V.2. Central Park Stormwater Plan; Pavek
CITY OF HOPKINS
City Council Report 2025-083
To: Honorable Mayor and Council Members
Mike Mornson, City Manager
From: Dustin Pavek, Public Works Director
Date: May 6, 2025
Subject: Public Hearing on the Central Park Stormwater Plan
_____________________________________________________________________
RECOMMENDED ACTION
MOTION TO Hold a Public Hearing on the Central Park Stormwater Plan
OVERVIEW
As discussed at the April 15, 2025 meeting, the City has been working alongside the Nine
Mile Creek Watershed District (NMCWD) and engineering firms Bolton and Menk and
BARR to develop a master plan for Central Park which aims to improve and expand
existing amenities, while also treating and managing stormwater and water quality.
The City and NMCWD have worked together to seek a number of grant opportunities,
including the Clean Water Revolving Fund (CWRF), a funding program administered
jointly by the Minnesota Public Facilities Authority (PFA) and the Minnesota Pollution
Control Agency (MPCA).
As a part of the City’s application to the CWRF, the City must prepare a stormwater plan
and then hold a public hearing for any comments to be made on the plan. Following the
public hearing, the City must then adopt a resolution formally adopting the stormwater
plan.
Tonight, Staff will provide a brief overview of the process and the proposed stormwater
plan.
SUPPORTING INFORMATION
• Central Park Stormwater Plan and CWRF Application
Administration
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Environmental Information
Worksheet (EIW) form
Clean Water State Revolving Fund Program
Minnesota Rule Chapter 7077.0272, subp. 2.a.F.
Minnesota Rule Chapter 7077.0277, subp. 3.E.
Doc Type: Wastewater Point Source
Eligible applicants seeking funds for clean water (stormwater and wastewater) projects through the Clean Water State Revolving
Fund (commonly referred to as the CWSRF Program) are required by Minn. R. ch. 7077.0272, subp. 2.a. F. and Minn. R. ch.
7077.0277, subp. 3.E., to complete an Environmental Information Worksheet (EIW). This information will be used to assess
environmental impacts, if any, caused by the project.
Questions: Contact Review Engineer or Bill Dunn at 651-757-2324 or bill.dunn@state.mn.us.
1. Project title: Hopkins Central Park Stormwater Enhancements
2. Proposer: City of Hopkins
Contact person: Laila Imihy
Title: Special Projects and Initiatives Manager
Address: 1010 1st St S.
Hopkins, MN 55343
Phone: 952-547-6344
Fax:
3. Project location: County: Hennepin City/Twp: Hopkins
SW 1/4 SW 1/4 Section: 24 Township: 117N Range: 22W
Tables, Figures, and Appendices attached to the EIW:
County map showing the general location of the project;
United States Geological Survey 7.5 minute, 1:24,000 scale map indicating project boundaries (photocopy acceptable);
Site plan showing all significant project and natural features.
4. Description:
a. Provide a project summary of 50 words or less.
The City of Hopkins (City) is partnering with the Nine Mile Creek Watershed District (NMCWD) to incorporate enhanced
stormwater treatment into redevelopment of Central Park, to improve the quality of water to Nine Mile Creek and create an
enhanced headwaters feature to promote education and awareness of Nine Mile Creek.
b. Give a complete description of the proposed project and related new construction. Attach additional sheets as necessary.
Emphasize construction, operation methods and features that will cause physical manipulation of the environment or will
produce wastes. Include modifications to existing equipment or industrial processes and significant demolition, removal or
remodeling of existing structures. Indicate the timing and duration of construction activities.
Central Park is the City’s most heavily used park at the center of this fully developed community. The park has been in place
since the 1960’s. Lacking improvements for decades, the park is scheduled for reinvestment. Taking advantage of this rare
opportunity within the urban watershed, the City and NMCWD are seeking to integrate stormwater resiliency into the park
design. The North Fork of Nine Mile Creek starts just south of Excelsior Boulevard, the southern boundary of Central Park.
Given the park developed prior to the stormwater management standards of today, most stormwater from the park and
adjacent developed areas currently flows directly to Nine Mile Creek, without treatment or rate reduction prior to discharge. The
project will provide volume reduction (where feasible), pollutant removal, and flow attenuation (rate reduction) of stormwater
runoff from previously untreated areas.
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The attached figure (SitePlan - CentralPark-SWTreatmentFeatures.pdf) shows the stormwater volume reduction and
management features proposed as part of this project. The project has been designed not only to treat the new impervious
surfaces, but also existing untreated impervious surfaces. A series of raingardens at the perimeter of the project are sized to
capture and infiltrate off-site impervious surfaces. At the core of the park, filtration basins will treat runoff from the existing
impervious surfaces as well as the new playground area. These smaller scale raingardens are interconnected through sub-
surface drainage which ultimately overflow into a proposed Nine Mile Creek headwaters stormwater feature, prior to discharge
to downstream creek through a new pipe under Excelsior Boulevard. The proposed infiltration (and filtration) features will
reduce the volume of runoff to downstream Nine Mile Creek, reduce the pollutant load to Nine Mile Creek, provide important
reduction in peak runoff rates to the creek from the contributing area, and provide improved habitat and access to green/natural
areas.
Central Park was constructed on the site of the former Hennepin County Fairgrounds, portions of which were then briefly
utilized as a landfill in the 1960s. Results of the preliminary soils investigation for the site indicate the presence of contaminants
that will hinder implementation of infiltration-based stormwater features on portions of the site. To avoid mobilization of
contaminants through infiltration, in accordance with Minnesota Pollution Control Agency (MPCA) guidance, filtration-based
stormwater features were selected for these areas. The proposed filtration features will provide volume reduction through
storage within the filtration media and evapotranspiration, while also providing pollutant removal and substantial reductions in
peak flows to the creek during rainfall events, which is especially important for this “flashy” portion of Nine Mile Creek.
The project will also include a small stormwater reuse system to capture and store runoff from the Pavilion rooftop or other
hard surfaces. The stored water can be used to periodically feed the dry creek bed feature that is planned to meander through
the site as part of the Nine Mile Creek headwaters BMP.
The proposed project also includes a natural ‘stadium style’ soccer field, which is designed to be inundated and store
floodwater during high intensity runoff events. While this funding request does not include the costs for the large flood storage
features (soccer field), that component of the project will require extensive excavation.
Overall, the proposed design creates over 52,000 sf of green infrastructure and conversion of over 2 acres of turf to native
plantings. The native plants will not only help slow and evapotranspire runoff, they will provide an important habitat patch
connected to the Nine Mile Creek corridor. Over 90 overstory and ornamental trees will be planted throughout the park, within
the green infrastructure, and along Excelsior Boulevard, supporting the City's goals for reducing heat island effect.
During the remainder of 2025, the agencies will progress on production of final plans and specifications in response to external
funding received. Should sufficient external funding not be received, it is anticipated that project scope will be reduced
commensurate with lack of available funding for all features. For example, without sufficient funding availability,
excavation/removal/disposal of regulated on-site soils for creation of stormwater resiliency features may be substantially
reduced or omitted to achieve the minimal park improvements needed. The final plans are to be produced in late 2025 or 2026,
pending exhaustion of all possible external funding sources to accomplish the project goals outlined herein, with intended
construction as early as summer 2026.
Construction of the proposed stormwater treatment features will consist of shallow excavation and grading mostly in existing
green space, along with some storm sewer work that would require pavement removal. Construction of the stormwater features
and associated work would occur during non-frozen ground conditions, with planting and vegetation establishment to be
completed directly following the earthwork.
Timing of construction of the project will be dependent on funding availability and associated timing constraints. Ideally,
construction of the project, including park improvements, stormwater management features, and the flood storage feature,
would occur together. If so, it is anticipated this work would be completed within one construction season, with active
construction for a duration anticipated to be six to nine months. If necessary, the project could potentially be phased, such that
construction would occur within two construction seasons. Under this scenario, disrupted areas would be left in a stablized
condition in between construction seasons.
c. Explain the project purpose; if the project will be carried out by a governmental unit, explain the need for the project and identify
its beneficiaries.
Central Park is the City’s most heavily used park at the center of this fully developed community, used by community groups
and park users of all ages for programmed and non-programmed activities. Lacking improvements for decades, the park is
scheduled for reinvestment in 2026, which will support continued and expanded use by community members for all ages,
abilities, and cultural interests.
