HomeMy WebLinkAbout05(H) - 2022 Stormwater Pond Maintenance Report
Title Sheet Page i
TEN YEAR STORMWATER POND MANAGEMENT PLAN
TEN YEAR STORMWATER POND MANAGEMENT PLAN
FOR:
THE CITY OF PRIOR LAKE
March 10, 2021
PREPARED BY:
Table of Contents Page ii
TEN YEAR STORMWATER POND MANAGEMENT PLAN
TITLE SHEET
TABLE OF CONTENTS
1. Overview & Purpose .............................................................................................................................. 3
Stormwater Asset Management Program (SWAMP) .................................................................... 3
Annual SWAMP Updates .............................................................................................................. 4
Annual Stormwater Pond Surveys ................................................................................................ 4
2. Pond Management Plan ........................................................................................................................ 5
Inspect and Maintain Priority Ponds ............................................................................................. 5
Survey Priority Ponds .................................................................................................................... 5
Maintenance Priority Ponds .......................................................................................................... 8
Pond Feasibility Memos .............................................................................................................. 11
3. BMP Retrofits ....................................................................................................................................... 12
Outlet Control Structures (OCS) ................................................................................................. 12
Pretreatment................................................................................................................................ 12
Filtration/Biofiltration .................................................................................................................... 12
4. Estimated Costs ................................................................................................................................... 13
Survey Priority Ponds Cost ......................................................................................................... 13
Maintenance Priority Ponds Cost ................................................................................................ 13
Ten-Year Cost ............................................................................................................................. 14
5. Next Steps ........................................................................................................................................... 15
LIST OF FIGURES
Survey Priority Ponds
Maintenance Priority Ponds
APPENDICES
Appendix A – Pond Feasibility Memorandum Example
Pond Management Plan Page 3
TEN YEAR STORMWATER POND MANAGEMENT PLAN
1. OVERVIEW & PURPOSE
The City of Prior Lake (the City) has approximately 300 stormwater ponds, including constructed wet and
dry ponds and wetlands. These assets provide the City with essential rate control for flood mitigation and
water quality treatment. Stormwater basins are designed to remove pollutants from runoff, including
sediment. Over time, the sediment builds up in a basin, making it shallower and less effective at
continuing to remove pollutants and manage stormwater. To most effectively manage stormwater and to
maintain the vitality of downstream waterbodies, stor mwater basins need to be inspected and maintained.
Inspection and maintenance of this infrastructure supports population growth, ensures compliance with
the City’s National Pollution Discharge Elimination System (NPDES) Municipal Separate Storm Sewer
System (MS4) Permit, and ensures water quality goals are met. Prioritization of inspection and
maintenance activities is crucial to a successful and cost-effective stormwater management program.
Stormwater basins typically have a 20- to 50-year lifespan. The variability can be attributed to factors
including, but not limited to, drainage area characteristics, impervious percentage, proximity to agriculture
and the amount of erosion occurring both naturally and during construction projects . Older basins, having
been designed with smaller rainfall depths, may not be sized appropriately to meet today’s stormwater
treatment standards. Aging basins that have elevated chloride concentrations from road salts or over -
abundant aquatic vegetation can become a source of nutrient loading to a watershed system. This is the
opposite intended effect of stormwater treatment best management practices (BMPs), and if not managed
properly, these issues can offset water quality projects implemented by the City.
The timing of stormwater inspections and maintenance is extremely important to ensure the health of
water bodies and adequate treatment of stormwater runoff. Prioritizing the cleanout schedule for
stormwater basins ensures the dollars spent by the City on stormwater maintenance are optimally
allocated to basins that require cleanout to return to original treatment levels. If a filled basin is left
unmaintained, its effectiveness at removing pollutants will continue to decrease and it may reach the end
of its life cycle prematurely.
