described in a Memorandum of Agreement with the PLSWD and
Memorandum of Understanding with the SWMO for local water planning and regulation.
2. No proposed change requested.
3. Will changed as indicated; please provide the tables and text in .doc format from the 2010
report.
OF PRIp*
4 11 i
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EXECUTIVE SUMMARY
This report provides the City of Prior Lake with a Local Surface Water Management Plan
( LSWMP) that will serve as a policy basis for the management of the surface water
system throughout the City. The LSWMP is intended to complement the City's
Comprehensive Plan 2030 and official controls governing stormwater. The LSWMP will
carry the City through the end of 2015. Periodic amendment to the Plan will occur in the
intervening 10 years so that the Plan remains current to watershed plan amendments and
revisions and current to the "state of the art" in surface water management. Amendment I
to the plan occurred at the request of the Scott WMO in late 2011.
The Prior Lake LSWMP will serve as a comprehensive planning document to guide the
City in conserving, protecting, and managing its surface water resources. The LSWMP
meets requirements as established in Minnesota Rules 8410. In addition, the participation
of other organizations, particularly Scott County WMO and Prior Lake Spring Lake
Watershed District, ensures the City's compliance with local and regional expectations.
The City will submit its LSWMP to Metropolitan Council, Scott County WMO, and
PLSLWD for review. These entities have 60 days for their review after written receipt of
the City Plan.
Three other activities complement the LSWMP. The Wetland Management Plan (WMP)
provides an assessment and management plan for numerous wetlands within the 2030
growth area. The WMP is based upon standard assessment methodology and is utilized,
in conjunction with the LSWMP hydrologic modeling, to determine future use of wetland
basins for storage, retention, and infiltration. The WMP constitutes section 4 of this
report. The second activity is the Natural Resources Inventory
Like its wetland counterpart, this Plan provides an assessment and management plan for
resources — this time upland resources. The City will utilize this information in open
City of Prior Lake v ii
Local Surface Water Management Plan
space and park planning. The third activity is the Public Works Design Manual
(PWDM). The PWDM summarizes the policy and recommendations set forth in the
LSWMP and provides design standards and a method of enforcing water resource
management concepts detailed in the LSWMP.
This report is a culmination of the activities described above and is organized as follows:
• Section 2, Land and Water Resources Inventory, describes the physical
environment including watersheds and drainage patterns, dominant land uses, and
significant water bodies within the City.
• Section 3 - Goals, Policies and Guidelines - lists the City's goals and policies along
with public agency requirements affecting surface water management in the City.
• Section 4, Wetland Management Plan, presents the results of an assessment of the
City's larger wetlands within the 2020 growth areas. The Wetland Plan identifies
specific strategies for mitigating wetland impacts often associated with
development.
• Section 5, System Assessment and Design, presents an overview of all the major
watersheds in the City. This section describes in detail the affect rural drainage
has on municipal systems both now and in the future. Section 5 also provides
detail on a model of the storm water management system within the four focus
areas. The focus areas are soon to develop portions of the larger study area where
conceptual ponds and trunk pipes are sized and shown, where trunk alignments are
shown, and where volumes, discharge rates, and capital costs are analyzed.
• Section 6, Implementation Plan, covers regulatory responsibilities, priority
implementation items, educational programs, operation and maintenance, the
capital improvement program, and financing considerations. A plan amendment
process is also identified and the distinction between major and minor amendment
outlined.
• Section 7, Summary and Recommendations, contains a summary the SWMP and
makes recommendations for implementing the Plan.
It should be noted that the land use plan identifies future land use for areas within the
2030 growth boundary. Service areas for the sewer and water system can be effectively
defined by this boundary. In contrast, the surface water system is defined by topography
and the drainage that currently moves through the newly developing areas must continue
to be accommodated in the post development condition. For this reason, the modeling
and management strategies incorporated in the LSWMP must deal substantively with the
large rural and agricultural areas that will continue to drain through the City even after
build out of the 2030 Plan. For instance, drainage to Prior Lake extends as far south as
the PLSLWD boundary. This drainage extends almost to Cynthia Lake, three miles south
of the growth boundary and incorporates the discharge from Fish Lake, which is over 2.5
miles south of the growth boundary. So, while the 2030 Land Use Plan forms the basis
of the urban system outlined in this report, this urban system is also determined by these
large rural drainage areas discharging to Prior Lake.
City of Prior Lake Viii
Local Surface Water Management Plan
The intent of the ponding system described in this report is to reduce the post
development peak to a rate more in line with natural conditions. This protects the city's
lakes, wetlands, and channels from erosion and flooding. Volume control, though not
specifically required by the LSWMP, is aimed at reducing the post development runoff
depth and is included as a requirement in the PWDM. By reducing the post development
runoff depth through volume reduction and infiltration — to something more akin to the
depths seen off the natural landscape — lake, wetland and channel protection is
augmented. Infiltration will also help achieve the PLSLWD's retention goals which are
outlined later in this report.
A change in land use from agricultural and natural to urban is the primary factor driving
the need for the Prior Lake Surface Water Management Plan. The goal of the plan is to
mitigate the impacts caused by urbanization.
Most of Prior Lake falls within the jurisdiction of the Prior Lake Spring Lake Watershed
District since, quite obviously, most the City's drainage — both current and within the
2030 growth area — ends up in either Prior Lake or in the Prior Lake outlet channel. A
portion of the City and City 2030 growth area falls within the Scott County WMO. This
area lies northwest of Spring Lake and generally drains toward Louisville Swamp, which
lies approximately 2 miles west of the 2030 growth area boundary.
The Prior Lake Spring Lake Watershed District encompasses approximately 42 square
miles of land in the jurisdictions of five local units of government: Prior Lake, Savage,
Shakopee, Sand Creek Township, and Spring Lake Township. Most of the district's land
area falls within Prior Lake's current limits and 2030 growth area. The primary water
resources within the district, which are discussed in detail below, include Spring Lake,
Upper and Lower Prior Lakes, Rice Lake, and Crystal Lake. Jeffers Pond and Pike Lake
are notable water resources that form a portion of the Prior Lake outlet channel.
Historically, three other watershed management organizations operated near the City of
Prior Lake. These were the Sand Creek, Credit River, and Shakopee Basin WMOs. All
three WMOs were determined to be "non- implementing" and subsequently they were
disbanded by the state Board of Soil and Water Resources. Scott County then assumed
the powers of these organizations through creation of the Scott County WMO. The Scott
WMO includes all of Scott County not currently managed by the PLSLWD, the Lower
Minnesota River Watershed District, the orthe Vermillion 3 ALN40 ef the Blaek Deg WMO.
The primary Scott WMO hydrologic features within Prior Lake's existing or 2030
boundary include Campbell, Markley, Mystic and Howard Lakes.
This Goals and Policies section of the `'•�LSWMP outlines goals and policies
specific to surface water management in Prior Lake and its environs. The goals and
policies are broad statements regarding the motivation and intent of the S LSWMP .
The policies that follow the individual goals are specific requirements that promote
attainment of the goal.
City ofPrior Lake ix
Local Surface Water Management Plan
The City of Prior Lake has maintained its natural drainage patterns throughout most of its
development. The City's goal is to foster continued optimum use of that natural drainage
system while enhancing the overall water quality entering the lakes. The intent is to
prevent flooding while using identified best management practices to enhance surface
water quality with minimal capital expenditures by the City.
Upen the inital approval of this LSWMP by the two watersheds with jurisdiction
over the City, iH-s -the City's intent to ,,..s•.me ~ "assumed permitting powers within Rits
jurisdiction.
this erganization wettld eeetrr. The L W t d D t-; d
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with a Memorandum of land area_ This th eld r i s es te ~«° a. fe4Agreement with the
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TlF_ LSLWD would Eentin ie Memorandum of Understanding with the SWMO. Formatted Font: Times New Roman
The PLSLWD continues in its role as a project review agency though it may def f t t, ,
Gity review pfeeess feF pfejeets that den't have a direet inipaet en Pfier bake of the Pfief
Lake eutlet ehannel. it's collaboration in the development Review Committee
Df RC . The Prior Lake- Spring Lake Watershed District will also continue to have
responsibility for water quality monitoring.
The Prior Lake LSWMP envisions the City and its two watersheds as partners in
implementing this plan. In the PLSLWD lands, the City envisions the watershed taking
the lead on water quality and lake water quality issues. The City and watershed would be
equally responsible for implementation of the volume management targets discussed in
Section 5 of this Plan with the City taking the lead in the 2030 expansion areas and the
watershed taking the lead in areas outside the 2030 boundary.
The goal of this wetland inventory is the management of wetlands based on the functions
they perform and to determine appropriate protection strategies for stormwater discharge
to the wetlands if a land use change occurs that triggers a NPDES permit. Since smaller
wetlands are not typically used as major components in a stormwater storage system, we
focused our inventory on wetlands shown on the National Wetland Inventory (NWI) Map
that were over 0.5 acres in size.
The inventory and assessment of wetlands through the Wetland Management Plan
(section 4) allows the city to set up priorities based upon wetland functions and values.
This plan includes a wetland inventory and ranking system that will assist the city in
City of Prior Lake x
Local Surface Water Management Plan
establishing priorities and focusing available resources for wetland protection,
enhancement and restoration. Because all wetlands have value, all are protected, to some
degree, in this plan.
The plan is designed to provide the following benefits:
• Provide wetland inventory, assessment, and management information:
• Aid in administration of the Wetland Conservation Act (WCA) by providing
information regarding the wetlands functions:
• Enhance wildlife values of wetlands:
• Provide and enhance recreational values:
• Designate wetland restoration/enhancement opportunities:
• Protect wetlands and adjacent resources that provide valuable ecological support:
• Provide stormwater protection for wetlands.
It should be noted that the wetland inventory has been created for planning purposes
only. Regulation of activities potentially impacting individual wetlands will be based on
a site - specific delineation of the wetland boundary as part of a proposed project.
All of the inventoried wetlands within the study area were classified for Stormwater and
Habitat Protection. Stormwater Protection standards are listed in Table 4.2 and 4.3 and
Habitat Protection Recommendations are listed in Table 4.4. The Stormwater Protection
Standards include Water Quality and Quantity Protection. The Habitat Protection
Recommendations include Buffer Zones and No Grading Recommendations.
Water quality plays a significant role in the overall quality of a wetland. When the
quality of the incoming water declines, the wetland's plant community may change to
fewer numbers of species and retain only those species that are tolerant of high nutrient
and sediment loads. Once a wetland's plant community is changed, the wetland's
character and ecosystem will change, often to a less valuable system in terms of
biodiversity, habitat for wildlife, and aesthetic enjoyment. Pretreatment requirements
have been developed to maintain the character of the wetland. BMPs can be used to
accomplish the pretreatment requirements given in Table 4.2.
In the recent past, surface water management plans have protected wetlands from
nutrients but not water fluctuations or duration. In fact, it was common to use wetlands
to reduce flooding potential through sizing storm sewer pipes to maximize bounce and
detention time in wetlands.
This plan addresses stormwater quantity impacts to wetlands by providing protection
strategies to maintain the existing integrity of the wetland through special protection
strategies for highly, moderately, and slightly susceptible rankings and are described in
Table 4.3.
Wetland restoration/enhancement sites were identified during the field inventory and will
be further investigated at the time of development under the requirements spelled out in
the PWDM and ordinance. The wetland restoration portion of the filled out MnRAM
City of Prior Lake xi
Local Surface Water Management Plan
will be reviewed at the time of development to determine the potential for restoration of
wetlands on the property. The potential for wetland restoration will be determined based
on the ease with which the wetland could be restored, the number of landowners within
the historic wetland basin, the size of the potential restoration area, the potential for
establishing buffer areas or water quality ponding, and the extent and type of hydrologic
alteration.
Section 5 of the Plan serves two functions. The system assessment portion catalogues the
various assessments of problems that the Plan must address whether they relate to water
quality, wetland protection, flooding, volume management, or lakes management. The
intent is to identify the source of problems and, more importantly, specific actions the
City will take to address these problems either independently or in collaboration with
some other organization — most commonly one of the watershed management
organizations. The purpose of the system design portion of this section is to identify and
quantify the infrastructure needed to allow continued development in Prior Lake while
avoiding the negative impacts, such as flooding and water resource degradation, often
associated with development.
The system design portion of this section describes the 2030 growth area surface water
management system and is intended to be used as a planning and analysis tool. This
system is shown in maps 1 through 5. The discussion of the system revolves around
answering the following questions:
• What are the general drainage patterns of the 2030 and existing system?
• What does the 2030 system entail in terms of storage, conveyance, volumes, and
discharge rates?
• Where does the proposed system discharge and what constraints in the existing
system limit discharge of the 2030 system?
• What is the impact of agricultural drainage, outside the 2030 growth area, on the
proposed and existing urban system?
• How have proposed wetland bounce, and duration of HWL, been determined by
management guidelines of the Wetland Management Plan, section 4 of the
LSWMP?
• What opportunities exist for obtaining the retention storage identified by the
PLSLWD both in the 2030 growth area and outside it?
• What is the impact of the City of Prior Lake's 2030 urban system on agricultural
areas and other municipalities?
• Are there any existing ponds where calculated HWL is a concern?
A number of water bodies within the existing City and its 2030 growth boundary are
listed in the state impaired waters list. Known as the 303(d) list from the applicable
section of the federal Clean Water Act, these waters are ones that do not currently meet
their designated use due to the impact of a particular pollutant or stressor. If monitoring
and assessment indicate that a water body is impaired by one or more pollutants, it is
placed on the list. At some point a strategy would be developed that would lead to
attainment of the applicable water quality standard. The process of developing this
strategy is commonly known as the Total Maximum Daily Load (TMDL) process.
City of Prior Lake x 11
Local Surface Water Management Plan
When discussing nutrient impacts to lakes the nutrient most commonly identified is
phosphorus. Through its own monitoring efforts and those of the Citizen Assisted
Monitoring Program (CAMP) run by Metropolitan Council, the PLSLWD has been
collecting data on nutrient loading into the impaired waters, and others, identified above.
According to the PLSLWD 2003 Annual Report:
All of the lakes in the District are either eutrophic or hypereutrophic except for Cates Lake and
Lower Prior Lake, which are on the upper boundary of mesotrophy. Review of Table 4.5 and
comparison with the TSI descriptions in Table 4.3 shows that both Cates Lake and Lower Prior
Lake are very close to the boundary for a eutrophic lake, and this boundary is where problems
really start to become evident. The western end of Lower Prior Lake is mesotrophic /eutrophic
largely because of water flowing through this end from Upper Prior Lake to the outlet. The rest of
Lower Prior Lake has a limited watershed and is isolated from a majority of the inflowing water
from Upper Prior Lake.
The continued assessment of these lakes has led the PLSLWD to emphasize reduction in
phosphorus loading to the lakes. This will also be the focus of a watershed -based TMDL,
when developed, for the impaired waters listed in table 5.1. Since the mercury TMDL
will be regional in nature, the City of Prior Lake and PLSLWD will focus their efforts on
reducing nutrient loading. According to the PLSLWD:
For noticeable improvements to occur in lake water quality, TSI values need to be reduced to 55 or
less. On the reverse, if these lakes are allowed to decline further, algae blooms will become worse
and fish kills are probable.
In addition to collecting and reporting on the above data, the PLSLWD has created a
model to quantify the internal and external phosphorus load for Spring and Upper Prior
Lakes. This modeling effort is summarized in the 2003 Annual Report:
In summary, sediment phosphorus release and recycling accounts for approximately 43 to 78% of
the total phosphorus load for Spring Lake and 49% of the total phosphorus load for Upper Prior
Lake. As a result, significant water quality improvements in each lake will require
implementation of lake improvement options that would greatly minimize the potential for
sediment phosphorus release. In addition, significant reductions in phosphorus from County Ditch
13 and Spring Lake should result in significant water quality improvements in Spring Lake and
Upper Prior Lake, respectively. To a lesser degree, senescing macrophytes and bottom - feeding
fish also affect the water quality of Spring and Upper Prior Lakes, since each of them contribute
approximately 5 to 15% of the total phosphorus load to each lake.
The Water Resources Management Plan for the PLSLWD, completed in 1999, identified
several planning efforts, that would occur subsequent to the Plan, to address issues with
the Prior Lake water levels and outlet operation. These included:
• Calibrating an hydrologic model for the watershed
• Designing improvements to the outlet channel for full- development conditions
• Addressing flood prone structures on Prior Lake
• Addressing increases in runoff volume as development occurs
The PLSLWD report Prior Lake Outlet Channel and Lake Volume Management Study
(May, 2003) addresses these issues in detail. The 100 -year floodplain elevation for Prior
City of Prior Lake xiii
Local Surface Water Management Plan
Lake established by FEMA is 908.9 MSL. There are 79 homes around the lake with low
openings lower than this floodplain elevation. Fifty -one of these have low openings
below 907.6 and ten have low openings below or within one foot of the lakes 904.0
OHW. According to PLSLWD information, this 904.0 elevation has been exceeded a
total of 259 days since 1983.
Since development tends to improve drainage pathways and increase runoff volume, the
impact of future development on Prior Lake could, without mitigation, increase the
frequency of water levels above the 904.0 OHW.
To assess the impact development might have on water levels in Prior Lake, the
PLSLWD created a calibrated model of the watershed. The calibration of this model
started with standard curve numbers for the subwatersheds tributary to the lake and,
through the calibration process, modified these until modeled results matched monitored
lake levels for the 1998 to 2001 period. The hydrologic modeling for the LSWMP is
based upon this calibrated watershed model. The difference between the two, is that the
LSWMP model looks at the conditions that will exist when build out occurs in the 2030
growth area. Additionally, the LSWMP model includes more detail on the storage and
conveyance system necessary to serve the 2030 growth area.
Subsection 5.4 provides specific issues in the surface water management system for Prior
Lake's 2030 growth area. The study area has been broken into 21 major drainage
districts, which are further divided into subdistricts. The nomenclature for the major
drainage districts is based on the Prior Lake Spring Lake Watershed District ( PLSLWD)
modeling and major tributary water bodies. Total acreage for major drainage districts
should roughly match the existing work completed by the Watershed District. Section
5.4 describes each drainage district in detail.
Section 6, Implementation Plan, of the Prior Lake SWMP describes those activities and
programs the City might develop toward improving its surface water management
program. Capital outlay for the surface water system (pipes, channels, and ponds) shown
on the system maps will be large. For this reason a financing mechanism, called an area
charge, is developed in this section. Based on the Capital Improvement Plan and the
developable acreage, an area charge is developed and application of this charge is
discussed.
The concept of an area charge to finance expansion of the trunk stormwater management
system is not a new concept for the City. Since its report titled Trunk Storm Sewer Fee
Determination Study (February, 2001) the City has quantified future trunk and ponding
needs and developed an area charge based on actual costs of these needs spread across
the potential developable acreage. With the analysis contained within the SWMP the
City will update the fees for the 2030 growth area.
Section 6 also includes:
• An overview of the City's NPDES permit
• A discussion of operation and maintenance procedures and strategies
• An outline of an education program
City of Prior Lake siv
Local Surface Water Management Plan
• Financial considerations for the storm water utility
• A section referencing applicable design standards for stormwater management
• A section on Watershed implementation priorities
• Implementation priorities for the City
• A discussion of the process for amending this plan and an annual report to council
Appendix D summarizes the modeled system costs by element, by major watershed, and
for the system as a whole.
The potential system, as shown in system maps, carries an estimated cost of $14,858,788.
and serves as a basis for development fees in the City. This cost includes indirect costs of
30% on trunk and pond construction and indirect costs of 10% on easement acquisition.
Table 6.1 presents a financial model for the City of Prior Lake. The cost elements come
directly from the 2030 stormwater system design as described in the system maps and the
appendices to this report. The various trunk elements are organized by prospective year
of implementation as well as whether they constitute a pond cost or trunk pipe cost.
Total costs for the 2030 system are $10,836,957. It is important to note that the system
analysis was complete to estimate costs, and does not represent final design.
Sections 6.2 and 6.3 develop an area charge for the City of Prior Lake that can be applied
to future development within the City. The area charge has been constructed
methodically as follows:
1. Pond and trunk costs for near term development have been estimated. A
stormwater CIP has been created as shown in appendix D and table 6.1.
2. Net assessable acreage has been determined.
3. The base area charge has been modified into a land use based area charge through
the use of equivalent acres.
A storm water system is a major investment for the City of Prior Lake — both in terms of
initial capital cost and in terms of ongoing maintenance costs. The capital improvement
program outlines the costs for new trunk system construction which will be funded by
area charges. System maintenance is funded by the city's storm water utility.
The city's storm water system maintenance responsibilities include the following:
• Street sweeping
• Cleaning of sump manholes and catch basins
• Repair of catch basins and manholes
• Assessing pipe condition (typically by televising)
• Inspection of storm sewer inlet and outlet structures
• Pond mowing and other vegetation maintenance
• Excavation of accumulated sediments from ponds
• Maintenance or other structural BMPs owned by the City
The city has maintained its pipe system for decades and staff has a strong grasp on the
costs associated with this. As new development brings more ponds into the system, city
staff will find that pond maintenance becomes an increasingly large portion of both staff
time and maintenance budget. It is important to quantify the extent of this future
City of Prior Lake X ,
Local Surface Water Management Plan
commitment so that the funds necessary for pond maintenance activities can be collected
via the city's storm water utility.
The City of Prior Lake implemented a stormwater utility in 1993. The current quarterly
residential charge is $6.00 per residential unit. Annual revenue from the stormwater
utility has grown as shown in table 6.5.
Generally, revenue has grown not because of increases in the charge (the charge has gone
from $5.63 in 1997 -t% $6.00 in 2005, to S7.25 in 2009 an annual increase of 676%)less
than 2% over the 14 years) but due to development bringing in more properties over
which to collect the charge. With this increased revenue, though, has come an increase in
the City's maintenance responsibilities.
In the past the stormwater utility has funded a staff position, programs, and capital
expenditures. The 20021n 2011 capital projects totaled $440610,000 and included a
d: cdgi p r jeet, a lake b ank ..iabilizatien p ,water quality maintenance and sere
stern drain ° °° . . 4s retrofit of 10 pond sites and retrofit water qualityvstems
as part of street reconstruction projects.
In order that storm water utility (SWU) funding keeps pace with increase in municipal
maintenance responsibilities, the city should plan for the costs to conduct periodic pond
maintenance. Limited data on maintenance activities has been developed by watershed
management organizations. A 2006 review of this data stiggestssuggestd an annual
maintenance budget of $1,250 per acre -foot of wet volume or $4,350 per acre of surface
at NWL. Either parameter is relatively easy to track. This $1,250 per acre -foot
maintenance item can be translated into a per household cost by virtue of the fact that one
acre -foot is sufficient pond wet volume for 20 acres of residential development.
Assuming 2.5 units per gross acre, then $1,250 per year is spread among 50 units - $25
per unit per year.
The etiff eHt2006 residential rate iswas $24 per unit per year. The etiff e1i TAt that time
charges provide approximately $300,000 per year in revenue of which only about
$20,000 to $40,000 hashad been used for pond maintenance. As the city's maintenance
responsibilities grow the storm water utility funding also needs to grow to keep pace.
Prior Lake is a regulated MS4 under the Phase II NPDES Permit. There is a cost
associated with preparing an NPDES permit and the associated Storm Water Pollution
Prevention Plan (SWPPP). Some estimate cities the size of Prior Lake will spend
$50,000 every five years for permit preparation. For Prior Lake it is reasonable to
assume that $10 per household will be spent every five years — adding $2 per year to the
individual household's storm water utility bill.
ROOM
City of Prior Lake xvi
Local Surface Water Management Plan
in SIA eelleetien the $10 per- year- figure shetild be tised. This estimate will be revised
again after the 2012 reissuance of the MS4 permit. but the liability is expected to
increase. Table 6.5 summarizes the additional storm water utility charges identified
above.
The City of Prior Lake's implementation priorities include building the stormwater
management system described in this report. Other implementations priorities relate to
downtown redevelopment, retention storage, and adequate funding.
Originally, City Prior Lake and Prior Lake Spring Lake Watershed District staff
discussed the possibility of creating an overall stormwater management plan for the
downtown area that, once approved by the Watershed, would allow the City sole permit
authority for construction and reconstruction projects in the downtown area. In 2003, as
the City moved forward designing the rainwater gardens for Erie Street and City Hall and
the street reconstruction project for downtown it became apparent that how downtown
redevelops, and what sort of water quality and quantity retrofits can be implemented,
depends on factors that cannot be adequately quantified at this time. Consequently, at
that time the City opted not to submit such a plan but rather would have the Watershed
permit the specific projects.
In 2007 the City will undertake a downtown stormwater management study in
cooperation with the district. Results of the study indicate that dense
development is more expensive to treat A portion of the requirement may be more
efficiently met outside the downtown pei:mi4ifig autheFify The City will be spelled
etit iFi pursue a N40A with the Distfiet. The festilts ef the 1007 stud) will begin te be
imp lemented ift 20" or °' eff 4h d owntown . water
management overlay that exempts downtown development from a portion of the
standard. make a clean -water bank of projects that will mitigate for the deficiency. In the
interim, the City will continue to look for opportunities to retrofit small site BMPs, water
quality improvements, and rate control improvements as warranted by downtown
redevelopment activities.
Other implementation priorities for the City as it adopts this Plan and begins the
implementation phase of the Plan include:
1. Assisting the PLSLWD in implementing its retention storage program. Specific
areas with high potential for City implementation are indicated on the system
maps and within the body of this Plan.
2. Increasing Storm Water Utility Funding so that the City can meet its current and
future obligations toward pond maintenance, NPDES compliance, and mitigation
that may come out of the City's non - degradation analysis.
3. Application of the revised area charge outlined in this report and update of the
area charge based on increases in land value and construction costs.
4. Implementation of the rate control targets as outlined in the appendices and
stormwater modeling that supports this plan.
5. Application of the wetland susceptibility criteria in determining how wetlands are
used for flood storage, retention, and rate control.
City ofPrtor Lake x ,ii
Local Surface Water Management Plan
6. Working with the PLSLWD regarding the feasibility of augmenting storage in
Buck Lake.
7. Working with the City of Shakopee toward redefining rate control objectives from
their Sand Creek drainage which will ultimately enter the City of Prior Lake
system through its Louisville Swamp system.
The Prior Lake SWMP is intended to extend through the year 2015. For the plan to
remain dynamic, an avenue must be available to implement new information, ideas,
methods, standards, management practices and any other changes that may affect the
intent and/or results of the SWMP.
A brief annual report will be made by City staff summarizing development changes,
capital improvements, and other water management- related issues that have occurred
over the past year. The review will also include an update on available funding sources
for water resource issues. Grant programs are especially important to review since they
may change annually. These changes do not necessarily require individual amendments.
The report can, however, be considered when the plan is brought up to date. The annual
report should be completed by July I' to allow implementation items to be considered in
the normal budget process.
The following recommendations arewere presented for the City Council's consideration
based upon the data compiled in this report:
1. The Surface Water Management Plan as presented herein be adopted by the City
of Prior Lake.
2. Standard review procedures be established to ensure all new development or
redevelopment within the City is in compliance with the grading and stormwater
management controls determined by this Plan.
3. Detailed hydrologic analyses be required or all development and redevelopment
activities.
4. Final high water levels governing building elevations adjacent to ponding areas
and floodplains be established as development occurs or when drainage facilities
are constructed.
5. Overflow routes be established and maintained to provide relief during extreme
storm conditions, which exceed design conditions.
6. A surface water system maintenance program be established to ensure the
successful operation of the system.
7. The erosion and sedimentation control criteria for new developments be enforced.
8. An education program for City residents, staff, and development community be
implemented.
9. Amendments to the plan be adopted and implemented as warranted by future
standards or regulations.
10. That the plan be updated in 2010 or earlier if needed.
11. Promote the use of small- site /distributed BMPs to help achieve water quality and
volume control goals.
City of Prior Lake x„iii
Local Surface Water Management Plan
12. Pursue partnerships with watershed management organizations and other agencies
to incorporate volume control BMPs into re- development projects, including City
proj ects.
13. Ordinances be revised to be consistent with rules detailed in the PWDM regarding
water resource management.
City of Prior Lake xix
Local Surface Water Management Plan
OF PRIG
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04 PR/04
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1. INTRODUCTION
1.1 Background
This report provides the City of Prior Lake with a Local Surface Water Management Plan
( LSWMP) that will serve as a guide to managing the surface water system throughout the
City. The LSWMP is intended to complement the City's 2030 land use plan as
formalized in the Comprehensive Plan 2030. The LSWMP will carry the City through
the end of 2015. Periodic amendment to the Plan will occur in the intervening 10 years
so that the Plan remains current to watershed plan amendments and revisions and current
to the "state of the art" in surface water management.
The City of Prior Lake is located in north central Scott County at the nexus of major
transportation corridors including Trunk Highway 13, Scott County Road 21 and Scott
County Road 42. According to some estimates, Scott County is the 15 fastest growing
county in the nation, and Prior Lake has seen a good portion of this growth.
The Village of Prior Lake was incorporated in 1891. In the period from the 1870's to the
1920's little growth occurred in the City. During this period, much of the activity in the
Village related to Prior Lake and its role as one of the preeminent recreation destinations
of that era. The lake remains a recreational focus and forms one part of the City's three-
fold recreational system:
1. Lakes and natural areas
2. Parks, trails and active recreational facilities
3. Venues such as Mystic Lake Casino and the City's golf clubs
It has been since the 1960's, and the City's emergence as a suburban community, that the
City's growth has escalated with the greatest growth occurring in the last 20 years. Table
1.1 provides City populations and population projections from 1980 through 2020. As
City ofPrior Lake 1 -1
Local Surface Water Management Plan
the city continues to grow, the importance of adequate surface water management
controls also grows. The intent of the Prior Lake LSWMP is to detail what these controls
are and make the connection between these controls and the overall city goal of
preserving and enhancing its natural resources and protecting its residents from flooding.
Lakes define the City since the core of the community developed between Upper and
Lower Prior Lake. The City's uniqueness is tied to the lake. Consequently, effective
surface water management cuts to the core of the City's vision for the future.
1.2 Purpose and Scope
The Prior Lake LSWMP will serve as a comprehensive planning document to guide the
City in conserving, protecting, and managing its surface water resources. The LSWMP
meets requirements as established in Minnesota Rules 8410. In addition, the participation
of other organizations, particularly Scott County WMO and Prior Lake Spring Lake
Watershed District, ensures the City's compliance with local and regional expectations.
According to the 1999 PLSLWD Plan local plans must do the following:
• Describe existing and proposed environment and land use
• Provide a narrative addressing stormwater infrastructure philosophy, which details
regulatory authority, and implementation and financial responsibilities.
• Define areas and elevations of stormwater storage adequate to meet performance
standards established in the watershed plan
• Identify quality and quantity protection methods which meet standards
• Identify regulated areas and potential easements or land acquisition areas
• Outline a procedure for submitting annual reports to agencies which document
Wetland Conservation Act and monitoring program data consistent with state
compatibility guidelines
• Set forth an implementation program, including a description of official controls,
inspection and maintenance, and capital improvement plan
• Describe official controls and the responsible unit of government in the following
areas: wetlands, erosion control, shoreland, floodplain, grading, and drainage
- - - Formatted Table
City of Prior Lake 1 -2
Local Surface Water Management Plan
Table 1.1
Population and Households
Year
Population
Number of Households
1980
7,284
2,313
1990
11,482
3,901
1995
13,427
4,630
2000
16,034
6,167
2010
21,000
8,077
2020
28,445
10,971
Lakes define the City since the core of the community developed between Upper and
Lower Prior Lake. The City's uniqueness is tied to the lake. Consequently, effective
surface water management cuts to the core of the City's vision for the future.
1.2 Purpose and Scope
The Prior Lake LSWMP will serve as a comprehensive planning document to guide the
City in conserving, protecting, and managing its surface water resources. The LSWMP
meets requirements as established in Minnesota Rules 8410. In addition, the participation
of other organizations, particularly Scott County WMO and Prior Lake Spring Lake
Watershed District, ensures the City's compliance with local and regional expectations.
According to the 1999 PLSLWD Plan local plans must do the following:
• Describe existing and proposed environment and land use
• Provide a narrative addressing stormwater infrastructure philosophy, which details
regulatory authority, and implementation and financial responsibilities.
• Define areas and elevations of stormwater storage adequate to meet performance
standards established in the watershed plan
• Identify quality and quantity protection methods which meet standards
• Identify regulated areas and potential easements or land acquisition areas
• Outline a procedure for submitting annual reports to agencies which document
Wetland Conservation Act and monitoring program data consistent with state
compatibility guidelines
• Set forth an implementation program, including a description of official controls,
inspection and maintenance, and capital improvement plan
• Describe official controls and the responsible unit of government in the following
areas: wetlands, erosion control, shoreland, floodplain, grading, and drainage
- - - Formatted Table
City of Prior Lake 1 -2
Local Surface Water Management Plan
The City will submit its LSWMP to Metropolitan Council, Scott County WMO, and
PLSLWD for review. These entities have 60 days for their review after written receipt of
the City Plan.
In a four -part process, the Prior Lake LSWMP does the following:
• Collects and compiles the efforts of agencies and organizations including the City,
its departments and residents. This includes past reports and studies, management
plans, monitoring studies, as well as completed and proposed improvement
projects.
• Reviews the current state of the City's surface water resources in the context of
goals and policies, ordinances, operations and maintenance, flood mitigation, and
achievement of targeted water quality levels in its surface water bodies.
• Establishes reasonable, achievable and affordable goals, and supports them by a
strong regulatory and management culture. Develops an implementation plan that
includes projects and processes that derive from a thorough assessment of current
City problem areas and current City surface water regulations and controls.
• Provides a blueprint for construction of new surface water systems as the City
expands into its 2030 growth area. Using advanced surface water modeling
software, a system of pond, wetlands and pipes is developed and costs applied to
these future systems. The costs give the City a framework for understanding the
impact development will have on City finances and applying these costs equitably
to development.
In order to arrive at a LSWMP that adequately addresses surface water related issues, the
emphasis has been to work with others to identify important issues through review and
meetings. City staff has participated in collecting data, providing feedback, and
contributing knowledge of local systems to aid in developing a strategy that encompasses
water quality and quantity issues. The City of Prior Lake is the organizer of the final
document though contributions from the watersheds have been substantial.