The proposed stormwater enhancements, an important component of the overall project, will serve several important purposes.
The stormwater features will provide stormwater volume reduction and pollutant removal to downstream Nine Mile Creek, while
also reducing peak flows to the creek during rainfall events, helping minimize “flashy” conditions that can cause or contribute to
erosion within the creek. These outcomes will help minimize erosion and improve habitat conditions for aquatic life within the
downstream creek. These outcomes will also reduce sediment and nutrient loading from the park and adjacent areas,
benefiting the health of Nine Mile Creek, downstream Normandale Lake, and the Minnesota River.
Beyond the water quality benefits to Nine Mile Creek, the proposed green infrastructure will create vegetated natural areas and
a new headwaters feature for Nine Mile Creek. These features will be highly visible but artfully interwoven into the reimagined
functionality of Central Park, creating improved access to natural areas, increased tree canopy to offset urban heat island
effects, and enhanced habitat.
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d. Are future stages of this development including development on any outlots planned or likely to happen? Yes No
If yes, briefly describe future stages, relationship to present project, timeline and plans for environmental review.
The Hopkins Pavilion is an existing ice arena and community center located at Central Park. Conceptual planning is underway
for a future Pavilion expansion, with full scope to be determined by the community. Any expansion preferred by the community
would be implemented as a separate project, although planning of the potential building footprint will be considered in the final
design of the parks stormwater features. No construction date is currently slated.
e. Is this project a subsequent stage of an earlier project? Yes No
If yes, briefly describe the past development, timeline and any past environmental review.
5. Project magnitude data
Total Project Area (acres) 28.3 (3 parcels) or Length (miles)
Number of Residential Units: Unattached 0 Attached 0 maximum units per building
Commercial/Industrial/Institutional Building Area (gross floor space): total square feet 4.2 acres of rooftop on 3 parcels
Indicate area of specific uses (in square feet): park, school, fire station, Hopkins Public Works facility, Hopkins Pavilion
community center
Office Manufacturing
Retail Other Industrial
Warehouse Institutional 1,232,748 square feet
Light Industrial Agricultural
Other Commercial (specify)
Building height If over 2 stories, compare to heights of nearby buildings
6. Permits and approvals required. List all known local, state and federal permits, approvals and financial assistance for the
project. Include modifications of any existing permits, governmental review of plans, and all direct and indirect forms of public
financial assistance including bond guarantees, Tax Increment Financing and infrastructure.
Unit of government Type of application Status
Nine Mile Creek Watershed District Grading and Land Alteration Permit Not yet applied
MPCA NPDES Construction Stormwater Permit Not yet applied
MDNR Work in Public Waters Permit Not yet applied
City of Hopkins Right-of-Way and Utility Excavation
Permit; Electrical permit for lighting
Not yet applied
7. Land use. Describe current and recent past land use and development on the site and on adjacent lands. Discuss project
compatibility with adjacent and nearby land uses. Indicate whether any potential conflicts involve environmental matters.
Identify any potential environmental hazards due to past site uses, such as soil contamination or abandoned storage tanks,
or proximity to nearby hazardous liquid or gas pipelines.
The project area was originally the site of the Hennepin County Fairgrounds circa 1930-1950, and contained a horse
racetrack, several barns, a grandstand, band stand, and arts and entertainment structures. However, by the 1960s, as
shown on 1960 and 1967 aerial photographs (Appendix 1; Draft Phase 1 ESA), the fairgrounds were demolished and the
majority of the project area was subjected to grading and fill. The eastern 2/3rd of the property also functioned as a landfill by
this time. By 1967, as shown on the USGS topographic map, only one building remained standing and the project area had
been converted to Central Park. By 1993, the park pavillion was constructed.
The site is currently used as a city park. Visitors can utilize two softball fields, a playground, turf open space and walking
trails, in addition to an outdoor hockey rink, tennis and pickleball courts. The pavilion houses an indoor hockey rink,
community gathering spaces, and restrooms. The park is served by several parking lots throughout the site. Many of the park
features are used by the two schools located at the perimeter of the park.
Environmental site assessment soil borings, taken to a depth of 15-25 feet throughout the project area in 2024, confirm the
disturbed nature of project area soils, with fill extending between 12 and 15 below ground surface. Several samples included
modern plastics up to 15 feet below ground surface.
The project is compatible with adjacent land uses. Land use adjacent to Central Park includes several multi-family residential
buildings on the east side and commercial and institutional properties (a church and a school) to the north. The improved
park and vegetated natural areas associated with the proposed stormwater features will serve as amenities, providing benefit
to community members that live, work, and/or visit the area.
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A Phase II Environmental Assessment Report was completed to evaluate potential subsurface impacts in areas of the project
that may be disturbed during construction activities. The Phase II Enivronmental Site Assessment (ESA) identified fill soils
across the entirety of the project area and the majority of those fill soils were found to contain varying amounts of debris.
Analytical testing of the fill soils identified elevated concentrations of VOCs, PAHs, DRO, and arsenic that exceeded
regulatory levels in the southeast quarter of the project area, where the two baseball fields are located. The observations and
testing indicated that debris related to the former dump/landfill are present at the project area and are likely the source of the
impacts identified in soil analyses. Given the findings of the investigation, soils from the project area will need to be
appropriately managed in accordance with MPCA guidance.
Standard city utilities exist within and surrounding the park. There are no high volume pipelines.
8. Cover types. Estimate the acreage of the site with each of the following cover types before and after development:
Before After Before After
Types 1-8 wetlands Lawn/landscaping 15.45 ac 12.24
Wooded/forest Impervious Surfaces 8.59 ac (at
grade)
9.55 ac (at grade)
Brush/grassland 2 ac Other (describe) 4.27 ac
(rooftop)
4.52 ac (rooftop)
Cropland
Total 28.31 ac 28.31 ac
9. Fish, wildlife, and ecologically sensitive resources.
a. Identify fish and wildlife resources and habitats on or near the site and describe how they would be affected by the
project. Describe any measures to be taken to minimize or avoid impacts.
The MnDNR’s Minnesota Conservation Explorer (MCE) was used to determine whether any sensitive ecological
resources are located within the vicinity of the project. No sensitive ecological resources or high quality fish or wildlife
habitats are located within or adjacent to the project area. Stormwater from the Central Park area currently discharges
to Nine Mile Creek just downstream of Excelsior Boulevard, a major roadway located directly on the south side of
Central Park. Currently stormwater from the park is conveyed to a large regional trunk storm sewer system under
Excelsior Boulevard, prior to discharge to the creek. As part of the project, installation of a separate small storm sewer
pipe from the park directly to the creek is anticipated. If this occurs, the storm sewer outfall would be designed to
minimize erosion and avoid other potential impacts, in accordance with guidance and/or requirements from MnDNR
and consistent with requirements of the NMCWD regulatory program.
The project is anticipated to benefit the fish and aquatic life community within Nine Mile Creek by reducing sediment
and nutrient loading to the creek. The enhance stormwater features will also reduce stormwater volume and peak flows
to the creek, reducing erosion potential. These benefits will likely improve water clarity (reduce turbidity) and enhance
habitat in the creek to support fish and other aquatic communities.
b. Are any state (endangered or threatened) species, rare plant communities or other sensitive ecological resources such
as native prairie habitat, colonial waterbird nesting colonies or regionally rare plant communities on or near the site?
Yes No
If yes, describe the resource and how it would be affected by the project. Indicate if a site survey of the resources has
been conducted and describe the results. If the Minnesota Department of Natural Resources (DNR) Natural Heritage and
Nongame Research program has been contacted give the correspondence reference number:
Describe measures to minimize or avoid adverse impacts.
The U.S. Fish and Wildlife Service (USFWS) Information for Planning and Consultation (IPaC) online tool was used to
obtain a list of federally protected species that could be present in the vicinity of the project area; the IPaC query
identified the following species:
• Rusty patched bumble bee (Bombus affinis) – endangered at the federal level and not protected at the state level.
• Tricolored bat (Perimyotis subflavus) – proposed endangered at the federal level, special concern at the state level.
• Monarch butterfly (Danaus plexippus) – proposed threatened at the federal level, not protected at the state level.
• Whooping crane (Grus americana) – experimental population, non-essentail at the federal level, not protected at the
state level.
The IPaC query also indicates that the project area intersects proposed designated critical habitat for the rusty patched
bumble bee; this proposed designated critical habitat covers much of the Twin Cities.