The purpose of this Ten-Year Stormwater Pond Management Plan is to provide guidance concerning the
planning and execution of pond maintenance activities within the City. This includes:
1. Routine field verification and calibration of the City’s Storm Water Asset Management Program
(SWAMP),
2. Prioritizing ponds for inspection/survey,
3. Prioritizing ponds for maintenance,
4. Conducting inspections and maintenance,
5. BMP retrofitting options, and
6. Cost estimates for these activities.
Stormwater Asset Management Program (SWAMP)
The City utilizes SWAMP to inventory, document, and prioritize inspection and maintenance activities,
and generate lifecycle estimates for constructed ponds. SWAMP provides a standard rating system to
help prioritize maintenance activities. The SWAMP score is calculated using user provided inputs
including construction year, basin area, drainage area, impervious percentage, estimated loading
rate, and receiving water body. The score is derived from comparing these variables against
Nationwide Urban Runoff Program (NURP) pond design standards.
Pond Management Plan Page 4
TEN YEAR STORMWATER POND MANAGEMENT PLAN
Newly constructed ponds (or a basin meeting the City’s treatment goals) will have a SWAMP score of
100, while a basin that is at the end of its life expectancy will have a SWAMP score approaching 50
or less. A score between 50-70 is an indication that maintenance should be evaluated. SWAMP also
provides estimates for water quality performance for total suspended solids and total phosphorus
removal efficiency.
Annual SWAMP Updates
To ensure the scores produced by SWAMP are accurate, annual updates should be incorporated into
the program to reflect changes to stormwater basin, drainage areas, and structural BMP data sets in
areas that have been recently changed.
SWAMP can also be calibrated using historical record plans to calculate an average pond depth.
This information is used similarly to survey data, except that the “survey date” in SWAMP would be
the estimated construction date from the grading plan. This is a cost-effective way for the City to
improve their SWAMP accuracy by reducing the number of pond surveys needed. If this method is
employed, the user should upload the grading plan and depth calculation methods into SWAMP for
record keeping purposes. One limitation is that basins are not always constructed exactly as planned
(either over excavated or not constructed correctly), and the construction erosion control techniques
today are much more effective than they were in the past.
If a basin is generating a SWAMP score that does not reflect observed conditions, the user should
consider three things before overriding a basin’s inputs:
1. Verify that all input data sets are accurate.
2. Complete a survey of the basin to confirm accurate current average depth.
3. Document supporting evidence for the use of alternative loading rates or managed depths.
One scenario for using an alternative loading rate is if it is known that a specific drainag e area
routinely receives more or less de-icing volume than other areas. The alternative loading rate can be
updated based on estimated deicing records and procedures.
It is most common to override the basin’s managed depth to reflect a smaller managed vo lume as
originally intended or approved by the City. This will help calibrate a basin and reprioritize
accordingly.
Annual Stormwater Pond Surveys
The process for selecting basins for surveying should follow the general guidance listed below:
1. Update the basin and drainage area files for all new and redeveloped areas within the City.
2. Update SWAMP with all historical grading plans available.
- Ponds with average depths and estimated construction dates from grading plans should
be considered last priority for surveying.
3. Select basins on public property with the lowest SWAMP scores to survey first.
- SWAMP should be updated with the survey date and average depth. Attach the
bathymetric map to its corresponding basin in SWAMP. This will prevent ponds from
being surveyed too frequently and will provide evidence for any program overrides.
4. The City may need to coordinate with private landowners to ensure the maintenance
expectations are met for private basins.
Pond Management Plan Page 5
TEN YEAR STORMWATER POND MANAGEMENT PLAN
2. POND MANAGEMENT PLAN
The following section describes the approach and schedule the City would follow to maintain the City’s
SWAMP data and plan for maintenance activities over a ten-year period.
Inspect and Maintain Priority Ponds
Using historical pond survey data that has been completed and evaluated in SWAMP, the City can
identify inspection and maintenance needs based on the following criteria:
If a basin has SWAMP score less than 70 or observed quality issues:
• A survey of the pond’s current conditions should be completed. This data will be used in the
pond feasibility memorandum below.
• If the survey confirms the basin is scoring less than 70, a pond feasibility memorandum
should be completed (if survey results in a SWAMP score higher than 70 then no further
action will likely be needed). This memorandum should outline maintenance and/or
improvement options based on the identified deficiencies and treatment goals for the basin.
Material quantities would be estimated at this time for construction and budget planning.
