HomeMy WebLinkAbout5A - Surface Water Mgmnt Plan
PREPARED BY:
PUBLIC HEARING:
DATE:
SA
PUBUC HEARING TO CONSIDER REVISIONS TO
THE PRIOR LAKE LOCAL SURFACE WATER
MANAGEMENT PLAN AND PUBLilC WORKS DESIGN
MANUAL
ROSS BINTNER, WATER RESOURCES ENGINEER
X '1ES NO
MAY 22, 2006
AGENDA ITEM:
SUBJECT:
INTRODUCTION
The City of Prior Lake has be~n a leader in water resource managemsnt
throughout its history. ThrougH cooperation with the Prior Lake I Sprin{ Lake
Watershed District, and careful planning and monitoring of water qualitj, the City
has taken an active role in the management and protection of its water
resources.
Within the municipal boundary of the City of Prior Lake are two water
management entities, the Priof Lake Spring Lake Watershed District (WD) and
the Scott Water Management Organization (WMO). Each o~ these organizations
has authority for management of water resources; however the rules al1d
approaches of the WMO and ~VD vary.
In an effort to streamline water resource management within the muniqipality and
maintain local control of water Iresource management, the City of Prior Lake has
undertaken an effort to update its rules and regulations to meet the requirements
of both WMO and WD. In add ition to streamlining, State Statute requi~es the City
of Prior Lake to maintain a Local Water Management Plan that is consistent and
equivalent with WMO plans.
This process of revising City planning documents, rules and regulation~ is
consistent with the active role ':he City has pursued in managing its water
resources and will ensure compliance with State Statute. Through application of
its modern rules and its prudent planning efforts, the City of Prior Lakewill
remain a leader in the management of its water resources.
DISCUSSION
For review and approval are two documents used by the City to plan for and
enforce water resource management issues within the City. The Local Surface
Water Management Plan (LSWMP or Plan) sets forth a framework for the
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Phone 9f2.447.4230 / Fax 952.447.4245
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management of water resources; serving as a guide, establishing policy,
highlighting and detailing the qverall water system, and providing a plan for
implementation, the LSWMP ~erves as a comprehensive planning document.
The Public Works Design Mar ual, Hydrology Appendix (PWDM, or RUlles) gives
specific engineering standard~ that govern the development and redevelopment
of land consistent with the policy spelled out by the WMO, WD and City.
In a practical sense, the PWDM will have a direct effect on development issues
seen in the Planning Commis~ion, while the LSWMP sets the policy a~d planning
framework behind the rules. !
Major elements of the LSWMP are summarized below.
LSWMP:
Chapter 2 details land and wa rer resources in the City, describing watmsheds
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land cover, sOils, and flood Ie" els. I
Chapter 3 details the goals and policies of the plan. Specific policy topics
include: water quality, water q~antity, fish and wildlife, public participation,
groundwater, wetlands, erosidn and sediment control, clean water permits, and
financial management.
Chapter 4 details the Wetland Management Plan for the City. This sec:tion sets
up a methodology for ranking iI\Ietlands base on vegetation and wildlifel and
recommends a tiered approach to protection.
Chapter 5 includes a detailed description of the current stormwater me: nagement
system, detailing ponds, wetlands, lakes, streams, general drainage p~ths, and
the effect of urbanization on each. Volume management issues are discussed
along with proposals and recommendations for dealing with urbanizati :m. Major
water bodies and subwatershnds are listed and issues specific to each are
discussed.
Chapter 6 describes a range (If activities and programs that support W;:lter
management. The implemen1ation plan developed in this chapter des:;ribes
conceptual models for financimg the system that formed the basis of dnvelopment
fees. Capital improvement costs are detailed in this conceptual analy~;is as well
as potential funding mechanisms. Operations and maintenance detail s are also
covered in this chapter.
Chapter 7 summarizes the do.::ument and provides final recommendations.
ANALYSIS
A series of comparisons are presented highlighting differences betweEfn existing
and proposed Rules. Each of these examples is developed with exanlples
specific of a single PWDM sec:tion.
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Section 2, "Formats and Stant.ards," requires that a wide variety of hydrology
calculations be assembled int a unified document called a "stormwat$r
management report." This do "ument will include a narrative describin~ major
plan elements and summarize the conclusions of the design Engineer. Under
current rules, many similar calculations are required, however they are not
required to be assembled or presented in any specific way.