Two other activities complement the LSWMP. The Wetland Management Plan (WMP)
provides an assessment and management plan for numerous wetlands within the 2030
growth area. The WMP is based upon standard assessment methodology and is utilized,
in conjunction with the LSWMP hydrologic modeling, to determine future use of wetland
basins for storage, retention, and infiltration. The WMP constitutes section 4 of this
report. The second activity is the Upland Management Plan. Like its wetland
counterpart, this Plan provides an assessment and management plan for resources — this
time upland resources. The City will utilize this information in open space and park
planning.
Based on the guidance provided by the Prior Lake city council and staff, this report
addresses the city's current surface water management needs and provides a framework
for successful implementation of a comprehensive storm water management program. A
specific outline of the steps involved in the preparation of the c.�LSWMP is
presented below:
City of Prior Lake 1_3
Local Surface Water Management Plan
1. System Inventory and Mapping — Analyze drainage patterns and develop a
trunk storm water system map for the 2030 drainage system.
2. Goals, Policies and Guidelines — Develop goals and policies that guide the
city's surface water management philosophy. Augment design guidelines for
development and redevelopment. This gives the City guidance for facilities
design and standards for reviewing development plans. Included in this
process is determining all regulatory agencies involved in the storm water
management of the City and working with City staff to develop feasible goals,
policies and guidelines.
3. System Analysis and Design — Analyze the storm water system and develop a
recommended system. A system model was created that extended beyond the
city's current boundary into future development areas. This step also includes
specific recommendations for system upgrades and improvements due to
erosion and flooding issues.
4. Cost Estimates and Capital Improvement Program — For the recommended
system, develop itemized cost estimates of facilities. These are planning -level
estimates, suitable for budgeting and decision making. Feasibility studies will
be needed for more detailed costs. In addition, a 5 -10 year CIP has been
developed to coordinate system construction with growth.
5. Storm water Ordinances — Recommend ordinances or revision to existing
ordinances.
6. Storm water System Management — Provide recommendations on operating
and maintaining the storm water system as well as best management practices
(BMPs) for water quality and erosion control. Information regarding
compliance with NPDES Phase II Storm water Permits is also included.
Prior Lake presents something of a contrast. In older parts of town, city staff must meet
the challenges of maintaining an older storm drainage system. In other areas, new
development is adding new infrastructure to the storm water system and thus increasing
the city's maintenance responsibilities. The S LSWMP is primarily aimed at this
new development and the goals, policies, guidelines, controls, and preliminary system
design reflect that emphasis.
1.3 Organization
This report is a culmination of the activities described above and is organized as follows:
Section 2, Land and Water Resources Inventory, describes the physical
environment including watersheds and drainage patterns, dominant land uses, and
significant water bodies within the City.
Section 3 - Goals, Policies and Guidelines - lists the City's goals and policies along
with public agency requirements affecting surface water management in the City.
Section 4, Wetland Management Plan, presents the results of an assessment of the
City's larger wetlands within the 2030 growth areas. The Wetland Plan identifies
City of Prior Lake 1-4
Local Surface Water Management Plan
specific strategies for mitigating wetland impacts often associated with
development.
• Section S, System Analysis and Design, presents an overview of all the major
watersheds in the City. This section describes in detail the affect rural drainage
has on municipal systems both now and in the future. Section 4 also provides
detail on the proposed storm water management system within the four focus
areas. The focus areas are soon to develop portions of the larger study area where
specific ponds and trunk pipes are sized and shown, where trunk alignments are
shown, and where specific volumes, discharge rates, and capital costs are
calculated.
• Section 6, Implementation Plan, covers regulatory responsibilities, priority
implementation items, educational programs, operation and maintenance, the
capital improvement program, and financing considerations. A plan amendment
process is also identified and the distinction between major and minor amendment
outlined.
• Section 7, Summary and Recommendations, contains a summary the SWMP and
makes recommendations for implementing the Plan.
City of Prior Lake 1 -5
Local Surface Water Management Plan
Figure 1 Location Map
City of Prior Lake 1 -6
Local Surface Water Management Plan
OF PRIpk
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3. GOALS AND POLICIES
3.1 Purpose
The primary goal of Prior Lake's Local Surface Water Management Plan ( LSWMP) is to
plan for the orderly management of stormwater as development occurs in the city. The
plan provides clear guidance on how Prior Lake intends to manage surface water in terms
of both quantity and quality.
Much has changed since the city prepared its first LSWMP in 1973. Since that time the
city has seen a marked increase in residential and commercial development. Not
accounting for population growth due to annexation, city population has increased by
4,552 pee from 11,482 in 1990 to 15,917 in 2000 (40%)- 22,796 in 2010.
Population growth combined with increased regulation of stormwater at both the state
and federal level necessitate that the city's stormwater management goals evolve.
The goals and policies detailed in the LSWMP focus on future development as much as
they do on the existing state of things. This dual emphasis on existing and future ensures
that future development augments rather than diminishes the natural and built
environments.
3.2 Background
3.2.1 290 2030 Vision and Strategic Plan
frl times since 2002, Prior Lake embarked on a strategic planning process intended to
identify the eemmunifies vision of itself in the year 2020 Th ,.,. fn ee
Style Definition: TOC I: Bulleted + Level: 1 +
Aligned at: 0" + Tab after: 0.25' + Indent at:
�2_ 25"
City of Prior Lake 3 -1
Local Surface Water Management Plan
walks ef life 2030. This gfeep identifiedvision identifies key issues facing the City:
• Quality Communes Growth
• Housing Qua]ity and L- a*d Diversity
• Community Capital Assets
• Economic Development
• Downtown Redevelopment
• Strong Financial Management ineladirg g "'land a nd
felatienship between FJ;�-�I*RIA and the lake.
b �,
b ,
• City/Caffifflunit Quality and Amenities, b
• Pfesefv&tien efNatural Resources, '
Safe and planning
• Healthy Community Leadefship and T.,.,,.1,.,.
• Transportation
• Communication
The Prior Lake LSWMP is a piece of a larger effort, conducted in partnership with the
City's two watershed organizations, toward addressing the 20282030 vision of natural
resources preservation.
The key issues facing the City constitute its vision st atemen ts statement The elements of
that vision become the City's implementation goals out into the future. The 242-02030
vision includes goals in a variety of areas. Of specific importance in the context of the
LSWMP are the following: Natural Resource Vision Elements (from the 2009 Vision
Update):
1; Adopt and implement a pla GOAL: Monitor and improve surface water
quality:
2) Ad an d „
mY .. !`,.....lo „.. a T M ....4 Dl f D L
I Adopt
and ethef in accordance with City water plans in partnership with stakeholders
i.e. lakes
e ......,.....e.......y . Wit.: ,..,..,.e .,.,., ... s..,. a...0 .' pleasing manner.
City of Prior Lake 3.2
Local Surface Water Management Plan
install minwalef gaf dens and ethef nee ponds, wetlands, streams, storm water
runoff and non -point runoff).
OBJECTIVES:
Work with Watershed. County and Township to establish a cooperative plan to
clean up Spring Lake, Upper and Lower Prior Lake within 10 years through State
and Federal funds.
Encourage construction of additional water quality facilities like rain gardens,
stormwater ponds and infiltration ponds; and encoura tree planting as part of
City improvement projects.
Promote water conservation and use runoff as a resource.
Preserve and restore narks and lakes from human and "natural" impacts.
Manage invasive species.
Assure erosion control /street cleaning in new development. redevelopment and
existing streets.
Assist in completion of the Prior Lake Channel Project and Prior Lake outlet
improvements.
OBJECTIVES:
Promote water conservation and use runoff as a resource.
Preserve and restore narks and lakes from human and "natural" impacts.
Jointly plan and implement water conservation techniques and educational efforts
with neighboring communities.
- Formatted: stylel3
Expand conservation and communication efforts emphasizing efficient use of
ground water and promote best management practices including providing
account consumption information to customers using the Internet.
Reduce the number of private wells and septic systems within the wellhead
protection area by extending municipal sewer and water.
3.2.2 Comprehensive Plan 2020
City of Prior Lake 3 -3
Local Surface Water Management Plan
The continued growth of Prior Lake has necessitated that its comprehensive plan be
updated. The primary purpose of this effort is determination of the land use plan
(included in the LSWMP as figure 2) which becomes the basis of the hydrologic
calculations summarized in the LSMWP. Prior Lake completed its first comprehensive
plan in 1973 and subsequent updates occurred in 1981 and 1996. These Comprehensive
Plans are mandated by the Metropolitan Land Planning Act. The goals of the Prior Lake
2020 Comprehensive Plan are:
• Housing Quality and Diversity
• Environmental and Natural Resource Protection
• Economic Vitality
• Security
• Access
• Information and Technology
• Human Development
Specific to the goals and policies of this Local Surface Water Management Plan are the
following 2020 Comprehensive Plan objectives under the Environmental and Natural
Resource Protection goal.
OBJECTIVE No. 1: Provide suitable passive open space for the
preservation of the natural environment and the enjoyment of residents.
POLICIES:
a. Retain natural ponding areas and wetlands, as appropriate.
b. Encourage platting of large planned unit developments.
OBJECTIVE No. 2: Provide for conservation and protection of the lakes
and surface water.
a. Adopt and implement a plan to improve surface water quality.
b. Adopt and implement a Comprehensive Lake Management Plan
for Prior Lake and other lakes within the City cooperatively with
the Watershed District.
c. Adopt a program which ensures an acceptable level of lake
access parking and responsible lake utilization.
d. Implement a groundwater plan emphasizing production,
conservation, education, communication, and landscape
maintenance.
e. Participate with the Prior Lake -Spring lake watershed District in
developing and implementing a land management program for
upstream storage.
The Prior Lake LSWMP expands upon the goals and objectives provided in the 2020
vision and the 2020 Comprehensive Plan.
City of Prior Lake 3_4
Local Surface Water Management Plan
3.3 City of Prior Lake LSWMP Goals and Policies
This section of the LSWMP outlines goals and policies specific to surface water
management in Prior Lake and its environs. The goals and policies identified below are
broad statements regarding the motivation and intent of the LSWMP. The policies that
follow individual goals are specific requirements that promote attainment of the goal.
The City of Prior Lake has maintained its natural drainage patterns throughout most of its
development. The City's goal is to foster continued optimum use of that natural drainage
system while enhancing the overall water quality entering the lakes. The intent is to
prevent flooding while using identified best management practices to enhance surface
water quality with minimal capital expenditures by the City.
Formatted: Tab stops: Not at 0.5"
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3.3.1 Water Quantity
Goal 1:
Protect, preserve, and use natural surface and groundwater storage and retention
systems to control excessive volumes and rates of runoff and flooding.
Policy 1.1:
Preserve and optimize where feasible the retention capacities of the present
drainage systems by utilizing lakes, ponds, and wetlands for storing stormwater runoff.
Measures shall be taken in newly developing watersheds to limit the proposed runoff
rates to the existing rates or lower, or to the rates as- specified in Peliey !-.9 MOA /JPA
for the e ffers Pend Di trietPrior Lake Outlet Channel The City will partner with the
PLSLWD toward implementing its retention storage goals within areas of the City that
fall under municipal jurisdiction.
Policy 1.2:
Establish 100 -year flood levels based on critical storm events and protect flood
storage capacity in low areas and flood flow capacity in channels and streams
City ofPrtor Lake 3 -5
Local Surface Water Management Plan
Policy 1.3:
Alteration of wetlands is discouraged. Alteration may be allowed on individual
basis if the alteration can be accomplished within the regulations of all federal, state,
county, and local agencies that have jurisdiction over the particular wetland.
Policy IA:
Newly constructed detention areas shall meet the standards of the Public Works
Design Manual (PWDM).
Policy 1.5:
All minor storm sewer system design and analyses shall be based on the 10 year
rainfall event consistent with the standards of this plan and the City's PWDM. All major
trunk conveyance and storage system design shall be based on the 100 year rainfall event
consistent with the standards of this plan and the City's PWDM.
Policy 1.6:
Pond detention basin facilities shall be designed for the 100 year rainfall event,
consistent with the standards of this plan and the City's Public Wer-ks Design
b
N4amia1PWDM
Policy 1.7:
All hydrologic studies and drainage design shall be based on ultimate
development of the 2929 plan. In some cases near term conditions should also be
analyzed to determine whether unrestricted drainage from rural areas may lead to
construction of interim facilities, or management base upon interim HWLs or discharge
rates.
Policy 1.8:
There are numerous basins throughout Prior Lake which have no surface water
outlet and are considered to be "landlocked ". It is Prior Lake's policy to require the
lowest building elevation opening be located 3 feet higher than the high water level of an
adjacent water body. In the case of a land- locked basin, the City may require the
openings to be set higher than the natural run -out elevation, depending on wetland
vegetation. Emergency overflows shall be provided to any areas in new development
without an overflow or outlet, however it is the policy of the City to include volume
storage and leave landlocked basins disconnected when possible.
The intent is to store two one - hundred year storms back -to -back within
landlocked basins and provide from this calculated elevation the required 3 feet of
freeboard because elevations in excess of 100 -year storms can be obtained through
incremental smaller events. The outlet elevation needs to be carefully scrutinized. In
cases of heavily wooded fringe areas around landlocked basins, it may be necessary to set
the outlet elevation lower to prevent the killing of trees.
City of Prior Lake 3-6
Local Surface Water Management Plan
Policy 1.9:
In order to mitigate future development flows from increasing erosion potential to
the outlet channel from Prior Lake the proposed two year event discharge rates will be
held to rates agreed to in the Joint Powers Agreement (JPA) with the PLSLWD.
Policy 1.10:
All developments shall, to an extent determined by the City, provide land,
funding, or a combination of both for developing regional detention sites to achieve the
existing rates as indicated in this plan.
Policy 1.11:
Implement volume control and encourage low impact development techniques in
developing and redeveloping areas to minimize runoff volumes that tend to increase with
an increase in impervious area.
Policy 1.12
Regional detention basins are used to manage peak flow rates and provide flood
storage and flood retention. On -site detention basins are utilized when regional basins
are not in place or are not feasible. The city encourages the use of regional versus on -site
basins for rate control and flood protection. Where flood and rate control basins are not
feasible or desired.
Policy 1.13
Promote the use of overland versus pipe conveyance so that the benefits of natural
channels can be realized. These benefits include filtration, flow attenuation, infiltration,
and other water quality and quantity benefits. The city encourages the use of natural
vegetation within overland conveyance systems.
3.3.2 Water Quality
Goal 2:
Identify and plan for means to effectively protect and improve water quality.
Policy 2.1:
The City will work with the PLSLWD on implementation of TMDL(s) for
impaired water bodies in the City. The City will also complete a Nondegradation
analysis as required by the MPCA.
Policy 2.2:
Actively develop and implement a community education program relating to
preserving and improving water quality.
throu a joint y partnership with local watershed organizations and nearby cities and
townships
Policy 2.3:
City of Prior Lake 3 -7
Local Surface Water Management Plan
Construct sediment basins at outlets of storm sewers meeting the requirements of
the Nationwide Urban Runoff Program (NURP) criteria, which serve to remove nutrients
and sediments from runoff.
Policy 2.4:
Construct skimmers on new pond outlets to retain floating debris and oils.
Policy 2.5:
Environmental manholes (3 ft. sumps) shall be placed at the last manhole
structure, which is road accessible, prior to discharge to remove sediments. Sump
manholes are scheduled to be cleaned thfee times pef yeffon-an as needed basis by the
Public Works Department depending on the rate of fill
Policy 2.6:
Construct, where practicably feasible, storm water quality ponds or alternate
BMPs which will serve not only new development, but also existing development where
the situation arises to treat those areas that were established prior to detention pond
criteria developed under EPA's Nationwide Urban Runoff Program (NURP).
Policy 2.7
Construct rainwater gardens or other smaller water quality retrofits within the
downtown area and as redevelopment occurs in other untreated areas.
Policy 2.8
An- site Re_eional treatment is the preferred method of implementing water quality.
The more erse because it is cost effective to implement, however on -site treatment
has the watef qualit. notential to increase system the lengef lasting its
per-feee On -site treatment refers to more than just water quality ponds. It
also includes reduced imperviousness, direct discharge of impervious surface onto
pervious and not directly into the storm sewer system, use of rainwater gardens and
filtration devices, and other such techniques that have the net result of reducing fidne€f
vel nes pollutant flux
3.3.3 Recreation and Fish and Wildlife
Goal 3:
Protect and enhance fish and wildlife habitat and water recreational facilities.
Policy 3.1:
To the greatest possible extent, natural areas shall be preserved, especially when
adjacent to wetland areas.
Policy 3.2:
Buffer zones of natural vegetation shall be maintained around lakes, ponds and
wetlands as much as possible.
City of Prior Lake 3 -8
Local Surface Water Management Plan
Policy 3.3:
Coordinate with the Department of Natural Resources (DNR) to protect rare and
endangered species.
Policy 3.4:
Explore with the DNR and the Prior Lake /Spring Lake Watershed District new
methods of erudiea iii~ ef eentrelling eafas manasine water fnAfeil quality affects of
invasive species
Policy 3.5:
Enforce the Wetland Conservation Act of 1991 in order to protect wetlands.
3.3.4 Enhancement of Public Participation; Information and Education
Goal 4: Formatted: Tab stops: 0.5 ", Left
Inform and educate the public concerning urban stormwater management and the
problems pollutants cause if allowed to enter into our water resources.
Policy 4.1:
Enact a public education program based on the following objectives to reduce
storm water pollution:
1) Raise awareness of the problem and solutions,
2) Promote community ownership of the lakes,
3) Recognize responsible parties and actions to date,
4) Merge public feedback into program execution.
3.3.5 Public Ditch Systems
Goal 5:
Organize a method in which to manage public ditch systems.
Policy 5.1:
No public ditches have been identified within the City of Prior Lake. If the need
arises, the City will organize a method to manage public ditches.
3.3.6 Groundwater
Goal 6:
Promote ground water recharge, unless prevented by wellhead protection plan.
Policy 6.1:
Contribute to regional groundwater and source water protection planning.
Policy 6.2:
Provide a permanent ponding volume below the outlet or overflow in ponds and
wetlands to promote ground water recharge.
City of Prior Lake 3_9
Local Surface Water Management Plan
Policy 6.3:
Maximize infiltration with the use of bioretention basins, infiltration basins, and
other BMPs whenever possible, in open areas within all proposed developments
following the State Stormwater Manual guidelines.
3.3.7 Wetlands
Goal 7:
Protect and preserve wetlands through administration of the Wetland
Conservation Act.
Policy 7.1
Act as the local government unit responsible for enforcing the Wetland
Conservation Act of 1991.
Policy 7.2
Discourage wetland disturbance. Wetlands must not be drained or filled, wholly
or partially, unless replaced by restoring or creating wetland areas of at equal public
value, as permitted by the Wetland Conservation Act. (Ord. 93 -05, 3- 15,93)
Policy 7.3
Up to one -half acre of "debit" wetland (filled or drained) will be allowed to be
replaced through wetland "credit" in a bank which is located outside of Prior Lake's city
limits, but State and County governments are exempt from this policy (M.S. 103G.222
(e))•
Policy 7.4
Restrict clearing and grading within close proximity of the wetland boundary to
provide for a protective buffer strip of natural vegetation to promote infiltration of
sediment and nutrients. In the event that grading occurs close to the wetland boundary
native plant materials shall be reestablished as a buffer strip.
Policy 7.5
Establish for City use a wetland bank account to allow for wetland debits and
credits for city projects and assist local watershed organizations to establish bank sites
where possible
Policy 7.6
Require that a wetland assessment be prepared for any project that includes a
wetland.
The Wetland Management Plan, section 4 of this report, incorporates assessments
of some of the larger wetlands within the 2020 growth area. These assessments will
serve in lieu of this requirement for these specific locations until the spring of 2010. For
projects that involve wetlands not assessed or for projects involving assessed wetlands
City of Prior Lake 3 -10
Local Surface Water Management Plan
after 2010, a wetland assessment using MnRAM methodology must be prepared and
submitted with other review materials as spelled out in the PWDM.
3.3.8 Erosion and Sediment Control
Goal 8:
Prevent erosion of soil into surface water systems through enforcement of City
S"�P P SWPPP and Permits
Policy 8.1:
Erosion control plans shall be required for all land disturbance activities. The
erosion control plans shall be consistent with the criteria as outlined in MPCA's
"Protecting Water Quality In Urban Areas". lTens to be eheeked aFe: silt f nee and
Policy 8.2:
Temporary sediment basins shall be constructed in areas of new development to
prevent sediment from leaving the construction area, as required by the NPDES Permit.
Policy 8.3:
Streets and property adjacent to construction areas shall be kept free from
sediment carried by construction traffic.
Policy 8.4:
The City may prohibit work in areas having steep slopes and high erosion
potential. The provisions of the shoreland ordinance should be followed to prevent
impact to these erosion sensitive areas.
Policy 8.5:
Street sweeping has the potential to be the most cost effective method of
reducing nutrient export from the MS4. The City shall maintain a street sweeping
program to minimize sediment entering the drainage system. Streets will be swept twice
SWPPPaccording to the City of Prior Lake Street Sweeping Policy
Policy 8.6:
Establishment of temporary and permanent vegetation shall be required to
minimize the time that a graded area remains in an exposed condition.
Policy 8.7:
All existing storm drain inlets and conveyance systems shall be adequately
protected from sedimentation.
3.3.9 Prior Lake's NPDES Permit and Wellhead Protection Planning
Goal 9:
City of Prior Lake 3 -11
Local Surface Water Management Plan
Operate and manage the City's surface water system consistent with best current
practices and the City's NPDES Permit and the City Wellhead Protection Plan.
Policy 9.1:
Projects to correct existing deficiencies, to the extent they are identified, will be
prioritized as follows:
1. Projects intended to reduce or eliminate flooding of structures in known problem
areas
2. Projects intended to improve water quality in the City's lakes
3. Projects intended to retrofit water quality treatment into
n sexistin dg evelopment.
4. Projects intended to reduce maintenance costs
5. Projects intended to restore wetlands and habitat
Policy 9.2:
The City will actively inspect, and properly operate, maintain and repair its storm
water system. The City will follow a regular inspection, cleaning, and repair schedule.
Frequency of maintenance will be event -based and informed by experience and
inspection history.
Policy 9.3:
The City will follow best management practices on its own lands and for its own
projects including street reconstruction projects — in accordance with the NPDES
construction site permit-and. the City's NPDES MS4 Permit and the PWDM
Policy 9.4:
The Ci will engage with local partners and the Minnesota Department of Health
to jointly plan and support wellhead protection activities as described in the City
Wellhead Protection Plan.
3.3.10 Financial Management
Goal 10:
Ensure that the costs of the surface water system are equitably distributed.
Policy 10.1:
The City will continue to update and apply area based charges so that the surface
water related costs of development can be fairly borne by the development.
Policy 10.2:
The City will periodically update its storm water utility rate structure to
accomplish the following:
1. Meet the requirements of its NPDES permit
2. Provide for the maintenance of ponds and outfall structures
3. Conduct repairs to the system
4. Update its system planning efforts
City ofPrior Lake 3 -12
Local Surface Water Management Plan
5. Implement water quality retrofits with its dewntewn OF
redevelopment
3.4 County, State and Federal Agency Requirements
This section of the LSWMP presents a synopsis of the current agency requirements while
acknowledging the existence of other requirements that may be applicable. The City is
committed to the preservation and enhancement of its wetlands and water resources
through full compliance with local, state, and federal wetland regulations. The City will
work actively and collaboratively with these stakeholder organizations on issues of
concern by attending Technical Advisory Committee meetings and sharing ertp inent
information and data.
3.4.1 Minnesota Department of Natural Resources
At the state level, Types 3, 4, and 5 wetlands are protected by the DNR by statute. These
are areas typically recognized as wetlands and are generally characterized by open water
and emergent vegetation throughout most of the year. The state has jurisdiction over
only those wetlands appearing on the state's inventory of protected waters. Further,
wetlands in the inventory were generally those in excess of 10 acres in rural areas or in
excess of 2.5 acres in municipalities and incorporated areas. Map 1 shows some of the
protected waters within the Prior Lake LSWMP study area.
If an area meets the jurisdictional criteria but is not on the state's inventory, it is not
regulated by the DNR. If it does not meet the statutory criteria but is listed on the
inventory, it still is subject to MNDNR regulation. There is no mechanism presently for
adding or deleting wetlands. The inventory was begun in the late 1970s and all state
inventories were completed during the early 1980s.
The MNDNR rules specify that permits may not be issued for any project except those
that provide for public health, safety, and welfare. Any private development projects are
effectively excluded from permit consideration by this requirement.
The other powers and duties of this Minnesota state agency and its commissioner are
wide - ranging. As they affect surface water management within the City they include:
• Regulation of all public waters inventory waterbodies within the City — to the
extent of their ordinary high water level.
• Regulation of certified floodplains around rivers, creeks, lakes and wetlands.
• Management of the Flood Hazard Mitigation program
3.4.2 U.S. Army Corps of Engineers (USACE)
City of Prior Lake 3.13
Local Surface Water Management Plan
Under Section 404 of the Clean Water Act, including subsequent modifications, the U.S.
Environmental Protection Agency (EPA) and the U.S. Army Corps of Engineers
( USACE) regulate the placement of fill into all wetlands of the U.S. In 1993, there was
a modification of the definition of "discharge of dredged material" to include incidental
discharges associated with excavation. This modification of the "discharge of dredged
material" definition meant that any excavation done within a wetland required the
applicant to go through Section 404 permitting procedures. In 1998, however, this
decision was modified so that excavation in wetlands is now regulated by the USACE
only when it is associated with a fill action.
3.4.3 Board of Water and Soil Resources (BWSR)
The local and regional wetland rules are governed by the Wetland Conservation Act
(WCA). The WCA, passed in 1991, extends protection to all wetlands unless they fall
under one of the exemptions of the WCA. The WCA follows a "no net loss" policy. The
wetlands covered under the WCA must not be drained or filled, wholly or partially,
unless replaced by restoring or creating wetland of at least equal public value under an
approved replacement plan. Replacement ratio is typically 2:1 (2 acres created for every
1 acre filled) for wetland impacts.
A designated Local Government Unit (LGU) is responsible for making exemption and
no -loss determinations and approving replacement plans. Currently, Prior Lake acts as
the LGU for WCA within the City's subdivision authority.
The powers and duties of this Minnesota state agency also include:
• Coordination of water and soil resources planning among counties, watersheds,
and local units of government.
• Facilitation of communication among state agencies in cooperation with the
Environmental Quality Board.
• Approval of watershed management plans.
3.4.4 Minnesota Pollution Control Agency
The USACE implements provisions of Section 404 of the Clean Water Act with guidance
from the EPA through a permitting process. The Section 404 permit also requires a
Section 401 water quality certification before it is valid. The EPA has given Section 401
certification authority to the MPCA.
The powers and duties of this Minnesota state agency and its commissioner include:
• Fulfilling mandates from the EPA, particularly in regard to the Clean Water Act.
• Administration of Prior Lake's NPDES Phase II MS4 permit.
• Administration of the NPDES construction site permit program.
• Administration of the NPDES industrial site discharge permit program.
• Development of TMDLs for waterbodies and watercourses in Minnesota (often in
conjunction with other agencies or joint powers organizations such as watersheds).
City of Prior Lake 3.14
Local Surface Water Management Plan
3.4.5 Environmental Protection Agency
As it relates to surface water management, this agency is charged with interpreting and
applying aspects of the Clean Water Act. This has led to the City's need for its NPDES
MS4 permit. Total maximum daily load limits, a new initiative mandated by the EPA,
also stem from the EPA's role as steward of the Clean Water Act.
3.4.6 Prior Lake Spring Lake Watershed District and Scott County Watershed
Management Organization
The powers and duties of these Minnesota statutory authorities include:
• Approval authority over local water management plans.
• Ability to develop rules regarding management of the surface water system
• Ability to determine a budget and raise revenue for the purpose of covering
administrative and capital improvement costs.
• Regulation of land use and development when one or more of the following apply:
• The City does not have an approved local plan in place
• The City is in violation of their approved local plan
• The City authorizes the watershed toward such regulation
3.4.7 State and Federal Jurisdictional Boundaries for Public Wetlands and Waters
Wetlands are delineated in accordance with the Federal Manual for Identifying and
Delineating Jurisdictional Wetlands (1987). Wetlands must have a predominance of
hydric soils. Hydric soils, by definition, are inundated or saturated by surface water or
groundwater at a frequency and duration sufficient to support, under normal
circumstances, a prevalence of hydrophytic (water tolerant) vegetation typically adapted
for life in saturated soil conditions. The USACE and the BWSR regulate wetlands as
defined by a jurisdictional delineation.
For wetlands that fall under the MNDNR jurisdiction, the Ordinary High Water Level
(OHW) determines the boundary of MNDNR jurisdiction. The OHW is established by
the DNR. A summary of agency jurisdiction is presented in figures 4 and 5.
City of Prior Lake 3 -15
Local Surface Water Management Plan
FIGURE 4
Public Waters: Water Basin
8 1 /2 x 11 black & white
City of Prior Lake 3 -16
Local Surface Water Management Plan
FIGURE 5
Public Waters: Water Course
8 1 /2 x 11 black & white
City of Prior Lake
Local Surface Water Management Plan
3 -17
3.5 Agency Contacts
The primary contacts for local regulating agencies described above are presented below.
These contacts are accurate as of December, -24942011.
City of Prior Lake
City Engineer
City of Prior Lake
16200 Eagle Greek Ave.4646 Dakota Street S.E.
Prior Lake, MN 55372
(952) 447 -9830
Director of Public Works
City of Prior Lake
17 073 ^ de S4.4646 Dakota Street S.E.
Prior Lake, MN 55372
(952) 440 -9890
Scott County WMO
c/o Scott County Natural Resources Manager
Scott County
200 Fourth Avenue West
Shakopee, MN 55379
(952) 496 -8054
Prior Lake Spring Lake Watershed District
District Administrator
15 41 5 -fan lin T a ,14070 Commerce Ave N.E. Suite 489300
Prior Lake, MN 55372
(952) 447 -4166
Scott County Soil and Water Conservation District
District Manager
Scott County Soil and Water Conservation District
7151 West 190 Street, Suite 125
Jordan, MN 55352
(952) 492 -5425
Minnesota Department of Natural Resources
Area Hydologist
Minnesota Department of Natural Resources
City of Prior Lake 3 -18
Local Surface Water Management Plan
1200 Warner Road
St. Paul, MN 55106
(651) 772 -7910
Board of Water and Soil Resources
Board Conservationist
Board of Water and Soil Resources
One West Water Street, Suite 200
St. Paul, MN 55107
(651) 296 -3767
3.6 Water Resource Management - related Agreements
The City of Prior Lake is party to a 49840ctober 2006 joint powers agreement with the
City of Shakopee and the Prior Lake Spring Lake Watershed District and an October
2006 memorandum of agreement with the SMSC regarding the outlet channel for Prior
Lake.
3.7 Impacts of the Prior Lake LSWMP on Other Units of Government
Upon approval of this LSWMP by the two watersheds with jurisdiction over the City, it is
the City's intent to assume all permitting powers within itits jurisdiction. Currently, the
Scott County WMO does not issue permits, so no impact to this organization would
occur. The Prior Lake Spring Lake Watershed District does issue permits for any
planned activity that disturbs more than 10,000 square feet of land area. This threshold
rises to one acre if the activity is not near a lake, wetland, or the Prior Lake outlet
channel.
Since the watershed would still permit activities outside the City's jurisdiction its permit
process would remain in place. Within its jurisdiction, the City will use the permit
submittal requirements outlined in the watershed rules and updates. This will ensure
consistency of approach for all projects.
The PLSLWD would continue in its role as a project review agency though it may defer
to the City review process for projects that don't have a direct impact on Prior Lake or
the Prior Lake outlet channel. The Prior Lake- Spring Lake Watershed District will also
continue to have responsibility for water quality monitoring.
The Prior Lake LSWMP envisions the City and its two watersheds as partners in
implementing this plan. In the PLSLWD lands, the City envisions the watershed taking
the lead on water quality and lake water quality issues. The City and watershed would be
equally responsible for implementation of the volume management targets discussed in
Section 5 of this Plan with the City taking the lead in the 29282030 expansion areas and
the watershed taking the lead in areas outside the 28282030 boundary.
City of Prior Lake 3 -19
Local Surface Water Management Plan
The Scott County WMO portion of the City's current-and-2420 boundary drains toward
the City of Shakopee and Credit River. The flows and routes that discharge from Prior
Lake into Shakopee were developed in consultation with the City of Shakopee and in
conjunction with their surface water planning efforts. Fufthef eeefdinatien will be
needed to address the eeneems ef !he ANO when afeas within the tipper r-eaehes ef the
Three drainage subdistricts in the City's
2030 boundary; Howard Lake (HLK), Campbell Lake (CALK), and Louisville Swamp
(LSW), described in section 5 drain into unincorporated areas of the WMO. Current
standards for matching predevelopment rates and reduction of post - development volumes
by 0.5" on a storm by storm basis may not be sufficient, appropriate or efficient ways to
prevent downstream impact from these three areas. Additional flood protection
improvements and/or peak rate discharge management to meet the unique challenge of
conveying urban stormwater down the Minnesota River bluff may be needed, but
currently standards do not exist in WMO equivalent rules enforced by the Citv.
The City will cooperate with the WMO to plan future infrastructure to meet the needs of
the unincorporated drainage path, but is relying on the WMO to lead the effort to
determine if or to what extent modified standards are required for this subwatershed.
The preferred method of planning for future infrastructure and modifying rules would be
through a cooperative downstream assessment prior to consideration of new
development. This cooperative assessment should include the Cities of Prior Lake and
Shakopee. Scott County and the Scott WMO. The scope and timing of a cooperative
assessment should be pursued with increasingly urgency when plans for trunk sanitga
extensions are beine planned from CR82 to Stemmer Ridge Road.
An alternate method of planning would be through a development driven downstream
assessment or an EAW or AUAR with participation from the WMO and City.
3.8 Watershed Goals and Strategies that Affect the City of Prior Lake
The City of Prior Lake goals and policies, outlined above, are a close reflection of those
of the watersheds, only presented through the municipal filter. The PLSLWD has, over
the past two years, developed goals related to volume management that will have a
profound a€€eet on the City as it implements its surface water system. Specifically,
the PLSLWD is looking for 1,500 to 3,000 acre -feet of retention storage so that the
impact of future development on Prior Lake and its outlet channel can be mitigated.