- Once the feasibility memorandum is completed, the City can budget and schedule
the maintenance and construction activities.
- This should include collection of sediment samples in accordance with MPCA
Guidance “Managing Stormwater Sediment Best Management Practices” to identify
material disposal requirements. Contaminated material can have a significant impact
on the project budget, so sampling should be completed as soon as the basin is
identified for dredge maintenance.
If a basin has a SWAMP score greater than 70:
• The City will likely take no immediate action and continue to monitor the basin per the MS4
permit requirements.
If a basin has a SWAMP score around 70:
• The basin may need to be resurveyed in the next 0-5 years to reevaluate maintenance
needs.
Survey priority ponds and maintenance priority ponds were identified and are shown in detail in
Sections 2.2 and 2.3 below, based on the 2021 SWAMP score.
Survey Priority Ponds
There are 7 stormwater basin that have no survey data associated with the location and scored less
than 70 in the Prior Lake SWAMP program. A low SWAMP score (< 70) indicates that the basin
needs to be surveyed to appropriately evaluate maintenance needs.
Table 1 indicates the current SWAMP score of the pond, the average estimated water depth of the
pond, whether the pond has been surveyed, and the average depth to which the pond should be
cleaned for optimal function (Managed NURP Depth). A SWAMP score of 0 indicates that the basin
has likely filled with sediment and needs to be surveyed to determine appropriate maintenance
activities.
Pond Management Plan Page 6
TEN YEAR STORMWATER POND MANAGEMENT PLAN
Table 1. Survey Priority Ponds
Basin ID Current SWAMP
Score
Survey
Data
(Y/N)
Est. Current
Depth (ft)
Managed
NURP
Depth (ft)
SWP-6654N-04 0 N 0.0 3.6
255 39 N 3.2 8.2
333 50 N 4.5 9.0
SWW-6852S-01 61 N 2.1 3.4
190 66 N 3.4 5.2
SWW-6654N-09 70 N 2.1 2.9
299 70 N 0.9 1.2
Pond Management Plan Page 7
TEN YEAR STORMWATER POND MANAGEMENT PLAN
Figure 1 indicates the location of the ponds in Table 1 that have been identified as survey priority
ponds.
Pond Management Plan Page 8
TEN YEAR STORMWATER POND MANAGEMENT PLAN
Maintenance Priority Ponds
There are 14 surveyed stormwater basins that generally scored less than 50 in the SWAMP program.
A pond that has been surveyed verified and returns a very low SWAMP score (generally < 50)
indicates a need for maintenance in order to achieve proper stormwater management and meet the
original intent of the basin.
Table 2 shows the current SWAMP score of the pond, whether the pond has been surveyed, the date
of the survey, the estimated current water depth of the pond, and the depth to which the pond should
be to function properly (Managed NURP Depth).
Pond Management Plan Page 9
TEN YEAR STORMWATER POND MANAGEMENT PLAN
Table 2. Maintenance Priority Ponds
Basin ID
Current
SWAMP
Score
Survey
Data
(Y/N)
Date of
Survey
Est.
Current
Depth (ft)
Managed
NURP
Depth
(ft)
207 0 Y 06-01-2014 0.0 4.9
204 9 Y 06-01-2014 0.4 4.5
96 10 Y 06-01-2014 0.5 5.6
178 11 Y 06-01-2014 0.7 6.8
233 11 Y 06-01-2014 0.7 6.4
177 13 Y 06-01-2014 0.8 5.9
168 14 Y 06-01-2014 1.0 7.3
135 18 Y 06-01-2014 1.0 5.3
155 20 Y 06-01-2014 1.1 5.7
169 24 Y 06-01-2014 1.7 6.9
154 31 Y 06-01-2014 1.4 4.6
259 37 Y 06-01-2014 3.3 8.9
172 46 Y 06-01-2014 2.2 4.7
145 49 Y 06-01-2014 1.4 3.0
Pond Management Plan Page 10
TEN YEAR STORMWATER POND MANAGEMENT PLAN
Figure 2 indicates the location of the ponds that have been identified in Table 2 as maintenance
priority ponds.