Federally proposed threatened or endangered species are species that the USFWS has determined are in danger of
extinction throughout all or a significant portion of their range and have proposed a draft rule to list them as threatened
or endangered. Proposed species are not protected by the take prohibitions of the federal Endangered Species Act
(ESA). A non-essential experimental population is a designation that refers to a population that has been established
within its historical range under Section 10(j) of the ESA to aid in recovery of the species. Species designated as non-
essential experimental populations are only protected by the federal ESA within a national wildlife refuge or a national
park, neither of which intersect the project area.
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The Natural Heritage Inventory System (NHIS) database was reviewed to assess the presence of state protected
species within one mile of the project area. Although the NHIS database does not represent a comprehensive survey, it
provides information on the potential presence of protected species. The NHIS database identifies one species, the
rusty patched bumble bee, located just under one mile south of the project area.
The project area is highly developed and consists of mowed lawn and impervious surfaces. As such, suitable habitat
for the federal or state protected species identified above is not present within the project area. The project will help
create potential habitat for pollinators such as the rusty patched bumble bee and monarch butterfly through conversion
of over 2 acres of turf to native prairie plantings, as well as flowring shrubs and trees.
10. Physical impacts on water resources. Will the project involve the physical or hydrologic alteration (dredging, filling, stream
diversion, outfall structure, diking, and impoundment) of any surface waters such as a lake, pond, wetland, stream or
drainage ditch? Yes No
If yes, identify water resource affected. Describe alternatives considered and proposed mitigation measures to minimize
impacts. Give the DNR Protected Waters Inventory (PWI) number(s) if the water resources affected are on the PWI.
The Project will affect Nine Mile Creek from installation of a new stormwater conveyance pipe outfall. Nine Mile Creek is
identified as a Public Water. Currently stormwater from the park is combined with flows in a large regional storm sewer pipe
under Excelsior Boulevard prior to discharge to the creek. As part of the project, it is anticipated that a separate small storm
sewer pipe will be installed from the park directly to the creek, in lieu of the stormwater being combined with flows in the
existing large regional storm sewer pipe prior to discharge. The separate storm pipe from Central Park to Nine Mile Creek is
likely necessary for the flood storage component of the project. The separate pipe will help avoid tailwater impacts and
minimize potential backflow from the large trunk storm pipe to optimize flood storage achieved in the park during large (e.g.,
1% annual chance) storm events.
The alternative to installing a new separate storm pipe and outfall from Central Park to Nine Mile Creek is to continue to
utilize the existing large storm sewer pipe and outfall. With either alternative, the rate and volume of stormwater discharged
to the creek will be very similar. The addition of a separate storm pipe from Central Park is not anticipated to alter the flows.
Installation of a new storm pipe from Central Park to Nine Mile Creek will be designed to minimize erosion and avoid other
potential impacts, in accordance with guidance and/or requirements from MnDNR and consistent with requirements of the
NMCWD regulatory program. Methods to minimize impacts will include permanent erosion control such as riprap at the
outfall and careful consideration of outfall alignment with the direction of flow.
11. Water use. Will the project involve installation or abandonment of any water wells, connection to or changes in any public
water supply or appropriation of any ground or surface water (including dewatering)? Yes No
If yes, as applicable, give location and purpose of any new wells; public supply affected, changes to be made, and water
quantities to be used; the source, duration, quantity and purpose of any appropriations; and unique well numbers and DNR
appropriation permit numbers, if known. Identify any existing and new wells on the site map. If there are no wells known on
site, explain methodology used to determine.
12. Water-related land use management districts. Does any part of the project involve a shoreland zoning district, a
delineated 100-year flood plain, or a state or federally designated wild or scenic river land use district? Yes No
If yes, identify the district and discuss project compatibility with district land use restrictions.
Currently stormwater from the park is conveyed to a large regional trunk storm sewer system under Excelsior Boulevard,
prior to discharge to the creek. As part of the project, installation of a separate small storm sewer pipe from the park directly
to Nine Mile Creek is anticipated. Nine Mile Creek has a delineated FEMA 100-year floodplain and a 100-year flood
management area regulated by NMCWD. The project is compatible with this land use restriction, as it will not result in
increased flows to Nine Mile Creek nor will it result in fill in the floodplain without required compensatory storage.
13. Water surface use. Will the project change the number or type of watercraft on any water body? Yes No
If yes, indicate the current and projected watercraft usage and discuss any potential overcrowding or conflicts with other uses.
14. Erosion and sedimentation. Give the acreage to be graded or excavated and the cubic yards of soil to be
moved: 13 Acres: 40,000 cubic yards. Describe any steep slopes or highly erodible soils and
identify them on the site map. Describe any erosion and sedimentation control measures to be used during and after project
construction.
During construction the contractor will utilize inlet protection, silt fence, sediment logs, and temporary cover such as
hydromulch or temporary erosion control blankets. It's possible construction will be phased, first completing the rough
grading of the basins and leaving the last foot of excavation depth until just prior to final filtration and planting soil installation
to avoid siltation. After construction, the site will be stabilized with planting and seeding, along with and erosion control
blankets, hydromulch, or hardwood mulch.
15. Water quality – surface-water runoff.
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a. Compare the quantity and quality of site runoff before and after the project. Describe permanent controls to manage or
treat runoff. Describe any storm water pollution prevention plans.
Under current conditions, there is limited stormwater treatment that occurs within the park and associated parcels; most
of the runoff is conveyed to the storm sewer and downstream creek without treatment.
The proposed project includes an increase in impervious surface in the park of approximately 1.2 acres, which results
in generation of an additional 2.6 acre-feet of stormwater volume, 2.2 lbs total phosphorus (TP), and 394 lbs total
suspended sediment (TSS) on an average annual basis.
However, the proposed project will provide treatment of stormwater from the new impervious surfaces, as well as other
untreated pervious and impervious surfaces in and nearby the park, resulting in significant volume reduction and
pollutant removal. The proposed project will remove 16.8 acre-feet of stormwater volume,
23.2 lbs of total phosphorus (TP), and 4,682 lbs of total suspended sediment (TSS) on an annual average basis.
Description of permanent controls to manage or treat runoff: A series of raingardens at the perimeter of the project are
sized to capture and infiltrate off-site impervious surfaces. At the core of the park, filtration basins will treat runoff from
the existing impervious surfaces as well as the new playground area. These smaller scale raingardens are
interconnected through sub-surface drainage which ultimately overflow into a proposed Nine Mile Creek headwaters
BMP feature, prior to discharge to downstream creek through a new pipe under Excelsior Boulevard. The proposed
infiltration and filtration BMPs will reduce the volume of runoff to downstream Nine Mile Creek, reduce the pollutant
load to Nine Mile Creek, provide important reduction in peak runoff rates to the creek from the contributing area, and
provide improved habitat and access to green/natural areas.
A stormwater pollution prevention plan will be prepared prior to project construction, in accordance with local, NMCWD,
and MPCA requirements.
b. Identify routes and receiving water bodies for runoff from the site; include major downstream water bodies as well as
the immediate receiving waters. Estimate impact runoff on the quality of receiving waters.
The entire project lies within the NMCWD and stormwater runoff from the project will discharge via storm sewer and
overland flow to Nine Mile Creek. Nine Mile Creek ultimately discharges into the Minnesota River.
As stated above, permanent stormwater quality management and quantity control measures will be constructed as part
of the project. These measures will provide the proper stormwater quality management and quantity control to minimize
potential impacts to downstream receiving waters.
16. Water quality – wastewater.
a. Describe sources, composition and quantities of all sanitary, municipal and industrial wastewater produced or treated at
the site.
Not Applicable
b. Describe waste treatment methods or pollution prevention efforts and give estimates of composition after treatment.
Identify receiving waters, including major downstream water bodies, and estimate the discharge impact on the quality of
receiving waters. If the project involves on-site sewage systems, discuss the suitability of site conditions for such systems.
Not Applicable
c. If wastes will be discharged into a publicly owned treatment facility, identify the facility, describe any pretreatment
provisions and discuss the facility’s ability to handle the volume and composition of wastes, identifying any
improvements necessary.
Not Applicable
d. If the project requires disposal of liquid animal manure, describe disposal technique and location and discuss capacity
to handle the volume and composition of manure. Identify any improvements necessary. Describe any required
setbacks for land disposal systems.