The PLSLWD has determined that increasing the outlet channel's permitted capacity
above the current 65 cubic feet per second is not a viable option due to high cost,
permitting problems, and downstream environmental impacts. What is needed is
retention storage, which is storage without discharge. This retention volume, once filled,
is emptied through evaporation, infiltration, or transpiration. One method of increasing
the capacity of volume storage is through the restoration and creation of new wetland
areas within the agricultural areas of the district. Through partnership with the District,
these potential wetland creation sites can be planned for and set aside for the benefit of
Chy of Prior Lake 3 -10
Local Surface Water Management Plan
water quality and volume storage. District identified wetlands and low areas can be
pursued through the City process as a result of this partnership
The 1,500 to 3,000 acre -feet of storage needed presents a challenge to both the City and
the watershed, as does obtaining this storage while managing the City's wetlands
according to the Wetland Management Plan. A large part of the volume storage will
occur in existing natural wetlands. Each wetland will be rated for its susceptibilities to
retaining the necessary volumes, forming a balance needed for wetland preservation with
the system's volume storage needs. This approach, as well as the creation of new
wetland areas will allow both wetland preservation and volume management to be
accomplished.
City of Prior Lake 3 -21
Local Surface Water Management Plan
OF PRI(j*
y
X
P
5. SYSTEM ASSESSMENT AND DESIGN
5.1 General
This section of the Prior Lake Local Surface Water Management Plan (LSWMP) serves
two functions. The system assessment portion catalogues the various assessments of
problems that the Plan must address whether they relate to water quality, wetland
protection, flooding, volume management, or lakes management. The intent is to identify
the source of problems and, more importantly, specific actions the City will take to
address these problems either independently or in collaboration with some other
organization — most commonly one of the watershed management organizations.
The system design portion of this section describes the 2030 growth area surface water
management system. This system is shown in maps 1 through 5. The discussion of the
proposed system revolves around answering the following questions:
• What are the general drainage patterns of the 2030 and existing system?
• What does the 2030 system entail in terms of storage, conveyance, volumes, and
discharge rates?
• Where does the proposed system discharge and what constraints in the existing
system limit discharge of the 2030 system?
• What is the impact of agricultural drainage, outside the 2030 growth area, on the
proposed and existing urban system?
• How have proposed wetland bounce, and duration of HWL, been determined by
management guidelines of the Wetland Management Plan, section 4 of the
LSWMP?
• What opportunities exist for obtaining the retention storage identified by the
PLSLWD both in the 2030 growth area and outside it?
• What is the impact of the City of Prior Lake's 2030 urban system on agricultural
areas and other municipalities?
• Are there any existing ponds where calculated HWL is a concern?
Maps 1 through 5 show the major drainage divides, storage areas, conveyance (including
pipe and channels), wetlands and lakes that have been incorporated into the Prior Lake
LSWMP.
City of Prior Lake 5 -1
Local Surface Water Management Plan
The purpose of Maps 1 through 5, and the system design portion of this section, is to
identify and quantify the infrastructure needed to allow continued development in Prior
Lake while avoiding the negative impacts, such as flooding and water resource
degradation, often associated with development.
5.2 System Assessment
5.2.1 Water Quality Assessments
5.2.1.1 Clean Water Act Assessments
A number of water bodies within the existing City and its 2030 growth boundary are
listed in the state impaired waters list. Known as the 303(d) list from the applicable
section of the federal Clean Water Act, these waters are ones that do not currently meet
their designated use due to the impact of a particular pollutant or stressor. If monitoring
and assessment indicate that a water body is impaired by one or more pollutants, it is
placed on the list. At some point a strategy would be developed that would lead to
attainment of the applicable water quality standard. The process of developing this
strategy is commonly known as the Total Maximum Daily Load (TMDL) process and
involves the following phases:
1. Assessment and listing
2. TMDL study
3. Implementation plan development and implementation
4. Monitoring of the effectiveness of implementation efforts
Responsibility for implementing the requirements of the federal Clean Water Act falls to
the U.S. Environmental Protection Agency ( USEPA). In Minnesota the USEPA
delegates much of the program responsibility to the state Pollution Control Agency
(MPCA). Information on the MPCA program can be obtained at the following web
address: http: / /www.pca.state.mn.us /water /tmdl/index.htmI The following is an excerpt
from the MPCA website describing the program and its need:
The Clean Water Act requires states to publish, every two years, an updated list of streams and
lakes that are not meeting their designated uses because of excess pollutants. The list, known as
the 303(d) list, is based on violations of water quality standards and is organized by river basin.
Environmental organizations and citizen groups have sued the EPA because states have not made
adequate progress to meet Section 303(d) requirements. The EPA has been sued for various
reasons. Over the past 10 years, lawsuits have been filed in 42 states and the District of Columbia.
Of those, 22 have been successful. There is currently no such lawsuit in Minnesota. However,
beyond the federal requirements, there are many reasons for us to move forward with the
development of TMDLs. Foremost is the need to clean up our rivers, streams and lakes to
maximize their contributions to the state's economy and quality of life and to protect them as a
resource for future generations.
For each pollutant that causes a water body to fail to meet state water quality standards, the federal
Clean Water Act requires the MPCA to conduct a TMDL study. A TMDL study identifies both
point and nonpoint sources of each pollutant that fails to meet water quality standards. Water
quality sampling and computer modeling determine how much each pollutant source must reduce
City of Prior Lake 5.2
Local Surface Water Management Plan
its contribution to assure the water quality standard is met. Rivers and streams may have several
TMDLs, each one determining the limit for a different pollutant.
Table 5.1 lists the 303(d) impaired waters within the existing boundary and 2030 growth
boundary.
The Minnesota River, downstream of the Prior Lake outlet channel, is also listed. This
listing will potentially affect management of drainage that directly discharges to the
outlet channel. The river's affected uses are aquatic consumption, aquatic recreation, and
aquatic life and the pollutants or stressors that have been identified as causing these
impairments are the following:
• Fecal coliform
• Low oxygen
• Mercury
• PCB
• Turbidity
The absence of a waterbody from the 303d List does not necessarily mean the reach is
meeting its designated uses. It may be that the reach has either not been sampled or there
are not enough data to make an impairment determination. Additionally, where mercury
is identified as a stressor, the TMDL approach will be regional in nature as mercury is
most commonly an air -borne pollutant.
City of Prior Lake 5 -3
Local Surface Water Management Plan
Table 5.1
303(d) 2004 Final List of Impaired Waters
Within the City of Prior Lake and its 2030 Growth Area
TMDL
Water Body
Year First DNR # Affected
Pollutant or
start/ Formatted Tame
Listed Use
Stressor
TMDL
complete
Spring
2002 70 -0054 Aquatic
Excess
2004/2008
recreation
nutrients
Spring
1998 70 -0054 Aquatic
Mercury,
1999/2011
consumption
FCA
Upper Prior
2002 70 -0072 Aquatic
Excess
2004/2008
recreation
nutrients
Upper Prior
2002 70 -0072 Aquatic
Mercury,
2002/2015
consumption
FCA
Lower Prior
2002 70 -0026 Aquatic
Mercury,
2002/2015
consumption
FCA
Pike
2002 70 -0076 Aquatic
Excess
2007/2011
recreation
nutrients
Notes: FCA stands for fish consumption advisory and is thus not an independent
pollutant or stressor.
Source: MPCA
The Minnesota River, downstream of the Prior Lake outlet channel, is also listed. This
listing will potentially affect management of drainage that directly discharges to the
outlet channel. The river's affected uses are aquatic consumption, aquatic recreation, and
aquatic life and the pollutants or stressors that have been identified as causing these
impairments are the following:
• Fecal coliform
• Low oxygen
• Mercury
• PCB
• Turbidity
The absence of a waterbody from the 303d List does not necessarily mean the reach is
meeting its designated uses. It may be that the reach has either not been sampled or there
are not enough data to make an impairment determination. Additionally, where mercury
is identified as a stressor, the TMDL approach will be regional in nature as mercury is
most commonly an air -borne pollutant.
City of Prior Lake 5 -3
Local Surface Water Management Plan
Most likely the PLSLWD will be the lead agency charged with developing TMDL's for
the basins identified above. The City must be involved in developing the implementation
plan. It is likely that once a TMDL plan is in place this LSWMP will have to be amended
to incorporate the requirements of the TMDL.
Only a handful of TMDLs have been completed or are in process — none for the water
bodies identified above. As shown in table 4.1 the first TMDL implementation plan is
due in 2008 for excess nutrients in Spring Lake and Upper Prior Lake.
City of Prior Lake Actions: The City of Prior Lake will, through its development review
and permitting process, quantify the change in nutrient loading due to implementation of
water quality treatment in developments. This quantification will be linked to the city's
GIS mapping so that a database can be maintained of how nutrient loading has been
changed. The City will use its hydrologic model to determine the extent to which volume
management has reduced nutrient loadings to the lakes and outlet channel.
5.2.1.2 Prior Lake Spring Lake Watershed District Assessments
When discussing nutrient impacts to lakes the nutrient most commonly identified is
phosphorus. Through its own monitoring efforts and those of the Citizen Assisted
Monitoring Program (CAMP) run by Metropolitan Council, the PLSLWD has been
collecting data on nutrient loading into the impaired waters, and others, identified above.
The PLSLWD water quality data collection and monitoring efforts consist of
tributary/outlet monitoring and in -lake monitoring. Tributary/Outlet monitoring
and other sampling occurs at the following locations:
• County Ditch 13 at the second/upstream crossing of Hwy 13 (PLSLWD site CD 1)
• Outlet of the Hwy 13 Treatment Wetland (PLSLWD site CD2)
• Outlet of the desiltation basin on County Ditch 13 tributary just upstream of Spring
Lake (PLSLWD site CD3)
• Outlet from Lower Prior Lake (PLSL)ND site PLO)
• Outlet from Spring Lake (PLSLWD site SLO)
A total of six lakes within the PLSLWD were monitored in 2003 as part of the
Metropolitan Council's CAMP. These were:
• Spring Lake
• Upper Prior Lake
• Lower Prior Lake
• Pike Lake
• Fish Lake
• Cates Lake
Each of the lakes was monitored by volunteers in one location, usually the deepest area of
the lake. Samples were collected approximately every two weeks between April and
October and were sent to the Metropolitan Council's laboratory for analysis of Total
Phosphorus, Total Kjeldahl Nitrogen, and Chlorophyll -a. Volunteers also measured
City of Prior Lake 5 -4
Local Surface Water Management Plan
surface water temperature and Secchi disk transparency, and rated the physical condition
and recreational suitability of the lake during each visit.
Summaries of the CAMP monitoring program results are provided the Metropolitan
Council's Environmental Services (MCES) 2003 report. Table 5.2 summarizes some of
this data and is reprinted from the PLSLWD 2003 Annual Report
Table 5.2
Growing Season (May - Sept.) Average Lake Monitoring Results, 2000 -2003
From PLSLWD 2003 Annual Report
Lake
Total Phosphorus, µg/L
Secchi disk, meters
Chlorophyll -g, pg1L • - Formatted Table
20M 2001 2002 2003
2000
2001
2002
2003
2000
2001
2002
2003
Spring
170 93 148.8 103.9
1.54
1.1
0.6
1.6
50
58.3
116.6
44.2
Upper
85 88* 102 64.5
1.36
0.8*
0.7
1.4
63
80*
62.3
54.9
Prior I
Upper
96.0
0.8
67.0
Prior 2
Lower
24 21 26.5 40.4
2.89
2.4
2.5
3.3
12
14
13.0
8.0
Prior 1
Lower
28 29 37.3
1.99
1.8
1.8
17
22
27.5
Prior 2
Fish
46 66 76.4 53.5
2.59
2.8
1.0
2.4
18
19
37.5
25
Pike 1
136 139 198 225.6
0.31
1.3
0.5
0.8
13
102
57.0
120.3
Pike 2
97.0'
0.5
74.0
Cates
1 22.2 29.1
1.7
1.8
7.7
4.8
Notes:
*Samples unintentionally weighted toward
poorer- quality late summer months, which may have biased
results.
'Three TP data points are missing from the
database.
Lake water quality is often described by the "trophic" or nutrient status. In oligotrophic
lakes low concentrations of nutrients lead to a reduced ability to support aquatic life,
including algal blooms. Oligotrophic lakes are considered clean. Further along the
spectrum of nutrient concentration are mesotrophic, eutrophic and hypereutrophic lakes.
Mesotrophic lakes are still considered suitable for recreational purposes while eutrophic,
and, particularly, hypereuthrophic lakes frequently see algal blooms thereby reducing
their suitability for recreational purposes.
Scientists use a tool called the Carlson Trophic State Index (TSI) to determine where a
lake lies on the spectrum from oligotrophic to hypereutrophic. TSIs are calculated based
on water quality indicators such as total phosphorus concentration (TP), chlorophyll -a
concentration (Chl -a), and Secchi disk transparency. Phosphorus is often the nutrient that
limits plant growth is lake systems. Additions of phosphorus (e.g., external P inputs) will
therefore enhance plant growth, including algae. Chl -a is a green pigment in algae. Chl-
a concentration provides an indication of how much algae are in the water body. Secchi
depth, the third trophic state indicator, is a measure of lake transparency or clarity.
Murky and cloudy lakes have low Secchi disk readings, which usually correspond to
higher TP and Chl -a concentrations.
City of Prior Lake 5 -5
Local Surface Water Management Plan
TSIs are calculated based on relationships between these indicators and trophic status.
Higher TSIs correspond to high nutrient status. Table 5.3 comes from the MPCA's lake
data website and explains the relationship between the TSI value and lake nutrient status.
Table 5.3
Carlson's Trophic State Index (TSI) Explanation
TSI <30 Classic Oligotrophy; Clear water, oxygen through the year in the hypolimnion,
salmonid fisheries in deep lakes.
TSI 3040 Deeper lakes still exhibit classical oligotrophy, but some shallower lakes will
become anoxic in the hypolimnion during the summer.
TSI 40 -50 Water moderately clear, but increasing probability of anoxia in hypolimnion during
summer.
TSI 50 -60 Lower boundary of classical eutrophy: Decreased transparency, anoxic hypolimnion
during the summer, macrophyte problems evident, warm -water fisheries only.
TSI 60 -70 Dominance of blue -green algae, algal scums probable, extensive macrophyte
problems.
TSI 70 -80 Heavy algal blooms possible throughout the summer, dense macrophyte beds, but
extent limited by light penetration. Often would be classified as hypereutrophic.
TSI > 80 Algal scums, summer fish kills, few macrophytes, dominance of rough fish.
From: The Minnesota Pollution Control Agency (MPCA) lake data web site.
MCES, in the context of its CAMP program, develops lake grades for its monitored
basins. Table 5.4, from the PLSLWD 2003 Annual Report, illustrates the relationship
between trophic status and this lake grade.
Table 5.4
Relationship of MCES Lake Grade to Trophic Status
MCES Lake Grade A B C D F - --
- Formatted Table
Trophic Status Oligotrophic Mesotrophic Eutrophic Hypereutrophic
Table 5.5 presents the TSI values with the MCES lake grades.
City of Prior Lake -6
Local Surface Water Management Plan
Table 5.5
Trophic Status of District Lakes, 2003
According to the PLSLWD 2003 Annual Report:
All of the lakes in the District are either eutrophic or hypereutrophic except for Cates Lake and
Lower Prior Lake, which are on the upper boundary of mesotrophy. Review of Table 4.5 and
comparison with the TSI descriptions in Table 4.3 shows that both Cates Lake and Lower Prior
Lake are very close to the boundary for a eutrophic lake, and this boundary is where problems
really start to become evident. The western end of Lower Prior Lake is mesotrophic /eutrophic
largely because of water flowing through this end from Upper Prior Lake to the outlet. The rest of
Lower Prior Lake has a limited watershed and is isolated from a majority of the inflowing water
from Upper Prior Lake.
The continued assessment of these lakes has led the PLSLWD to emphasize reduction in
phosphorus loading to the lakes. This will also be the focus of a watershed -based TMDL,
when developed, for the impaired waters listed in table 5.1. Since the mercury TMDL
will be regional in nature, the City of Prior Lake and PLSLWD will focus their efforts on
reducing nutrient loading. According to the PLSLWD:
For noticeable improvements to occur in lake water quality, TSI values need to be reduced to 55 or
less. On the reverse, if these lakes are allowed to decline further, algae blooms will become worse
and fish kills are probable.
In addition to collecting and reporting on the above data, the PLSLWD has created a
model to quantify the internal and external phosphorus load for Spring and Upper Prior
Lakes. This modeling effort is summarized in the 2003 Annual Report:
In summary, sediment phosphorus release and recycling accounts for approximately 43 to 78% of
the total phosphorus load for Spring Lake and 49% of the total phosphorus load for Upper Prior
Lake. As a result, significant water quality improvements in each lake will require
implementation of lake improvement options that would greatly minimize the potential for
sediment phosphorus release. In addition, significant reductions in phosphorus from County Ditch
13 and Spring Lake should result in significant water quality improvements in Spring Lake and
Upper Prior Lake, respectively. To a lesser degree, senescing macrophytes and bottom - feeding
fish also affect the water quality of Spring and Upper Prior Lakes, since each of them contribute
approximately 5 to 15% of the total phosphorus load to each lake.
City of Prior Lake 5 -7
Local Surface Water Management Plan
2003
Previous MCES Grades
Lake
TSI
TP )
TSI
(Chl-a)
TSI
(SD
TSI
Ave
MCES
Grade
Trophic Status
2002
2001
2000
Spring
71
68
53
64
C
Eutrophic
F
D
D
Upper Prior 1
64
70
55
63
C
Eutrophic
D
D
D
Lower Prior
1
1 57
51
43
50
B
Mesotrophic
B
B
B
Fish
62
1 62
1 47
1 57
1 C
Eutrophic
D
B
C
Pike 1
82
78
63
74
F
Hypereutrophic
F
D
D
Cates
53
46
52
50
B
Mesotrophic
B
N/A
I N/A
According to the PLSLWD 2003 Annual Report:
All of the lakes in the District are either eutrophic or hypereutrophic except for Cates Lake and
Lower Prior Lake, which are on the upper boundary of mesotrophy. Review of Table 4.5 and
comparison with the TSI descriptions in Table 4.3 shows that both Cates Lake and Lower Prior
Lake are very close to the boundary for a eutrophic lake, and this boundary is where problems
really start to become evident. The western end of Lower Prior Lake is mesotrophic /eutrophic
largely because of water flowing through this end from Upper Prior Lake to the outlet. The rest of
Lower Prior Lake has a limited watershed and is isolated from a majority of the inflowing water
from Upper Prior Lake.
The continued assessment of these lakes has led the PLSLWD to emphasize reduction in
phosphorus loading to the lakes. This will also be the focus of a watershed -based TMDL,
when developed, for the impaired waters listed in table 5.1. Since the mercury TMDL
will be regional in nature, the City of Prior Lake and PLSLWD will focus their efforts on
reducing nutrient loading. According to the PLSLWD:
For noticeable improvements to occur in lake water quality, TSI values need to be reduced to 55 or
less. On the reverse, if these lakes are allowed to decline further, algae blooms will become worse
and fish kills are probable.
In addition to collecting and reporting on the above data, the PLSLWD has created a
model to quantify the internal and external phosphorus load for Spring and Upper Prior
Lakes. This modeling effort is summarized in the 2003 Annual Report:
In summary, sediment phosphorus release and recycling accounts for approximately 43 to 78% of
the total phosphorus load for Spring Lake and 49% of the total phosphorus load for Upper Prior
Lake. As a result, significant water quality improvements in each lake will require
implementation of lake improvement options that would greatly minimize the potential for
sediment phosphorus release. In addition, significant reductions in phosphorus from County Ditch
13 and Spring Lake should result in significant water quality improvements in Spring Lake and
Upper Prior Lake, respectively. To a lesser degree, senescing macrophytes and bottom - feeding
fish also affect the water quality of Spring and Upper Prior Lakes, since each of them contribute
approximately 5 to 15% of the total phosphorus load to each lake.
City of Prior Lake 5 -7
Local Surface Water Management Plan
City of Prior Lake Actions: The City of Prior Lake and Prior Lake Spring Lake
Watershed District should consider whether moving forward jointly on a nutrient TMDL
is warranted. Near term development of a TMDL and the subsequent implementation
plan makes sense for several reasons:
• The TMDL will target nutrients. Nutrient reduction, and improvement in lake
water quality, is a primary goal of both the City and watershed district.
• The tributary area to all the impaired lakes is completely under the jurisdiction of
either the City (existing boundary and 2030 growth boundary) or watershed, which
makes for clearer lines of authority in implementation.
• Certain efforts toward volume retention — necessary for managing Prior Lake and
the outlet — will tend to reduce nutrient loading. It is not known if efforts
completed before creation of a TMDL will be credited toward the TMDL
implementation. Both the City and the watershed would stand to benefit if their
volume management strategies, as they are implemented, were also considered
steps to TMDL implementation.
• The more of the City that develops prior to a TMDL, the more of the City that
might be subject to retrofits to meet the requirements of the TMDL
implementation plan. If the TMDL precedes development then the cost of
implementation can be borne by development rather than directly through the
City's storm water utility and general fund or the watershed levy.
5.2.1.3 Scott County Watershed Management Organization Assessments
The Scott County WMO is in the early stages of its existence and thus has not had the
time to organize around an assessment of water quality within its jurisdiction. Its 2004
Comprehensive Water Resources Management Plan includes limited assessments of a
couple lakes including Markley within the City of Prior Lake. To date no long term
water quality trend is obtainable from the Markley Lake monitoring, which has been
occurring for seven years. In 2003 the lake was given a grade of "C ", which indicates
that it lies between mesotrophic and eutrophic. Refer to table 4.3 for a description of
these terms.
Campbell Lake and Howard Lake have not been assessed as to their water quality. It is
generally understood that these lakes are subject to frequent late summer algal blooms
indicating that they likely tend toward the eutrophic to hypereutrophic end of the water
quality spectrum.
5.2.2 Water Quantity Assessments
5.2.2.1 City Identified Problem Areas
Cates channel should be monitored for future erosion.
5.2.2.2 Pike Lake and Jeffers Pond Districts
City of Prior Lake 5_8
Local Surface Water Management Plan
In 2001 the City of Prior Lake prepared its Trunk Storm Sewer Fee Determination Study.
The purpose of this study was to take the land slated for development at that time
(generally land within the City limits) and develop a plan for providing a stormwater
management system for that land. The study's emphasis was toward developing a
defensible area charge. In order to estimate costs for the future stormwater management
system some modeling was conducted. Within the Jeffers Pond and Pike Lake Districts
this modeling became the basis for an agreement between the Prior Lake Spring Lake
Watershed District and the City of Prior Lake regarding allowable discharge rates from
the Pike Lake and Jeffers Pond districts.
The agreement that was arrived at between the Watershed and City is summarized in a
memorandum to the City from the Watershed's engineer. This memorandum is dated
July 21, 2003 and is included in appendix E. The essence of the agreement is that
allowable 100 -year rates of 35 cfs and 300 cfs were set for the Jeffers Pond and Pike
Lake Districts, respectively. The allowable 2 -year rates were set at 23.3 cfs and 206 cfs
from the Jeffers Pond and Pike Lake Districts, respectively. Tables 5.6 and 5.7 are
reprinted from that memorandum and distribute the allowable flow to specific
subdistricts. The subdistrict nomenclature is from the 2001 Study. Similar tables appear
in section 6 of this Plan detailing the revised targets for these areas in the context of more
recent modeling efforts. The allowable rates will remain those in tables 5.6 and 5.7. The
more recent modeling results in section 6 are not intended to revise that already agreed
upon rates and are presented merely as illustration that the allowable rates have been
considered in the modeling and system planning efforts. This rate scheduled will be
replaced when a Joint Powers Agreement (JPA) for the operation and maintenance of the
Prior Lake Outlet channel is approved by the City.
City of Prior Lake 5_9
Local Surface Water Management Plan
Table 5.6
PLSLWD memo Table #1: 2 -YR Peak Flow Rates
Discharge
Subwatersheds Total Subwatershed Subwatershed
Discharge/
Subwatershed
Upstream Subwatershed Regulated
Regulated
Acre
Area (ac) Peak Flo W Peak Flow +
(cfs)
(cfs)
25% (cfs)
JP -2
JP -1 105.2 18.6
23.3
0.22
Jeffers District Total 18.6
23.3
0.22
PL -5
PL -1, 2, 3, 4, 350.1 51.5*
51.5*
0.20
17
PL -7
PL -6, 8, 9, 10 232.7 45.8
57.3
0.25
PL -11
144.2 29.7
37.1
0.26
PL -12
PL -13 173.5 7.6
7.7*
0.04
PL -16
34.0 7.6
9.5
0.28
PL -18
7.7 1.8
2.3
0.30
PL -21
4.9 1.6
2
0.41
Pike Lake District Total 164.7
206.0
0.22
Table 5.7
PLSLWD memo Table 92: 100 -YR Peak Flow Rates
Discharge
Subwatersheds Total
Subwatershed
Discharge /Acre
Subwatershed
Upstream Subwatershed
Regulated Peak
(cfs)
Area (ac)
Flow" (cfs)
JP -2
JP -1 105.2
35
0.33
Jeffers District Total
35
0.33
PL -5
PL -1, 2, 3, 4, 17 350.1
51.5
0.20
PL -7
PL-6,8,9, 10 232.7
93.5
0.40
PL -11
144.2
114.0
0.79
PL -12
PL -13 173.5
7.7
0.04
PL -16
34.0
26.4
0.78
PL -18
7.7
3.2
0.42
PL -21
4.9
2.7
0.55
Pike Lake District Total
299
0.42
'- - Formatted Table
- - - - f Formatted Table
T Peak flow values taken from Prior Lake - Spring Lake Watershed District Outlet Channel XP -SWMM model.
* Maximum runoff value assumed as 100 -yr peak flow rate from City of Prior Lake Trunk Storm Sewer Study if runoff
value in Prior Lake - Spring Lake Watershed District Outlet Channel XP -S WMM model was greater.
** Peak flow values taken from City of Prior Lake Trunk Storm Sewer Study.
5.2.2.3 PLSLWD Volume Management
The Water Resources Management Plan for the PLSLWD, completed in 1999, identified
several planning efforts, which would occur subsequent to the Plan, to address issues
with the Prior Lake water levels and outlet operation. These included:
• Calibrating an hydrologic model for the watershed
• Designing improvements to the outlet channel for full- development conditions
• Addressing flood prone structures on Prior Lake
• Addressing increases in runoff volume as development occurs
City of Prior Lake 5 -10
Local Surface Water Management Plan
The PLSLWD report Prior Lake Outlet Channel and Lake Volume Management Study
(May, 2003) addresses these issues in detail. The 100 -year floodplain elevation for Prior
Lake established by FEMA is 908.9 MSL. There are 79 homes around the lake with low
openings lower than this floodplain elevation. Fifty -one of these have low openings
below 907.6 and ten have low openings below or within one foot of the lakes 904.0
OHW. According to PLSLWD information this 904.0 elevation has been exceeded a
total of 259 days since 1983.
Since development tends to improve drainage pathways and increase runoff volume, the
impact of future development on Prior Lake could, without mitigation, increase the
frequency of water levels above the 904.0 OHW.
To assess the impact development might have on water levels in Prior Lake, the
PLSLWD created a calibrated model of the watershed. The calibration of this model
started with standard curve numbers for the subwatersheds tributary to the lake and,
through the calibration process, modified these until modeled results matched monitored
lake levels for the 1998 to 2001 period. The hydrologic modeling for the LSWMP is
based upon this calibrated watershed model. The difference between the two, is that the
LSWMP model looks at the conditions that will exist when build out occurs in the 2030
growth area. Additionally, the LSWMP model includes more detail on the storage and
conveyance system necessary to serve the 2030 growth area.
Table 5.8 summarizes the volumetric increase in runoff volume as the study area converts
from current uses to future, with future consisting primarily of residential. The reader
should refer to the study itself for the finer distinctions between existing and future land
use assumptions. It should also be noted that the volume calculations assumed no
application of any runoff management techniques.
Table 5.8
PLSLWD Volume Study
Model Results Summary
Based on the representative years and the assumptions regarding land use change, annual
runoff volume increases anywhere from 2,100 ac -ft from the year 2000 rainfall season to
4,600 ac -ft in the 1999 rainfall season. This increase runoff volume has a direct
correlation to levels in Prior Lake and the frequency of exceedence of the 904.0 level.
The conclusions are that if no water resource management actions are taken to reduce
these developed runoff volumes, then Prior Lake will experience more frequent flooding
and this flooding will occur for longer durations than currently seen.
— - - - Formatted Table
City of Prior Lake 5 -11
Local Surface Water Management Plan
Runoff Volume (ac -ft)
Year
Existing
Future
1998
19,700
23,900
1999
19,400
23,000
2000
10,800
12,900
2001
17,300
20,600
Based on the representative years and the assumptions regarding land use change, annual
runoff volume increases anywhere from 2,100 ac -ft from the year 2000 rainfall season to
4,600 ac -ft in the 1999 rainfall season. This increase runoff volume has a direct
correlation to levels in Prior Lake and the frequency of exceedence of the 904.0 level.
The conclusions are that if no water resource management actions are taken to reduce
these developed runoff volumes, then Prior Lake will experience more frequent flooding
and this flooding will occur for longer durations than currently seen.
— - - - Formatted Table
City of Prior Lake 5 -11
Local Surface Water Management Plan
The PLSLWD volume assessment identified five strategies for addressing future lake
levels. These included:
• Outlet structure modifications
• Rule revisions
• A Land Management Program for acquiring and preserving upstream storage
• Low home flood - proofing or buy out
• Outlet channel improvements
• Implementing volume management rules for new and re- development
The district eliminated the option of increasing the overall capacity of the outlet (by
adding a second pipe) due to the high cost, difficulty in permitting, and downstream
environmental impacts. Instead, the district intends to improve the efficiency of the
current structure and optimizing outlet operation, which will provide a small calculated
reduction in the future HWLs in Prior Lake.
Flood proofing and buy out have high potential but require substantial funding. Whether
this strategy can be used or not depends upon this funding as well as the willing
participation of landowners around the lake.
The most effective mitigation strategies, other than removing the homes, are retention
storage in the watershed and volume control measures. The District's goal is to acquire
between 1,500 and 3,000 acre -feet of retention storage. By District estimates this would
be 38 to 75 acre -feet per year.
5.3 System Design
5.3.1 Hydrologic Modeling Discussion
Stormwater runoff is defined as that portion of precipitation which flows over the ground
surface during, and for a short time after, a storm. The quantity of runoff is dependent on
the intensity of the storm, the amount of antecedent rainfall, the length of the storm, the
type of surface upon which the rain falls, and the slope of the ground surface.
The intensity of a storm is described by the amount of rainfall that occurs over a given
time interval. Storms are typically characterized by their return frequency. A return
frequency designates the average time span during which a single storm of a specific
magnitude is expected to recur. Thus, the degree of protection afforded by storm sewer
facilities is determined by selecting a return frequency for analysis.
For the Prior Lake SWMP the following return frequencies were used:
• 10 -year Rational Method for storm sewer design
• 100 -year, 24 -hour (Type II distribution) event for overland drainage and pond
storage design
City of Prior Lake 5.12
Local Surface Water Management Plan
A 100 -year, 24 -hour frequency event (6.0 inches in 24 hours for Scott County) has a 1%
chance of occurring or being exceeded in any given year. This design rainfall return
period is commonly used for flood control throughout Minnesota.
As development occurs in Prior Lake, actual storm sewer design should be a 10 -year
minimum recurrence for lateral, or local, systems in residential and commercial areas.
This implies that no street, parking lot, or backyard ponding would occur for the 10 -year
design event. Trunk facilities should be analyzed and designed to accommodate the 100 -
year ponded discharges plus 10 -year rational flows from areas that enter the trunk to be
carried to the next storage area downstream.
In general, complete protection against large, infrequent storms with return intervals
greater than 100 years is only justified for important flood control projects. For most
developing areas like Prior Lake, the cost of constructing a large capacity storm drainage
system (for events greater than the 100 -year) is much greater than the amount of property
damage that would result from flooding caused by a larger than 100 -year event occurring
in a system designed for the 100 -year event.
The excess runoff caused by storms greater than the 10 -year will be accommodated by
transient street ponding and overland drainage routes. Providing areas for this short-term
flooding and overland drainage reduce flood damage due to larger than design events.
Provisions should be made to provide or preserve overland drainage routes for emergency
overflows.
A number of methods have been developed to determine the expected maximum rate of
runoff from a known area for a specific design storm, given land use and soil moisture
conditions. The preliminary trunk storm sewer design presented in this plan is based on
the Rational Method and the pond design on the XP -SWMM computer program.
The modeling involves the selection or computation of a time of concentration and a
runoff coefficient. The time of concentration is the time required for the runoff from a
storm to become established and for the flow from the most remote point (in time, not
distance) of the drainage area to reach the design point. The time of concentration will
vary with the type of surface receiving rain and the slope of the surface.
A minimum time of concentration of 15 minutes was selected for the design of the trunk
storm sewer system. Shorter times may be utilized in lateral system design. As the
stormwater runoff enters the system, the flow time in the storm sewer is then added to the
time of concentration, resulting in a longer time of concentration and thus lower average
rainfall intensity as the flow moves downstream from the initial design point.
The percentage of rainfall falling on an area that must be collected by a storm sewer
facility is dependent on watershed variables such as:
• Soil perviousness
• Ground slope
• Vegetation
City of Prior Lake 5 -13
Local Surface Water Management Plan
• Surface depressions
• Development type
• Antecedent rainfall
These factors are taken into account when selecting a runoff coefficient (C) in the
Rational Method or a runoff curve number (CN) for use in XP -SWMM.
In the Rational Method, the runoff coefficient for urban areas varies from 0.2 for parks to
0.95 for asphalt and concrete surfaces, while in XP -SWMM (or more correctly, the SCS
methodology which XP -SWMM incorporates), the CN varies from 58 for parks to 98 for
asphalt and concrete surfaces. CN values depend on the type of soil, cover type and
hydrologic condition. Under fully developed conditions, the values of CN will rise with
increases in impervious area caused by street surfacing, building construction, and
grading.