Pond Management Plan Page 11
TEN YEAR STORMWATER POND MANAGEMENT PLAN
Pond Feasibility Memos
Pond feasibility memorandums are highly recommended before pursuing cleanout operations for
ponds identified for maintenance. These memorandums identify permitting requirements, access
issues or needs related to cleanout project, cost benefit analyses, and potential inlet and outlet
improvements. Also included is a review of historical data, a field inspection of the basin and
bathymetric survey, and updating the SWAMP application to reflect the survey. See Appendix A for a
Pond Feasibility Memorandum completed for the City of Prior Lake.
Pond feasibility memorandums identify a tailored cleanout plan for each pond to restore optimal
treatment efficiency, rather than maximum efficiency. Significant cost reductions occur when a pond
is identified for a partial cleanout (i.e. inlet dredging) rather than a full pond cleanout. A partial
cleanout has been found to be effective in achieving stormwater treatment goals while simultaneously
reducing excavation costs. For example, a pond may be cleaned so that it returns to 80% functionality
for half the cost it would take to return to 85% functionality, saving the City a significant amount of
money.
If a pond’s overall functionality is adjusted during maintenance operations, SWAMP is also updated
so that the program calculations are adjusted according to these changes. SWAMP recalculates the
stormwater treatment capacity of the basin so that the program returns an accurate SWAMP score.
BMP Retrofits Page 12
TEN YEAR STORMWATER POND MANAGEMENT PLAN
3. BMP RETROFITS
When ponds and other BMPs are no longer meeting their designed objectives, retrofits may be
considered as opposed to complete replacement of the BMP. Many retrofits are needed or designed
based on changing regulatory conditions. BMPs constructed before 2013 were typically designed based
on the TP-40 rainfall standards. In 2013, NOAA released the Atlas-14 rainfall data for the state of
Minnesota. The Atlas-14 data predicted over a 1.0-inch increase in precipitation depth for the modeled
100-year event in many areas, therefore BMPs constructed before 2013 may be undersized for flood
prevention based on current rainfall modeling. The City recently completed an Atlas 14 Report for several
ponds to identify at-risk infrastructure.
Retrofitting of a BMP may also be desired if the BMP cannot achieve adequate water treatment
performance based on updated water quality thresholds, which in some cases have become more
stringent overtime. This section presents a summary of common BMP retrofits options that may be
considered.
Outlet Control Structures (OCS)
Outlet control structures are engineered devices that help to control water level and outflow rate of
water discharging from the BMP. Modifications to these structures can many times improve treatment
provided by the BMP. These structures typically have openings of varying sizes that can be easily
modified. Outlet control structures can also contain designs for preventing floating and settling debris
from continuing downstream.
Pretreatment
Pretreatment structures are BMPs designed to catch and settle stormwater particulates and pollutants
prior to discharge into a subsequent BMP. These systems are often small and require frequent
maintenance. They are intended to extend the functional life of the downstream BMP and provide
easier maintenance. Examples of pretreatment include, but are not limited to, pond forebays, sumps,
a SAFL Baffle, and hydrodynamic separators.
Filtration/Biofiltration
In areas where soils, ground water, contamination, or bedrock prohibit infiltration, filtration or
biofiltration BMPs should be considered. Filtration BMPs function primarily as a rate control and water
treatment structure and are not intended for volume reduction. Stormwater is temporarily retained
within the BMP, then filtered through a minimum of 18-inches of filter media. It is then collected in
perforated drain tile beneath the media and discharged back into the storm sewer system. Many
permitting agencies consider this as treating less than 100 percent of the pollutants contained within
the filtered volume. Filtration benches or areas can be added to ponds if conditions are appropriate to
retrofit a pond.
Estimated Costs Page 13
TEN YEAR STORMWATER POND MANAGEMENT PLAN
4. ESTIMATED COSTS
Pond survey costs were estimated for the survey priority ponds and excavation costs were estimated for
the maintenance priority ponds owned by the City. Ponds that are not owned by the City should be
surveyed and evaluated for maintenance by the private/state/county pond owner.
Survey Priority Ponds Cost
Pond surveys cost approximately $500 to $1,000 per basin (depending on size). This includes a
review of historical data, a field inspection of the basin and bathymetric survey , and updating the
SWAMP application to reflect the survey.