Not Applicable
17. Geologic hazards and soil conditions.
a. Approximate depth (in feet) to Groundwater 10 minimum; 15 average.
Bedrock: 100 minimum; >100 average.
Describe any of the following geologic site hazards to groundwater and also identify them on the site map: sinkholes,
shallow limestone formations or karst conditions. Describe measures to avoid or minimize environmental problems due
to any of these hazards.
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As identified in the Phase II ESA, published hydrogeologic information indicates the depth to groundwater in the vicinity
of the project area is expected to lie within 20 feet below land surface and the regional groundwater flow direction
within the unconsolidated deposits in the Site vicinity is generally to the south.
Soil borings collected from the project area in September 2024 indicated water observations at depths ranging from 10
to 20 feet.
b. Describe the soils on the site, giving U.S. Soil Conservation Service (SCS) classifications, if known. Discuss soil
granularity and potential for groundwater contamination from wastes or chemicals spread or spilled onto the soils.
Discuss any mitigation measures to prevent such contamination.
According to published geologic information, in the northwest portion of the project area, the unconsolidated sediments
consist of late Pleistocene age Twin Cities Member outwash deposits. These deposits are fine-grained sand to gravel
of mixed province. In the southeast portion of the project area, the unconsolidated sediments are fill soils associated
with sediments that are comprised of Holocene age Lacustrine deposits. These deposits are fine-grained organic
matter than can be massive or laminated, fine-grained sand, silt, and clay in current or former lake basins or other
areas of non-flowing water. According to published geologic information, the uppermost bedrock unit in the project
vicinity consists of the middle to late Ordovician, St. Peter Sandstone. The unit is a mostly white to tan, fine- to
medium-grained, friable quartzose sandstone. The depth to bedrock in the project vicinity is approximately 100 to 250
feet below land surface.
Soil in the project area is mapped as urban land and udipsamments (cut and fill land) with 0 to 2 percent slopes. Soil
borings throughout the project area indicate fill material at depths ranging from 9 to 24 feet in depth, with underlying
soils ranging from glacial outwash to peat to sandy clay.
The project is unlikely to cause groundwater contamination.
18. Solid wastes, hazardous wastes, storage tanks.
a. Describe types, amounts and compositions of solid or hazardous wastes, including solid animal manure, sludge and
ash, produced during construction and operation. Identify method and location of disposal. For projects generating
municipal solid waste, indicate if there is a source separation plan; describe how the project will be modified for
recycling. If hazardous waste is generated, indicate if there is a hazardous waste minimization plan and routine
hazardous waste reduction assessments.
Not applicable.
b. Identify any toxic or hazardous materials to be used or present at the site and identify measures to be used to prevent
them from contaminating groundwater. If the use of toxic or hazardous materials will lead to a regulated waste,
discharge or emission, discuss any alternatives considered to minimize or eliminate the waste, discharge or emission.
None.
c. Indicate the number, location, size and use of any above or below ground tanks to store petroleum products or other
materials, except water. Describe any emergency response containment plans.
Not applicable.
19. Traffic. Parking spaces added: 23 Existing spaces (if project involves expansion): 215
Estimated total average daily traffic generated: Estimated maximum peak hour traffic
generated (if known) and its timing: Provide an estimate of the impact on traffic
congestion affected roads and describe any traffic improvements necessary. If the project is within the Twin Cities metropolitan
area, discuss its impact on the regional transportation system.
Construction traffic related to the delivery of supplies and the hauling of materials will temporarily increase traffic during
construction. Traffic will be spaced out through the day and is not expected to have an effect on peak hour traffic or the regional
transportation system. A traffic plan will be required by the construction contractor and submitted to the City for approval.
There are no permanent traffic increases anticipated as a result of the project.
20. Vehicle-related air emissions. Estimate the effect of the project’s traffic generation on air quality, including carbon monoxide
levels. Discuss the effect of traffic improvements or other mitigation measures on air quality impacts. Note: If the project involves
500 or more parking spaces, consult Environmental Assessment Worksheet (EAW) Guidelines about whether a detailed air
quality analysis is needed.
During construction, varying numbers of vehicles will be involved in construction activities and the delivery and removal of
construction materials. These vehicles may have short-term impacts on local air emissions due to construction equipment
exhaust and fugitive dust emissions (particulate matter). Post construction vehicle traffic will not increase based on the project;
therefore, there will not be any long-term traffic-related air impacts from the project. It is anticipated that the short-term
construction-related vehicle air emissions will not cause or contribute to a violation of ambient air quality standards for any
pollutants.
21. Stationary source air emissions. Describe the type, sources, quantities and compositions of any emissions from stationary
sources of air emissions such as boilers, exhaust stacks or fugitive dust sources. Include any hazardous air pollutants (consult
EAW Guidelines for a listing), any greenhouse gases (such as carbon dioxide, methane, and nitrous oxides), and ozone-
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depleting chemicals (chlorofluorocarbons, hydrofluorocarbons, perfluorocarbons or sulfur hexafluoride). Also describe any
proposed pollution prevention techniques and proposed air pollution control devices. Describe the impacts on air quality.
The project is not expected to result in any increases in air pollution.
22. Odors, noise, and dust. Will the project generate odors, noise or dust during construction or during operation? Yes No
If yes, describe sources, characteristics, duration, quantities or intensity and any proposed measures to mitigate adverse
impacts. Also identify locations of nearby sensitive receptors and estimate impacts on them. Discuss potential impacts on human
health or quality of life. (Note: fugitive dust generated by operations may be discussed at item 23 instead of here.)
Construction activities will expose soils, with the potential for generating dust. During construction, haul roads and other
exposed areas will be maintained to minimize dust, and exposed surfaces will be watered on windy days. Construction activities
will be undertaken during operational hours as permitted by the City.
23a. Nearby resources. Are any of the following resources on or in proximity to the site? Projects should search the Minnesota State
Historic Preservation Office’s (SHPO) National Register of Historic Places database.
*Note: Project proposers must contact the SHPO at datarequestshpo@mnhs.org to request a database review to obtain
information on any known historical or archaeological sites in the project area.
Include a copy of correspondence with SHPO with the submittal of this EIW form.
a. Archaeological, historical, or architectural resources? Yes No
b. Prime or unique farmlands or land within an agricultural preserve? Yes No
c. Designated parks, recreation areas, or trails? Yes No
d. Scenic views and vistas? Yes No
e. Other unique resources? Yes No
If yes, describe the resource and identify any project-related impacts on the resources. Describe any measures to minimize or
avoid adverse impacts.
Central Park will be temporarily disrupted during construction, however, users will benefit from the improvements after
construction.
23b. Section 106 Review (36 CFR 800) is required for all CWRF projects. The following forms can be found on the MPCA
Wastewater and Stormwater Financial Assistance website at https://www.pca.state.mn.us/ppl. Select Clean Water Revolving
Fund tab; then scroll to Facilities Plan and Facilities Plan Supplement for Wastewater Treatment Systems heading.
a. Project is exempt from review (attach completed Exemption Checklist) Yes No
b. Project is required to complete further Section 106 Review: Yes No
a. SHPO
b. Tribal consultation
c. Other Consulting parties
24. Visual impacts. Will the project create adverse visual impacts during construction or operation? Such as glare from intense
lights, lights visible in wilderness areas and large visible plumes from cooling towers or exhaust stacks? Yes No
If yes, explain.
25. Compatibility with plans and land use regulations. Is the project subject to an adopted local comprehensive plan, land use
plan or regulation, or other applicable land use, water, or resource management plan of a local, regional, state or federal
agency? Yes No
If yes, describe the plan, discuss its compatibility with the project and explain how any conflicts will be resolved. If no, explain.
The project is compatible with the City of Hopkins 2040 Comprehensive Plan, approved in November 2020, which includes a
policy to prioritize and execute improvements at designated focus parks such as Central Park.
The project is compatible with the NMCWD Water Management Plan, which was originally adopted in 2017 and amended in April
2025. The amended NMCWD Water Management Plan specifically includes the Hopkins Central Park project as a capital
improvement project.
26. Impact on infrastructure and public services. Will new or expanded utilities, roads, other infrastructure or public services be
required to serve the project? Yes No
If yes, describe the new or additional infrastructure or services needed. (Note: any infrastructure that is a connected action with
respect to the project must be assessed in the EAW; see EAW Guidelines for details.)