Table 5.9 provides CN values and runoff coefficients used in the SWMP modeling. To
ensure consistency with this Plan future analyses, whether they be for development
proposals or other city projects, should use the values contained within Table 5.7. For
other types of land use not identified in the table, SCS Technical Release 55 (TR -55)
curve numbers should be used.
As noted earlier, the predominant hydrologic soil group (HSG) within the study area is
HSG B to HSG D. Table 4.7 CN values reflect HSG B. To the extent that soils fall into
the C or D categories they should be modified accordingly. The CN values also reflect
Antecedent Moisture Condition II (AMC II), which is a typical assumption in hydrologic
analyses. AMC II simply implies that average soil moisture conditions apply prior to
simulation of the design event.
Table 5.9
Runoff Coefficients
Land Use Type
Average Runoff Coefficient C for Rational Method
CN Value � - - Formatted Table
Park/Open Space
Low Density
Residential (30%
impervious)
Medium Density
Residential (65%
impervious)
High Density
Residential (72%
impervious)
Commercial/Industrial
(85% impervious)
Ponds
5 year
10 year
0.16
0.25
0.33
0.45
0.59
0.63
0.66 0.70
0.76 0.79
100 year
0.30
0.50
0.72
0.77
0.85
City of Prior Lake
Local Surface Water Management Plan
60
72
85
88
92
99
5 -14
As mentioned, the computer modeling of stormwater quantities for pond design and trunk
pipes was carried out using the computer software HydroCAD. HydroCAD stormwater
runoff hydrographs; are calculated in accordance with SCS TR -20 methodology.
Hydrograph routing through channels and detention basins is performed using the
Storage- Indication method. Storm distributions of SCS 24 -hour Type I, IA, II, and III
storm distributions are allowed in the model. All analyses performed within the context
of this report have been conducted using Type II storm distributions.
5.3.2 System Design Recommendations and Discussion
The City of Prior Lake has a Public Works Design Manual (PWDM) first prepared in
2002, is eutTently bein revised to include rules governing development hydrology
and water resource management issues. The following discussion is meant give
background information and provide the technical basis of some of the PWDMs
requirements. This discussion and background information should not be considered rule
and it does not substitute for or supersede the specific requirements of the City's
Ordinances and PWDM, or the Rules of the Prior Lake- Spring Lake Watershed District
and the Scott Watershed Management Organization.
5.3.2.1 Conveyance and Storage System Concepts
Storm Sewer and Channels
In the Prior Lake SWMP, a combination of storm sewer and channels has been used to
transport simulated stormwater runoff. Only major storm sewer trunks, 24 inches and
larger and related facilities have been considered in this study. A complete system
consists of a complex web of trunks, manholes, lateral lines, overland drainage ways,
catch basin leads, catch basins, pond inlets and outlets and all other items.
Proper design of a storm sewer system requires that all sewer lines be provided with
access through manholes for maintenance and repair operations. Generally, spacing of
manholes should be no greater than 400 feet. Intervals on larger diameter lines can be
increased when the pipes are sufficiently large for a person to physically enter the storm
sewer pipe for maintenance operations. Regardless of sewer size, manholes should
normally be provided at all junction points and at points of abrupt alignment or grade
changes.
Although lateral systems are designed for the 10 -year storm event, their performance
must be analyzed for storms exceeding the design storm. Lateral and trunk pipes will
surcharge when the design storm is exceeded. During surcharging, the pipes operate as
closed conduits and become pressurized with different pressure heads throughout the
system. Low areas that are commonly provided with catch basins become small
detention ponds often performing like pressure relief valves with water gushing out of
some locations. For this reason, it is extremely important to ensure that these low areas
have an acceptable overland drainage route with proper transfer capacity.
City of Prior Lake 5 -15
Local Surface Water Management Plan
At a minimum, ponding on streets must meet all of the requirements of the 100 -year
design criteria. For safety reasons, the maximum depth should not exceed two feet at the
deepest point and the lowest exposed building elevation should be at least one foot above
the elevation to which water could rise before overflowing through adjacent overland
routes.
All storm sewer facilities, especially those conveying large quantities of water at high
velocities, should be designed with efficient hydraulic characteristics. Manholes and
other structures at points of transition should be designed and constructed to provide
gradual changes in alignment and grade. Pond outlet control structures should be
designed to allow water movement in natural flow line patterns, to minimize turbulence,
to provide good self - cleaning characteristics, and to prevent damage from erosion.
Intake structures should be liberally provided at all low points where stormwater collects
and at points where overland flow is to be intercepted. Inlet structures are of special
importance, since it is a poor investment to have an expensive storm sewer line flowing
partially full while property is being flooded due to inadequate inlet capacity. Inlets
should be placed and located to eliminate overland flow in excess of 1,000 feet on minor
streets, or a combination of minor streets and swales, and 600 feet on collector streets and
arterials. Additionally, inlets should be located such that 3 cfs is the maximum flow at
the inlet for the 10 -year design storm. Intake grates and opening should be self - cleaning
and designed to minimize capacity reduction when clogged with twigs, leaves and other
debris.
Effective energy dissipation devices or stilling basins to prevent stream bank or channel
erosion at all stormwater outfalls should be provided. The following recommendations
should be kept in mind when designing an outlet:
• Inlet and outlet pipes of stormwater ponds should be extended to the pond
normal water level whenever possible.
• Outfalls with velocities of less than 4 fps that project flows downstream into
the channel in a direction 30 degrees or less from the normal channel axis
generally do not require energy dissipators or stilling basins, but do require rip
rap protection.
• Where an energy dissipator is used, it should be sized to provide an average
outlet velocity of less than 6 fps, unless rip rap is also used. In the latter case,
the average outlet velocity should not exceed 8 fps.
• Where outlet velocities exceed 8 fps, the design should be based on the unique
site conditions present. Submergence of the outlet or installation of a stilling
basin approved by the City is required when excessive outlet velocities are
experienced.
• In the case of discharge to channels, rip rap should be provided on all outlets
to an adequate depth below the channel grade and to a height above the outfall
or channel bottom. It should be placed over a suitably graded filter material
and filter fabric to ensure that soil particles do not migrate through the rip rap
and reduce its stability. Rip rap should be placed to a thickness at least 2.5
times the mean rock diameter so as to ensure that it will not be undermined or
City of Prior Lake 5 -16
Local Surface Water Management Plan
rendered ineffective by displacement. If rip rap is used as protection for
overland drainage routes, grouting may be recommended.
• Overland drainage routes where velocities exceed 8 fps should be reviewed by
the City Engineer and approved only when suitable stabilization measures are
proposed.
Open channels and swales are recommended where flows and small grade differences
prohibit the economical construction of an underground conduit and in areas where open
channel type drainage will enhance the aesthetic qualities of a development. Whenever
possible, a minimum slope of 2% should be maintained in unlined open channels and
overland drainage routes. Slopes less than 2% and greater than 1% are difficult to
construct and maintain and may require an underdrain system. Slopes less than 1%
should not be allowed. Side slopes should be a maximum of 4:1 (horizontal to vertical)
with gentler slopes being desirable. Where space permits, slopes should be cut back to
match existing grade.
In general the flatter the channel side slopes and the more meandering the channel
alignment the more natural the channel will appear. Natural looking channels use
significantly more space than common ditches. One method of providing this space is to
incorporate greenway corridors over the channel area.
Rock rip rap should be provided at all points of juncture between two open channels and
where storm sewer pipes discharge into a channel. The design velocity of an open
channel should be sufficiently low to prevent erosion of the bottom. Rip rap or concrete
liners should be provided in areas where high velocities cannot be avoided. Periodic
cleaning of an open channel is required to ensure that the design capacity is maintained.
Therefore, all channels should be designed to allow easy access for equipment.
Sanitary sewer manholes that could be subject to temporary inundation, due to their
proximity to ponds, channels, or roadway low points, should be equipped with watertight
castings. Precautions should be taken during construction to prevent the entrance of
stormwater into the sanitary sewer. When access is required at all times, sanitary
manholes located near ponding areas should be raised above the 100 -year high water
level. Future storm drainage construction should include provisions for improving the
water tightness of nearby sanitary sewer manholes. All newly constructed sanitary
manholes in the vicinity of ponding areas and open channels described in this report
should be waterproof.
Ponds
Stormwater ponding areas are an essential part of any storm drainage system. These
areas provide locations where stormwater flows can be reduced to provide flood
protection for downstream areas. The numerous natural depressions found throughout
Prior Lake have been incorporated into the Plan as ponding areas. The effective use of
ponding areas enables the installation of outflow storm sewers and channels with reduced
capacities, since the duration of the design storm is effectively increased over the total
City of Prior Lake 5 -17
Local Surface Water Management Plan
time required to fill and empty ponds. Smaller capacity trunk storm sewer and channels
provide a cost savings to the City.
The use of ponds to control stormwater runoff rates is a recent phenomenon.
Historically, older cities (including the older portions of Prior Lake) have piped
stormwater directly to the nearest large receiving water or river. Continued use of this
practice has both cost and regulatory implications. In terms of cost, few cities have the
funds necessary to build pipes that provide 100 -year protection to properties. In fact, the
older cities that have historically piped all their stormwater find that the systems they
constructed provide nowhere near the 100 -year protection found in newer cities that have
used ponds. In terms of the regulatory control, many direct discharges (without ponding)
to waters of the state are precluded. At present, even direct discharges to wetlands that
are not considered waters of the state are regulated through the NPDES construction
permit.
Cost and regulatory considerations aside, well designed ponds:
1. Improve water quality
2. Recharge the groundwater table
3. Provide aesthetic, recreational and wildlife benefits
Ponds improve stormwater quality by allowing nutrients and sediments carried by runoff
to settle before discharge to important receiving waters. Groundwater recharge is
increased by restricting the outflow rate from a pond, thus allowing more water to
infiltrate into the soil. Careful planning of ponds can enhance a development's appeal
and still provide efficient stormwater management. In fact, lots with pond frontage
command a higher price than lots without.
Most of the ponding areas proposed in this plan collect water from large regional
drainage areas. To provide proper protection for adjacent property, the design storm for
ponding areas is the maximum flood from a Type II, 24 -hour, 100 -year rainfall event (6.0
inches of rain in 24 hours). To provide an additional safety factor, the lowest exposed
structure elevation in a development should be at least two feet above the 100 -year high
water level. The lowest exposed elevations of structures that are adjacent to ponds
should be certified by the builder during basement construction to ensure adequate
freeboard.
Runoff determinations for pond design vary from those for storm sewer calculations. The
critical storm for storm sewer design is the short, high intensity storm, whereas the
critical storm for pond design is of longer duration, since water is being stored for longer
periods of time and released at a slower rate.
The use of computer modeling in the analysis of the ponding system has allowed the
efficient review of several complicated routing patterns, each comprised of several ponds.
The pond storage and outflow rates, adjusted by lag time, were determined by the
program for all the ponds identified in this Plan. The lag time is significant as it
represents the attenuation of peak flows at each pond and generally shows that the peaks
are not occurring at the same time. This implies that the direct runoff to a pond has
City of Prior Lake 5 -18
Local Surface Water Management Plan
generally passed through to the downstream trunk system before the inflow of large
volumes of runoff from upstream ponds.
5.3.2.2 Water Quality System Concepts
Establishing the highest water quality goals that are both reasonable and sustainable is
one of the objectives of the Prior Lake Local Surface Water Management Plan. The only
effective way to maintain high quality water bodies is to prevent sediment, nutrients and
other materials from entering the storm drainage system. Complete interception of
stormwater for treatment at the point of discharge is not currently feasible, though the
City encourages the implementation of techniques such as rainwater gardens, infiltration
areas, and filtration swales etc. that capture a portion of runoff at the point of generation.
Application of these small -scale techniques should be on a site specific basis.
Pollutant Control
The three main sources for degradation of water quality are:
1. Solids and associated chemicals (including calcium chloride and salt) from
erosion and street sanding,
2. Composted decay around ponds, and
3. Fertilizers and other chemicals from farming practices, impervious surfaces, or
lawn care.
Identification of the source and implementation of reasonable control measures can
minimize the degradation of Prior Lake's water bodies.
In areas where extensive development is taking place, stormwater runoff frequently
contains substantial quantities of solids. Most commonly, these sediments are carried by
runoff into the storm sewer from large grading sites though fully developed areas also
generate sediment loads particularly from winter sanding operations and in areas of
structurally failing pipes. For developing areas, strict on -site erosion control practices are
required to prevent sediments from entering downstream water bodies. Inspections
should be conducted by the City to verify that the erosion control practices have been
installed and maintained properly. Even with extensive erosion control practices,
sediment and airborne particulates will continue to enter surface waters of the City.
The importance of erosion control measures during construction cannot be
overemphasized. The Best Management Practices (BMPs) recommended in the
Minnesota Pollution Control Agency's (MPCA) Protecting Water Qualfty in Urban Areas
should be followed for all development. The Minnesota general National Pollutant
Discharge Elimination System (NPDES) stormwater permit for construction activity
requires a permit for construction activities that disturb one or more acres.
When disturbing 10 or more acres, developers are required to provide temporary settling
ponds to treat the runoff from their grading sites. These ponds are intended to prevent the
introduction of sediment and its associated pollution into the storm sewer system and are
City of Prior Lake 5 -19
Local Surface Water Management Plan
required to function, in their various forms, until grading has ceased and adequate cover
has been established. At a minimum, these temporary sedimentation basins should meet
the requirements set forth in the NPDES general permit for construction activities.
When the outlet for a siltation basin, either permanent or temporary, is located below the
normal water surface, the basin can also serve to confine floating solids that may
otherwise enter a downstream pond or lake. This practice is typically referred to as
skimming. If a hazardous material such as fuel oil were to spill, a skimmer structure
would retain it within the basin and thus isolate it for easy access and prompt cleanup.
Skimmer structures should be used for all constructed ponds upstream of wetlands, lakes,
rivers and streams. For constructed ponds that discharge into other constructed ponds,
skimmer structures are not as important.
Ideally, some sort of solids removal system should be installed wherever a storm sewer
outlets into a pond. In certain cases, settling chamber (sump) type catch basins or
manholes can be provided for storm sewers that discharge into ponds. The Prior Lake
Public Works Design Manual requires 3 -foot sumps in the last manhole prior to discharge
into a water body. These can provide effective removal of sand and gravel, which may
be flushed into the storm sewer from streets and highways, but are ineffective in the
removal of finer particles such as silts and clays. Use of this type of catch basin or
manhole should be limited to those areas where regular maintenance is practical and to
where the sump can be realistically expected to intercept sand from winter sanding
operations and gravel from driveways and construction sites.
Of late a concern regarding West Nile virus and mosquito breeding habitat has called into
question the use of sump manholes. The latest data suggests that many different breeding
environments exist for the mosquitoes that carry the virus including ponds, wetlands,
catch basins, and manholes. Obviously, eliminating these elements of the system is not
feasible. Though they should be used sparingly, sump manholes should not be prohibited
due to a concern over West Nile virus.
It bears repetition that a solids removal structure must be regularly maintained if it is to
remain effective. Since maintenance is the controlling factor in the long term
performance of sediment control measures, ponds are recommended over sump
manholes. Sump manholes, if numerous, often go without maintenance. An individual
pond requires more maintenance time than a sump, but system maintenance time goes
down when ponds are the preferred method of sediment removal as long as pond slopes
and benching allow access by maintenance equipment (see Chapter 5 for pond grading
requirements). For this reason sump manholes should be limited to storm sewer lines
discharging directly to wetlands, lakes, rivers, streams, ravines, and constructed channels
and should be avoided upstream of constructed ponds. In all cases, the location, type,
and number of sediment control structures must be established at the time of final design
of that portion of the storm sewer system. Maintenance of the system is discussed further
in Section 6.
City of Prior Lake 5 -20
Local Surface Water Management Plan
Even with the best and most expensive solids removal system, contamination of ponds
and lakes will occur unless particular attention is paid to those activities that occur after
development of a site. Developers must utilize the BMPs to minimize erosion during the
mass grading phase of construction. But property owners must also use care in the
development and maintenance of their lawns and open areas. Debris is frequently raked
from lawns into gutters; from there, if it is not removed, it washes into the storm sewer
system.
Generally speaking, water quality ponding within a development has to treat storm water
to the level required by the downstream receiving water body and its attendant
management strategy. The Prior Lake Public Works Design Manual calls for detention
pond design according to the design program developed by William Walker. At a
minimum, though, detention ponds should contain wet volume equivalent to the runoff
from a 2.5 inch rainfall over their tributary area.
Occasionally, with small plats (of 5 acres of less), water quality ponding cannot be
constructed to the extent required by the Plan without severely hampering the site
development or destroying other habitat such as upland grasslands and forests. In such
cases, it is within the City's discretion to reduce the required water quality ponding
and/or require other methods such as filtration swales or filter beds.
Water Quality Modeling
When necessary for modeling a series of water quality ponds, PondNet water quality
management model or P -8 model is recommended. PondNet is an empirical model
developed from data collected by the Environmental Protection Agency (EPA)
Nationwide Urban Runoff Program (NURP). The model predicts the phosphorus
removal efficiency of a large number of hydrologically connected ponds. Phosphorus is
the primary nutrient modeled because it has been found to be the nutrient most likely to
promote the growth of algae in lakes.
A limitation of the PondNet model is its inability to predict phosphorus concentrations in
large, deep water bodies. In general, water bodies larger than 20 acres or with mean
depths greater than 10 feet should be modeled with in -lake models, many of which are
now available.
Values for average runoff phosphorus concentrations, average annual summer runoff
coefficients and the resulting phosphorus export coefficients were determined for use in
the model. The values are shown in Table 5.10 along with the range of published
literature values.
City of Prior Lake 5 -21
Local Surface Water Management Plan
The export coefficients reflect a large increase in nutrient loading as land use changes
from open space and agricultural to urban. The main reason for this increase is the large
increase in runoff rate and volume, caused by the amount of impervious area, which
washes off the pollutant buildup from those surfaces.
Computer models that predict concentrations and removal efficiencies for heavy metals
are currently available. These models predict removal efficiency in terms of inflow
particle distribution and the pond's ability to remove suspended solids. Based on a
number of studies recently performed by various agencies, it can be assumed that wet
detention ponds which remove 60 percent of phosphorus also remove high percentages of
heavy metals. Table 5.11 shows the benefits of wet detention ponds as estimated by the
DNR in Wisconsin.
Table 5.11
Benefits of Wet Detention Ponds
Pollutant Average Reduction ( %) - - Formatted Table
Lead 70
Zinc 70
Bacteria 70
Diazinon (pesticide) 17
Phthalate 80
Sediment 90
City of Prior Lake 5 -22
Local Surface Water Management Plan
Table 5. 10
Phosphorus Concentrations and Export Coefficients
Model Parameters
Published Formatted Table
Land Use
Values
P concentration
Runoff'
P export
P export
(µg/1)
Coefficient*
Coefficients
Coefficients
( %)
(lbs /ac)
(lbs /ac)
Park/Open Space
200
0.07
0.14
0.09-0.3
Low Density
Residential (30%
450
0.21
0.97
0.45-2.7
impervious)
Medium Density
Residential (65%
500
0.47
1.64
0.45-2.7
impervious)
High Density
Residential (72%
500
0.55
2.31
0.45-2.7
impervious)
Commercial/Industrial
(85% impervious)
600
0.68
3.08
0.70-3.0
* 2 -year storm frequency (2.5" of precipitation in 24 hours)
The export coefficients reflect a large increase in nutrient loading as land use changes
from open space and agricultural to urban. The main reason for this increase is the large
increase in runoff rate and volume, caused by the amount of impervious area, which
washes off the pollutant buildup from those surfaces.
Computer models that predict concentrations and removal efficiencies for heavy metals
are currently available. These models predict removal efficiency in terms of inflow
particle distribution and the pond's ability to remove suspended solids. Based on a
number of studies recently performed by various agencies, it can be assumed that wet
detention ponds which remove 60 percent of phosphorus also remove high percentages of
heavy metals. Table 5.11 shows the benefits of wet detention ponds as estimated by the
DNR in Wisconsin.
Table 5.11
Benefits of Wet Detention Ponds
Pollutant Average Reduction ( %) - - Formatted Table
Lead 70
Zinc 70
Bacteria 70
Diazinon (pesticide) 17
Phthalate 80
Sediment 90
City of Prior Lake 5 -22
Local Surface Water Management Plan
Based on these findings, it can be assumed that water quality ponds which reduce
phosphorus loadings by 60% under standard runoff concentrations will also reduce heavy
metal concentrations by 70% and sediments by 90 %. For this reason it is sufficient to
model for phosphorus and from those results infer removals of other pollutants according
to the percentages in table 4.3.
Actual modeling of water quality basins and their treatment capacities can be
cumbersome for developers and their engineers. A simple criterion is that every water
quality basin should provide wet volume (volume below the normal water level)
equivalent to the post development site runoff for the 2.5 -inch rainfall event. Ponds
designed in this manner will meet a 60% removal efficiency while providing excess
volume for sediment storage.
Local vs. Regional Water Quality
The ponds shown in maps 1 through 5 are flood control basins and are not generally
considered areas for water quality treatment. Water quality treatment is not considered a
regional element but rather something to be installed with individual developments.
Regional water quality treatment is considered less effective than local treatment and
some analyses suggest that regional water quality basins can become pollutant sources
rather than sumps. Additionally, by dispersing water quality to the local level, a wider
range of techniques can be used such as:
• filtration swales
• infiltration swales
• infiltration basins
• structural units like swirl separators
• sand filters
• reducing and disconnecting impervious surface
5.3.2.3 The Use of Wetlands in the Surface Water System
This LSWMP seeks to use the abundant wetlands within the City as a part of the natural
storm drainage system. This involves maintaining water quality, reducing flooding and
erosion, and stabilizing or restoring water levels. Wetlands are important physical,
educational, ecological, aesthetic, recreational and economic assets to the City.
Historically, most of the wetlands in the City have been affected by agriculture or
urbanization. In urbanizing areas, wetland degradation can be an ongoing process.
However, some degraded wetlands can be improved by stabilizing water levels and
reducing sediment loads.
Water quality plays a significant role in the overall quality of a wetland. When the
quality of the incoming stormwater declines, the wetland's plant community may become
less diverse, retaining only those species that are tolerant of high nutrient and sediment
loads. Once a wetland's plant community is changed, the wetland's character and
ecosystem will change, often to a less valuable system in terms of diversity, wildlife
habitat and aesthetic qualities.
City of Prior Lake 5 -23
Local Surface Water Management Plan
Aerial photos show that numerous wetlands within the 2030 growth area have been
drained, via tile or ditching, and are now vegetated primarily with reed canary grass.
These areas are potential restoration sites since the wetland's natural storage will be
needed when the area develops. Storage can be restored by breaking tile lines and
berming across ditches.
In the recent past, LSWMPs have addressed wetland protection from nutrient loadings,
but not from water fluctuations or sustained water levels. Wetlands were commonly used
for flood storage. The Minnesota Stormwater Advisory Group published a guidance
document that looked at the implications of this practice. It was found that stormwater
bounce and duration affected some types of wetlands, but not others. The guidance
document presented specific guidelines on what wetlands were most affected by
stormwater bounce and sustained water levels. A wetland's sensitivity is affected by
vegetation type, hydrology, soils, topography and chemistry. Section 4, Wetland
Management Plan, applies the concept of susceptibility to the Prior Lake surface water
system.
In all instances, future developments (including road projects and redevelopment
projects) should incorporate some ponding upstream of wetlands. It is the method of the
Plan to show storage in wetland locations with the understanding that minimum control
measures upstream of the wetland will be installed. These minimum control measures
include:
• Water quality ponding for runoff generated by the 2.5 -inch rainfall event
• Rate control to predevelopment conditions for the 10 -year, 24 -hour rainfall event
Where wetlands are identified as high quality and susceptible to negative impacts from
urban runoff quality and volume then additional control measures should be implemented
including:
• Infiltration in addition to 2.5 -inch water quality criterion
• Filtration (via swales or rainwater gardens) in addition to 2.5 -inch water quality
criterion
• Rate control to predevelopment conditions for the 100 -year, 24 -hour event
In order to determine what level of upstream control is necessary, assessments of
wetlands using standard assessment methodology (Minnesota Routine Assessment
Methodology, for instance) should be provided in submittals for developments and
projects that involve discharges to wetlands, unless these wetlands were included in the
assessment summary in Section 4. In such a case, only after 2010 would these also have
to be assessed by project proposers.
Depending on the quality of the wetland in question, rate control upstream of the wetland
could be to the 100 -year predevelopment rate. Generally, the rate control proposed in the
Plan is to a lower rate, which approaches a preagricultural rate. The additional rate
City of Prior Lake 5 -24
Local Surface Water Management Plan
reduction would occur in the wetlands themselves. In many cases this will involve
constructing multi -stage control structures for wetland outlets. Construction of these
wetland outlets should be a part of any project that uses the wetland for a portion of its
flood storage. In some cases developments and other projects will rely solely on
constructed ponds that discharge directly to waterways or lakes. In some cases these
wetlands, along with other basins, would also incorporate a retention volume — as
discussed above regarding volume impacts to Prior Lake.
Table 5.12 lists differing wetland types and their susceptibility to impacts from
stormwater. Table 5.12 also appears as table 4.1 in section 4. It is reprinted here for ease
of reference.
Table 5.12
Wetland Community Susceptibility to Stormwater Impacts
Highly Susceptible Wetland Communities* Moderately Susceptible - Formatted Table
Wetland Communities*
Sedge Meadow Low Prairies Shrub -Carrs
Bogs Coniferous Swamps Alder Thickets
Coniferous Bogs Hardwood Swamps Fresh (wet) Meadows
Open Bogs Seasonally Flooded Basins Shallow Marsh
Calcareous Fens Deep Marsh
* Wetland community (- ities) determined using key provided in MnRAM Version 2.0.
Subsection 5.4 describes the surface water system proposed for development within the
2030 growth area. In general, storage is located in existing topographic low areas and
these areas are often wetlands. Appendix C provides calculated flood storage for the
proposed basins.
In many cases, the numbered ponds shown on maps 1 through 5 will be wetlands and
these wetlands will have differing susceptibilities to stormwater impacts as indicated in
the table above and, more substantively, in section 4. To the extent that some of the
proposed ponds in maps 1 through 5 are wetlands, then a portion of the flood storage
indicated in appendix C will fall outside and not within the wetland area.
The following general criteria should be used to determine what type of rate control and
water quality treatment would likely occur upstream of a wetland.
• Case 1: regional pond is a "least susceptible" wetland or not a wetland
• Water quality volume can be built into the regional pond if it is not a
wetland, otherwise water quality volume per the requirements of the
NPDES construction permit is required.
• All flood storage can occur within the regional pond
• Case 2: regional pond is a "slightly susceptible" or "moderately susceptible"
wetland
■ Water quality volume is built upstream of the regional pond/wetland
City of Prior Lake 5 -25
Local Surface Water Management Plan
■ Flood storage is provide upstream of regional pond/wetland such that
the predevelopment 10 -year rate is maintained to the wetland
• Case 3: regional pond is a "highly susceptible" wetland
• Water quality volume is built upstream of the regional pond/wetland
• Flood storage is provided upstream of the regional pond/wetland such
that the predevelopment 100 -year rate is maintained to the wetland
Tables 4.2 and 4.3 provide numeric targets that augment the concepts described above.
5.4 System Description
This subsection provides information on the surface water management system for Prior
Lake's 2030 growth area. The model was built based on the Prior Lake Spring Lake
Watershed District (PLSLWD) model and served the purpose of determining overall
infrastructure capital requirements.
The Study area is broke into 21 major drainage districts, which are further divided into
sub - districts. Total acreage for major drainage districts should roughly match the
existing work completed by the Watershed District.
The model included outlets for many of the landlocked basins within the City, to
determine the potential future infrastructure needs. The inclusion of a landlocked basin
outlet in the model is not a guarantee that the outlet will be approved or built. Proposals
to add outlets to landlocked basins will be evaluated on an individual basis at the time of
development, and must meet the requirements of the PWDM and the Rules of the
PLSLWD or Scott WMO, and as stated in chapter 3 it is the policy to encourage that
landlocked basins remain disconnected whenever possible.
Some changes are bound to occur in the growth assumptions on which this model is
based. Further study, or a more detail added to the District's model may result in
recommendations for changes to the stormwater management rules implemented by the
City of Prior Lake. The City should work under the leadership of the Watershed District
on issues of floodplain management by assisting in periodically refining the active
surface water management model and changing stormwater management policy when
warranted.
The following table lists the major drainage districts and abbreviation used for mapping.
The following sections describe each drainage district in detail.
City of Prior Lake 5 -26
Local Surface Water Management Plan
Table 5.13
Drainage Districts
Drainage District Abbreviation
Acres
Buck Lake
BLK
4336.7 **
Campbell Lake
CALK
422.0
County Ditch 13
CD13
5638.2*
Credit River
CR
976.4
Crystal Bay
CRBA
529.0
Crystal Lake
CRLK
164.6
East Rice Lake
ERLK
435.1
Howard Lake
HLK
558.8
Jeffers Pond
JP
812.8
Louisville Swamp
LSW
1987.3
Lower Prior Lake
LPPL
2859.0
Markley Lake
ML
528.6
Mystic Lake
MLK
227.8
Pike Lake
PL
1507.8
Rice Lake
RLK
727.0
Sioux Community
SC
771.2
Spring Central
SPC
416.2
Spring Lake
SPLK
1857.4
Spring West
SPW
384.5
Upper Prior Lake
UPPL
1516.2
*Includes Swamp and Sutton Lake drainage area
* *Includes Fish Lake drainage area
Appendix A details the drainage areas for the subdistricts within each drainage district.
Appendices B and C detail the pond and trunk storm sewer data. Appendix D lists the
proposed pond and storm sewer costs for each district. Refer to the sytem maps at the
end of the report for detailed topography, storm sewer, pond locations and drainage
districts. The discussion of specific major drainage districts is generally organized in an
upstream to downstream manner.
The system maps that show the 2030 system include the "Vc" notation on several ponds.
This designator refers to the PLSLWD having identified that basin as a potential
component in its volume management strategy — the general parameters of which are
discussed earlier in this section. The "V" refers to volume and the subscript "c" refers to
the Watershed's desire that the City take the lead in implementing volume management
in areas that are, or soon will be, within the City limits. In other locations a "Vw" is
noted. These are also potential components in a volume management system with the
subscript "w" indicating that the Watershed would take the implementation lead in these
locations since they lie outside the 2030 growth boundary and thus will not fall within
City jurisdiction.
- - I Formatted Table
City of Prior Lake 5 -27
Local Surface Water Management Plan
EAST RICE LAKE (ERLK)
The East Rice Lake drainage district is the farthest upstream area tributary to Crystal
Lake. Under existing conditions it consists of a system of wetlands connected by
agricultural ditches. Runoff flows from south to north. ERLK -P1 provides the primary
rate control before discharging to Rice Lake under Panama Avenue. This major district's
tributary area is primarily agricultural and outside the 2030 Urban Boundary. ERLK is
shown on map 3.
RICE LAKE (RLK)
Rice Lake is the central feature of this district. Rice Lake is located west of Panama
Avenue and south of County Road 13, as shown on map 4. The majority of land that
constitutes this district lies outside the 2030 growth area but will drain into the growth
area with no additional rate control over what occurs today. Modeling for the Rice Lake
district assumes existing land cover and discharge patterns.
Under existing conditions Rice Lake (RLK -P1) and Crystal Lake are connected via a
channel. For proposed conditions the outlet has been revised to a 48" outlet to restrict
flows upstream into fully developed Prior Lake. Three subdistricts, beyond RLK -P1,
provide additional rate control and flood storage. There are 170.5 acres of agricultural
drainage tributary to RLK -P1 from the south via an existing ditch. The 100 -year
discharge from the agricultural land is 33.6 cfs and the location where this enters the
2030 system is indicated on map 4.
Some grading and excavation is necessary at RLK -P2 to provide additional flood storage
RLK -P4 is designated a highly susceptible wetland (MNRAM number 191142210013).
Since it is the farthest upstream in the system, meeting the water quality and quantity
standards for wetlands of this type should be feasible. Even with the small drainage area
local ponding is required to maintain the integrity of RLK -P4.
CRYSTAL LAKE (CRLK)
The Crystal Lake drainage district consists only of Crystal Lake and a small existing
NURP pond, CRLK -P2 northwest of County Road 13. The total drainage area is 176.4
acres, and is shown on map 3 and 4. Proposed development in CRLK is medium density
residential and preliminary plans for Heritage Landing are currently being developed for
the area tributary to CRLK -P2. Crystal Lake is tributary to UPPL -P 13 via a 24" outlet.
CRLK -P1 receives runoff from RLK -P1. To protect the downstream fully developed
storm sewer system, significant rate control was provided in Rice Lake and Crystal Lake
due to the tributary off -site agricultural drainage from the south.
City of Prior Lake 5 -28
Local Surface Water Management Plan
BUCK LAKE (BLK)
The Buck Lake drainage district consists of 4,336.7 acres. It is located on the south side
of Spring Lake. It lies fully outside the study area, but is tributary to SPLK -P8 and
therefore was modeled to determine the impact from the agricultural drainage on the
urban system.
The extensive Buck Lake drainage system begins as far south as Fish Lake and consists
of channels and wetlands. Overall the land tributary to this system is fairly well drained.
It should be noted that the channel that connects Fish Lake to Buck Lake and Buck Lake
to DNR wetland 206W (BLK -PI) is a DNR protected waterway. Buck Lake provides the
majority of the flood storage and rate control before discharging to SPLK -P8. The
drainage area is well connected by channels, although several large wetlands provide
storage on the east side of Fairlawn Avenue.
As stated, Buck Lake and its drainage is not within the 2030 growth boundary.
Consequently, modeling of the 2030 system assumes the entirety of this drainage remains
under its current land cover, which is primarily agricultural. Based on existing conditions
modeling, the 100 -year discharge from the Buck Lake drainage district into the urban
system is 497.6 cfs. The 100 -year HWL in the farthest downstream wetland is 922.0,
which overtops Trunk Highway 13 (Langford Boulevard). The simulated HWL for
BLK -P1 backs into Buck Lake to a limited extent. Ultimately, though, not a lot of
storage in Buck Lake can be used before the water tops Trunk Highway 13.