To survey the 7 city-owned ponds identified in Table 1, the total cost is approximately $7,000.
Depending on the results of the survey, the pond may also be identified for maintenance. It is highly
recommended that the City survey the pond soon so that the City can budget forecast accurately.
Maintenance Priority Ponds Cost
The annual stormwater maintenance cost estimate was developed using the calibrated SWAMP
results. SWAMP approximates the amount of sediment that needs to be removed from each basin to
achieve the City’s managed volume needs (the approximate excavation volume). The basins outlined
are the basins in the City that are most likely to need maintenance in the next ten years.
In addition to excavation, pond cleanout activities include, but are not limited to, engineering and
design, sediment sampling, basin dewatering, construction mobilization, dredging, erosion control,
and site restoration.
Pond feasibility memorandums are recommended for each of the basins to create a tailored
maintenance plan that optimizes the money spent on basin cleanout operations. It is likely that the
City will encounter contaminated soils at most (50% or more) of these basins based on the number of
past projects in the City that addressed soil contamination.
Contamination is identified through soil sampling prior to maintenance activities. Sediment sample
results are typically valid for two years based on acceptance from landfills. Because of this short time
window, contamination sampling should be completed as close to the actual maintenance period as
possible.
Estimated Costs Page 14
TEN YEAR STORMWATER POND MANAGEMENT PLAN
Table 3 shows the City owned maintenance priority ponds identified in Table 2 and their approximate
excavation volume and estimated excavation cost. Soil disposal is estimated at approximately $30
per cubic yard (CY) for non-contaminated areas based on previous pond cleanout projects.
Table 3. Maintenance Priority Pond Cleanout Costs
Basin ID
Current
SWAMP
Score
Est. Excavation
Volume (CY) Est. Cost ($)
207 0 848 $ 25,440
204 9 634 $ 19,020
96 10 2,260 $ 67,800
178 11 2,364 $ 70,920
233 11 5,087 $ 152,610
177 13 3,008 $ 90,240
168 14 3,221 $ 96,630
135 18 1,150 $ 34,500
155 20 1,157 $ 34,710
169 24 11,561 $ 346,830
154 31 489 $ 14,670
259 37 3,274 $ 98,220
172 46 876 $ 26,280
145 49 304 $ 9,120
Total* 36,233 $ 1,086,990
*Does not include costs for contaminated material, restoration, erosion control, and other work.
The presence of contaminated soil will increase the cost of disposal to approximately $50 per cubic
yard. When contamination is encountered, this will most likely cause a shift in the pond maintenance
schedule, as these basins cost more to maintain. Fewer ponds may be maintained in that year, but
typically, over a five- to ten-year period, the City’s maintenance schedule will still accommodate all
cleanout operations.
Table 3 costs were increased to account for restoration, erosion control, all appurtenant work, and
indirect/contingency costs using a factor of 1.75. This factor is based on an average multiplier of 1.4,
which was calculated from historical project trends and includes 25% for indirect/contingency costs.
The estimated cost to maintain the city-owned ponds identified is $1.90 million. If any of the 7 ponds
identified for survey are selected for maintenance, the list requiring maintenance will expand.
Ten-Year Cost
The total cost to survey the 7 City owned survey priority ponds is $7,000.
Maintaining the 14 City owned ponds identified for cleanout would cost approximately $1.90 million.
Depending on the conditions of the ponds surveyed, additional funds may be needed to maintain the
ponds that are added to the maintenance list.
The total cost of survey and maintenance activities for the City owned ponds is approximately
$1,910,000. The total pond improvement cost was divided by ten years to create an annualized pond
improvements cost, which equates to approximately $191,000 per year.
Next Steps Page 15
TEN YEAR STORMWATER POND MANAGEMENT PLAN
5. NEXT STEPS
WSB recommends the City complete the following steps:
1. Complete pond cleanout projects for the 14 city-owned maintenance priority ponds identified in
this report.
2. Survey the remaining 7 city-owned pond identified for survey in this report (and any additional
private ponds the City wants to survey).