The project includes modifications to existing storm sewer and installation of new storm sewer within Central Park and adjacent
public property to redirect stormwater to the proposed stormwater and flood control features. Site circulation improvements
including roadways for site access, parking lots, and public trails and sidewalks will also be improved.
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wq-wwtp2-20 • 1/12/18 Page 9 of 9
27. Cumulative impacts. Minn. R. 4410.1700, subp. 7, item B requires that the RGU consider the “cumulative potential effects of
related or anticipated future projects” when determining the need for an environmental impact statement. Identify any past,
present or reasonably foreseeable future projects that may interact with the project described in this EAW in such a way as to
cause cumulative impacts. Describe the nature of the cumulative impacts and summarize any other available information
relevant to determining whether there is potential for significant environmental effects due to cumulative impacts (or discuss each
cumulative impact under appropriate item(s) elsewhere on this form).
The Hopkins Pavilion is an existing ice arena and community center located at Central Park. Conceptual planning is underway
for a future Pavilion expansion to provide another sheet of ice and expanded community services. Potential effects of the
Pavilion expansion could include an increase in parking stalls and an increase in traffic related to community use of the
expanded facility. Significant environmental effects due to cumulative impacts of the Pavillion Expansion are not anticipated.
There are no future projects known to exist at this time. In addition, no cumulative effects are expected from this project. There
will be no point source air emission or water discharges. The City will be complying with the MPCA General Stormwater Permit
for construction to control stormwater during construction and will provide stormwater quality and quantity control at the site.
28. Other potential environmental impacts. If the project may cause any adverse environmental impacts not addressed by items 1
to 28, identify and discuss them here, along with any proposed mitigation.
There are no other potential environmental impacts.
29. Summary of issues. List any impacts and issues identified above that may require further investigation before the project is
begun. Discuss any alternatives or mitigative measures that have been or may be considered for these impacts and issues,
including those that have been or may be ordered as permit conditions.
There are no known issues to exist that may require further investigation.
$+
$+
")
#*
$+$+
$+$+
#*
#*
")
1st St S
Main St 13th Ave N15th Ave S2nd St S18th Ave S1st St N
12th Ave N17th Ave S13th Ave S15th Ave N14th Ave N16th Ave N18th Ave N12th Ave S17th Ave NExcelsior Blvd45673
4.5
1.5
2.2 1.2
4.5
3.7
4.74.7
0.4
0.2
4.4 P1
P2
S1
P8
P6P5
P4 P3
W1
W2
U1
Central Park Proposed Stormwater Features
FIGURE
Barr Footer:!;N
$+Filtration Basins
#*Vegetation Infiltration Basins
")Stormwater Storage
")Underground Storage
Storm Main
BMP Subwatershed (Acres)
Project Area
Parcels
Creek Centerline
1st St S
Main St 13th Ave N15th Ave S2nd St S18th Ave S1st St N
12th Ave N17th Ave S13th Ave S15th Ave N14th Ave N16th Ave N18th Ave N12th Ave S17th Ave NExcelsior Blvd45673
Existing Stormwater Conveyance
FIGURE
Barr Footer:!;N
Storm Main
Project Area
Parcels
Creek Centerline
0 2,0001,000
Feet !;N
Barr Footer: ArcGISPro, 4/18/2025 11:27 AM File: I:\Client\Nine_Mile_Creek_WD\Work_Orders\23272042_Hopkins Park Stormwater\Users\DRM3\Central_Park_Hopkins_Surfaces.aprx Layout: USGS User: DRM3
FIGURE 02
Project Site Parcel Ownsership
CITY OF HOPKINS
IND SCHOOL DIST NO 274
USGS 7.5 Minute
Central Park Site Location
Nine Mile Creek WD
Hopkins, MN
HOPKINS CENTRAL PARK IMPROVEMENT PLAN APRIL 4, 2025
0’100’200’
1
4
5
6
6
6
6
8
9
92
2
3
3
2
2
SOFTBALL FIELD 1
280’ FENCELINE
SOFTBALL FIELD 2
275’ FENCELINE
SUNKEN SOCCER/
FLEX FIELD BASIN
STORMWATER
NODE
STORMWATER
PRETREATEMENT
+ SCIENCE YARD
GREEN STORMWATER INFRASTRUCTURE
PLAY AREA
SUNKEN SOCCER / FLEX FIELD
WEIR / SPILLWAY
SHELTERS
SKATE LOOP
PARK ENTRY NODE
STORMWATER NODE
INTEGRATED SEAT WALLS
DRY CREEK BED
EXISTING
PICKLEBALL
EXISTING
PARKING
EXISTING
TENNIS
HOPKINS
PAVILION
EXISTING
HOCKEY +
WIFFLEBALL
FUTURE PHASE
FUTURE PHASE
FUTURE PHASE
FUTURE PHASE
EXPANDED PARKING
PARK ENTRANCE
PARK ENTRANCE
EXISTING HOCKEY RINK + WIFFLEBALL
PLAY AREA
SKATE LOOP
SHELTER
1
7
6
4
5 55
8
9
10
10
7
FUTURE PHASE
SHELTER
>>>
>
>>
>>
>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
60"
RCP
60" RCP42" RCP 42" RCP42" RCP42" RCP1
5
"
R
C
P
12"
RCP12" RCP12" RCP12" RCP
18" RCP18"RCP
12"
R
C
P12" RCP12" RCP12" R
C
P
12" RCP24"RCP12" RCP
12"
R
C
P 12" CORR. HDPE12" CORR. HDPE12" CORR. HDPE12" CORR. HDPE 12" CORR. HDPE 12" CORR. HDPE12" CORR. HDPE12" CORR. HDPE12" CORR. HDPE 12" CORR. HDPE 12" CORR. HDPE 12" CORR. HDPE
12" CORR. HDPE
12" RCP
12"CORR.
HDPE
12" CORR. HDPE14" HDPE DR 1714" HDPE DR 1712" CORR. HDPE>>>>>>>>>>>>
>>
B
C
C
H
TRASH
C
CBRCR=912.78INV:INV:INV:INV:INV:INV:
V V
V VBBB
H
G
H
H E
D
MHSTR=912.70INV:INV:INV:INV:INV:INV:
H
P P P P
PPPP
P
H
PP
CBRC / IRON CURB CASTING FOR DRAINAGE THROUGH CURBR=915.73INV:INV:INV:INV:INV:INV:
HCC
G
M
B B
CBRC / IRON CURB CASTING FOR DRAINAGE THROUGH CURBR=915.74INV:INV:INV:INV:INV:INV:
CBRCR=909.36INV:INV:INV:INV:INV:INV:
E
CBRCR=904.00INV:INV:INV:INV:INV:INV:
E
D
MHSTR=905.23INV:INV:INV:INV:INV:INV:
D
MHSTR=905.31INV:INV:INV:INV:INV:INV:
H
G
D MHSTR=905.47INV:INV:INV:INV:INV:INV:
P
P P
P
P
CBRCR=909.20INV:INV:INV:INV:INV:INV:
P
H
P P P P
PPPP
C
H
P P P PPPPPPP
PC
XXXXXXXX X XXXXXXXXXXX X X X X
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X X X X X X
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CBRC CGFL /PRECAST ,4 Rings @ 0.8 thick ,Cond:FairR=915.13
W (12 IN RCP)910.60INV:INV:INV:INV:INV:INV:
D
MHST /PRECAST ,3 Rings @ 0.6 thick ,Cond:FairR=915.68
S (12 IN RCP)
E (12 IN RCP)