It should be noted that the PLSLWD has not targeted Buck Lake as a location for volume
management. Considering that the basin is quite large and apparently under utilized for
storage, it would make sense for the City and Watershed to study the feasibility of
controlling discharge from Buck Lake with the intent of creating more storage in this
basin.
Refer to system map 4 for detailed topography, subdistricts, ponding and storm sewer.
The off -site drainage area to Buck Lake includes Concord, Spring Southeast and Spring
East from the Prior Lake Spring Lake Watershed District (PLSLWD) model.
SPRING CENTRAL (SPC)
The Spring Central drainage lies between the Buck Lake and County Ditch 13 drainage
districts and, like these districts, discharges into Spring Lake's southwest lobe. The
Spring Central drainage currently consists of ditches that pass through wetland areas
designated as least susceptible in the Wetland Management Plan (section 4). A total of
416 acres drain to Spring Lake via the Spring Central system — approximately 186 acres
of which lie outside the City's 2030 growth boundary.
City of Prior Lake 5 -29
Local Surface Water Management Plan
Two basins are proposed upon development of this drainage. These basins, SC -P1 and
P2, occur in locations identified by the PLSLWD as strategic locations for considering
retention storage — with the City taking the lead on implementation. The proposed
normal water levels for these basins were developed with the idea of providing some
retention in the basins. Thorough study of retention implementation is not within the
scope of this Plan and no specific direction is provided by the Watershed as to the
amounts of retention desired in any one location.
COUNTY DITCH 13 (CD13)
County Ditch 13 drainage district lies on the southwest side of Spring Lake, shown on
system map 4 and 5. As with Buck Lake, a significant drainage area outside the 2030
growth boundary is tributary to the small portion of this drainage within the boundary.
This drainage spans 3763.5 acres and reaches as far south as Sutton Lake. These areas,
though within PLSLWD jurisdiction, would lie outside City jurisdiction well beyond the
2030 timeframe. County Ditch 13 is the primary conveyance from Sutton Lake to CD -P1
— the only 2030 proposed basin within this drainage. The high modeled flow under
existing agricultural conditions (assumed conditions for 2030 as well) result from the lake
of storage evident is this district due to decades of agricultural drainage practices.
CD13 -P1 is a very important wetland because it is strategically located to intercept and
control the extensive upstream drainage, and, as a wetland determined to be "least
susceptible" to impacts from urban stormwater, it is appropriate to use the basin as a
major flood storage component without running into excessive concerns for the impacts
of bounce. This Plan proposes a substantial bounce on this wetland, from 916.0' to
930.0'— a HWL that would require raising Langford Blvd. If the PLSLWD were to
pursue storage upstream of CD13 -P1, the storage proposed in this basin could be
reduced. Note that CD13 -PI is designated as a strategic location for considering
retention storage — with the City as the lead in implementation.
SPRING WEST (SPW)
Spring West is located southwest of Spring Lake. It consists of 385 acres, shown on
system map 5. Under existing conditions it consists of a system of agricultural ditches,
ponding behind Langford Avenue before discharging to SPLK -P1. Drainage flows from
the south to north.
Grading revisions are necessary at SPW -P1 to create a large pond, outside the existing
channel. The modeled outlet is a 24" rather than the existing 36" to provide additional
rate control. The existing channel was primarily used for ponding at SPW -P2. The
proposed outlet under Langford Avenue, from SPW -P2, is also smaller.
The locations for ponds SPW -P1 and P2 do not occur on inventoried wetland sites but on
otherwise low areas adjacent to the ditches that drain these districts. Note that both
subdistricts SPW -1 and SPW -2 have locations where potential retention areas are
identified.
City of Prior Lake 5 -30
Local Surface Water Management Plan
SPRING LAKE (SPLK)
Spring Lake is located directly upstream of Upper Prior Lake. The primary waterbody is
Spring Lake, SPLK -P1 in modeling nomenclature. There are 1,858 acres within the
Spring Lake district, plus 11,629 acres of other drainage much of which, like the Buck
Lake and CD13 drainage, lies outside the 2030 growth area. Subdistrict 1 is by far the
largest within this system and includes Spring Lake itself, wetland areas adjacent to the
lake and slopes that drain directly to the lake.
Other than the large central subdistrict and Spring Lake itself, the remainder of this
district is organized into a system of drainage areas and ponds around the periphery of
Spring Lake. The predominant 2030 land use is urban low density residential. SPLK -2
consists primarily of land that forms Spring Lake Regional Park and as such is one area
where no change to existing drainage patterns is anticipated. Otherwise notable features
of the 2030 system include regional ponds for SPLK -2 and SPLK -5 subdistricts. SPLK-
P5 is a potential wetland/storage restoration to provide rate control and sedimentation
capacity to an existing drainage notable for the amount of sediment it currently delivers
to Spring Lake.
Proposed pond SPLK -P7 would be formed by excavation and berming. Otherwise the
storage in other proposed ponds would be provided by existing topography. There are
several wetlands identified as least susceptible by the Wetland Plan. Among these,
SPLK -P2, P3, P4, and P5 have been proposed with more restrictive outlets to maximize
rate control under proposed conditions. Appendix B provides detail on the outlet sizes
proposed for these basins while appendix C provides the basin discharge rates.
SPLK -P5, P6, P7 and P9 have all been designated as potential retention areas. The table
at the end of this section provides prospective retention volumes based on the modeling
assumptions that guide this Plan. As with any retention basin, if a valved outlet were
provided then flood storage and retention volume could overlap. Without the ability to
draw a basin down, any increase in retention volume comes at the expense of guaranteed
flood storage.
Spring Lake discharges into Upper Prior Lake via an existing channel. No modifications
to this route or its capacity are proposed in this Plan.
CRYSTAL BAY (CRBA)
The Crystal Bay district lies west of Upper Prior Lake, bounded by County Road 82 to
the north and Howard Lake Road to the west. It is shown on system map 1. A large
portion of Spring Lake Regional Park lies within CRBA -2. Of the 529 acre drainage
area, only the eastern edge of CRBA -2 has been developed (as urban low density
residential). The entire CRBA drainage district is tributary to Upper Prior Lake via the
18" culvert under Fremont Avenue. Only a small portion west of Arctic Lake, CRBA-
P2, is left to be developed medium density residential.
City of Prior Lake 5 -31
Local Surface Water Management Plan
The topography on the east side of CRBA -P2 is characterized by steep slopes. Drainage
travels west to east. No agricultural drainage from off -site is tributary to the CRBA
system. CRBA -P1, P2, and P3 were all designated as least susceptible wetlands in the
Wetland Management Plan — incorporated as section 4 of this report. Therefore, flood
storage and rate control have been maximized in these basins.
UPPER PRIOR LAKE (UPPL)
The Upper Prior Lake drainage district consists of 1,516 acres and is shown on system
maps 1, 3 and 4. The major waterbody is UPPL -P4, Upper Prior Lake. It is directly
tributary to Lower Prior Lake (LPPL -P1) via an existing channel under County Road 21.
No changes are proposed for this channel connection between the two portions of Prior
Lake.
The majority of the area in UPPL is fully developed. Therefore no major changes are
proposed to the existing trunk storm sewer routing. Several least susceptible wetlands are
utilized for regional ponding. UPPL -P5 is a moderately susceptible wetland (MNRAM
number 191142203001). Refer to tables 4.2 and 4.3 for specific requirements regarding
treatment for these two wetland types.
UPPL -P13 receives discharge from CRLK and its upstream tributaries via an existing 24"
outlet. UPPL -P13 discharges via a 48" culvert under County Road 13 to an existing
backyard ravine. This is a potential problem area due to the high discharge and should be
evaluated for erosion.
UPPL -P14 overflows the road during 100 -year events, assuming the existing outlet
The ravine that UPPL -P7 and P9 discharge into adjacent to UPPL -P4 has been utilized
for proposed conditions. To protect the ravine a 36" outlet from P7 and a 12" outlet from
P6 was modeled. The revised HWLs provide adequate freeboard to adjacent structures.
LOWER PRIOR LAKE (LPPL)
The Lower Prior Lake drainage district is the downstream portion of the Prior Lake
chain. Much of its drainage area is developed and includes the Prior Lake downtown.
No significant changes are proposed for the existing drainage patterns and routing. The
only additions are outlets to currently landlocked ponds LPPL -P6, P2, P10, P8 and P3.
With ponds P2 and P3, small lift stations and force main were modeled. It is also
possible to raise the NWL of the ponds and use gravity pipe as outlets (i.e. provide a
piped emergency overflow and allow infiltration to operate below this).
There are 2,859 acres within the LPPL district, 1,921 acres of which are tributary to
LPPL -P1. The district is shown on system maps 1, 2 and 3. LPPL -P1 outlets to JP -P5
via the Prior Lake outlet channel.
City of Prior Lake 5 -32
Local Surface Water Management Plan
JEFFERS POND (JP)
Jeffers Pond drainage district is located in the northwest corner of Prior Lake. The
topography is characterized by steep wooded bluffs and several interconnected wetlands.
The district is bounded to the north by County Road 42 and to the east by County Road
21, as shown on system map 1. Drainage is routed from southwest to northeast.
The majority of the Jeffers Pond district is undeveloped woods and grasslands. The
southwest portion is developed as low density residential. Preliminary design is
underway for the undeveloped portions of Jeffers Pond district in JP -5 and JP -6. There
are 732 acres of tributary area, with 19,298 acres of ponded tributary area from LPPL -P1.
Lower Prior Lake outlets via the Prior Lake Outlet Channel into the Jeffers Pond district
at JP -P5. The channel is noted on map 1 by dashed lines. Proposed conditions modeling
assumes the upgrades noted in the Environmental Assessment Worksheet (EAW) for the
Prior Lake Outlet and Channel Improvement Project, prepared by PLSLWD in 2004,
have been implemented. These improvements include, but aren't limited to: a new outlet
for LPPL -P1, a weir waterfall overflow from JP -P5, upgrades to the channel crossing
from JP -P7 under County Road 42. The improvements are designed to improve wildlife
habitat, aesthetics and stabilize the outlet channel. The channel stabilization will also
improve the water quality in Jeffers Pond and downstream Pike Lake. It is important to
provide water quality ponds in new developments before discharging to the Jeffers Pond
district regional ponds. The cost estimates in Appendix D do not include any upgrades
that are a part of the EAW because these costs will be borne by the PLSLWD.
Berming is necessary on the east side of JP -P1, P2, and P3 to provide additional storage.
Construction costs have been included for these ponds since they lie outside the EAW
study area. The final downstream pond in the system is JP -P7. JP -P7 acts primarily as a
channel during low flow events; during high flow 100 -year events, ponding occurs
behind County Road 42.
Section 5 of this report summarizes an agreement regarding discharge rate from a small
portion of the Jeffers Pond district into the outlet channel. Table 5.12, which follows the
discussion of Pike Lake, summarizes the modeling conducted for this plan and compares
the new rates obtained from this modeling to those previously agreed to.
PIKE LAKE (PL)
Pike Lake drainage district is in the far northern portion of the study area, adjacent to
Shakopee. There are a total of 1,508 acres within the district and 19,405 acres of ponded
area tributary to PL -P 16 (Pike Lake). The region is shown on system maps 1 and 2.
Drainage travels from east to west via a system of wetlands, proposed ponds, and trunk
storm sewer.
City of Prior Lake 5 -33
Local Surface Water Management Plan
Pike Lake is the farthest downstream portion of the Prior Lake watershed within the study
area — it receives discharge from JP -P7 through the Prior Lake outlet channel under
County Road 42. Pike Lake discharges via a 36" outlet north to Shakopee. For fully
developed conditions, 100 -year event, PL -P16 overflows the existing road, elevation 824,
roughly 0.5 -feet.
PL -P9 is a highly susceptible wetland (MNRAM number 191152225002). Refer to
tables 4.2 and 4.3 for quantity and quality standards when discharging to a highly
susceptible wetland. It is important to construct local ponds to protect the regional PL-
P9.
Berming and some excavation are necessary for the ponds north of County Road 42 to
provide additional storage. Significant excavation is required for PL -P7.
Table 5.14 compares the proposed discharges from the Prior Lake storm water model to
the agreements for Pike Lake and Jeffers Pond discharge that were enacted in 2003. The
Prior Lake storm water model was created for the Surface Water Management Plan from
XP -SWMM software using a model provided by the PLSLWD as a base. The original
agreement on subwatershed discharge rates resulted in part from HydroCAD modeling
done for Prior Lake in the preparation of the 2001 Trunk Storm Sewer Fee Determination
Study. The new software was chosen to promote consistency between City and
Watershed modeling efforts. The new software uses different algorithms for calculating
peak water levels and discharges and leads to slightly different results for these over what
the older HydroCAD model provided — even given the same input parameters. The
strategy in modeling Pike Lake and Jeffers Pond in XP -SWMM has been to keep the
modeled flows below those memorialized in the agreement with the intent that the
agreement remains the final word on rate control for the Jeffers Pond and Pike Lake
Districts.
City of Prior Lake 5 -34
Local Surface Water Management Plan
100 -YR
Table 5.14
JP -2
Comparison of SWMP Modeled Flows
28.6
0.18
Table 5.6
to 2003 City of Prior Lake/PLSLWD Agreement
35
Rainfall 2003 Agreement 2005 SWMP
JP -2
' - - Formatted Table
Event District
Area Subwatershed Discharge District Area
Discharge
Discharge
Regulated Per Acre
Rate
Per Acre
Peak Flow+
PL -5
3501
51.5
25%
PL -5
437.0
48.0
(ac) (cfs) (cfs/ac) (ac)
(cfs)
(cfs/ac)
2 -YR JP -2
105.2 23.3 0.22 JP -2 105.3
15.9
0.15
Table 5.6
105.2 23.3 0.22 105.3
15.9
0.15
Jeffers Pond
0.79
PL -12
172.2
PL -5
350.1 51.5 0.20 PL-5 437.0
32.3
0.07
PL-7
232.7 45.8 0.25 PL -7 289.2
22.7
0.08
PL-11
144.2 29.7 0.26 PL-12 172.2
7.0
0.04
PL-12
173.5 7.6 0.04 PL-14 130.4
13.0
0.10
PL -16
34.0 7.6 0.28 PL -15 31.3
0.8
0.03
PL -18
7.7 1.8 0.30 PL-18 16.1
1.2
0.07
PL-21
4.9 1.6 0.41 PL -20 38.1
2.6
0.07
Table 5.7
947.1 206 0.22 1114.3
79.6
0.07
Pike Lake
0.11
Table 5.7
947.1
100 -YR
JP -2
105.3
28.6
0.18
Table 5.6
1051
35
0 33
JP -2
105.3
28.6
0.18
Jeffers Pond
PL -5
3501
51.5
0.20
PL -5
437.0
48.0
0.11
PL -7
232.7
93.5
0.40
PL -7
289.2
71.5
0.25
PL -11
144.2
114.0
0.79
PL -12
172.2
7.4
0.04
PL -12
173.5
7.7
0.04
PL -14
130.4
17.4
0.13
PL -16
34.0
26.4
0.78
PL-15
31.3
4.3
0.14
PL -18
7.7
3.2
0.42
PL -18
16.1
5.9
0.37
PL -21
4.9
2.7
0.55
PL -20
38.1
4.3
0.11
Table 5.7
947.1
299
0.42
1114 .3"
158.8
0.14
Pike Lake
" PL -P 19 not part of comparison since it
is outside of the previous study area Pond added due to level of detail of SWMP.
HOWARD LAKE (HLK)
Information collected for the Wetland Inventory indicates that Howard Lake is highly
susceptible to impacts associated with urban stormwater. Consequently, the use of this
basin in the 2030 urban system must be restricted compared to similarly sized basins
elsewhere in the City. Fortunately, Howard Lake's smaller natural tributary drainage
area also means that the future urban drainage area to the lake will also be small - so
meeting the management strategy for Howard Lake should not be an issue. In part, the
high quality of the lake is a function of its limited drainage area.
Howard L-ak Lake drainage district totals 559 acres and includes small wetlands
separated from Howard Lake by steep slopes and hills. In order to protect Howard Lake,
existing discharge and bounce is essentially maintained in the 2030 proposed system.
This holds true for the 1, 10, and 100 -YR rainfall events. Currently the lake discharges
through a culvert under Marschall Road into a complex of wetlands within the Campbell
Lake subdistrict CALK -2. The 2030 drainage plan anticipates that the future Howard
Lake drainage will continue in this pattern to proposed basin CALK -P2, which will
discharge into Campbell Lake. Alternately, if development in CALK -2 benefits from
City ofPrior Lake 5 -35
Local Surface Water Management Plan
routing discharge around this subdistrict and its wetland complex, then Howard Lake's
discharge could be sent directly to Campbell Lake via a pipe under Marschall Road.
From a stormwater management perspective, either route would be acceptable since the
choice of route has no bearing on the calculated discharge from Campbell Lake.
CAMPBELL LAKE (CALK)
Campbell Lake drainage district is located northwest of Spring Lake, bounded by 170
Street and Marschall Road. It consists of roughly 422 acres and is shown on system map
5. The district is characterized by steep slopes surrounding Campbell Lake: CALK -P1.
Campbell Lake is designated as a least susceptible wetland in the Wetland Inventory
(section 4).
Given Campbell Lake's status as "least susceptible" to impacts from urban stormwater
and its large size, it follows that maximum rate control should be obtained within
Campbell Lake. This said, the proposed bounce of 926.0' to 927.8' would be considered
moderate and more in line with a higher susceptibility ranking.
Th 1. t identified a sti by !he DL S IAID in thei initial look at retent p ote n tial
beeattse it lies etitside their- Campbell lake outlets to an agricultural ditch
system in the Louisville Swamp drainage district. Campbell Lake holds some promise as
a retention basin and implementing some retention here would promote reduction in
volumetric discharge to Louisville Swamp Picha Creek and, ultimately, the Minnesota
River.
LOUISVILLE SWAMP (LSW)
The Louisville Swamp drainage district is located on the far western portion of the 2030
growth area and is shown on system map 5. It is bounded on the western edge by
Baseline Road. It covers roughly 1,987 acres of currently agricultural land. Proposed
development is urban low density residential in this districts northern portion and a mix
of urban medium and high density residential and planned industrial in its southern
portions.
Under existing conditions, the LSW drainage is characterized by agricultural ditches.
Two specific ditch alignments occur in the 2030 growth area portion of the drainage:
1. A northerly ditch beginning at Campbell Lake through DNR 57W (LSW -P9)
under Baseline Road to Marystown Road (County Road 15).
2. A southerly ditch beginning at pond LSW -P2 and meeting the northerly ditch east
of Marystown Road. These ditches are more defined and other tributary ditches
more prevalent in areas east of Baseline Road — areas that are outside the 2030
growth boundary.
East of Marystown Road the combined ditches become Picha Creek, a DNR protected
waterway, that crosses under U.S. Highway 169. T h i s afmiamed preteeted w t om mty
e nters Picha Creek flows nearly 3 miles to the northwest dropping 200' in elevation
City of Prior Lake 5 -36
Local Surface Water Management Plan
between the public ditch and Louisville Swamp, which lies adjacent to the Minnesota
River near the confluence of Sand Creek with the River. The WMO has recently
competed proiects in Picha Creek to stabilize eroding banks. The system may already be
in an active eg omorphic unbalance caused by the private agricultural drainage network
For the 2030 system this Plan envisions eliminating the current ditch and drained wetland
system and restoring storage to the landscape. At LSW -P2, for instance, the future
storage could be significantly increased and infiltration promoted if the large wetland
south of the proposed storage basin were restored and used for retention storage and
infiltration. This implementation concept would be particularly appropriate here as the
surrounding landscape is envisioned as planned industrial in the 2030 growth plan —
implying that more runoff will be generated in these areas than elsewhere in the
Louisville Swamp drainage.
Similarly, within proposed basin LSW -P9 a significant amount of storage exists such that
retention volume and infiltration, in addition to the rate control set by this Plan, could
occur — significantly lowering both peak rates and annual runoff volumes discharged
downstream into Louisville Swamp and the Minnesota River — However. this level of
coordination will take leadership from the WMO. The City will work in coordination
with the WMO in this effort.
LSW -P9 holds a strategic location for implementation of the retention concept since it
receives runoff from approximately 756 acres of agricultural land in Shakopee from an
area designated as their Sand Creek Drainage by Shakopee's 1999 Comprehensive
Stormwater Mana eg ment Plan. According to Shakopee's Plan developed discharge rates
of 1/3 cfs /acre will be allowed from this area upon development. This is approximately
the existing rate off the currently agricultural land. It would make sense for Prior Lake
and Shakopee to work cooperatively with the WMO toward lowering this discharge rate
particularly since the ditch system that currently delivers runoff south across the border
drains a particularly large wetland within Shakopee — a wetland that seemingly has
significant potential for decreasing the target discharge rate and implementing some
retention.
There are 756.3 acres of off -site agricultural land tributary from the north in Shakopee.
This runoff enters at West 160 Street East, roughly 500 -feet west of Baseline Avenue.
LSW -1.4. 5.6 and 7 are outside the 2030 boundary , but hold much promise to further
reduce ditch drainage and restore wetlands, thus increasing retention volume infiltration
and flood volume storage. The Cities of Shakopee Prior Lake and Scott WMO should
consider a coordinating planning of trunk stormwater facilities in this drainage district
The City will participate in any coordinated planning of these subwatersheds lead by the
WMO.
CREDIT RIVER (CR)
City ofPrtor Lake 5 -37
Local Surface Water Management Plan
The Credit River district lies on the southeast corner of the study area, shown on system
map 3. It consists of 976 acres of primarily developed area. Subdistricts 1 through 4 are
tributary to CR -P2 which is currently landlocked. Drainage districts 5 -7 travels west to
east, toward the Credit River. Since Credit River district is tributary to existing
agricultural area outside the City limits, this is a priority region for volume control since
increased volume associated with urban stormwater systems has been shown to
negatively impact agricultural lands due to frequent inundation of crop during late season
times when crop drying is important.
The bounce and inundation period requirements are being met for CR -P5, the only
moderately susceptible wetland within the system without an existing piped outlet.
CR -P5 requires berming on the east side to close contours around the pond and protect
developed lots to the east.
MARKLEY LAKE (ML)
The Markley Lake drainage district consists of 529 acres in the southeast corner of Prior
Lake, as shown on system map 3. The drainage moves southwest to northeast to Markley
Lake (ML -P2). ML -P2 will discharge via a 12" forcemain to the Credit River — as
proposed in the 2001 Trunk Storm Sewer Fee Determination Study Much of Markley
Lake is developed in a mix of commercial/industrial and residential. Portion of the ML-
1, 2, and 3 subdistricts remain to be developed.
There are several moderately and least susceptible wetlands in Markley Lake district. To
maintain the integrity of these wetlands, especially as commercial /industrial development
progresses, local water quality ponding is necessary.
ML -P1 requires excavation to create a pond adjacent to Markley Lake. Most of the other
ponds and wetlands utilized for regional ponding in Markley Lake don't require any
grading. Since ML discharge east outside the Prior Lake City Limits to existing
agricultural land, this area has been identified as a priority for volume control.
MYSTIC LAKE (MLK)
Mystic Lake drainage district lies just south of County Road 42. It consists of 228 acres,
shown on system map 1. Much of the Mystic Lake drainage area is Shakopee
Mdewaketan Sioux Community Trust Land and Mystic Lake Casino property.
MLK -P1 is tributary to SC -P1 (Haas Lake) which is a moderately susceptible wetland.
Therefore rate control from MLK -P1 has been greatly restricted by the 12" outlet on the
north side of the lake.
SIOUX COMMUNITY (SC)
City of Prior Lake 5-38
Local Surface Water Management Plan
The Sioux Community drainage district drains south to north into Shakopee. It is so
named due to the large amount of SMSC Trust land within the district. It consists of 771
acres, shown on system map 1. County Road 42 splits the drainage area.
Much of the drainage area within the Sioux Community remains to be developed. A
portion of SC -3 and the majority of SC -7 are SMSC Trust Land with low development
densities. The remaining land is slated for medium density residential, except a small
portion of commercial in SC -2 along County Road 42.
Haas Lake (SC -P1) is the largest regional pond in the system. It receives discharge from
MLK -P1. SC -P1 is characterized by steep slopes adjacent to the lake and is designated a
moderately susceptible wetland (MNRAM number 19115227006). Currently discharge
is restricted from MLK -P1 to sustain existing inundation and bounce in SC -P1. Future
development around the lake should required local ponding to protect the lake and
ravines that surround it. Shoreline protection is required by the City around the lake.
There are a series of ravines north of County Road 42 that SC drains to at the Shakopee
city limits. To prevent erosion in these ravines, ponds are located upstream with
significant rate control. Additional excavation and grading is required at SC -P7 in order
to provide adequate flood storage before discharging north into Shakopee due to the large
ponded and direct tributary area.
POTENTIAL RETENTION
As stated earlier, this Plan identifies certain areas identified by the Prior Lake Spring
Lake Watershed District as having high potential for volume retention. In the discussion
of specific drainage systems other basins are identified that also have some potential for
application of this concept. The system maps identify only those prospective locations
for retention identified by the Watershed, and do not show those that may be discussed in
the preceding text. It should be emphasized that any large basin, regardless of which
Watershed it lies in, has potential for application of retention and infiltration concepts.
This is particularly true for basins termed "least susceptible" where the fluctuations in
water level that occur due to retention storage will have less impact on current wetland
functions and values. Table 5.15 summarizes retention volumes that might be available
between this Plan's proposed outlet elevations and the lowest elevation evident in a
particular basin. Table 5.15 is not intended to stipulate that a particular amount retention
is required, it is only intended a first step in defining what the current surface water
modeling provides by way of potential retention volume.
City of Prior Lake 5 -39
Local Surface Water Management Plan
Table 5.15
Potential Retention Volume
Pond Number
SPLK -P5
SPLK -P6
SPLK -P7
SPLK -P9
SPC -P 1
SPC -P2
CRLK -P 1
RLK -P 1
SPW -P1
SPW -P2
CD13 -P1
Retention Volume (ac -ft)
5.6
7.7
6.1
3.5
9.2
9.0
41.5
262.8
7.7
3.2
42.9
- - - I Formatted Table
City of Prior Lake 5 -40
Local Surface Water Management Plan
OF PRIr,*
T
6. IMPLEMENTATION PLAN
6.1 General
The Implementation Plan section of the Prior Lake LSWMP describes a range of
activities and programs that support improvement of the City's surface water
management program. Capital outlay for the surface water system (pipes, channels, and
ponds) shown on the system maps will be large. For this reason a financing mechanism,
called an area charge, is developed in this section. Based on the Capital Improvement
Plan and the developable acreage, an area charge is developed and application of this
charge is discussed.
The City of Prior Lake adds new water quality and flood control features into th
landscape at the time of new development and assesses redevelopment of transportation
infrastructure for the potential for retrofit of new water quality and flood control features
During major system maintenance, system retrofits have also be pursued.
The concept of an area charge to finance expansion of the trunk stormwater management
system is not a new concept for the City. Since its report titled Trunk Storm Sewer Fee
Determination Study (February, 2001) the City has quantified future trunk and ponding
needs and developed an area charge based on actual costs of these needs spread across
the potential developable acreage. With the analysis contained within the LSWMP the
City will update the fees for the 2030 growth area.
Much of this section of Prior Lake's LSWMP focuses on the analysis that supports the
development of the area charge. There are also several City planning and budgeting
documents that outline surface water management activities undertaken by the City.
Those documents are identified in Table 6.0, and are incorporated by reference into this
Plan.
Table 6.0
Formatted: Font color: Black
e Formatted: Justified, Tab stops: 0.5 ", Left +
1 ", Left + 1.5 ", Left + 2", Left,Leader:... +
2.5 ", Left + 3 ", Left + 3.5 ", Left + 4 ", Left +
4.5", Left + 5 ", Left + 5.5 ", Left + 6 ", Left +
6.5 ", Left
Plan/Document
Revision Frequency/Notes
Capital Improvement Program
Annuall
City Budget Documents
Annually
Storm Water Pollution Prevention Program
Every five years minimum
Joint Stormwater Education Plan for Scott
Every five years
City of Prior Lake 6 -1 6 -1
Local Surface Water Management Plan
Downtown Stormwater Plan I To be developed in 2007 - - - Formatted Table
Section 6 also includes:
• An overview of the City's NPDES permit
• A discussion of operation and maintenance procedures and strategies
• An outline of an education program
• Financial considerations for the storm water utility
• A section referencing applicable design standards for stormwater management
• A section on Watershed implementation priorities
• Implementation priorities for the City
• A discussion of the process for amending this plan and an annual report to council
6.2 Cost Analysis and Capital Improvement Plan
One of the basic objectives of this study was to determine the cost of completing the City
of Prior Lake's trunk stormwater system and at the same time to determine new trunk
area charges that will insure availability of sufficient funds for future trunk and pond
construction.
The cost estimates presented in this report are based on 2004 construction costs and can
be related to the Engineering News Record (ENR) cost index of 7017 (April, 2004).
Future changes in this index are expected to fairly accurately reflect changes in
construction costs for the trunk stormwater system. This cost analysis is completed for
estimation purposed and should not be interpreted as policy.
6.2.1 Cost Estimation Methods
To minimize excavation ponds have generally been proposed for existing low areas.
Where natural topography does not lend itself to ponds either excavation or berming is
proposed to create the requisite pond areas.
Ponds serve to reduce peak flows. In that capacity they are desirable in and of
themselves. Ponds also have an added benefit of reducing downstream pipe sizes and
thus trunk pipe costs. Since ponds themselves involve cost it is desirable to reach a
balance point between ponds and larger pipes so that the least expensive system is
proposed. Generally, when pipes larger than 48- inches are prevalent, overall system
costs might be reduced by additional ponding areas.
Trunk pipes are generally located in existing drainage ways so that excessive pipe depth
can be avoided. This keeps pipe costs down and is the specific reason why it is best to
install trunk pipes in existing drainage ways.
City of Prior Lake 6 -2 6 -2
Local Surface Water Management Plan
Appendix B provides detail on the pipe system and channel reaches while appendix D
provides cost estimates for building these reaches used in the analysis. Appendix D also
includes construction costs for ponds, which follow from the pond data provided in
appendix C.
6.2.1.1 Pipe Costs
Pipe costs are based upon:
• Pipe construction
• Easement Acquisition
• Indirect Costs
Pipe Construction:
The appendix D pipe costs are based upon a pipe cost matrix that relates pipe cost to
diameter and pipe depth. This matrix is based on an analysis of bid tabulations and
discussions with large utility contractors. The matrix is updated annually based on the
ENR index and more recent bid tabulations as they become available. The per linear foot
pipe costs given in appendix D include pipe material costs, installation, manholes, and
bedding, as well as restoration and are thus comprehensive in terms of the various costs
associated with installing pipe. In many cases, existing channels are used in lieu of trunk
pipe. The costs associated with channels are for the excavation and shaping that is
usually necessary to make channels function properly.
Easement Acquisition Assumption:
For each pipe reach a cost is included for permanent and temporary easement. Permanent
easement is calculated at 100% the fee title value of upland areas — estimated at $100,000
per acre in the year 2004. Appendix D includes no costs for temporary easement.
Temporary easement is usually not necessary since construction of facilities occurs on
development sites. As pipe depths increase the permanent easement width around the
pipe also increases. This is reflected in the cost estimates. For the purposes of estimating
costs, it is assumed that 75% of future trunk pipe will fall in dedicated easement or right -
of -way, so easement costs are applied to only 25% of trunk footage.
Indirect Costs:
A 30% factor for indirect costs is included in the cost estimate presented in Appendix D —
applicable to pipe, channel and pond construction. Indirect costs include engineering,
administration, contingencies, and fiscal costs. For easement acquisition a 10% indirect
cost has been applied. This accounts for the appraisal and administrative costs associated
with easement acquisition.
6.2.1.2 Pond Costs
City of Prior Lake
Local Surface Water Management Plan
6 -3
6 -3
Pond costs involve the following:
• Pond construction (excavation and berming)
• Easement acquisition
Pond Construction:
The primary element of pond construction is excavation. To some extent berming will
also be necessary to create the ponds shown in the system maps at the end of this report.
Pond construction costs vary considerably depending on whether excavation is necessary.
At one extreme are ponds that obtain their requisite flood storage solely by excavation.
At the other extreme are ponds that are existing depressions with the required storage
provided or ponds that can be created by berming. To account for the variability in pond
construction costs, three different pond construction costs are used. Each of the three is
based on a unit cost per acre of pond at high water level (HWL). The three costs and the
rationale behind their use are as follows:
1. Minimal excavation or berming: $4,500 /acre of pond at HWL
2. Combination of excavation and berming: $9,000 /acre of pond at HWL
3. Full excavation of flood storage volume: $13,000 /acre of pond at HWL
Appendix D details the costs of pond construction. The construction cost is for providing
flood storage only and does not include costs associated with providing water quality
treatment. As stated previously, water quality treatment is considered a development cost
and not a trunk cost. Creation of water quality volume could occur in the ponds proposed
within the developable area, but this cost would be strictly a developer cost with no
reimbursement or participation by the City.
Pond Easement Acquisition:
For each pond, a cost is included for permanent easement. Permanent easement is
calculated at 50% the fee title value of upland areas (50% x $100,000 /acre =
$50,000 /acre). 50% fee title, instead of 100 %, is used to account for the fact that many of
these low areas are otherwise undevelopable since many are jurisdictional wetlands or
would be used for the required water quality ponding.
No easement cost is associated with existing NWI wetlands or wetlands inventoried as
part of the Wetland Management Plan (section 4 of this Plan), although there may be a
construction cost to account for required berming or expansion. The easement costs for
pond are applied only to those areas that appear to be non - wetland by the methods
employed in preparing this plan.
6.2.2 System Costs and Capital Improvement Plan
Appendix D summarizes the analyzed system costs by element, by major watershed, and
for the system as a whole. Appendix D serves as the City's stormwater CIP for future
development and for calculating area charges.
City of Prior Lake 6 -4
Local Surface Water Management Plan
6 -4
The analyzed system, as shown in system maps, has an estimated cost of $10,992,289.
This cost includes indirect costs of 30% on trunk and pond construction and indirect costs
of 10% on easement acquisition.