3. Adjust City pond maintenance budget, as needed, for the annualized pond improvements cost.
4. Determine ponds to survey and maintain in 2021 and 2022.
5. Conduct sediment sampling during the spring or summer of 2021 and 2022 for the initial ponds
planned for maintenance.
6. Based on contamination results from sediment sampling, refine budget accordingly.
Appendices
TEN YEAR STORMWATER POND MANAGEMENT PLAN
Appendix A – Example Pond Feasibility Memorandum
Mr. Pete Young
November 10, 2020
Page 4
K:\016481-000\Admin\Docs\016481-000_Pond Maintenance Memo.docx
Pond SWP-6751S-06
Pond SWP-6751S-06 was inspected in August 2020. The pond is owned by the City of Prior Lake
and is located near Summer Street and adjacent to Cardinal Ridge Park. The pond is shown in
the NWI. The pond was constructed between 2006 and 2008, confirmed by available aerial
photos prior to and following construction (Appendix A: Figure 2a and Figure 2b). Refer to
Appendix B for the bathymetric survey results, drainage area map, and photos (Figure 2a,
Figure 2b, Figure 2c, and Figure 2d).
Table 3: Pond SWP-6751S-06 Summary
Direct Drainage Area 73.5 acres
Impervious Surface 37.3 acres
Impervious Surface 50.7%
Pond Area 0.15 acres
Current Average Depth 0.6 feet
Current Wet Volume 0.09 acre-feet
Outlet Diameter 36-inch RCP (E)
Inlet Diameter 2 - 30-inch RCPs (W)
SWAMP Score 10
Inspection Observations
A large sediment delta was observed at the pond inlet. The pond inlet grates are beginning to rust
and bend. The pond outlet flared end section appears in good condition, but evidence of dumped
grass clippings can be seen around the outlet.
Water Quality Analysis
SWAMP was used to estimate the TP and TSS annual reductions for Pond SWP-6751S-06 under
various maintenance options, as shown in Table 4.
Recommendations
Because the pond is undersized for the drainage area, excavate the pond to an average depth of
5.7 feet or as deep as possible given the small footprint (Table 4 Option 7). As part of the pond
maintenance, remove the sediment delta at the inlet to the pond and repair the inlet grates. If
possible, consider expanding the pond footprint. If the City chooses to do maintenance, sediment
samples will be required consistent with MPCA guideli nes. Following maintenance, update the
managed depth and basin area in SWAMP.
Mr. Pete Young
November 10, 2020
Page 5
K:\016481-000\Admin\Docs\016481-000_Pond Maintenance Memo.docx
Table 4: Pond SWP-6751S-06 Maintenance Options
*Cost estimates do not include indirect costs, contingencies, access/restoration costs, or disposal of contaminated materials.
Option Description
Volume
to
Excavate
(cy)
Estimated
Cost to
Excavate*
($)
TP
Removal
Efficiency
(%)
Annual
TP
Reduction
(lbs/yr)
TP Cost
Benefit
($/lb)
TSS
Removal
Efficiency
(%)
Annual
TSS
Reduction
(tons/yr)
TSS
Cost
Benefit
($/ton)
1
(Existing) 0.6’ average depth N/A N/A 6.1 3.97 N/A 13.8 1.35 N/A
2 Excavate to 1.0’
average depth 100 3,000 10.0 6.46 996 19.6 2.00 3,562
3 Excavate to 2.0’
average depth 340 10,200 16.9 11.0 282 33.4 3.29 982
4 Excavate to 3.0’
average depth 590 17,700 22.3 14.5 222 45.2 4.45 741
5 Excavate to 4.0’
average depth 830 24,900 26.5 17.2 213 53.0 5.22 721
6 Excavate to 5.0’
average depth 1,070 32,100 30.0 19.5 242 57.6 5.67 840
7
Excavate to 5.7’
average depth
(SWAMP managed
depth)
1,230 36,900 32.1 20.9 261 59.4 5.84 921
APPENDIX A
HISTORIC IMAGERY
Figure 2a: Historic Google Earth Aerial, USDA Farm Service Agency, September 2006,
Pond SWP-6751S-06 Not Yet Constructed
Figure 2b: Historic Google Earth Aerial, USDA Farm Service Agency, September 2008,
Pond SWP-6751S-06
APPENDIX B
MAPS AND PHOTOS
Figure 2c: Pond SWP-6751S-06, Sediment delta at the dual 30-inch Inlets
Figure 2d: Pond SWP-6751S-06, Grass Clippings at Pond Outlet
Page 1 of 2
Public Works Consultant Pool
Work Order (2022 Stormwater Pond Maintenance)
WSB & ASSOCIATES, INCORPORATED, dba WSB
This work order (“Work Order”) is issued on this _______ day of _________________, 2021 by
the City of Prior Lake (“City”) pursuant to the Public Works Consultant Pool – Master Agreement
dated April 20, 2020 (“Contract”) between the City and WSB & Associates, Incorporated, dba
WSB (“Consultant”).