W (12 IN RCP)
909.98
909.50
INV:
INV:910.13INV:INV:INV:
INV:
CBRC /PRECAST ,4 Rings @ 0.8 thick ,Cond:FairR=915.58
E (12 IN RCP)
NW (12 IN RCP)910.93
910.35
INV:INV:INV:INV:INV:
INV:
CBRC CGFL1 /PRECAST ,3 Rings @ 0.6 thick ,Cond:FairR=916.28
SE (12 IN RCP)911.46INV:INV:INV:INV:INV:INV:
D
MHST /PRECAST ,3 Rings @ 0.6 thick ,Cond:FairR=915.82
W (12 IN RCP)
E (12 IN RCP)
SUMP
911.47
911.30
INV:
INV:907.07INV:INV:INV:
INV:CBRC CGFL /PRECAST ,1 Rings @ 0.2 thick ,Cond:FairR=914.54
W (12 IN RCP)
SE (12 IN HDPE)911.89
911.86
INV:INV:INV:INV:INV:
INV:
CBRC CGFL /BLOCK ,2 Rings @ 0.4 thick ,Cond:FairR=915.19
NW (12 IN RCP)
E (12 IN RCP)911.14
911.04
INV:INV:INV:INV:INV:
INV:
D
MHST /PRECAST ,5 Rings @ 1 thick ,Cond:FairR=919.61
S (15 IN RCP)
N (12 IN RCP)
NE (12 IN RCP)
NW (12 IN RCP)
912.98
912.88
INV:
INV:914.26
INV:914.26INV:INV:
INV:
CBRC CGFL1 /PRECAST ,Total Ring Depth:0 ,Cond:FairR=918.65
SW (12 IN RCP)914.80INV:INV:INV:INV:INV:INV:
CBRC CGFL1 PC /PRECAST ,Total Ring Depth:0 ,Cond:FairR=918.61
SE (12 IN RCP)914.81INV:INV:INV:INV:INV:INV:
CBRC CGFL1 /PRECAST ,2 Rings @ 0.4 thick ,Cond:FairR=915.37
S (12 IN RCP)
N (12 IN RCP)
SE (12 IN RCP)
908.22
908.12
INV:
INV:909.62INV:INV:INV:
INV:
CBRC /PRECAST ,2 Rings @ 0.4 thick ,Cond:FairR=912.81
W (12 IN RCP)907.89INV:INV:INV:INV:INV:INV:D
MHST /PRECAST ,2 Rings @ 0.4 thick ,Cond:FairR=913.13
S (24 IN RCP)
N (24 IN RCP)
E (12 IN RCP)
W (12 IN RCP)
902.52
902.51
INV:
INV:907.23
INV:907.03INV:INV:
INV:
CBRC /PRECAST ,3 Rings @ 0.6 thick ,Cond:FairR=911.14
S (12 IN RCP)
E (12 IN RCP)907.14
907.04
INV:INV:INV:INV:INV:
INV:
CBRC /PRECAST ,2 Rings @ 0.4 thick ,Cond:FairR=911.13
W (12 IN RCP)907.28INV:INV:INV:INV:INV:INV:
CBRC /PRECAST ,2 Rings @ 0.4 thick ,Cond:FairR=911.01
E (12 IN RCP)
W (12 IN RCP)906.56
906.46
INV:INV:INV:INV:INV:
INV:
CBRC /PRECAST ,1 Rings @ 0.2 thick ,Cond:FairR=911.07
E (12 IN RCP)
N (12 IN RCP)906.87
906.77
INV:INV:INV:INV:INV:
INV:
CBRC /PRECAST ,5 Rings @ 1 thick ,Cond:FairR=911.85
E (36 IN RCP)
NW (15 IN RCP)901.00
900.30
INV:
INV:
D
MHST /PRECAST ,10 Rings @ 2 thick ,Cond:PoorR=913.01
SE (15 IN RCP)
NW (12 IN PVC)906.04
902.55
INV:INV:INV:INV:INV:
INV:
D
MHST /PRECAST. CONNECTED TO 40582 ,2 Rings @ 0.4 thick ,Cond:FairR=911.78
W (12 IN RCP)905.96INV:INV:INV:INV:INV:INV:D
MHST /PRECAST,2 Rings @ 0.4 thick ,Cond:FairR=911.82
SE (12 IN PVC) TOP OF PIPE
SUMP 901.12
907.25
INV:INV:INV:INV:INV:
INV:
D
MHST /PRECAST ,3 Rings @ 0.6 thick ,Cond:FairR=912.70
S (24 IN PVC)
N (24 IN RCP)
SUMP
902.68
900.50
INV:
INV:898.20INV:INV:INV:
INV:
D
MHST /PRECAST. TOP OF WALL = 4.60'. SOUTH OF WALL SUMP = 14.66'.NORTH OF WALL SUMP = 12.42'. ,2 Rings @ 0.4 thick ,Cond:FairR=912.56
S (24 IN RCP)
N (24 IN PVC)
SUMP
SUMP
900.08
902.31
INV:
INV: 900.14
INV: 897.90INV:INV:
INV:
CBRC /PRECAST ,1 Rings @ 0.2 thick ,Cond:FairR=912.71
S (24 IN RCP)
N (24 IN RCP)903.86
903.49
INV:INV:INV:INV:INV:
INV:
CBRC /PRECAST ,4 Rings @ 0.8 thick ,Cond:FairR=914.67
SE (18 IN RCP)
NW (18 IN RCP)908.07
908.02
INV:INV:INV:INV:INV:
INV:
CBRC /PRECAST ,3 Rings @ 0.6 thick ,Cond:FairR=914.84
S (24 IN RCP)
N (24 IN RCP)
E (4 IN DRAIN TILE)
906.24
906.14
INV:
INV:913.74INV:INV:INV:
INV:
CBRC /PRECAST ,6 Rings @ 1.2 thick ,Cond:FairR=915.21
S (24 IN RCP)
NW (18 IN RCP)
N (12 IN RCP)
908.11
907.41
INV:
INV:908.66INV:INV:INV:
INV:
CBRC / DRAIN ,1' X 1' PLASTICR=915.96
S (4 IN DRAIN TILE)915.06INV:INV:INV:INV:INV:INV:
CBRC / DRAIN ,1' X 1' PLASTICR=915.93
N (4 IN DRAIN TILE)
S (4 IN DRAIN TILE)915.13
915.13
INV:INV:INV:INV:INV:
INV:
CBRC / DRAIN ,1' X 1' PLASTICR=915.53
N (4 IN DRAIN TILE)
S (4 IN DRAIN TILE)914.53
914.53
INV:INV:INV:INV:INV:
INV:
CBRC /PRECAST ,4 Rings @ 0.8 thick ,Cond:FairR=916.56
W (12 IN RCP)911.84INV:INV:INV:INV:INV:INV:
CBRC /PRECAST ,6 Rings @ 1.2 thick ,Cond:FairR=916.88
W (12 IN RCP)
E (12 IN RCP)911.61
911.59
INV:INV:INV:INV:INV:
INV:
CBCC / BEE HIVE ,PRECAST ,4 Rings @ 0.8 thick ,Cond:FairR=913.88
SE (18 IN RCP)905.78INV:INV:INV:INV:INV:INV:
CBCC /PRECAST ,Total Ring Depth:0 ,Cond:FairR=916.24
S (12 IN RCP)
E (12 IN RCP)911.51
911.41
INV:INV:INV:INV:INV:
INV:
D
MHST /PRECAST ,9 Rings @ 1.8 thick ,Cond:FairR=915.94
W (18 IN RCP)
N (12 IN RCP)906.67
906.08
INV:INV:INV:INV:INV:
INV:
CBCC /PRECAST ,2 Rings @ 0.4 thick ,Cond:FairR=913.50
W (18 IN RCP)
E (18 IN RCP)
SW (12 IN HDPE)
905.64
905.54
INV:
INV:910.06INV:INV:INV:
INV:
CBRC /PRECAST ,3 Rings @ 0.6 thick ,Cond:FairR=914.18
S (24 IN RCP)
N (24 IN RCP)904.09
904.07
INV:INV:INV:INV:INV:
INV:
CBCC /PRECAST ,4 Rings @ 0.8 thick ,Cond:FairR=915.29
E (24 IN RCP)
W (24 IN RCP)907.79
907.69
INV:INV:INV:INV:INV:
INV:
D
MHST /PRECAST ,2 Rings @ 0.4 thick ,Cond:FairR=916.36
S (24 IN RCP)
N (24 IN RCP)903.90
903.84
INV:INV:INV:INV:INV:
INV:
S
D
MHST /BLOCK ,3 Rings @ 0.6 thick ,Cond:FairR=915.89
E (24 IN RCP)
W (24 IN RCP)
N (15 IN RCP)
907.59
905.63
INV:
INV:909.83INV:INV:INV:
INV:
CBCC /PRECAST. SE PIPE FILLED IN. ,Total Ring Depth:0 ,Cond:FairR=914.17
S (24 IN RCP)
W (24 IN RCP)
E (18 IN RCP)
SE (15 IN HDPE)
904.94
904.63
INV:
INV:904.67
INV:908.97INV:INV:
INV:
CBCC /PRECAST ,3 Rings @ 0.6 thick ,Cond:FairR=914.90
S (12 IN RCP)911.93INV:INV:INV:INV:INV:INV:CBCC /PRECAST. 16 RINGS. ,Total Ring Depth:3.2 ,Cond:FairR=916.07
S (15 IN RCP)
N (15 IN RCP)
N (12 IN RCP)
909.85
909.84
INV:
INV:911.63INV:INV:INV:
INV:
D
MHST /PRECAST. UNKNOWN PIPE SIZE. ,1 Rings @ 0.2 thick ,Cond:FairR=905.46
E (RCP)
SE (RCP)896.46
896.46
INV:INV:INV:INV:INV:
INV:
CBRC /PRECAST ,5 Rings @ 1 thick ,Cond:FairR=909.09
SW (54 IN RCP)
N (12 IN RCP)
E (48 IN RCP)
905.09
899.59
INV:
INV:899.74INV:INV:INV:
INV:
CBRC /PRECAST ,6 Rings @ 1.2 thick ,Cond:PoorR=909.13
S (12 IN RCP)905.23INV:INV:INV:INV:INV:INV:
CBRC /BLOCK. UNKNOWN CONNECTING STRUCTURE??? BURIED IN FIELD??? ,Total Ring Depth:0 ,Cond:PoorR=909.21
W (24 IN RCP)905.16INV:INV:INV:INV:INV:INV:
D
MHST /PRECAST ,2 Rings @ 0.4 thick ,Cond:FairR=910.97
S (54 IN RCP)
W (24 IN RCP)
NE (54 IN RCP)
SUMP
901.39
898.52
INV:
INV:899.35
INV: 897.64INV:INV:
INV:
D
MHST /WEST PIPE FILLED IN. PRECAST ,1 Rings @ 0.2 thick ,Cond:FairR=911.39