Table 6.1 presents the stormwater management CIP for the City of Prior Lake. The cost
elements come directly from the 2030 stormwater system design as described in the
system maps and the appendices to this report. The various trunk elements are organized
by prospective year of implementation as well as whether they constitute a pond cost or
trunk pipe cost. Total costs for the 2030 system are $10,836,957.
Table 6.1
Capital Improvement Plan
Year/Phase
Trunk Storm Sewer Element
Pond Cost (S)
Trunk Cost($)
Pipe
From Point
To Point
2004
CRLK -P2
CRLK -PI
32,163
147,987
RLK -P2
RLK -P1
543,201
147,987
RLK -P3
RLK -P1
145,174
30,003
RLK -P1
CRLK -PI
157,536
SPLK -P3
SPLK -P1
18,909
SPLK -P10
16,283
Total
736,822
502,422
2006
CR -P3
CR -P2
18,609
315,277
CR -P5
CR -P6
7,564
CR -P4
8,723
CR -P6
Credit River
90,763
CRBA -P3
CRBA -P2
215,563
HLK -P2
HLK -Pl
68,073
JP -P1
JP -P2
23,261
38,605
JP -P2
JP -P3
8,141
19,303
JP -P3
JP -P4
23,843
38,605
JP -P4
JP -P5
90,763
LPPL -P2
LPPL -P1
41,647
LPPL -P4
LPPL -P1
43,615
30,254
LPPL -P10
LPPL -P1
75,636
LPPL -P12
LPPL -P1
115,816
LPPL -P5
1,163
LPPL -P9
7,560
LPPL -P1 l
LPPL -P1
45,360
115,816
ML -P5
ML -P7
19,191
ML -P6
ML-Pi
166,400
NIL-Pi
ML -P2
414,548
15,001
ML -P2
Credit River
113,128
ML -Pl l
Credit River
7,564
City ofPrtor Lake 6 -5 6 -5
Local Surface Water Management Plan
City of Prior Lake 6 -6 6 -6
Local Surface Water Management Plan
SPLK -P6
SPLK -P7
44,270
SPLK -P7
SPLK -PI
40,707
45,382
SPLK -P5
SPLK -PI
29,077
18,909
SPLK -P4
SPLK -P1
18,909
UPPL -P15
UPPL -P8
397,828
52,945
UPPL -P8
UPPL -P9
26,473
UPPL -P6
UPPL -P4
71,854
UPPL -P7
UPPL -P4
25,055
Total
1,081,626
1,862,013
2008
CALK -P2
CALK-PI
29,658
13,615
CALK -P3
CALK-PI
17,446
75,636
CALK-PI
LSW -P9
200,436
ERLK -P1
RLK -P1
114,562
13,281
Total
161,666
302,967
2010
LSW -P2
55,827
LSW -P9
LSW -P7
218,075
12,868
LSW -P10
LSW -P7
59,316
7,564
LSW -PI l
Shakopee
15,120
7,564
SPW -P2
SPLK -PI
387,132
200,020
Total
735,470
228,015
2012
CD13 -PI
SPLK -PI
350,664
94,521
PL-pi
PL -P2
214,422
98,327
PL -P2
PL -P4
19,191
310,030
PL -P3
PL -P4
34,892
40,004
PL -P4
PL -P5
41,870
154,422
PL -P5
PL -P16
26,751
115,816
PL -P6
PL -P7
25,006
166,400
PL -P9
PL -P8
109,672
PL -P10
PL -P8
45,382
PL -P8
PL -P7
6,397
25,737
PL -P7
PL -P16
106,087
87,694
PL -P11
PL -P16
75,636
PL -P13
PL -P12
125,581
PL -P12
PL -P16
20,935
30,254
PL -P14
PL -P16
55,827
30,003
PL -P15
PL -P16
45,382
PL -P16
Shakopee
50,111
PL -P17
Shakopee
165,762
3,782
PL -P18
PL -P16
33,152
7,564
PL -P19
PL -P16
66,305
37,818
PL -P20
PL -P16
79,566
41,600
SC -P1
SC -P2
75,636
SC -P2
SC -P7
45,941
450,396
City of Prior Lake 6 -6 6 -6
Local Surface Water Management Plan
6.3 Financing and Cost Recovery
6.3.1 Area Charges and Cost Recovery Calculations
.- - - Formatted: Normal
Formatted: Font: 14 pt, Bold
The City of Prior Lake currently recovers the cost of its trunk stormwater system through
an area charge. This Plan is updating those charges for the 2030 growth area.
At present, the City reduces gross acreage by wetland area and park area to determine a
developable acreage. This developable acreage is reduced further to account for area that
would not be subject to area charges: storm pond easements, major road right -of -way,
greenway corridors, park dedication, and wetland buffers.
The total acreage then available for application of area charges was set at 3,524 acres out
of the developable acreage within the 2030 growth area. The acreage to which area
charges apply is termed the financing area and includes only those areas developing
within the financing analysis period.
For financing purposes, the net developable acreage within the 2030 growth area is 3,524
acres. In order to determine an equitable financing schedule it is also necessary to
convert acres into equivalent acres and base the financing analysis on a reasonable break
even period.
City of Prior Lake 6 -7 6 -7
Local Surface Water Management Plan
SC -P7
Shakopee
106,087
200,442
SC -P3
SC -P4
81,415
136,145
SC -P4
Shakopee
23,261
35,003
SC -P5
Shakopee
18,028
52,945
SC -P6
Shakopee
20,354
15,127
SC -P8
Shakopee
55,827
7,564
SC -P9
Shakopee
152,501
7,564
SPC -P2
SPC -P1
171,358
20,002
SPW -P1
SPW -P2
51,756
238,067
Total
1,973,354
2,937,627
2014
LSW -P3
75,599
Total
75,599
2024
SPLK -P9
SPLK -P1
26,169
22
SPLK -P8
SPLK -P1
15,217
SPC -P1
SPLK -P1
175,387
Total
26
213,205
Grand Total
10 836,967
6.3 Financing and Cost Recovery
6.3.1 Area Charges and Cost Recovery Calculations
.- - - Formatted: Normal
Formatted: Font: 14 pt, Bold
The City of Prior Lake currently recovers the cost of its trunk stormwater system through
an area charge. This Plan is updating those charges for the 2030 growth area.
At present, the City reduces gross acreage by wetland area and park area to determine a
developable acreage. This developable acreage is reduced further to account for area that
would not be subject to area charges: storm pond easements, major road right -of -way,
greenway corridors, park dedication, and wetland buffers.
The total acreage then available for application of area charges was set at 3,524 acres out
of the developable acreage within the 2030 growth area. The acreage to which area
charges apply is termed the financing area and includes only those areas developing
within the financing analysis period.
For financing purposes, the net developable acreage within the 2030 growth area is 3,524
acres. In order to determine an equitable financing schedule it is also necessary to
convert acres into equivalent acres and base the financing analysis on a reasonable break
even period.
City of Prior Lake 6 -7 6 -7
Local Surface Water Management Plan
Typically stormwater area charges are applied to equivalent area with and equivalent acre
adjusted to reflect the greater burden placed upon the stormwater system by more
impervious land uses like commercial, industrial, and high density residential. Table 6.2
provides a summary of equivalency factors used by the City of Prior Lake. Equivalency
factors are based upon runoff coefficients for the different land uses with urban low and
medium density residential considered as a base case.
Table 6.2
Land Use Based Equivalency Factors
Land Use
Factor
Urban Low and Medium
1.0
Density
Urban High Density
1.65
Residential
Commercial and Industrial
2.07
Table 6.3 presents the cost recovery analysis based upon application of these equivalency
factors and a 20 -year break even assumption.
- - - Formatted Table
City ofPrior Lake 6 -8 6 -8
Local Surface Water Management Plan
Table 6.3
Stormwater Area Charge
50% Land Cost for Constructed Pond Easement
A
B -1
B -2
B -3
C
D
E
Phase
Net Developable
(Assessable)
Acreage Added -
Residential
Net Developable
(Assessable)
Acreage Added -
Non - Residential
Net
Developable
(Assessable)
Acreage Added
-TOTAL
Equivalent
Area Added
REVENUE
Column C x Area
Charge of
$2790 Ac
EXPENDITURE City
Trunk Costs
r
ac
ac
ac
E Ac
$
$
2004 -2009
1312
133
1445
1587
4,428
4,647,517
2010 -2014
1467
224
1691
1931
5386 597
5
2015 -2019
243
]0
253
264
735
0
2020 -2024
135
0
135
135
376
239 374
Totals 3,157 367 3,524 3,917 10,927,565 10,836,967 • - - - Formatted: Centered
Note: Developable Area within municipal boundary phased in between 2004 -2014.
City of Prior Lake &9
Local Surface Water Management Plan
In some instances developers will dedicate or construct at their own cost the trunk
infrastructure necessary to serve future upstream development. This Plan serves as a
guide as to what is necessary for upstream development. In these cases developers may
seek a credit toward area charges — a credit that can be quantified based upon the analysis
of the preceding sections.
6.3.2 Area Charge Summary
Sections 6.2 and 6.3 develop an area charge for the City of Prior Lake that can be applied
to future development within the City. The area charge has been constructed
methodically as follows:
1. Pond and trunk costs for near term development have been estimated. A
stormwater CIP has been created as shown in appendix D and table 6.1.
2. Net assessable acreage has been determined.
3. The base area charge has been modified into a land use based area charge through
the use of equivalent acres.
6.4 NPDES Permit
Refer to City MS4 permit and Storm Water Pollution Prevention Plan for additional
operations, maintenance, and reporting requirements.
6.5 Operation and Maintenance
6.5.1 Activities
A storm water system is a major investment for the City of Prior Lake — both in terms of
initial capital cost and in terms of ongoing maintenance costs. The capital improvement
program outlines the costs for new trunk system construction which will be funded by
area charges. System maintenance is funded by the city's storm water utility.
The city's storm water system maintenance responsibilities include the following:
■ Street sweeping
■ Cleaning of sump manholes and catch basins
■ Repair of catch basins and manholes
■ Assessing pipe condition (typically by televising)
■ Inspection of storm sewer inlet and outlet structures
■ Pond mowing and other vegetation maintenance
■ Excavation of accumulated sediments from ponds
The city has maintained its pipe system for decades and staff has a strong grasp on the
costs associated with this. As new development brings more ponds into the system, city
staff will find that pond maintenance becomes an increasingly large portion of both staff
time and maintenance budget. It is important to quantify the extent of this future
commitment so that the funds necessary for pond maintenance activities can be collected
via the city's storm water utility.
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Local Surface Water Management Plan
6 -10
Table 6.4 provides a typical maintenance schedule for wet ponds.
Table 6.4
Wet Pond Maintenance Schedule
Activity
Schedule
Inspect regional pond outlets for clogging.
After significant
rainfalls
Inspect for damage.
Annual inspection
Note signs of hydrocarbon build up.
Monitor for sediment accumulation in the facility and forebay.
Examine to ensure that inlet and outlet devices are free of debris
and operational.
Repair undercut or eroded areas.
As needed
Mow slopes
Twice annuall
Remove sediments from forebay
5 to 7 year cycle
Remove sediment accumulated in main pool
20 to 30 year cycle
naaptea trom watersnea management institute. iYY t. t)peration, maintenance, ana management or ;mormwater
Management Systems.
As the city obtains more ponds, the management of these might be facilitated by creation
of a GIS database for all storm water system infrastructure. Via this database the city
could reference, via interactive mapping, maintenance records, videotapes, and
maintenance costs for portions of their system.
6.5.2 Stormwater Basins
Stormwater basins represent a sizable investment in the City's drainage system. General
maintenance of these facilities helps ensure proper performance and reduces the need for
major repairs. Periodic inspections are performed to identify possible problems in and
around the basin. Inspection and maintenance cover the following:
• Basin outlets
• Basin inlets
• Side slopes
• Illicit dumping and discharges
• Sediment buildup
Basin Outlets
A key issue with stormwater basins is ensuring that the outlets perform at design
capacity. Inspection and maintenance of basin outlets address the following:
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Local Surface Water Management Plan
6 -11
• The area around outlets is kept free and clear of debris, litter, and heavy vegetation.
• Trash guards are installed and maintained over all outlets to prevent clogging of
the downstream storm sewer.
• Trash guards are inspected at least once a year, typically in the spring, to remove
debris that may clog the outlet. Problem areas are addressed more frequently, as
required.
• Emergency overflow outlets are provided for all ponds when possible. These are
kept clear of debris, equipment, and other materials and properly protected against
erosion.
Basin Inlets
Inspection and maintenance of basin inlets address the following:
• Inlets are inspected for erosion.
• Where erosion occurs near an inlet, energy dissipaters or riprap are installed.
• Inlets are inspected for sediment deposits, which can form at the inlets due to poor
erosion practices upstream.
• Where sediment deposits occur, these are removed to ensure design capacities of
storm sewers entering the basin are maintained.
Side Slopes
Inspection and maintenance of basin side slopes address the following:
• Side slopes are kept well- vegetated to prevent erosion and sediment deposition into
the basin. Severe erosion along side slopes can reduce the quality of water
discharging from the basin and require dredging of sediments from the basin.
• Noxious weeds are periodically removed from around basins.
• Some basins in highly developed areas require mowing. If mowing is performed, a
buffer strip of 20 feet or more adjacent to the normal water level is typically
maintained. This provides filtration of runoff and protects wildlife habitat.
Illicit Dumping and Discharges
Inspection and maintenance of illicit dumping and discharges into basins address the
following:
City of Prior Lake 6 -12 6 -12
Local Surface Water Management Plan
• Basins are periodically inspected for evidence of illicit dumping or discharges.
The most common of these is dumping of yard waste into the basin.
• Where found, illicit material is removed, and signs are posted as needed
prohibiting the dumping of yard waste.
• Water surfaces are inspected for oil sheens. These can be present where waste
motor oil is dumped into upstream storm sewers.
• Skimmer structures are installed as needed at outlet structures to prevent oil spills
and other floatable material from being carried downstream.
• Skimmer structures are periodically inspected for damage, particularly from
freeze -thaw cycles.
Sediment Buildup
Inspection and maintenance of sediment buildup in basins address the following:
• Basins are inspected to determine if sediment buildup is causing significant loss
of storage capacity from design levels. Excessive sediment buildup significantly
reduces the stormwater treatment efficiency of water quality ponds.
• Sediment removal is performed where excessive sediment buildup has occurred.
As a general guideline, ponds require dredging every 15 to 20 years.
6.5.3 Sump Manholes and Sump Catch Basins
Sump manholes and sump catch basins are included in storm sewer systems to collect
sediments before they are transported to downstream water bodies. These structures keep
sediments from degrading downstream water bodies. Once sediments are transported to a
lake or pond, they become much more expensive to remove.
Sediments originate primarily from road sanding operations, although construction
activity and erosion can also contribute. Since these structures are designed to collect
these sediments, they are routinely inspected and cleaned to provide capacity for future
sedimentation. Suction vacuum equipment is typically used.
6.5.4 Storm Sewer Inlet Structures
To fully utilize storm sewer capacity, inlet structures are kept operational in order to get
runoff into the system. All efforts are made to keep catch basins and inlet flared ends
free of debris and sediments so as not to restrict inflow and cause flood damage. Leaf
and lawn litter are the most frequent cause of inlet obstructions. On a routine basis, City
staff visually inspects inlet structures to ensure they are operational.
City of Prior Lake 6 -13 6 -13
Local Surface Water Management Plan
6.5.5 Open Channels
Overland flow routes constitute an important part of the surface water drainage system.
Open channels are typically vegetated and occasionally lined with more substantial
materials. The lined channels typically require little or no maintenance. Vegetated
channels are periodically inspected and maintained, as high flows may create erosion
within the channel.
Eroded channels can contribute to water quality problems in downstream water bodies as
the soil is continually swept away. If not maintained, the erosion of open channels would
accelerate and the repair would become increasingly more costly. The use of
bioengineering and natural stream technology, which mimics the characteristics of
natural streams to promote channel stability, can reduce the potential for erosion.
6.5.6 Piping System
The storm sewer piping system constitutes a multimillion - dollar investment for the City.
The City performs a comprehensive maintenance program to maximize the life of the
facilities and optimize capital expenditures. The following periodic inspection and
maintenance procedures are followed:
• Catch basin and manhole castings are inspected and are cleaned and replaced as
necessary.
• Catch basin and manhole rings are inspected and are replaced and/or regrouted as
necessary.
• Catch basin and manhole structures are inspected and are repaired or replaced as
needed. Pipe inverts, benches, steps (verifying integrity for safety), and walls are
checked. Cracked, deteriorated, and spalled areas are grouted, patched, or
replaced.
• Storm sewer piping is inspected either manually or by television to assess pipe
condition. Items looked for include root damage, deteriorated joints, leaky joints,
excessive spalling, and sediment buildup. The piping system is programmed for
cleaning, repair, or replacement as needed to ensure the integrity of the system.
6.5.7 De -Icing Practices
Minnesota receives approximately 54 inches of snow during a typical year. This requires
a large amount of de -icing chemicals (primarily salt) to be applied to roads and sidewalks
each winter.
Estimates indicate that 80 percent of the environmental damage caused from de -icing
chemicals is a result of inadequate storage of the material (MPCA 1989). Improper
City of Prior Lake 6 -14 6 -14
Local Surface Water Management Plan
storage as well as overuse of salt increases the risk of high chloride concentrations in
runoff and groundwater. High chloride concentrations can be toxic to fish, wildlife, and
vegetation.
The following procedures are used for storing de -icing chemicals in the City.
1. De -icing material is stored in waterproof sheds. Where this is not possible,
stockpiles are covered with polyethylene and placed on impervious surfaces.
2. Road de -icing stockpiles are not located near municipal well areas or in other
sensitive groundwater areas.
3. Runoff from stockpiles is not allowed to flow directly into streams or
wetlands where environmental damage can occur.
Prior Lake has established a detailed "snow and ice removal policy" that is included in
the 2009 "Street Maintenance Policy" reference document to address winter maintenance
needs. Street conditions are assessed for each individual event and ice control material
application is adjusted accordingly. Equipment is maintained in good working order to
place ice control material on roadways and is properly calibrated to prevent excessive
application. The City is in the process of building its own sand/salt storage facility.
6.5.8 Street Sweeping
Street sweeping is an integral part of the City's effective surface water management
system. It greatly reduces the volume of sediments that have to be cleaned out of sump
structures and downstream water bodies. The City has a "street sweeping policy" that
includes t#Fee tareeted intensive sweeping operations ' I , - e efteii as dietated
b� the City F. based on drainage area and frequency of sweeping. Spring sweeping
begins eithePin late Mafeh ef „-,. April after th _isk of later sne v h passed d
targets sand i;-A-. fifeem- vaiii-teir sanding epef:aAefis. Fall sweeping eeews after leaf fall. The
ebruary and ends in mid November,
depending on snow
Prior Lake does not allow residents to rake leaves into the street for pick up, but does
provide a compost site where residents can bring their leaves. This greatly reduces the
incidence of inlet blockages and protects the water quality of downstream water bodies.
The objective of both programs is to minimize impacts from leaf litter, sand, salt and
other debris on the surface waters of the City. The Sweeping Policy is included in the
"Street Maintenance Policy." reference document listed in table 6.
6.5.9 Detection of Illicit Connections
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Local Surface Water Management Plan
As presented in the goals section Prior Lake will modify its ordinance to prohibit the
dumping of hazardous material into the stormwater system. As staffing allows the City
will also inspect storm sewer outfalls during dry periods to determine if any illicit
sanitary sewer connections are evident.
The City will also begin the process, as staffing allows, of mapping its storm sewer
outfalls and integrating this mapping with inspection data.
6.6 Education
6.6.1 General
Education can play an important role in any effort to implement a stormwater
management program like the one outlined in this LSWMP. The objectives of an
education effort are different, depending on the target audience. In general, the target
audience for this education program is City staff, City residents, and the development
community. The following sections describe why education of each of these groups is
important and presents educational methods that may be used for each audience.
6.6.2 City Staff
City Staff have a wide range of responsibilities for implementing this plan. These
include:
• Implementing street sweeping and spill response programs.
• Maintaining detention basin/stormwater management pond performance and
system operability.
• Planning for, and management of projects to enhance pollutant removal
performance, wetland quality, etc.
• Carrying out grounds maintenance of City-owned lands /facilities in a way that
sets a good example for residents.
• Utilizing BMPs in application of ice control material.
• Application of Best Management Practice policies and regulations to new and
redevelopment projects.
• Planning and delivering education programs.
• Working out cooperative arrangements with regulatory and non - regulatory
organizations to achieve LSWMP objectives.
• Assisting the City Council in the application of the LSWMP policies.
City of Prior Lake 6 -16
Local Surface Water Management Plan
6 -16
Because these responsibilities involve many different levels of City staff, City staff
members are trained to have a basic understanding of the LSWMP, including:
• A description of the major stormwater management issues (including known
stormwater management problem areas, stormwater management expectations for
new and re- development projects, and incorporation of stormwater mitigation into
capital improvement projects, and regulatory jurisdictions).
• The objectives of the LSWMP and the general approach outlined in the LSWMP
for resolution of these issues.
• The responsibilities of the different work units in implementing the LSWMP.
• The information the LSWMP provides.
• Identification of in -house experts.
This information is disseminated in presentations at staff meetings, coverage in internal
newsletters, and issuance of internal memos.
6.6.3 City Residents
In order to obtain the necessary political and economic support for successful LSWMP
implementation, it is vital to inform City residents about basic stormwater management
and water quality concepts, policies and recommendations in the LSWMP, and the
progress of stormwater management efforts.
For example, the City has incorporated stormwater management practices into a number
of utility reconstruction projects that benefit stormwater quality in the watersheds of
some of the City's most visible lakes. It is important that residents know about these
projects (including how they were funded) so that they develop an awareness that the
City is being responsive to the public interest in protecting these high priority resources
and that dedicated financial resources such as revenue from the stormwater utility are
being put to work.
This information is presented to the public through the City newsletter: The Wavelength,
press releases on the City website or to local papers, through the Mayor's and City
Manager's columns, and at public meetings as appropriate. Periodic updates on the
progress of LSWMP implementation and information on specific improvement projects is
also provided to the public. Again, the City newsletter and press releases to local papers
are good methods by which this information is disseminated.
The City's Lake Advisory Committee provides educational brochures on a periodic basis.
The City also contributes, through its stormwater utility, to the Citizens Assisted
Monitoring Program (CAMP). This Metropolitan Council sponsored program has as one
of its primary goals the development of a lakes water quality database to facilitate
understanding of the processes involved in urban lakes. The City also conducts bacteria
testing at beaches and makes these results available to the public.
City of Prior Lake 6 -17 6 -17
Local Surface Water Management Plan
6.6.4 Development Community
The LSWMP is designed to provide the official policy direction that City staff and the
City Council desire to guide stormwater mitigation for new and redevelopment projects.
The information contained within this plan is disseminated to developers and their
consulting engineers as early as possible in the development review process. In this way
developers know what is expected of them and can consider the requirements in their
initial assessments of the site as well as incorporate the necessary BMPs in any
subsequent designs. Much of the necessary information is disseminated to the developers
in an information packet in the development submittal information they receive from the
City.
While dissemination of information is valuable, there is no substitute for a meeting
between key City staff and the developer as early as possible in the review process. This
helps define expectations for submittals, clarify regulatory compliance issues, and
provide additional detailed guidance. Developers are encouraged to do this as soon as
possible after they have reviewed the LSWMP information and thought about how it
applies to their site.
6.7 Financing and the Stormwater Utility
6.7.1 Current Status - Summary
The City of Prior Lake implemented a stormwater utility in 1993. The current quarterly
residential charge is $897.25 per residential unit. Annual revenue from the stormwater
utility has grown as shown in table 6.5.
Table 6.5
Stone Water Utility Revenue
Year Annual Revenue ($) t _ Formatted Table
1997 137,000
49W +
2001 257,000 - Formatted Table
2802 2.83428,000
Generally, revenue has grown not because of increases in the charge (the charge has gone
from $5.63 in 1997 to $6.00 in 2005, to 7.25 in 2009, an annual increase e€-6 6 less than
2 %) but due to development bringing in more properties over which to collect the charge.
With this increased revenue, though, has come an increase in the City's maintenance
responsibilities.
In the past the stormwater utility has funded a staff position, programs, and capital
expenditures. The 20Q capital projects totaled $448610,000 and included a
, water quality maintenance and seine
City of Prior Lake 6 -18 6 -18
Local Surface Water Management Plan
retrofit of 10 pond sites and retrofit water qualit+ systems
as part of street reconstruction projects.
6.7.2 The Stormwater Utility into the Future
In order that storm water utility (SWU) funding keeps pace with increase in municipal
maintenance responsibilities, the city should plan for the costs to conduct periodic pond
maintenance. Limited data on maintenance activities has been developed by watershed
management organizations. A review of this data suggests an annual maintenance budget
of $1,250 per acre -foot of wet volume or $4,350 per acre of surface at NWL. Either
parameter is relatively easy to track. This $1,250 per acre -foot maintenance item can be
translated into a per household cost by virtue of the fact that one acre -foot is sufficient
pond wet volume for 20 acres of residential development. Assuming 2.5 units per gross
acre, then $1,250 per year is spread among 50 units - $25 per unit per year.
The current residential rate is $24 per unit per year. The current charges provide
approximately $300,000 per year in revenue of which only about $20,000 to $40,000 has
been used for pond maintenance. As the city's maintenance responsibilities grow the
storm water utility funding also needs to grow to keep pace.
Prior Lake is a regulated MS4 under the Phase II NPDES Permit. There is a cost
associated with preparing an NPDES permit and the associated Storm Water Pollution
Prevention Plan ( SWPPP). Some estimate cities the size of Prior Lake will spend
$50,000 every five years for permit preparation. For Prior Lake it is reasonable to
assume that $10 per household will be spent every five years — adding $2 per year to the
individual household's storm water utility bill.
The NPDES permit and SWPPP commit the city to certain activities, including capital
projects, for the purpose of improving the quality of the city's storm water discharge.
The U.S. EPA has estimated that the financial commitments that city's will make may
total $10 per household per year. Others place this figure at $20. Since many of the
activities identified by the SWPPP may already be funded (like street sweeping and pond
maintenance) the $20 figure is probably too high. For the purposes of planning increases
in SWU collection the $10 per year figure should be used. Table 6.5 summarizes the
additional storm water utility charges identified above.
Table 6.6
Future Storm Water Utility Funding
Item
Annual Charge to Single
Residential Unit
Quarterly Charge to Single
Residential Unit
Current commitments
$24.00
$6.00
Future pond maintenance
$25.00
$6.25
NPDES permit and SWPPP
$2.00
$0.50
NPDES permit compliance
1 $10.00
$2.50
Total
1 $61.00
$15.25
City of Prior Lake 6 -19 6 -19
Local Surface Water Management Plan
The estimate of stormwater utility funding needs does not include City participation in
TMDL processes nor does it include preparation by the City of a non - degradation
analysis as currently required in the draft of the new Phase II NPDES Permit. And the
estimate of funding needs does not include any mitigation that may occur due to the
TMDL or non - degradation processes.
A $61.00 /residential unit charge would be close to one of the highest rates among Metro
Area cities.
City of Prior Lake 6 -20 6 -20
Local Surface Water Management Plan
6.8 Design Standards
The City of Prior Lake has produced and regularly updates a Public Works Design
Manual. The latest version of this manual is titled Public Works Design Manual. Lfty of
Prior Lake, 3anuary, 16 2007. This manual, as revised, is adopted by reference
into this Surface Water Management Plan as the applicable design standard for surface
water management.
6.9 Watershed Implementation Priorities
Among the two watershed districts that cover the City, only the Prior Lake Spring Lake
Watershed District has developed a detailed list of implementation priorities. At present
the primary implementation priority for Scott WMO is implementation of its Rules,
adopted on May 10, 2005.
The Prior Lake- Spring Lake Watershed District has adopted a Water Resources
Management Plan that includes programs and projects focused on water quality and
runoff management, land management to improve water quality and reduce runoff
volumes, and management of the Prior Lake Outlet System. Additional information
about the District's implementation priorities, programs and projects can be found at
www.plslwd.org or by contacting the District office at (952) 447 -4166.
6.10 City of Prior Lake Implementation Priorities
Downtown Redevelopment
In 2007 the City will pfepese a downtown stormwater management study that
will estimated costs to provide a plan hestormwater management within a downtown
overlay. This plan will spell-etit site specific BMPs for rate and volume control,
as well as proposed centralized facilities that will meet City and District rules.
the dewntevffi area is sehedtiled te begin in 2011. When !his r-eeenstfuefieft begins, the
appreved dewmewn stefmweAer- management stud) will be implemented At draft, it
appeared prohibitively expensive to treat to a uniform standard in the highly impervious,
small lot downtown condition. The Citv intends to engage the Watershed District in a
cooperative effort to create a downtown water management overlay that exempts
downtown development from a portion of the standard, make a clean -water bank of
projects that will mitigate for the deficiency. In the interim. the City will continue to look
for opportunities to retrofit small site BMPs, water quali , improvements, and rate
control improvements as warranted by downtown redevelopment activities
City of Prior Lake 6 -21 6 -21
Local Surface Water Management Plan
Other implementation priorities for the City as it adopts this Plan and begins the
implementation phase of the Plan include:
1. Assisting the PLSLWD in implementing its retention storage program. Specific
areas with high potential for City implementation are indicated on the system
maps and within the body of this Plan.
2. Increasing Storm Water Utility Funding so that the City can meet its current and
future obligations toward pond maintenance, NPDES compliance, and mitigation
that may come out of the City's non - degradation analysis.
3. Application of the revised area charge outlined in this report and update of the
area charge based on increases in land value and construction costs.
4. Implementation of the rate control targets as outlined in the appendices and
stormwater modeling that supports this plan.
5. Application of the wetland susceptibility criteria in determining how wetlands are
used for flood storage, retention, and rate control.
6. Working with the PLSLWD regarding the feasibility of augmenting storage in
Buck Lake.
7. Working with the City of Shakopee toward redefining rate control objectives from
their Sand Creek drainage which will ultimately enter the City of Prior Lake
system through its Louisville Swamp system.
8. Gaining equivalency with Scott WMO and PLSLWD rules.
9. Working in partnership with WMO and WD to minimize for downstream impacts
due to urbanization.
10. Passing ordinance revisions consistent with rules regarding buffer widths by
August 9, 2006.
11. Implement the City NPDES permit and SWPPP.
6.11 Amendment Procedures
The Prior Lake LSWMP is intended to extend through the year 2016. For the plan to
remain dynamic, an avenue must be available to implement new information, ideas,
methods, standards, management practices and any other changes that may affect the
intent and/or results of the LSWMP. The amendment procedure for the LSWMP is
presented below.
Request for Amendment
Written request for plan amendment is submitted to City staff. The request shall
outline the need for the amendment as well as additional materials that the City will
need to consider before making its decision.
Staff review of Amendment
A decision is made as to the validity of the request. Three options exist: 1) reject the
amendment, 2) accept the amendment as a minor issue, with minor issues collectively
added to the plan at a later date, or 3) accept the amendment as a major issue, with
major issues requiring an immediate amendment. In acting on an amendment request,
City of Prior Lake 6-22
Local Surface Water Management Plan
6 -22
City staff shall recommend to City Council whether or not a public hearing is
warranted.
Council Consideration
The amendment and the need for a public hearing shall be considered at a regular or
special Council meeting. Staff recommendations should also be considered before
decisions on appropriate action(s) are made.
Public Hearing and Council
This step allows for public input based on public interest. Council shall determine
when the public hearing should occur in the process. Based on the public hearing, the
City Council could approve the amendment.
Council Adoption
Final action on an amendment is City Council adoption. However, prior to the
adoption, an additional public hearing could be held to review the plan changes and
notify the appropriate stakeholders.
Coordination with WMO and WD
To the extent and manner required by the Scott WMO all amendments to the LSWMP
shall be submitted to the WMO for review and approval in accordance with applicable
state rules and statutes. (Section 103B and Rules)
To the extent and manner required by the PLSLWD all amendments to the LSWMP
shall be submitted to the WD for review and approval in accordance with applicable
state rules and statutes. (Sections 103B, 103D and Rules)
When new LS amendments are considered, associated official controls should
be considered and updated concurrently. or within 120 days following the approval of
the LSWMP amendments.
6.11.1 Minor amendments:
Changes required for TMDL's, Nondegradation Planning, and Ground Water Protection
plans will be considered minor amendments to this document.
6.12 Annual Report to Council
A brief annual report will be made by City staff summarizing development changes,
capital improvements, and other water management- related issues that have occurred
over the past year. The review will also include an update on available funding sources
for water resource issues. Grant programs are especially important to review since they
may change annually. These changes do not necessarily require individual amendments.
The report can, however, be considered when the plan is brought up to date. The annual
City ofPrior Lake 6 -23 6 -23
Local Surface Water Management Plan
report should be completed by July 0 to allow implementation items to be considered in
the normal budget process.
The City's LSWMP will remain in effect through 2016. The City will then review the
LSWMP for consistency with current water resource management methods. At that time,
all annual reports and past amendments will be added to the document. Depending on the
significance of changes, a new printing of the LSWMP may be appropriate. At a
minimum, the Capital Improvement Program should be amended every five years.
City of Prior Lake
Local Surface Water Management Plan
6 -24 6 -24
Street Maintenance Policies
City of Prior Lake
O� PRIOR
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Adopted December 2009
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Table of Contents
I .
II.
III..
IV
V.
Street Maintenance Policy
Street Sign Policy
Sidewalk and Trail Inspection /Maintenance Policy
Street Sweeping Policy
Winter Maintenance Policy
December 2009
December 2009
December 2009
May 2007
November 2010
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Adopted December 2009
(P RIO +P ES
Street Maintenance Policy
STREET MAINTENANCE POLICY
STREET MAINTENANCE POLICY
Adopted by City Council
On December 7, 2009
1. Introduction /Purpose
The purpose of this policy is to define and outline street maintenance criteria and procedures
for the City of Prior Lake.
The City of Prior Lake, Minnesota has 99 center lane miles of public streets. Streets vary in
age and in quality of condition. The City recognizes that some street conditions can create
unreasonable hazards to motor vehicles and other street users. The City of Prior Lake will
use this policy to ensure efficient, cost effective, and organized maintenance of City owned
streets throughout the community. This will ensure better safety for residents, and a
prolonged and improved life of Prior Lake streets and infrastructure. The City will use City
employee's, City owned or rented equipment, and /or private contractors to provide the
maintenance necessary.