Based on the mutual promises and covenants set forth herein, the sufficiency of which are hereby
acknowledged, the City and Consultant agree as follows:
1. Scope of Work Order. Consultant agrees to provide, perform and complete all the services
requested by the City in this Work Order and attached Exhibit 1 (“Work”), which Work shall be
subject to the terms and conditions of this Work Order and the Contract.
2. Term of Work Order. All Work requested by this Work Order shall be completed by
December 31, 2022.
3. Compensation for Work Order. City agrees to pay the Consultant a fixed sum of
$40,600.00 as full and complete payment for the Work requested by this Work Order.
4. Consultant Representative. Consultant has designated ___________________ to manage
the Work Order subject to the supervision of Consultant’s representative.
ISSUED BY CITY OF PRIOR LAKE
___________________________________
City Manager
RECEIVED AND ACCEPTED BY
CONSULTANT
_____________________________________
By:_________________________
Its:_________________________
Page 2 of 2
Exhibit 1 – Scope of Work Order
G:\Group Data\WATER RESOURCES\WR Proposal Folder\Prior Lake\LTR PROP-pyoung-20210604-2022PondMaintenance.docx 701 XENIA AVENUE S | SUITE 300 | MINNEAPOLIS, MN | 55416 | 763.541.4800 | WSBENG.COM June 4, 2021
Mr. Pete Young
Water Resources Engineer
City of Prior Lake
4646 Dakota Street SE
Prior Lake, MN 55372
Re: 2022 Pond Maintenance Project
City of Prior Lake, MN
Dear Mr. Young:
Attached for your review and approval is our proposed scope of services, fee, and schedule for
providing professional engineering services to complete pond inspections, pond review memos,
design, specification, permitting, bidding documents, and construction management for the 2022
Pond Maintenance Project.
We look forward to working with you on the 2022 Pond Maintenance Project. If you are in
agreement with this proposal, please sign where indicated below and return one copy. The
necessary contract documents will then be provided. WSB will start work upon receip t of a signed
contract. Please do not hesitate to contact Jake at 763 -231-4861 with any questions.
Sincerely,
WSB
Jake Newhall, PE Earth Evans, PE
Water Resources Project Manager Director of Water Resources
Attachment
ACCEPTED BY:
City of Prior Lake, MN
Name
Title
Date
Mr. Pete Young
June 4, 2021
Page 2
G:\Group Data\WATER RESOURCES\WR Proposal Folder\Prior Lake\LTR PROP-pyoung-20210604-2022PondMaintenance.docx
SCOPE OF ENGINEERING SERVICES
FOR
2022 POND MAINTENANCE PROJECT
CITY OF PRIOR LAKE, MN
SCOPE OF ENGINEERING SERVICES
Task 1 – Project Management ($4,000)
Project management will be performed throughout the course of the project. The following
subtasks are included as part of Project Management:
1.1 Attend project update meetings with City staff. This will include developing the
agenda, preparing handouts and graphics, and attending the meeting.
1.2 Work with project team to coordinate project deliverables, schedule, and budget.
Deliverables: Two (2) meetings. One meeting with City Staff to discuss draft plans and one to
discuss final plans for pond cleanout project.