Section 3, "Grading, Erosion and Sediment Control," summarizes exis~ing
standards and does not require any substantive changes from existing rules.
Section 4, "Site Hydrology, Stormwater and Volume Management," inc ludes new
rate and volume control requirements and sets up an incentive systerll to
promote sensitive development techniques. Under the current rules, a
stormwater pond is required t(l provide water quality treatment and sloN the flow
from a development site so thft peak rates do not exceed those seenirior to
development. The current rul s extend the concept of rate control an cut the
peak rate of water flowing off ite to a fixed schedule that promotes le..,s water
flowing offsite then seen prior to development. An additional requirem ant of the
new rules is the inclusion of a Volume Control rule. Volume control has been a
requirement of the WD for years; however this is the first time it is pro~iQsed in
City Rules.
In addition to setting new rate and volume standards for development and
redevelopment within the City, section four sets up two "Stormwater
Management Overlay Districts." This concept requires separate standards to be
enforced over different areas of the City. The first Overlay District mo<1iifies the
rate control standard for those areas that drain directly to the Prior La~e Outlet
Channel, which is controlled by the Watershed District. This provision is
consistent with negotiations w th the Watershed District over the opere:,tions and
maintenance of the Outlet ChHnnel that will be formalized in a Joint Pcwers
Agreement. The second Overlay District modifies the volume control
requirement for all landlocked areas.
Section 5, "Drainage Alterations and Floodplain Management," include s rules
that govern the placement of f II below the flood elevation, the connect on and
development of landlocked basins, and alterations in the patterns of drainage.
The current ordinance deals with maintaining flow paths, however the scope of
the proposed rules has no cor"elation in current rules. Under current rules the
question of drainage alteratiorls and floodplain management only came from the
Watershed District.
Section 6, 'Wetlands," requires that development near wetlands make a standard
assessment of the vegetation land wildlife of the wetland to determine Its quality.
The quality of a wetland then is used to determine both its functional ranking and
its stormwater susceptibility. uhese factors describing wetland quality will be
used to determine the buffer width and acceptable stormwater utilization of a
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wetland. In general, wetlands of higher quality will have higher buffer widths and
less stormwater allowed. Wetlands of low quality will have lower buffEjlr widths
and more stormwater allowed. Under current rules all wetlands are treated
equal, using a standard 30 foct wide buffer average, and a 20 foot butler
minimum. The new rules pro~oses average buffer widths as high as 60 feet with
minimums as high as 30 feet f::>r the highest quality wetlands. All other buffer
widths will remain the standard 30/20 (Avg/Min) similar to the current rule.
Section 7, "Pond Design Criteria," Spells out requirements that are currently
required by the City, but have never been formalized in a single locaticn.
Section 8, "Storm Sewer Desi~n Criteria," summarizes existing standa ids and
does not require any substantive changes from existing rules.
Section 9, "Miscellaneous and CN Reductions," provides additional inflxmation
on the use of the incentive system set up under the volume control nulH in
Section 4.
CONCLUSION
The proposed revisions to the LSWMP and PWDM provide the City wi':h a
comprehensive water management plan and corresponding design stendards
equivalent to Scott WMO and the PLSLWD plans. Updates to the PW)M and
LSWMP are needed both to comply with the watershed planning fram~work set
forth in State Statute and to m Jdernize local controls to remain a lead r in the
field of water resource managfment. These revisions are undertaken 0
preserve and protect the wate resources of the City of Prior Lake.
Adoption of these revisions wi I also trigger changes to some sections Jf the
Subdivision Ordinance. TheSE! changes will be reviewed at a future public
hearing.
ACTION REQUIRED:
A motion and second recomm ending approval of the proposed revisiol11s as
recommended by staff.
ALTERNATIVES:
1. Recommend the Council approve the revisions as proposed.
2. Recommend the Council a pprove the revisions with changes specFied by the
Planning Commission.
3. Recommend the Council deny the proposed amendment.
4. Table or continue discussion of the item for specific purpose.
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RECOMMENDATION:
The staff recommends Alternative #1.
ATTACHMENTS:
1. Draft LSWMP.
2. Draft PWDM Hydrology Appendix.
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