This policy supersedes any and all previously written or unwritten policies of the City
regarding street maintenance. The Public Works Department will review this policy
periodically and will recommend amendments as appropriate.
In the event of an emergency or other unanticipated event, deviation from any standards may
be expected.
2. Street Repair Criteria
The City has limited employee and financial resources and cannot reasonably
replace /maintain all roadways needing repair within the same year the street is identified as
needing replacement or repair. Street repair and replacement is expensive. Accordingly, the
City and its Public Works Department must exercise both discretion and professional
judgment when determining whether a street is in need of repair and what type of repair will
be most beneficial and cost effective. The criteria in determining such, is listed but not
limited to the following:
a. Location of the street
b. Location with respect to other streets in need of repair
c. Amount of traffic the street carries
d. City resources for repair
e. Existence of holes deeper than 2 inches
f. Existence of cracks wider than 1.5 inches
The City of Prior Lake utilizes a Pavement Management Program to rate street conditions.
Condition ratings are established for each street using an Overall Condition Index (OCI)
which illustrates the level of distress and overall street condition on a 0 (worst) to 100 (best)
VADocuments \Downloads \Street Maintenance Policy \Street Maintenance Policy- 2009.docxl
1
STREET MAINTENANCE POLICY
scale. An example of low (left), medium (middle), and high (right) severity cracks is shown
below.
3. Maintenance and Inspection Schedules
The City is divided into three sections with one of the three being inspected every year from
May to October. The inspections are used to reevaluate each street and make adjustments to
its pavement condition rating. Upon completion of the street inspections, the Public Works
Supervisor and the Engineering Staff establish a maintenance and replacement schedule.
This schedule is subject to modification by the Director of Public Works under the following
circumstances:
a. Budgetary limitations
b. Time limitations
c. Resource limitations or changes
d. Priority changes
e. Emergency situations
f. Poor weather conditions
A schedule for maintenance activities, inspections, and planning is shown below:
May - September
Record all maintenance activities during year (mill and overlay (M &
O), sealcoat, maintenance resurfacing and patching)
Supply info to pavement database manager for updates
May - October 15
Complete annual inspections of 1/3 of city streets
October 1 — 31
Re -rate areas of maintenance activities for the year
October 1 — 31
Rate all streets in 5 -year CEP and take pictures of current conditions
(need photos of each recon area in 5 -year CEP, also include M & O
and sealcoat photos of the next year)
October 31
Update database according to inspections & maintenance activities
this year
Export OCI for use in GIS mappin
October 31
Determine the M & O, Sealcoat and Maintenance Resurfacing areas
for next 5 -year CIP
Provide schedule to be included in revised maps
November 15
Update all Pavement Management maps
December 31
Prepare photos & end -of -year alphabetical segment/OCI list for
record-keeping binder
January
Group to present PM at Council Workshop
( only when new Council members take office
January
CIP planning begins
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http: / /www.tib.wa.gov /tibinfo /publications /GeneralInfol Pavement% 20Conditions %2OManual % 2 0for %
Transportation Improvement Board
STREET MAINTENANCE POLICY
4. Maintenance Procedures
The City of Prior Lake uses six main forms of street maintenance as a preventative repair and
one method of full replacement. The preventative methods are cost effective procedures that
prolong the life of a street and postpone a full street reconstruction. Each form of
maintenance requires its own equipment and materials, and each provides its own benefit to
the street.
a. Crackseal
In most instances cracks are routed to provide an acceptable form to allow filling of
the crack with a hot applied rubberized material to prevent water infiltration into the
road base. This repair may take place one to two years in advance of other scheduled
maintenance activities due to budgetary limitations. There are no OCI increases
following this maintenance activity. Reasoning is due to the fact that the entire street
surface area is not being protected.
b. Mill and Overlay
Milling consists of grinding the old bituminous surface down at the outside edges to
establish a uniform cross - section of pavement prior to installing new bituminous. M
& O is only used on streets with existing concrete curb and gutter. An overlay is an
asphalt structural improvement of 1.5 to 2.5 inches, which extends the life of the
existing pavement typically by about 15 -20
years. Prior to an overlay being installed,
damaged areas must be repaired to prevent
existing cracks, holes, or weak areas from
deflecting up through the new surface over
time. OCI increases to 95 following this
maintenance activity. OCI Range: 50 -65
c. Maintenance Resurfacing
Maintenance resurfacing is only used on
streets with existing bituminous curb or no
curb. Resurfacing can be an asphalt
structural improvement of 1.5 inches, which
extends the life of the existing pavement,
typically by about 10 years. However, many
times, resurfacing is needed to hold a street
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Asphalt Oveday
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together or make it passable until it can be
reconstructed. OCI increases to 80 following this maintenance activity. OCI Range:
50 -65
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STREET MAINTENANCE POLICY
d. Seal Coat
This is a surface application of an asphalt emulsion followed by the placement of
small graded aggregate. The improvement is non - structural, but it is a wear - resistant
coating that protects the pavement from the effects of oxidation, moisture, and water
penetration. Typically, this form of maintenance extends the life of the pavement 8 -10
years. Crack sealing practice is highly recommended prior to seal coating to prevent
surface water from entering the base layer where it begins its damage. Thermal
cracks develop because the asphalt expands and contracts from temperature
fluctuations as seasons change. The OCI increase following this activity is determined
by re- rating the segment. OCI Range: 60 -90
e. Patch and Repair
This activity involves the repair of the typical "pothole" or other similar small
isolated section of structural failure. This may include the milling, grinding, or
removal and repair of the street section. These methods will create a bed to better
hold the new pavement layer and will allow for drainage flow to be maintained. If
the pavement is cracked or damaged full depth or the aggregate base has failed, the
deteriorated area will need to be removed and replaced. Maintenance areas are
determined by Streets Supervisor
Note: Patch and Repair will be limited on streets within one year of a planned
reconstruction.
E Full Depth Reclamation
This process is utilized when there are pavement distresses related from a road sub-
base or trench settlement issue. The repaired area is ground from the surface area
through to the gravel base material, thus allowing maintenance staff to recycle and
reuse the material after making sub -base corrections. Maintenance areas are
determined by Street Supervisor.
g. Reconstruction
In most cases the reconstruction process is predetermined by a street with an OCI in
the range of 0 -56 or increased utility issues which are in need of repair. This is
when curb and pavement is removed, and subgrade soil corrections and utilities are
upgraded. New concrete curb and bituminous surface is installed. A full
reconstruction is a structural change. The life of the new pavement is typically 30-
40 years (with continued maintenance). Below ground utility's age, stresses and
condition weigh into the overall determination of a reconstruction project.
Reconstruction of Prior Lake streets began in 1994. OCI increases to 100 following
the reconstruction activity.
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STREET MAINTENANCE POLICY
5. Gravel/Unimiproved Roads
The City of Prior Lake generally maintains its 2.63 miles of gravel roads by performing
routine maintenance to maintain a crowned, smooth driving surface. Surface gravel is
added by City staff as needed either by "Spot Graveling" or placing fresh gravel on the
entire section. One application of Calcium Chloride may be applied per year in efforts to
control dust.
6. Priorities
Following the completion of the street inspections, the Public Works Superintendant will
determine which streets are in need of repair first. Many factors are considered when
determining priority streets. Considerations are listed but are not limited to the following:
a. High volume
b. High speed
c. Streets that serve hospitals, schools, and nursing homes
d. Commercial areas
7. Right- of- W"Aoulevard
a. County Roads
City Maintenance Staff or subcontractors conduct mowing in County boulevards
with -in the corporate limits of the City of Prior Lake.
b. City Collector Streets
City Maintenance Staff or subcontractors conduct mowing in City collector streets on
an as- needed basis.
c. Gravel/Ditches
City Maintenance Staff or subcontractors will conduct mowing of these areas twice
per year.
d. Out lots/Ponds
City Maintenance Staff or subcontractors will conduct mowing of these areas only if
required to minimize noxious weeds or for maintenance access purposes.
8. Response to Complaints or Accidents
Residents of the City of Prior Lake typically report any complaints or accidents that occur on
City streets to the Department of Public Works. The City has provided a link on the Prior
Lake website (www.cityofpriorlake.com) that will direct concerned residents to an
appropriate City employee according to the type of concern or complaint. All complaints and
accidents will be documented by the employee that receives them. In a timely manner, the
area of concern will be inspected and documented for determination of whether and when to
repair. Repairs will be made with safety, budget, personnel and environmental conditions in
mind.
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STREET MAINTENANCE POLICY
9. Documentation
All maintenance that occurs on a City street during the year is documented during the months
of May to September. The information is then supplied to the pavement management
database manager. This pavement condition documentation provides the City with a means
of organizing future repairs and determining priority of repair over other streets through the
pavement management program.
10. Warning Devices or Signs
The City uses warning signs and other devices upon discovery of a condition which merits
repair until repair takes place during construction. The City uses the following warning
devices in the stated circumstance:
a. Cones -used with any obstruction less than 2" in depth and 25% or less of the
roadway.
b. Flashing lights -used with any obstruction over 2" in depth and over 50% of the
roadway.
c. Construction /Detours -will follow Minnesota Temporary Traffic Control Zone
layouts, fixed or moving, through the Minnesota Manual of Uniform Traffic Control
Devices (MN MUTCD).
d. Spray paint -used to mark buried utilities and to mark areas for repairs.
e. Flags -call attention to certain points of interest for utility infrastructure.
11. Safety of Employees
Employee safety is a high priority. While hazards cannot be completely avoided, warning
devices will be employed in such a fashion to reduce hazards to an acceptable level as
determined by the supervisor. If the supervisor deems the conditions unacceptable from an
employee safety perspective, he /she may postpone the project until conditions are considered
acceptable.
12. Trainine of Policy
A copy of the Street Maintenance Policy will be distributed to the employees in the City's
Engineering Department, the Public Works Department, and the Parks Department. Each of
these departments will be responsible for conducting a training session with their staff to
ensure employees are familiar with the policy. The City of Prior Lake also uses outside
resources to conduct training for their employees.
13. Communication of Policy
A copy of the policy will be made available on the City's website (www.cityofpriorlake.com)
under the Public Works, Street Maintenance section. It is the City's hope that residents of
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STREET MAINTENANCE POLICY
Prior Lake will see the policy and will use it to report street conditions to the Public Works
Department.
14. Review of Policy
The City of Prior Lake will review and adjust the Street Maintenance Policy yearly. This will
ensure the policy maintains effectiveness as the City grows and develops. As ideas for
changes and alterations come about they are to be documented.
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The City of Prior Lake does not require sign permits for Yard Sale or Election signs.
There are, however, criteria for the location of these signs. These criteria are listed
and shown in the picture below.
• Do not place these signs within the street right-of-way. Instead, locate the
signs on the building side of the curb, sidewalks, utility poles and
electrical boxes. This area is usually private property.
• On corners, you can determine the approximate right-of-way line by
measuring 20 feet along the curb line on each street, and drawing an
imaginary line connecting these two points to form a triangle. No signs
should be located within this triangle. Instead, place the signs on the
building side of the imaginary line you have just created.
• Do not attach signs to utility poles or light standards, as these are also
considered public property.
• Do not place signs on any publicly owned property, such as parks,
wetlands and City buildings.
NO SIGNS
(u18QlAN,
SIDEWALK --
Signs located within City, County or State right-of-way, or on other City property,
may be removed by City staff. These signs will be stored at the City Public Works
building for two weeks. The signs may be retrieved by visiting the Public Works
Building at 17073 Adelmann Street during regular business hours of Monday
through Friday, 8 =00 AM to 4 :30 PM. Any unclaimed signs will be discarded after
two weeks.
This sign policy has been adopted by the City Council to preserve the appearance of
our community. For more information about sign placement, please contact the
Planning Department at 952-447-9810.
c: \documents and settings \frank.priorlakech\local settings \temporary internet fi1es \o1k2a \sign policy.doc
Street Maintenance Seasonal Operations
City of Prior Lake
Sustain - High_® Transition -
Operating Tempo:
Responsibilities I Jan i Feb I Mar I Apr I May I Jun I Jul I Aug Sep I Oct I Nov I Dec
Snow Removal
Anti -Icing
Crack Seal
Overlay
Seal Coat
Street Sweeping
Street Lights
Boulevard Tree
Trimming
Stripping,
Crosswalks
Pothole Patching
Cold Mix
Hot Asphalt
Pothole Patching
Seasonal
Equipment
Maintenance
Responsibilities
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Gravel
Unimproved Roads
Utility Cut Repairs
Asphalt
Mill /Repairs
Seasonal Operations Matrix
Most of the street activities are seasonally based. Variables such as staff, weather, and equipment availability play a role in the
timelines of many street projects.
STREET SIGN POLICY
Adopted December 2009
PRIp�
V eri
SIGN REQUEST POLICY
SIGN REQUEST POLICY
For Signs Located Within the Public Right -of -Way
Adopted by City Council on
December 7, 2009
1. Rationale:
The City of Prior Lake receives many requests for sign installations within the public right -of-
way from residents and City Council members. Such requests are directed to Public Works,
Engineering, and Traffic Safety Committee. This policy establishes how the City will respond
to such requests and allocate the resources necessary for determining need, installation, and
maintenance.
2. Sian Types:
This document classifies signing into six general categories:
a. Regulatory
b. Warning
C. Directional
d. Construction
e. Special Purpose
f. Not permitted
a. Regulatory
Regulatory signing is defined as signing that informs drivers on how to function at
an intersection or on a street. In the case of most regulatory signing there are
certain criteria that must be met before they are installed. These criteria are set
out in the Manual of Uniform Traffic Control Devices (MUTCD) and the
Minnesota Manual of Uniform Traffic Control Devices (MMUTCD). Both
documents specify conditions for installation as well as requirements of
maintenance. The courts look to this national publication, MUTCD, and also state
publication, MMUTCD, when determining the reasonableness of installation and
maintenance.
Examples of Regulatory Signs:
Stop signs, Yield signs, Do Not Enter, No U -Turn, etc.
b. Warning
Warning signs are signs that provide advanced warning to drivers or pedestrians
that something dangerous or unexpected may be ahead. As with the Regulatory
signs, these signs are generally mandated by the standards as to where and
when they must be installed.
Examples of Warning Signs:
Curve Ahead signs, Steep Slope signs, Stop Ahead signs, etc.
c. Directional
Directional signs provide additional information to help drivers find particular
streets or to direct them in certain areas. Directional signs are required on higher
speed roadways and are sometimes installed on lower speed roadways but they
are not required.
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SIGN REQUEST POLICY
Examples of Direction Signs:
Jamaica Avenue South, Ideal Avenue South, 70th Street South, etc.
d. Construction
Construction signing is self explanatory. These signs are installed to move
vehicles and pedestrians safely through or around a construction zone. These
signs provide safety to both vehicles and workers in the area. Their placement is
mandated by law.
Examples of construction signs:
Detour Ahead, No Left Turn, etc
e. Special Purpose Signs
Special Purpose Signs are signs that are not required to be provided by the City
for general traffic purposes or to provide for the safe and efficient movement of
people and goods. These signs are usually requested by a small group of people
or individuals and benefit only a limited number of citizens.
Examples of Special Purpose Signs:
Crime Watch, Drug Free Zone, Special Events, Deaf Child, Dual Street Names,
No Parking Between Signs, Building Entrance, Children Playing, Limited Time
Parking, etc.
f. Not Permitted
Not Permitted signs are those that are prohibited by State Statute, City
Ordinance, or City Policy. These signs may create a false sense of security that
actually worsens the situation, detracts from other signs which have a much
higher public safety benefit or the cost of installation and maintenance far
outweighs the benefit.
Examples of Not Permitted signs:
Garage Sale, Special Purchase, Home for Sale
3. Procedure for Sian Reauests:
All signs installed in the public right -of -way must be approved in advance by the Public
Works department, Traffic Safety Committee or by City Council resolution.
When a sign request is received, the Engineering department will complete a request form,
including the requester's information, and will forward the form to the Traffic Committee
members. The committee will meet to discuss and act upon the request with the information
prepared by Engineering as set forth below:
The Engineering department will gather information required and assign the request to one
of the six sign classifications explained above. Once the sign has been classified, the
necessary judgment will be applied and any studies and reviews required for that
classification will be completed. This staff evaluation will result in one of the following
recommendations:
Recommended for installation
Engineering department recommends, or sees no harm in, installing the sign, installation of
the signs will be approved and cost allocations for the installation will be set. The requester
will be notified by the Traffic Committee Chair Person by phone or mail.
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SIGN REQUEST POLICY
Not recommended for installation:
Engineering department determines that the sign not be installed. The department
representative will send a letter explaining the decision to the requester, including available
informational materials, and a summary of the following appeals process. The sign request
will be completed and the documentation supporting the decision will be filed.
Appeals Process
The requester may appeal the Engineering Department the not recommended for installation
decision to the Traffic Safety Committee as follows:
The requester may present their rationale and additional information at the next available
Traffic Safety Committee meeting. A decision regarding the sign request will be made by the
Committee and the requester will be notified about the decision in writing.
Additional information needed.
If the department requires more information from the requesting party and / or other
departments, the department will schedule the sign request to be reviewed at the next
available Traffic Safety Committee meeting and will invite the requester to present additional
information to the Committee. A decision regarding the sign request will be made and the
requester will be notified about the decision in writing.
4. Procedure for Sign Installation:
All signs installed in the public right -of -way shall be installed by the Department of Public
Works or under the Department's supervision. Once cost allocations have been determined,
and all funding received, a work order to install the signs will be written. The Department of
Public Works will administratively establish guidelines for the location, number, design and
maintenance of the signs. Routine maintenance of the signs, once they are installed, will be
performed by the Department of Public Works at no charge.
Extraordinary maintenance, such as a high amount of vandalism or theft may result in the
removal of the signs, or the costs of all maintenance to be billed to the requesting party.
5. Procedure for Sign Maintenance and Removal
The City will inspect signs approximately every twelve years. At this time, all Special Purpose
signs will be removed. If the Special Purpose signs are still desired, the requesting party
must participate in the funding for reinstallation according to the schedule of fees for that
year.
When a sign is scheduled to be replaced or removed, the Department of Public Works will
attempt to notify the original requesting party. If the requested sign is to remind the public of
a state law, statute or City ordinance, the Department of Public Works shall install and
maintain the sign only after receiving a written request to do so from the Prior Lake Traffic
Safety Committee.
6. Procedure for Cost Allocation:
When the City determines that a sign is necessary and /or a sign meets warrants, the City
shall pay for engineering services required (such as a traffic study), installation, and
maintenance of the sign as follows:
Regulatory, Warning, Directional, Construction Sians:
These signs are required to be installed and maintained by the City of Prior Lake for the safe
and efficient movement of people and goods. The City shall be responsible for all costs of
installation, routine maintenance and refurbishing of signs.
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SIGN REQUEST POLICY
For extraordinary maintenance such as vandalism, theft, damage, etc., the City shall charge
for the full cost of replacement to the responsible party and they shall be held responsible
according to state and local ordinances.
For signs not recommended for installation by Engineering staff and Traffic Safety
Committee but approved by Council through the appeals process, the requesting party shall
be responsible for costs incurred for engineering services, document preparation and sign
manufacture and installation.
Special Purpose Signs:
Special Purpose signs because of their temporary nature and private benefit are treated
differently. Because they serve a limited number of citizens and are not signs required for
the safe and efficient movement of people and goods the City will charge for installing such
signs in order to defray installation costs and maintenance.
If the Engineering Department recommends, or sees no harm in, installing a requested
Special Purpose sign, the City will charge the requester per the City's established fee
schedule. The sign costs also will be determined based on the availability of other fund
sources and the contribution that the sign makes to the public good.
The public will be informed about the fees through the Sign Request procedure and the fees
will be approved by City Council annually in the Schedule of Fees.
For signs not recommended for installation by Engineering Department but approved by
Council through the appeals process, the requesting party shall be responsible for costs
incurred for engineering services, document preparation and sign manufacture and
installation.
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Inspection /Maintenance Policy
Adopted December 2009
CFRIO
SIDEWALK
AND TRAIL
Inspection /Maintenance Policy
Adopted December 2009
CFRIO
SIDEWALK AND TRAIL INSPECTIONIMAINTENANCE POLICY
Adopted by City Council
On December 7, 2009
1. Introduction
The City of Prior Lake, Minnesota has 70 miles of public sidewalks and trails. The trails and
sidewalks throughout the community vary in age, subbase, quality and condition. Although some
may be irregular on the surface they are not necessarily deemed defective. The city recognizes
that unmaintained sidewalks or trails can create hazards for pedestrians and other users.
The goal of the sidewalk and trail system is to provide a safe area for walking, jogging,
rollerblading, and biking. The corresponding goal of the sidewalk and trail inspection and
maintenance policy is to make repairs quickly and in a financially prudent manner recognizing
that the City of Prior Lake has limited employee and financial resources.
The most common safety concern is the potential for trips and falls on uneven sidewalks and
trails. Uneven sidewalks and trails can be the result of heaving, settling, cracking, and spalling.
The main reasons for these failures are tree root growth, ground shift during the freeze -thaw
cycle, improper subsoil and the age of the sidewalk or trail.
Six procedures are routinely used by the City of Prior Lake under this policy: removal and
replacement, mud jacking, grinding, crack sealing, seal coating and over lays. There are many
variables to consider when deciding which procedure should be used, including age and
condition, probable cause of failure, potential issues with slope, and cost of repairs.
Sidewalks and trail should not be replaced for cosmetic reasons such as minor cracking or
spalling. Only hazards to pedestrians should be repaired or replaced under this policy.
2. Sidewalk/Trail Inspection Procedures
The Director of Public Works shall establish procedures for regular sidewalk/trail inspection.
Those procedures will include:
A. A City wide sidewalk and trail survey.
B. A schedule for routine sidewalk and trail inspections.
C. Criteria for determining whether a particular sidewalk or trail is in need of replacement or
repair.
3. Sidewalk/Trail Replacement and Repair Policy
The Parks Supervisor shall establish a replacement and repair schedule. This schedule is subject
to modification based on sidewalk and trail condition, availability of resources, and the timing of
City, County, and State road way reconstruction projects.
VADocuments \Downloads \Sidewalk & Trail Inspection & Maintenance \Sidewalk and Trail Inspection and Maintenance Policy -
2009.docx
SIDEWALK AND TRAIL INSPECTION /MAINTENANCE POLICY
The sidewalk and trail replacement and repair inspection schedule will divide the City into three
sections and will prioritize the replacement or repairs needed. The replacement and repair policy
takes into consideration the following factors:
A. Sidewalk and trail location and amount of pedestrian traffic.
B. The nature and severity of the condition needing replacement or repair.
C. The City's budget for replacement or repair of sidewalks or trails.
D. Whether or not and to what extent the cost of the replacement or repairs can be recovered at
the same time as road way reconstruction projects.
E. Availability of employees, equipment, and other resources for replacement or repairs.
F. Public safety.
G. History of prior accidents or complaints.
4. Common sidewalk failures and recommendations
a. Raised Sections or Faulting
Faulting is caused by tree roots or frost heaving. Cutting the tree roots is not
recommended as it will weaken the root structure and allow the tree to topple by wind.
If sidewalk replacement requires the removal of a significant tree, a replacement tree
may be offered to the property owner of a type and size recommended by the City's
Forester.
Grinding a sidewalk may provide a temporary solution to an offset resulting from a
raised or faulted sidewalk section. If the raised section is caused by tree roots, in time
the sidewalk or trail section may require removal and replacement.
A property owner opposed to the removal of a boulevard tree which is causing damage
to the public sidewalk adjacent to their property may elect to pay for the sidewalk
removal and replacement as necessary to maintain it in accordance with City Policy.
The criteria for replacing or repairing a raised or faulted sidewalk section are as
follows:
Severity Level
Difference in Elevation
Low Less than 1"
Medium 1" to 2"
High Greater than 2"
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SIDEWALK AND TRAIL INSPECTION /MAINTENANCE POLICY
b. Linear Cracking
Linear cracking of sidewalk sections may occur due to improper construction, abuse, or
frost heaves. Small cracks will occur and continue to grow as the sidewalk ages. As
the cracks widen and deepen, chunks of sidewalk may separate from the slab creating
trip hazards. When this occurs the sidewalk may need to be removed and replaced.
Replacement of a sidewalk section should be considered when:
A. The sidewalk has cracked into more than three pieces per section and the sections
are distorted or distressed with a vertical height of one -half inch or more.
B. A horizontal separation of two inches or more.
C. The sidewalk section has cracked and part of the sidewalk is missing, forming
holes.
C. Settlement
Settlement may occur if there was improper or insufficient base material or compaction
thereof. It may occur when utility installations transverse the sidewalk. If the sidewalk
sections are intact in a settlement area, the maintenance choice may be mud jacking. If
the sections are broken, removal and replacement may be needed.
The sidewalk section or sections that have settled more than two inches in twelve feet
from the normal line of grade of the sidewalk should be either replaced or mud jacked.
d. Joint Spalling
Joint spalling is the breakdown of the slab edges. A spall usually does not extend
vertically through the slab, but intersects the joint at an angle. Spalling is a result of
weak concrete, water accumulation in the joint and freeze — thaw action and excessive
stresses at the joint. The preferred maintenance is to remove and replace.
Replacement of the sidewalk sections that display spalling should be considered for
replacement when the width of the spall is greater than two inches over 50% or more of
the joint and the spalled pieces are loose or missing.
e. Durability ( "D ") Cracking
"D" cracking is caused by freeze -thaw expansion of the large aggregate which, over
time, gradually breaks down the concrete. This distress usually appears as a pattern of
cracks running parallel and close to the joint or linear crack. Since the concrete
becomes saturated near the joints and cracks, a dark - colored deposit can usually be
found around fine "D" cracks. This type of distress may eventually lead to
disintegration of the entire slab.
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SIDEWALK AND TRAIL INSPECTION /MAINTENANCE POLICY
Sidewalks the display "D" cracks that cover more than 25% of the sidewalk section
causing the accumulation of loose material should be considered for replacement.
5. Common trail failures and recommendations:
Description
Cause
Cracking, low or moderate
Begins at bottom of asphalt surface where
stress and strain are highest under wheel load
Rutting or settlement
Poor sub -base material or improper drainage of
sub -base area
Heaving
Poor sub - surface drainage, potentially from
frost conditions, impacts form adjacent trees
Oxidation
Continuous exposure to sun light through all
seasons, disintegration of oils and fine particles
which make up asphalt
6. Sidewalk/Trail Winter Maintenance Policy
Criteria and priorities for removing snow from sidewalks and trail are documented in the City of
Prior Lake Winter Maintenance Policy. The Winter Maintenance Policy is updated and
approved by City Council on a yearly basis.
7. Review and Modification of Policy
The Parks Supervisor will keep on file comments and complaints received regarding this policy.
The policy will be reviewed yearly with all of the City's maintenance policies by the City
Council. The reviews will consider comments, complaints, and modifications since the last
review and any other factors affecting the policy or its implementations. Modifications of this
policy shall be effective on the said date they are approved by City Council Resolution.
VADocuments\Downloads \Sidewalk & Trail Inspection & Maintenance \Sidewalk and Trail Inspection and Maintenance Policy- 2009.docx
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Street Sweeping Policy
Adopted May 2007
C Cs
SWEEPING POLICY
Prior Lake Street Sweeping Policy
Adopted by City Council on
May 2007
Updated: December 7, 2009
1. Introduction
The City of Prior Lake assumes basic responsibility for sweeping City streets. Sweeping is necessary to
promote clean and clear driving and walking surfaces and to remove particulate pollution before they enter
natural waters. The City will provide street sweeping with the following goal: Sweeping should be done in safe,
cost effective and environmentally sensitive manner. The City will use City employees, equipment and /or
private contractors to provide this service. Operation dates are dependent on weather conditions, personnel and
equipment availability. The Street and Utility Supervisor or his /her designee will be responsible for scheduling of
personnel and equipment.
2. Statement of Need
In an effort to create a consistent and measurable sweeping effort, this policy sets forth goals and recording
requirements that will allow the City of Prior Lake to monitor and improve its street sweeping effort as new
science, information, practices and techniques are developed in the City and the sweeping Industry.
3. Time of Operation
Street sweeping will occur seasonally when roads are clear of snow and ice, generally from March to
November. Hours of operation normally will be between 7:00am and 3:30pm, Monday to Friday. Extended
work days may be utilized for spring sweeping or emergency operations.
4. Areas of Operation
Street sweeping will occur citywide as well as in a series of zones that require extra sweeping effort due to land
use or specific water quality concerns. The following zones are established under this policy and are depicted
on the attached map 1. These zones are listed ranked by environmental susceptibility from least to most:
a. Citywide residential.
b. Commercial / Industrial zone.
c. Downtown zone.
d. Wellhead zone.
e. Direct to Lake zone.
Sweeping may occur outside Prior Lake City boundaries on contract or under agreement with other
municipalities. Sweeping efforts within the watershed draining to Spring and Prior Lakes has a benefit for the
City of Prior Lake, due to the connectivity of water resources.
5. Method of Operation
Equipment
The City owns two street sweepers, a mechanical broom sweeper and regenerative air sweeper. These two
pieces of equipment vary in utility and efficiency. The following is a summary of capabilities of each piece of
equipment:
Mechanical Brush:
The mechanical brush sweeper is good for picking up gross pollutants such as gravel and coarse sand. The
mechanical brush is well suited for streets with heavy loads of construction material. The mechanical brush is
best for dry sweeping of roads, using its brushes to loosen up any caked on mud and then lifting it into its
hopper. The mechanical brush is less effective for picking up fine grained sand and silt material, and does not
clean out cracks well.
Regenerative Air:
The regenerative air sweeper is good for picking up a wider array of sediment and is especially effective at
picking up finer grained pollutants such as coarse sand to silt and can clean into cracks. The regenerative air is
also well suited for Wet biomass such as grass clipping and leaves and can be used on wet surfaces.
VADocuments \Downloads \Street Sweeping Policy\Street Sweeping Policy.doc
1
SWEEPING POLICY
Speed and safety
Both machines are operated between 2 and 5 mph. This speed allows for safe and efficient pickup. Sweeping
operators must be vigilant to keep watch for pedestrians and children at play, due to the residential nature of
many City roads.
R Crnnimnru of f%nnrtk4inn
ZONE
Minimum Frequenc
1 Citywide residential
4 times
per YEAR
2 Commercial / Industrial
6 times
per YEAR
3 Downtown
1 time per
MONTH
4 Wellhead
1 time per
MONTH
5 Direct -to -Lake
2 times
per MONTH
Citywide residential areas and areas not in another zone will be the target for cleaning at a minimum 4 times per
year. The first sweeping will take place in late winter or early spring when roads are mostly dry and clear from
snow. A follow up cleaning will occur the following month after the risk of late snow has passed. Fall sweepings
will occur one or two weeks after leaves start to drop, and continue just prior to snowfall.
Commercial / Industrial zones will be cleaned on the same schedule as residential areas with two additional
sweepings taking place in the summer.
Downtown and wellhead zone will be swept monthly. Monthly sweepings can occur any time during the month;
however, efforts should be made to time the sweepings prior to periods of expected rainfall.
Areas that drain directly to lakes will be swept 2 times per month. Hotspots with notable dirt or sediment in the
direct -to -lake zone will be covered with multiple passes of the regenerative air sweeper.
The frequencies set forth above are City standards. In extenuating circumstances, the standards may not be
achieved.
7. Record Keeoina and Use of Data
Over the course of the first two years implementing this policy the City will collect and track data related to the
sweeping effort. Information will be collected for dual purposes; to track the short term variations in time,
distance and volume of material collected in and to collect data for analyzing the long term efficiency of
sweeping operations. Through data collection and continual reassessment of the effectiveness of operations
the City will strive to continually improve operations.
Data will be summarized on the daily use of each sweeper. A sample of the data for used is presented below:
Al
OPERATOR
E':-Ier IS u, e H"-'-
A2
61
EQUIPMENT
E;vr
132
C1
C2
D1
START TIME
t._ <:..:,. ± ': , .u_i E Ir<
D2
E1
END TIME
E_r 0 t - En,-
E2
F1
TOTAL TIME
F2
E_rl'e Brr:;:k anj
G1
IDLE TIME
Tr<:! rsit H OLlrs
G2
H1
SWEEP TIME
Li'{ E - '.ira =: fl
H2
SWEEP ZONE N , - -. ' l rt
DAILY VOLUME
MATERIAL COLLECTED
START ODOMETER
END ODOMETER
TOTAL DISTANCE
APX IDLE DISTANCE
SWEEP DISTANCE
f f ':,,
E -Tltf 3 End odo ((
.'.C' Here
V: \Documents \Downloads \Street Sweeping Policy \Street Sweeping Policy.doc
2
SWEEPING POLICY
J1
PRODUCTION
K1
EFFICIENCY
L1
SAFE SPEED
(Daily Volume/Total
Hours)
(Daily Volume /Sweep
Distance)
(Sweep
These data can then be used by the operator to make an immediate assessment of the current day's
operations. Production and efficiency can be compared and safe average operating speeds can be confirmed.
These data can also be used in the long term monitoring of sweeping data. Analysis of the data as well as
observations of the operators will give the public works department a firm basis to modify and improve the
sweeping policy in the future. This continual improvement of the process will promote an efficient use of pubic
funds and an assessment of the benefit.
8. Storage and disposal of waste material.
Material gathered through sweeping operations will be stockpiled at a City stockpile site. This and all stockpiles
are inspected as part of the City MS4 Permit at least annually for erosion. Ultimate disposal or reuse of the
material is dependant on potential contaminants determine by testing the soil. Stockpile may be required to be
disposed of in a sanitary landfill. If soil tests show material to be under recommended thresholds for tested
pollutants other appropriate uses may be available; such as, non - sanitary Iandfilling, use as miscellaneous fill
material, or topsoil.
9. Contract Sweeaina and Erosion Control Enforcement.
The City includes provisions in development agreements that state if a developer fails to sweep within the
prescribed period according to NPDES construction site permit the City has the right to sweep the area and bill
the developer. The contract rate for sweeping will be set at $150 per hour. This rate is meant to safely cover
staff time and capital and maintenance costs of equipment so that the enforcement of this provision does result
in a loss for the city.