Task 2 – Pond Surveys ($8,500)
This task consists of completing 21 pond surveys. This includes the 20 ponds identified for
maintenance (14) and inspection (6) in the recent pond assessment report as well as pond 197.
Findings from the inspections will be used in developing the pond review memos and
maintenance recommendations. SWAMP will be updated to reflect the survey results.
Deliverables: Bathymetric maps for each pond survey and updated SWAMP.
Task 3 – Pond Review Memos and Recommendations ($3,000)
This task includes completing 3-5 pond review memos. This will include memos for ponds 177
and 178 and up to three others based on survey results. The memos will include a
comprehensive review of each pond and outfall and the associated drainage area. A cost-benefit
analysis will be completed for each pond to determine the “best bang for the buck” maintenance
activities. Recommendations for each basin will be provided.
Deliverables: 3-5 pond review memos.
Task 4 – Sediment Testing ($1,500)
This task includes sediment sampling and analysis to determine the appropriate sediment
disposal methods (consistent with the MPCA’s Managing Stormwater Sediment: Best
Management Practice Guidance) for three ponds: Ponds 177 and 178 and another pond if it will
be included in the 2022 maintenance project.
Deliverables: Sediment Testing Spreadsheet. This task does not include lab fees. The fees will
be passed on to the City and are anticipated to be approximately $300 per sample.
Task 5 – Permit Coordination ($3,000)
This task consists of coordinating and obtaining the required permits for the proposed pond/outfall
maintenance activities. It is anticipated that US Army Corps of Engineers permitting will be
required based on experience with similar projects. WSB will coordinate the necessary Wetland
Conservation Act (WCA) no-loss applications.
5.1 US Army Corps of Engineers approval for the excavated ponds.
Mr. Pete Young
June 4, 2021
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5.2 WCA no-loss applications.
Deliverables: Necessary permitting documentation for the US Army Corps of Engineers and
WCA. This task does not include any necessary permit application fees; these will be pa ssed on
to the City if applicable.
Task 6 – Construction Documents ($9,800)
This task consists of completing construction plans, specifications , and bidding documents for all
recommended pond maintenance activities for three ponds: Ponds 177 and 178 and other pond
as identified by the pond surveys and review memos. Plans will be developed using previously
collected pond survey/inspection data.
Plans are anticipated to include cover sheet, details, grading plan, restoration /erosion control, and
site access/traffic control. One site visit per pond is anticipated during final design to confirm
construction access and other constructability details. In addition, an updated cost estimate will
be developed to verify consistency between the proposed improve ments and the City’s budget.
This scope assumes answering questions during the bid process to help facilitate the
understanding of construction expectations. It is important to note that this task does not include
negotiating site access with property owners and obtaining temporary easements or right-of-
entry; however, we can assist with this as needed.
6.1 Prepare draft construction plans, specifications, and updated cost estimate
6.2 Finalize construction plans, specifications and bidding documents based on feedback
from City staff.
Deliverables: Draft Plans, Final Plans, Specifications, and Bid Documents.
Task 7 – Construction Management ($10,800)
Construction management will be performed throughout the course of the construction schedule
for the pond maintenance work. This will include attending weekly progress meetings throughout
the project, and other necessary construction coordination.
This task will include part-time observation (approximately 10-15 hours per week). This will
include inspection of all critical construction components as well as regular check -ins with the
contractor and the City.
This scope of services also assumes WSB will complete all necessary construction staking and
survey work.
7.1 Attend pre-construction meeting and weekly construction meetings.
7.2 Part-time construction observation.
7.3 Review and approve pay vouchers.
7.4 Construction Staking
Deliverables: Construction Meetings, Construction Observation, and Construction Staking.
TOTAL ESTIMATED ENGINEERING FEE
Mr. Pete Young
June 4, 2021
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The scope of services outlined in this proposal will be billed hourly, based on our current hourly
rates. We are proposing to complete the tasks outlined above for the 20 22 Pond Maintenance
Project for a not-to-exceed fee of $40,600.00.
TIME SCHEDULE
Based on the current project schedule, WSB proposes to complete tasks 1-6 prior to October of
2021 to allow for bidding to occur in November of 2021 and construction in
December/January/February.