SE (24 IN RCP)
W (24 IN RCP)901.96
901.75
INV:INV:INV:INV:INV:
INV:
S
CBRC /PRECAST ,3 Rings @ 0.6 thick ,Cond:FairR=909.96
W (12 IN RCP)
E (12 IN RCP)906.49
906.43
INV:INV:INV:INV:INV:
INV:
CBRC /PRECAST ,1 Rings @ 0.2 thick ,Cond:FairR=913.05
E (15 IN RCP)909.93INV:INV:INV:INV:INV:INV:
CBRC /PRECAST ,5 Rings @ 1 thick ,Cond:FairR=909.20
SE (12 IN RCP)905.63INV:INV:INV:INV:INV:INV:
CBRC /PRECAST ,6 Rings @ 1.2 thick ,Cond:FairR=908.46
S (15 IN RCP)
NW (12 IN RCP)904.86
904.76
INV:INV:INV:INV:INV:
INV:
D
MHST /PRECAST ,6 Rings @ 1.2 thick ,Cond:FairR=908.93
W (48 IN RCP)
E (48 IN RCP)
N (15 IN RCP)
S (15 IN RCP)
900.31
900.21
INV:
INV:902.13
INV:904.59INV:INV:
INV:
CBRC /PRECAST ,7 Rings @ 1.4 thick ,Cond:FairR=908.44
N (15 IN RCP)
SW (12 IN RCP)903.42
902.89
INV:INV:INV:INV:INV:
INV:
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Bolton & Menk, Inc. 2025, All Rights ReservedcH:\HOPK\24X135101000\CAD\C3D\135101C301.dwg 2/26/2025 3:22:36 PMDESIGNED
DRAWN
CHECKED
CLIENT PROJ. NO.
ISSUED FOR DATENO.CITY OF HOPKINS, MINNESOTA
CENTRAL PARK IMPROVEMENTS & PAVILLION EXPANSION
24X.135101.000DATELIC. NO.
I HEREBY CERTIFY THAT THIS PLAN, SPECIFICATION, OR REPORT WAS PREPAREDBY ME OR UNDER MY DIRECT SUPERVISION AND THAT I AM A DULY LICENSEDPROFESSIONAL ENGINEER UNDER THE LAWS OF THE STATE OF MINNESOTA.
MICHAEL J. WALTMAN48696 MM/DD/YYYY
JR
ZLK
AS/MJW
12224 NICOLLET AVENUEBURNSVILLE, MN 55337
Phone: (952) 890-0509Email: Burnsville@bolton-menk.comwww.bolton-menk.comR
C3.01C3 - GRADING & DRAINAGE OVERVIEW
GRADING PLAN
FEETSCALE
0 50 100
HORZ.
R
BOTTOM ELEVATION: 904.99'
BOTTOMELEVATION: 908.00'
BOTTOMELEVATION: 907.00'
FIELD 1
FIELD 2
FUTUREEXPANSIONPAVILIONBUILDING
FLOOD STORAGE
FACILITY /SOCCER FIELD
soccer field will treat new
impervious from within the
soccer field drainage area, was
not included in impervious ratio
calculations due to not being
treated by the infiltration/filtration
BMPs on site
proposed treats
some impervious
from fire station
Existing BMP
Off site treatment
from church/parking
lot
PROPOSED INFILTRATION
BMP - TREATS WATER
FROM OFF SITE
EXISTING INFILTRATION
BMP TREATS WATER
FROM ON SITE
PROPOSED FILTRATION
BMP FOR EXISTING AND
PROPOSED IMPERVIOUS
SURFACES
Rooftop
storage and
reuse as
interpretive
feature
All on site treatment eventually
drains to this feature and out to
Nine Mile Creek
www.pca.state.mn.us • 651-296-6300 • 800-657-3864 • Use your preferred relay service • Available in alternative formats
wq-wwtp2-57 • 1/25/21 Page 1 of 4
Stormwater project plan
and plan supplement checklist
Stormwater Treatment Assistance Program
Minn. R. 7077.0277
Doc Type: Self Evaluation
Instructions: This form should be used by participants in the Clean Water Revolving Fund loan program to create a Stormwater
Project Plan for submittal to the Minnesota Pollution Control Agency. This form can either be filled in directly and submitted, or it can
be used as a reference to create a Stormwater Project Plan in a format of the participant’s choosing. The Stormwater Project Plan
must be signed by a registered Professional Engineer in the state of Minnesota.
Project information
Applicant name: City of Hopkins Project number: 281065
Project name: Hopkins Central Park Stormwater Enhancements *Project engineer: Janna Kieffer, Barr Engineering
*Stormwater Project Plan must be signed by a registered P.E. in the state of Minnesota.
Stormwater Project Plan content
Minn. R. 7077.0277, subp. 2a, A. - F.
A. Current stormwater collection system:
Provide a complete description of the current stormwater collection system in the project service area:
The current stormwater collection system is shown in the attached figure (Figure - Existing Stormwater
Conveyance.pdf).
Provide a complete description of the current stormwater treatment system (if existent) in the project service area:
Under current conditions, there is limited stormwater treatment that occurs within the park and associated parcels;
much of the runoff is conveyed to the storm sewer and downstream creek without treatment. Currently, there is a
small surface infiltration basin on the west side of the pickleball courts in the north part of the park to remove total
phosphorus (TP) and total suspended sediment (TSS) from the runoff from the pickleball courts. The northern
parking lot includes a sump manhole with a SAFL baffle constructed within the storm sewer system to remove TSS
from the parking lot runoff. There is a small surface infiltration basin located just north of the Pavilion which was
installed in 2018 as part of an expansion to the Pavilion ice arena. There is a hydrodynamic separator manhole
constructed in the storm sewer system in the southern parking lot to remove TSS from the parking lot runoff. The
hydrodynamic separator manhole and manhole with SAFL baffle provide limited phosphorus removal.
Provide a complete description of the identified need in the project service area:
Central Park is located within three publicly owned parcels that also include the Hopkins Public Works facility, a fire
station, and a school. These three parcels cover approximately 28.3 acres, 12.9 acres of which is impervious
surface (including rooftops, roadways, parking lots). Currently, stormwater from most of the impervious surfaces
within these parcels is not treated prior to discharge to Nine Mile Creek. Of the 12.9 acres of impervious surface
within these three parcels, stormwater from approximately 0.5 acres of the impervious surfaces is treated by
conventional stormwater BMPs that provide pollutant removal (TP and TSS) and stormwater rate control.
B. Project service area – provide a complete description of the following:
The number of acres served
The estimated flow
A description of the watershed:
The proposed stormwater treatment features will serve 23.9 acres, 12.2 acres of which is impervious surface. The
estimated runoff from the tributary watershed for a 1-inch storm is 42,000 cubic feet (approximately 1 acre-feet).