VADocuments \Downloads \Street Sweeping Policy \Street Sweeping Policy.doc
3
City of Prior Lake
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2007
STREET
SWEEPING
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Winter Maintenance Policy
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WINTER MAINTENANCE POLICY
WINTER MAINTENANCE POLICY
Adopted by City Council
On October 7 th , 2002
Updated: November 3 2003
Updated: December 20 2004
Updated: September 19 2005
Updated: October 16 2006
Updated: September 17, 2007
Updated: October 20, 2008
Update: December 7 th , 2009
Updated: November 1, 2010
1. Summary/Purnose
The purpose of this Policy is to define and outline snow and ice control objectives and
procedures as established by the City of Prior Lake.
The City of Prior Lake believes that it is in the best interest of the residents for the City to
assume basic responsibility for control of snow and ice on City streets. Reasonable ice and snow
control is necessary for routine travel and emergency services. The City will attempt to provide such
control in a safe and cost effective manner, keeping in mind safety, budget, personnel and
environmental concerns. The City will use City employee's, City owned or rented equipment and/or
private contractors to provide the following level of service:
Street Snow Removal — Level of Service
Snow Accumulation
1 -3"
4 -12"
12 "+
Removal Time (hrs)
8
10 -12
12+
Pavement Above 15 °F
Removal Time (hrs)
10
12+
12+
Pavement Below 15 °F
Note: Removal time is the time necessary to remove snow from all City Streets at least one time.
Parks 1 Trails 1 Sidewalks 1 Parking Lots — Level of Service
Snow Accumulation
1 1 -3"
1 4 -12"
1 12 "+
Removal Time hrs
8
1 10 -12
1 12 11 +
It should be noted that every winter storm has different temperatures and intensities that can
alter the amount of time crews spend with snow and ice control. The absence of even one employee,
the break -down of one piece of equipment, or not replacing equipment that has become unreliable or
requires repairs and maintenance that are not cost - effective can also alter snow and ice control and
WINTER MAINTENANCE POLICY
removal time
This Policy supersedes any and all previously written or unwritten policies of the City
regarding snow and ice removal. The Public Works Department will review this policy periodically
and will amend it as appropriate.
2. When Will City Start Snow or Ice Control Operations?
The Public Works Superintendent or his designee will decide when to begin anti - icing, snow
removal, or ice control operations. The criteria for that decision are:
A. Air and Pavement Temperatures;
B. Anti -Icing operations may occur 48 hours in advance of an approaching storm,
anticipated frost or prior to weekends in which forecasts call for some form of
precipitation;
C. Drifting of snow that causes problems for travel;
D. Icy conditions which seriously affect travel;
E. Time of snowfall in relationship to heavy use of streets.
Snow and ice control operations are expensive and involve the use of limited personnel and
equipment. In order to remain cost effective, the Public Works Department will utilize a variety of
ice control products and continually monitor the effectiveness, environmental impact and costs of
each product applied. The Public Works Superintendant or his designee will determine the
appropriate combination of chemicals to effectively control ice in the given weather conditions.
Effects on the environment are of the highest priority in selection of ice control products.
To assure completion of priority areas, snow removal may be conducted on a 24 -hour
basis, which may result in snow removal equipment being operated in residential areas during
the evening, night, and early morning hours.
3. Anti -icing
This is a more common practice of being proactive to an impending snowfall event. This
practice prevents the snow from bonding or compacting to the pavement surface and providing
direct contact to the pavement surface when traveling the residential streets at a much lower cost
than applying dry salt products. The product in most cases is salt brine, which is chloride diluted to a
23% solution with water. In relevant terms, one gallon of brine consists of 2 pounds of salt.
4. How Snow Will be Plowed
WINTER MAINTENANCE POLICY
Snow will be plowed in a manner so as to minimize any traffic obstructions. Generally, the
center of the roadway will be plowed first. The snow shall then be pushed from left to right. The
discharge shall go onto the boulevard area of the street. In times of extreme snowfall, the process of
clearing the streets of snow may be delayed, and it may not be reasonably possible to completely
clear the streets of snow.
Generally, operations shall continue until all roads are passable. Widening and clean up
operations may continue immediately or on the following working day depending upon conditions
and circumstances. Due to safety concerns for the plow operators and the public, operations may be
terminated after 10 -12 hours to allow personnel adequate time for rest.
Cul -de -sacs will be plowed with one pass along the curb to provide an outlet for the
driveways, with snow being piled in the middle of the cul -de -sac, where possible. Crews will clean
up the cul -de -sac later that day or the following work day as time permits. Snow removal will only
occur when no storage space is available in the cul -de -sac area.
The downtown area will be plowed from curb to curb with the snow pushed into piles where
feasible. Crews will remove the snow piles during non - business hours as stated below.
5. Snow Removal
The Public Works Superintendent or his designee will determine when snow will be removed
by truck from an area. Such snow removal will occur in areas where there is no room on the
boulevard for snow storage and in areas where piles of snow have been created by City crews. Snow
removal operations will not commence until other snowplowing operations have been completed.
Snow removal operations may also be delayed depending on weather conditions, personnel and
budget availability. The snow will be removed and hauled to a snow storage area.
6. Priorities and Schedule for Which Streets will be Plowed
The City has classified City streets based on the street function, traffic volume, and
importance to the welfare of the community. Those streets classified as "Snow Plow Routes" will be
plowed first. These are high volume streets, which connect major sections of the City and provide
access for emergency fire, police and medical services. Exhibit A lists the "Priority Snow Plow
Routes ". Exhibit B lists the "Daytime Snow Emergency Routes ".
The second priority streets are those streets providing access to schools and commercial
businesses. The third priority streets are low volume residential streets. The fourth priority areas are
alleys.
Snow removal around fire hydrants will be performed when personnel and equipment are
available and will follow the same priorities as explained above, with top priority assigned to
3
WINTER MAINTENANCE POLICY
clearing around hydrants at schools.
7. Parking Restrictions
City Code 901.207 Winter Parking Restrictions: In order to expedite the prompt and
efficient removal of snow from the Streets of the City, it is unlawful for any Person to stop, stand or
park any Vehicle or permit it to stand on any Street within the City between the hours of two o'clock
(2:00) A.M. and six o'clock (6:00) A.M. from November 1 until March 31 of the following year. At
all other times of the year it is unlawful for any Person to stop, stand or park any Vehicle or permit it
to stand on any public Street within the City between the hours of two o'clock (2:00) A.M. and six
o' clock (6:00) A.M. after a continuous or intermittent snowfall during which there has been an
accumulation of two inches (2 ") or more of snow on any Street, the Street Superintendent or
designee has issued a snow emergency, and until the snow has been plowed or removed to the full
width of the Street. Any Vehicle parked in violation of this subsection may be towed pursuant to
Minnesota Statutes section 169.041. A violation of this subsection shall be a petty misdemeanor.
8. Work Schedule for Snow and Ice Control Equipment Operators
Equipment operators will be expected to work eight to ten hour shifts on a regular basis. In
severe snow emergencies, operators sometimes have to work in excess of ten -hour shifts. After a
twelve -hour day, the operators will be replaced if additional qualified personnel are available.
9. Weather Conditions
Snow and ice control operations will normally be conducted only when weather conditions
do not endanger the safety of City employees and equipment. Factors that may delay snow and ice
control operations include: severe cold, significant winds, and limited visibility.
10. Use of Salt and Other Chemicals
The City will use salt and other chemicals when there is hazardous ice or slippery conditions.
The City is concerned about the cost and the effect of such chemicals on the environment and may
limit its use for that reason.
11. Sidewalks/Trails/Parking Lots
Parks Department Winter Maintenance operations are prioritized according to the following eight
categories:
HIGH PRIORITY
Safety
Emergency
School Access
MEDIUM PRIORITY
High Use Recreation
Hockey Rinks
LOW PRIORITY
Community Trails
Pleasure Rinks
4
WINTER MAINTENANCE POLICY
Public Facility- Building Access
Time tables for snow removal are based upon the priority of the particular trail, sidewalk,
parking lot, skating rink or access as set forth below.
High Snow removal should commence at the end of any snowfall and high
priority areas should be cleared in approximately 12 hours.
Medium Snow removal will commence after high priority areas have been cleared
of snow and may be cleared in approximately 36 hours.
Low Snow removal will commence any time after high and medium priority
areas have been cleared of snow. Low priority areas may be cleared in
approximately 48 -72 hours.
a. Trails. Sidewalks, Parking Lots, and Accesses
It is the policy of the City to remove snow from the trails, sidewalks, parking lots,
and winter lake access areas in accordance with our Winter Maintenance Policy.
Exhibit C identifies each trail and sidewalk and whether each is considered high,
medium, or low in maintenance priority.
Generally the City will remove snow on at least one side of all collector and arterial
streets within the City. The City will generally remove snow on trails near schools,
most on collector streets, and some that would have to be driven by on the way to
other trails. These are listed in Exhibit C.
The following standards are adopted for providing winter maintenance to designated
trails, sidewalks, parking lots, and winter lake access:
1. Sidewalks and trails which abut private property shall not normally be cleared
of snow unless designated within this Policy. It shall be the responsibility of
the property owner to keep sidewalks clear of snow or ice in accordance with
City Code 701.100. If notice has been sent to owner /occupant and snow has
not been removed, the City may choose to remove the snow and ice and
charge the cost of removal to the property owner. The property owner would
first receive an invoice showing the appropriate charges. Failing to pay the
invoice would result in a one year special assessment against the benefiting
property. There is a minimum of $100 flat fee (or as determined periodically
by the City Council) for snow removal, and the City reserves the right to
charge additional fees as may be reasonable and appropriate.
2. The designated sidewalks, trails, parking lots, accesses, and rinks are normally
plowed, blown or swept. The method of snow removal depends on the
amount and type of snowfall.
5
WINTER MAINTENANCE POLICY
3. Designated trails and sidewalks will be cleared as thoroughly as possible but
need not be cleared of all ice and snow, nor maintained to bare pavement.
b. SkatinL Rinks
The following standards are adopted for providing winter maintenance to hockey and
pleasure ice - skating rinks which are listed on Exhibit D:
1. All rinks will be swept and flooded Monday through Friday, if needed.
2. If rinks become rough or uneven due to weather conditions, i.e., warm weather,
frost boils, or freezing rain, rinks will be shaved Monday through Friday to
improve ice surface.
3. In the event of snow:
a. No rink will be maintained until snow fall ceases.
b. Maintenance crews will not be called in on the weekends or holidays to
maintain rinks, unless snow fall exceeds 2 ".
c. Hockey rinks are ranked as a medium priority and therefore will not be
maintained until high priority winter operations are completed.
d. Pleasure rinks are ranked as a low priority and therefore will not be
maintained until high and medium winter operations are completed.
4. If the condition of the ice becomes a safety concern, rinks may be closed at the
discretion of the Parks Maintenance Superintendent or his designee.
For safety reasons, the City has a weather policy which determines rink closing.
The warming house and rinks will be closed if the actual air temperature is -5
degrees Fahrenheit or colder, or the wind chill is -25 degrees Fahrenheit or
colder. The weather cancellation hotline is 952.447.9825
12. Right -of -Way Use
The intent of the right -of -way is to provide room for snow storage, public and private
utilities, sidewalks, street lights, signage and other City uses. However certain private
improvements such as mailboxes are permitted within this area. Other private improvements are not
permitted.
a. Mailbox
Mailboxes must be installed in such a manner as to provide access by Post Office personnel
or other parcel carriers and to allow for Public Works equipment to maintain the streets.
Newspaper boxes installed under mailboxes in most cases do not allow for snow equipment
to pass under and can cause an indirect hit to the mailbox. A drawing showing the proper
WINTER MAINTENANCE POLICY
details for mailbox placement is attached as Exhibit E. Mailboxes and posts should be
constructed securely enough to withstand snow rolling off a plow or wing. Any posts that
are rotten or too weak to withstand winter weather will not be the responsibility of the City.
The City will bear the cost of the repair of a damaged mailbox only if it is a result of City
equipment actually hitting the mailbox, not from the weight of snow. The City will install a
replacement mailbox and post which shall be a standard size non - decorative type; or the
mailbox owner will be reimbursed up to $30.00 toward the cost of a replacement mailbox
and post provided the owner has contacted the Public Works Department within 48 hours for
verification and authorization from the Public Works Superintendant or his designee. The
City will make temporary repairs to mailboxes for mail delivery if City plows actually hit a
mailbox. When weather and time permit, the Public Works Department will complete the
repairs.
Damage resulting from snow is the responsibility of the property owner /resident. Removing
snow from the mailbox and maintaining access to the mailbox is the responsibility of the
property owner.
A property owner assumes all risk and responsibilities for replacement of mailboxes and
supports that are constructed of materials such as, but not limited to, brick and mortar, stone
aggregate, ornamental railings, or antique type support.
Snow plow operators make every effort to remove snow as close to the curb line as practical
to provide access to mailboxes for the postal department. It is not possible to provide perfect
conditions and minimize damage to mailboxes with the size of equipment the City operates.
The final cleaning adjacent to mailboxes is the responsibility of each resident.
b. Boulevard Sod
The City shall, when it receives a complaint, record the location of alleged damage to sod
caused by contact with City equipment. The location will be reviewed by the Public Works
Department in the spring when the extent of the alleged damage can be verified. Frequently,
the damage looks more severe immediately after the occurrence than it does when the snow
has melted in the spring. If the sod needs repair as determined by the Public Works
Department, the Public Works Department shall either sod or seed the damaged area. In the
interest of water conservation, deadlines are established due to dry weather conditions. All
boulevard sod requests noted prior to May 10 will receive sod. All noted boulevard sod
requests after May 10 will be made with top soil, seed and straw blanket. Once staff has
restored the area with sod replacement, it will then be the resident's responsibility to water
and maintain the damaged area. The City provides replacement costs for one (1) sod or
seeding service.
To reduce the areas of damaged sod by City equipment, the City will provide markers free of
charge to residents to place along their curb to mark the edge of the road for the equipment
operators. If there is damage to a boulevard area caused by City equipment, the City
WINTER MAINTENANCE POLICY
maintenance crews will give priority to those residents who placed the markers along their
property.
C. Irrigation, Lighting, Trees, Fences, Etc.
The City will assume no responsibility for damage to underground irrigation systems, private
lighting systems, trees, shrubs, specialty grasses, rocks, fences, underground dog
containment wires, retaining walls or similar landscaping installed in City controlled right -
of -way or easements.
Garbage cans left for pickup by a resident must be located in the driveway of the residence.
Storage of garbage cans in the roadway surface in which snow is to be removed requires
extra staff time due to potential future drainage issues from the inability to clean to the curb
line and safety issues during the snow removal process.
d. Driveway or Private Street Access
The City of Prior Lake reminds everyone, including commercial snow removal operators,
that Minnesota Statute 160.27 states that it is against the law to deposit snow on to a public roadway.
Dumping or plowing snow on to a roadway can create a slippery area, frozen rut or bump, which
could contribute to a motor vehicle and pedestrian accident. Snowforts and children playing in the
vicinity of the curb are strongly discouraged for safety's sake.
The following tip may be of assistance for proper placement of snow and minimize your
inconvenience when a snow plow comes along after you've cleared your driveway. First, place as
much snow as possible from the end of your driveway downstream in the direction of traffic.
Second, clear an area upstream from your driveway to create an open "pocket ". Much of the snow
pushed by the plow truck will empty into this pocket and less will wind up in the driveway entrance.
You must maintain this area throughout the winter for it to be effective.
The City of Prior Lake cautions anyone working close to a roadway to watch for oncoming traffic
and warns drivers to be alert to people clearing snow. Unknown objects left in the snow may be
displaced from the snow movement from the snow plow vehicle.
4/15/2010
EXHIBIT A
PRIORITY SNOW PLOW ROUTES
STREET
FROM
TO
Belmont Avenue
CSAH 17
Stemmer Ridge
Carriage Hill Road
Crest Avenue
Western Terminus
Carriage Hills Parkway
CSAH 21
Eastern Terminus
Crest Avenue
CSAH 42
Carriage Hill Road
Duluth Avenue
TH 13
Village Lake Drive
Fairlawn Shores
150th Street
TH 13
Fish Point Road
TH 13
Southern Terminus
Fish Point Road
CSAH 21
E & W Oak Point
Fountain Hills Drive
CSAH 21
CSAH 42
Franklin Trail
TH 13
TH 13
Fremont Avenue
CSAH 82
Northwood Road
Main Avenue
Pleasant Street
Ridgemount Avenue
McKenna Road
Wilds Ridge
North Terminus
Northwood Road
Fremont Avenue
CSAH 12
Park Nicollet Avenue
Franklin Trail
Toronto Avenue
Pike Lake Trail
Carriage Hills Parkway
Shakopee Border
Ridgemount Avenue
Rutledge Street
Main Avenue
Stemmer Ridge
CSAH 12
North Terminus
Sunset Trail
TH 13
CSAH 12
Village Lake Drive
Toronto Avenue
TH 13
Wilds Parkway
CSAH 83
CSAH 82
11!82010
EXHIBIT B
DAYTIME SNOW EMERGENCY ROUTES
STREET
FROM
TO
150th Street
TH 13
Fairlawn Shores
Adelmann Street
CSAH 21
Revere Wa
Belmont Avenue
CSAH 17
Stemmer Ridge
Boudins Street
Watersed e Trail
TH 13
Candy Cove Trail
CSAH 44
TH 13
Candy Cove Trail
TH 13
TH 13
Carriage Hill Road
Crest Avenue
Western Terminus
Carriage Hills Parkway
CSAH 21
Eastern Terminus
Cottonwood Drive
Fish Point
Adelmann Street
Crest Avenue
CSAH 42
Carriage Hill Road
Dakota Street
TH 13
Arcadia Avenue
Duluth Avenue
TH 13
Village Lake Drive
Fairlawn Shores
150th Street
TH 13
Fish Point Road
TH 13
Southern Terminus
Fish Point Road
CSAH 21
E & W Oak Point
Five Hawks Avenue
TH 13
Tranquility Court
Fountain Hills Drive
CSAH 21
CSAH 42
Franklin Trail
TH 13
TH 13
Fremont Avenue
CSAH 82
Northwood Road
Glendale Avenue
Northern Terminus
Southern Terminus
Jeffer's Parkway
Fountain Hills Drive
McKenna Road
Jeffer's Pass
CSAH 21
CSAH 21
Lords Street
CSAH 21
Eastern Terminus
Main Avenue
Pleasant Street
Rid emount Avenue
Mushtown Road
North Berens Road
Village Lake Drive
McKenna Road
Southern Terminus
Shepherds Path
Northwood Road
Fremont Avenue
CSAH 12
Oakland Beach Avenue
Northern Terminus
TH 13
Park Nicollet Avenue
Franklin Trail
Toronto Avenue
Pike Lake Trail
Carriage Hills Parkway
Shakopee Border
Rid emount Avenue
Rutledge Street
Main Avenue
Rustic Road
TH 13
Glendale Avenue
Rutgers Street
CSAH 42
Southern Terminus
Shady Beach Trail
CSAH 42
Southern Terminus
Shepherds Path
North Berens Road
CSAH 42
Stemmer Ride
CSAH 12
Northern Terminus
Sunset Trail
TH 13
CSAH 12
Toronto Avenue
Park Nicollet Avenue
Mushtown Road
Tower Street
Village Lake Drive
Eastern Terminus
Village Lake Drive
Toronto Avenue
TH 13
Watersedge Trail
Rutgers Street
Southern Terminus
Wilds Parkway
CSAH 83
CSAH 82
Wilds Ride
Jeffer's Pass
Wilds Parkwa
Wilds Path
CSAH 83
CSAH 42
11/8/2010 Trails Masterlist For Winter Maintenance City of Prior Lake
Exhibit C
TRAIL OR YEAR
^^A—^u 0MC1a1A1 L< IId4TA1 1 Pn PRAM To Lenath (ft) Catenory Priorlty
Belmont Avenue
Trail
2006
Stemmer Ridge Road
CSAH17
2989
Community Trail
Low
Cardinal Ridge Park
Trail
1996
CSAH 44
Crossandra St
910
Community Trail
Low
Carriage Hills
Trail
1996
CSAH 21
Bluebird Tr
4435
Community Trail
Low
Carria a Hills
Trail
2001
Bluebird Tr
East terminus
776
Community Trail
Low
Crest Avenue
Trail
1984
Shore Lane
West terminus
967
Community Trail
Low
Crest Avenue
Trail
2000
CSAH 42
Shore Lane
2624
Community Trail
Low
Crvstal Lake Park
Trail
2005
Throu h Park
1253
Community Trail
Low
CSAH 12
Trail
2007
Hwy 13
Stemmer Ride
1316
Community Trail
Low
CSAH 21
Trail
1985
Revere Way
CSAH 82
12900
Community Trail
Low
CSAH 21
Trail
1994
Lords St
CSAH 42
7990
Community Trail
Low
CSAH 21
Trail
2006
Jeffers Pass
Carriage Hills Pkwy
1470
School Access/Safety
High
CSAH 42
Trail
1990
Timothy Ave
Femdale Ave
7820
Community Trail
Low
CSAH 42
Trail
1994
CSAH 21
Ferndale Ave
6500
Community Trail
Low
CSAH 42
Trail
2003
CSAH 21
CSAH 83
7545
Community Trail
Low
CSAH 82
Trail
2007
CSAH 21
CSAH83
6957
Community Trail
Low
CSAH 83
Trail
2003
CSAH 42
Mystic Lake Blvd
2115
Community Trail
Low
Deerfield Park
Trail
Fish Point Rd
Wilderness Trl
Community Trail
Low
Duluth Ave
Trail
1 1997
Pleasant Street
Highway 13
2173
School Access/Safety
High
Fish Point Rd
Trail
1994
1 CSAH 44
South terminus
2490
School Access/Safety
High
Fish Point Rd
Trail
1994
CSAH 21
Blind Lake Tr
596
Community Trail
Low
Fish Point Rd
Trail
2000
Blind Lake Tr
South terminus
3857
Community Trail
Low
Fountain Hills Dr
Trail
2006
CSAH 21
Jeffers Pkwy
1650
School Access/Safety
High
Green Oaks Park
Trail
2003
Through Park
373
Community Trail
Low
Hickory Shores
Trail
2006
Through Park
4678
Hi h Use Recreation
Medium
Hwv 13
Trail
2008
CSAH 12
Five Hawks
2768
School Access/Safety
High
Indian Ridge Park
Trail
2003
Through Park
478
Community Trail
Low
Jeffers Parkway
Trail
2006
Fountain Hills Dr
McKenna Rd
2200
Community Trail
Low
Lakefront Park
Trail
1990
Thru Park
3803
High Use Recreation
Medium
Lakefront Park
Trail
1999
Thru Park
17078
High Use Recreation
Medium
Lakefront Park
Trail
2003
Thru Park
668
High Use Recreation
Medium
McKenna Rd
Trail
2006
Jeffers Pkwv
Wilds Ride
690
Community Trail
Low
McKenna Rd
Trail
2007
CSAH 42
North Berrens Rd
Hi h Use Recreation
Medium
Memorial Park
Trail
1996
Park lot
Basketball court
321
School Access /Safe
High
Memorial Park
Trail
1997
CSAH 44
Into Park
353
School Access/Safety
High
Memorial Park
Trail
2003
Basketball Court
Grainwood Elam School
342
School Access /Safe
High
CADocuments and Settings\mtpeterson \Desktop \Winter Maintenance Policy \trail and sidewalk winter maintenance - changes made 1025 10
11/13/2010 Trails Masterlist For Winter Maintenance City of Prior Lake
Exhibit C
Ave
m
Ponds
1
iFa
Ave
Trail
Trail
Medium
2006 McKenna Rd I Wlltls PKwy i "I 'urm t tau ww
1986 Willow Beach Willow Lane 293 HE h' Use Recreation Medium
Total Bituminous Trails 1
CADocuments and Settngs\mtpeterson \Desktop \Winter Maintenance Policy\trail and sidewalk winter maintenance - changes made 10 25 10
TRAIL OR YEAR
LOCATION
SIDEWALK INSTALLED
FROM
TO Length
ern Rd
Trail
1997
Toronto Ave
Ponds Park entrance
1589
Deerfield
Trail
1998/2001
Mushtown Rd
Fish Pt Rd
5881
ko Park
I
Trail I
I
Tumer Dr
I West terminus
I
Ave
m
Ponds
1
iFa
Ave
Trail
Trail
Medium
2006 McKenna Rd I Wlltls PKwy i "I 'urm t tau ww
1986 Willow Beach Willow Lane 293 HE h' Use Recreation Medium
Total Bituminous Trails 1
CADocuments and Settngs\mtpeterson \Desktop \Winter Maintenance Policy\trail and sidewalk winter maintenance - changes made 10 25 10
11/10/2010 Sidewalk Masterlist For Winter Maintenance City of Prior Lake
Exhibit C
TRAIL OR YEAR
nrAV1^U mno"uAi K iNSTet I ED 1:12nu Tn Length (ft) Category Priority
150th Street
Sidewalk
2003
Estate Ave
Entrance to Fish Point Park
3127
Community Trail
Low
Adelmann /Cottonwood
Sidewalk
1997
CSAH 21
Fish Point Rd
1740
School AccesstSafety
High
Blind Lake Trail
Sidewalk
2000
In front Wilderness Ponds Pk
350
Community Trail
Low
Candy Cove
Sidewalk
2005
CSAH 44
TH 13
1841
School Access/Safety
High
Carriage Hills Pkwy
Sidewalk
1996
Carria a Hills Pkwy
In front of Knob Hill Park
469
Community Trail
Low
City Hall /Police Station
Sidewalk
2006
Around buildings
1270
Emergency/Public Facility
High
Credit River Rd
Sidewalk 1
1990
Hwy 13
Franklin Trail
3184
School AccesstSafety
High
Crossandra
Sidewalk 1
1995
Franklin Tr
Fish Point Rd
2368
School Access/Safety
High
CSAH 21
Sidewalk
1997
Heritage
Grainwood
3705
Community Trail
Low
CSAH 21
Sidewalk
1997
CSAH 82
Lords St
1347
Community Trail
Low
CSAH 21
Sidewalk
2006
School Property
Fountain Hills Dr
1824
School AccesslSafety
High
CSAH 21
Sidewalk
2006
Jeffers Pass
Raspberry Ride
1365
School Access/Safety
High
CSAH 21
Sidewalk
1997
Hwy 13
Arcadia Ave
1046
Community Trail
Low
CSAH 44 southside
Sidewalk
1995
Hwy 13
East terminus
5333
School Access/Safety
High
Dakota St
Sidewalk
2004
TH 13
Arcadia Ave
1101
Emer enc /Public Facility
High
Duluth Ave eastside
Sidewalk
1988
CSAH 21
Pleasant St
599
School Access/Safety
High
Duluth Ave westside
Sidewalk
1988
CSAH 21
Pleasant St
599
School Access/Safe
High
Evanston
Sidewalk
2002
Credit River Rd
Minnesota St
700
School Access/Safety
High
Fire Station
Sidewalk
1994
Around buildings
454
Eme enc /Public Facility
High
Fish Point Rd
Sidewalk
1978
Hwy 13
Fairlawn Shores Tr
221
School Access/Safety
High
Fish Point Rd
Sidewalk
1978
CSAH 44
Hwy 13
4335
School Access/Safety
High
Fish Point Rd
Sidewalk
1994
CSAH 44
South terminus
2490
School Access/Safety
High
Five Hawks Ave
Sidewalk
1978
Hwy 13
Priorwood Street
1578
School AccesstSafety
High
Franklin TH
Sidewalk
1992
Hwy 13
Hwy 13
6072
School Access/Safety
High
Hummingbird TH
Sidewalk
1996
4699 Hummingbird TH
4760 Hummin bird Trl
425
Community Trail
Low
Indian Ridge Park
Sidewalk
2003
150th St.
Park
267
Community Trail
LOW
Jeffers Pass
Sidewalk
2001/2005
CSAH 21
CSAH 21
4530
School Access/Safety
High
Jordan Ave
Sidewalk
2002
Minnesota Ave
CSAH 44
779
School Access/Safety
High
Library
Sidewalk
1978
Around buildings
2084
Emergency/Public Facility
High
Main Ave
Sidewalk
2004
Pleasant St
160th
1032
Emer en /Public Facility
High
Maintenance Center
Sidewalk
1997
Around buildings
199
Emergency/Public Facility
High
Minnesota St
Sidewalk
2002
Evanston Ave
Jordan Ave
865
School Access/Safety
High
Northwood Rd
Sidewalk
1996
CSAH 12
Fremont Ave
5707
Community Trail
Low
Panama Ave East
Sidewalk
2005
Hwy 13
Village Lake Dr
510
Community Trail
Low
Panama Ave West
Sidewalk
2005
Hwy 13
Village Lake Dr
510
Community Trail
Low
Colorado
Sidewalk
Main
Park -N -Ride
118
School Access/Safety
High
CADocuments and Settings\"terson\Local Settings \Temporary Internet Files \Content.Outlook\KEKWFNHD\tmil and sidewalk winter maintenance - changes made 10 25 10
11/10/2010 Sidewalk Masterlist For Winter Maintenance City of Prior Lake
Exhibit C
TRAIL OR YEAR
V 1KI07A! 1 en cones Tn Lanoth (fill Categiory Prloritv
Park Nicollet Ave
Sidewalk
v 2004
Franklin Tr
Toronto Ave
1295
School Access/Safety
High
Park Nicollet Ave
Sidewalk
2004
Franklin Tr
Toronto Ave
1295
Community Trail
Low
Pike Lake Trail
Priorwood Street
Rid emont Ave
Rutledge St
Sidewalk
Sidewalk
Sidewalk
Sidewalk
1997
1999
1997
1997
CSAH 42
Duluth Ave
Lipper Lakefront park lot
Rid emontAve
Carriage Hills Pkwy
Five Hawks Ave
Rutledge St
Red Oaks Rd
2442
1507
1315
1815
Community Trail
School Access/Safety
Community Trail
Community Trail
Low
High
Low
Low
Toronto Ave East
Sidewalk
1 1993
Village Lake Dr
Tower St
615
School Access/Safety
High
Toronto Ave West
Sidewalk
1 1993
Village Lake Dr
Tower St
615
School Access/Safety
High
Toronto Ave
Sidewalk
1993
Woodridge Park
310
School AccesslSafety
High
Tower St North
Village Lake Dr
Village Lake Dr
Sidewalk
Sidewalk
Sidewalk
1993
2004
2004
Toronto Ave
23
Toronto Ave
Village Lake Dr
Kennett Curve
23
785
1251
3264
School Acoess/Safety
School Access/Safety
Community Trail
High
High
Low
Villa a Lake Dr
Sidewalk
2004
Toronto Ave
TH 13
3264
Community Trail
Low
Wilds Ride
Sidewalk
2007
Mckenna
Jeffers Pass
4037
Community Trail
Low
Wildwood Trl
Sidewalk
1 2006
Wilds Parkwav
Timberwolf TH.
1408
Community Trail
Low
1 owl %,onurere oiuewarn my
Cmowments and Settings\nlpetersontl.ocal Setflngs \Temporary Internet Files \Content.Outlook\KEKWFNHD\trail and sidewalk winter maintenance -changes made 10 25 10
Skating Rinks — Exhibit D
LOCATION
CATEGORY
PRIORITY
Lakefront Park
2 Hockey Rinks
Medium
Boudins Park
Pleasure Rink
Low
Carri a e Hills Park
Pleasure Rink
Low
Green Oaks Park
Pleasure Rink
Low
Howard Lake Park
Pleasure Rink
Low
Indian Ridge Park
Pleasure Rink
Low
Jeffers Pond Park
Pleasure Rink
Low
Lakefront Park
Pleasure Rink
Low
Northwood Park
Pleasure Rink
Low
Oakland Beach Park
Pleasure Rink
Low
Raspberry Ridge Park
Pleasure Rink
Low
Sand Point Park
Pleasure Rink
Low
Sunset Hills Park
Pleasure Rink
Low
Wilds Park
Pleasure Rink
Low
Willows Park
Pleasure Rink
Low
Woodridge Park
Pleasure Rink
Low
VADocuments0ownloads\Winter Maintenance Policy\Skating Rinks exhibit D.doc
Updated 4/8/2010
Mailbox ABC's
Helpful hints to protect your mailbox from the snowplow
12345 Lake View
Newspaper
6 inches
.a
0
U
Mailbox
shown is at
correct
height.
Snowplow
blade clears
the mailbox.
Mailbox
shown is
below correct
height.
Snowplow
blade hits the
mailbox.
The Prior Lake Public Works Department would like to remind residents to check their
mailboxes to ensure that they meet the following criteria:
Q Front
of mailbox should be flush with the back of the curb.
Bottom of mail box should be 42 -45 inches to the top of the street.
O Newspaper
boxes and other containers should be set back a minimum
of 6 inches from the back of the curb.
S
C
�
�
o
�
N
.a
0
U
Mailbox
shown is at
correct
height.
Snowplow
blade clears
the mailbox.
Mailbox
shown is
below correct
height.
Snowplow
blade hits the
mailbox.
The Prior Lake Public Works Department would like to remind residents to check their
mailboxes to ensure that they meet the following criteria:
Q Front
of mailbox should be flush with the back of the curb.
Bottom of mail box should be 42 -45 inches to the top of the street.
O Newspaper
boxes and other containers should be set back a minimum
of 6 inches from the back of the curb.
� PRIp ?`
City of Prior Lake Public Works Department
u 17073 Adelmann Street SE, Prior Lake, MN 55337
952- 447 -9830
A ES�SP
EXHIBIT F
Snow Plowing for Laker Lines Parking Lot
at Safe Haven for Youth
13780 McKenna Rd NW
City of Prior Lake x
5 Q
d Minnesota
ZOOS YE
TRAILS
SNOW PLOW —
STATUS
/ TRAIL /SIDEWALK BY PLOWING STATUS
1 \� PLOWED TRAIL OR WALK {
NOT PLOWED TRAIL OR WALK
{( SKATING RINK .` \
E T
SCHOOL
CRY BOUNDARY
LAID:
WNK]PAL PAW( C
I _m_
s L
COUNTY/REGIONAL PARK -
'
ANNEXATION AREA
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City of Prior Lake
Minnesota
2010
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PRIORITY MAP
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DAYTIME EMERGENCY
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