The tributary subwatersheds to the proposed stormwater treatment features are shown in the attached figure
(Figure - Central Park Proposed Stormwater Features.pdf) and include some offsite areas beyond the three publicly
owned parcels that encompass Central Park. Note that stormwater from all subwatersheds shown will be treated by
the proposed stormwater features, with exception of subwatersheds U1 and S1. The S1 subwatershed is the
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wq-wwtp2-57 • 1/25/21 Page 2 of 4
location of the proposed soccer field that will provide significant regional flood storage. Stormwater from
subwatershed U1 may be treated at a future time if the Pavilion is expanded (currently under evaluation for future
implementation).
C. Project alternatives:
Provide a brief narrative describing the project alternatives that were considered:
The intent of the proposed project design is to maximize the amount of stormwater treatment provided within the
project area, including treating offsite stormwater, while still providing the desired park programming and amenities.
Other alternatives considered include reducing the stormwater treatment footprint to just treat stormwater from the
areas of impervious that are new or disturbed as part of the Central Park improvements project. This scenario would
meet the NMCWD’s permitting requirements but does not optimize the stormwater treatment and associated
benefits for downstream Nine Mile Creek.
The proposed project utilizes surface stormwater features, including raingardens and vegetated filtration basins.
Use of underground stormwater treatment systems was considered to maximize space for park programming.
However, underground stormwater treatment systems are more difficult to maintain and do not provide the
additional benefits of improved habitat and access to green/natural areas for park users.
Provide a description of how the proposed project was selected:
The proposed project was selected because it maximizes the stormwater treatment benefits for the park and
tributary drainage areas, while also offering the additional benefits of improved habitat, additional access to
green/natural areas for park users, and a new Nine Mile Creek headwaters feature to promote education and
awareness of the proximity to the creek and the importance of stormwater management to protect and preserve
healthy stream systems.
D. Project description – provide a complete description of the following:
Location.
Best management practices to be implemented for the use of stormwater treatment.
Estimated construction costs.
Equipment replacement costs.
The proposed project is located in Central Park, the City of Hopkins’ most heavily used park, located just north of
Excelsior Boulevard between 13th Avenue and 17th Avenue. The park has been in place since the 1960’s and is in
need of improvements. As part of the redesign of Central Park, the City of Hopkins is partnering with the Nine Mile
Creek Watershed District to incorporate enhanced stormwater management as an integral part of the park
redevelopment. Given the area was developed prior to the stormwater management standards of today, most
stormwater from the park and adjacent developed areas currently flows directly to Nine Mile Creek, without
treatment or flowrate reduction prior to discharge. The proposed project will provide volume reduction (where
feasible), pollutant removal, and rate reduction of stormwater runoff from previously untreated areas. The current
North Fork of Nine Mile Creek originates just south of Central Park and Excelsior Boulevard as an outfall from a
large stormwater pipe. Based on historic aerial photos, it is possible that the park may have been the original
location of the Nine Mile Creek headwaters. The proposed project includes stormwater features that will mimic a
natural creek headwaters to promote education and awareness of the proximity to Nine Mile Creek and the
importance of stormwater management to protect and preserve healthy stream systems.
The attached figure (SitePlan - CentralPark-SWTreatmentFeatures.pdf) shows the proposed stormwater features
proposed as part of this project. The proposed site has been designed not only to treat new impervious surfaces,
but also existing untreated impervious surfaces from the project service area and tributary areas beyond the project
service area. A series of raingardens at the perimeter of the project are sized to capture and infiltrate off-site
impervious surfaces. At the core of the park, filtration basins will treat runoff from the existing impervious surfaces
as well as the new playground area. These smaller scale raingardens are interconnected through sub-surface
drainage which ultimately overflow into a proposed Nine Mile Creek headwaters BMP feature, prior to discharge to
downstream creek through a new pipe under Excelsior Boulevard. The proposed infiltration and filtration BMPs will
reduce the volume of runoff to downstream Nine Mile Creek, reduce the pollutant load to Nine Mile Creek, provide
important reduction in peak runoff rates to the creek from the contributing area, and provide improved habitat and
access to green/natural areas.
Central Park was constructed on the site of the former Hennepin County Fairgrounds, portions of which were then
briefly utilized as a landfill in the 1960s. Results of the preliminary soils investigation for the site indicate the
presence of contaminants that will hinder implementation of infiltration BMPs on portions of the site. To avoid
mobilization of contaminants through infiltration, in accordance with MPCA guidance, filtration-based stormwater
BMPs were selected for these areas. The proposed filtration BMPs will provide volume reduction through storage
within the filtration media and evapotranspiration, while also providing pollutant removal and substantial reductions
in peak flows to the creek during rainfall events, which is especially important for this “flashy” portion of Nine Mile
Creek.
www.pca.state.mn.us • 651-296-6300 • 800-657-3864 • Use your preferred relay service • Available in alternative formats
wq-wwtp2-57 • 1/25/21 Page 3 of 4
The proposed project also will include a small stormwater reuse system to capture and store runoff from the Pavilion
rooftop or other hard surfaces. The stored water can be used to periodically feed the dry creek bed feature that is
planned to meander through the site as part of the Nine Mile Creek headwaters BMP.
Overall, the proposed design creates over 52,000 sf of green infrastructure and conversion of over 2 acres of turf to
native plantings. The native plants not only will help slow and evapotranspire runoff, they will provide a critical
habitat patch connected to the Nine Mile Creek corridor. Over 90 overstory and ornamental trees will be planted
throughout the park and within the green infrastructure.
The estimated cost for the overall Central Park project, including park improvements, enhanced stormwater
management, and a large flood detention facility (soccer field), is $9,525,000. The estimated construction cost for
the enhanced stormwater management features described above is $2,300,000.
` Long-term maintenance plan – provide a complete description of the following:
Annual operation and maintenance costs.
Party responsible for performing maintenance activities.
Intended life span of any proposed stormwater treatment system.
Maintenance of the proposed stormwater features will generally include debris removal, vegetation management,
and periodic removal of accumulated sediment, as needed. Vegetation management will include weeding, periodic
mulch replacement, and periodic replacement of plants, as needed. The City of Hopkins will be responsible for
conducting maintenance of the proposed stormwater features.
The intended life span of the proposed stormwater treatment features is 30 years. The estimated annual operation
and maintenance cost is $20,000 per year.
F. Reduction of pollutants
Provide an estimate of the reduction in pollutants.
Note: When applicable, the estimate must include any pollutants causing or contributing to the impairments in
receiving waters.
The proposed project will remove 23.2 lbs of total phosphorus (TP) a year, on average, based on the MPCA MIDS
calculator.
The proposed project will remove 4,682 lbs of total suspended sediment (TSS) a year, on average, based on the
MPCA MIDS calculator.
Federal Water Pollution Control Act Sec. 602 (b) (13)
Submit a Cost and effectiveness certification form.
Stormwater Project Plan supplement
Minn. R. 7077.0277, subp. 3, A. - F.
A. Environmental Information Worksheet (EIW)
Include a completed EIW.
B. Public notice
Provide a complete list of addresses the commissioner will use for a 30-day public notice of a summary of the
Environmental Information Worksheet.
Note: The addresses used for public notice purposes must be listed on a form prescribed by the commissioner
C. Public hearing
Date of public hearing:
Provide a summary of the information presented and the public comments received at a public hearing (required
under subp. 4):
Provide a summary of the action taken to address those comments:
www.pca.state.mn.us • 651-296-6300 • 800-657-3864 • Use your preferred relay service • Available in alternative formats
wq-wwtp2-57 • 1/25/21 Page 4 of 4
D. Formal resolution
A formal resolution of the municipality’s governing body adopting the Stormwater Project Plan.
Date of resolution adoption: May 6, 2025
E. Ordinances and intermunicipal agreements
Provide a list of ordinances and intermunicipal agreements necessary for the successful implementation and
administration of the project:
F. Certification
Provide a certification from the appropriate county or watershed management organization assuring that the
Stormwater Project Plan is consistent with the comprehensive local water plan.
Stormwater Project Plan Signature
I hereby certify that this plan, specification, or
report was prepared by me or under my direct
supervision and that I am a duly Licensed
Professional Engineer under the laws of the state
of Minnesota.
April 29, 2025
Janna Kieffer
MN License No. 43571
Date