Loading...
Engineering and WR Review Memo - Eden Springs Senior Living Planning Case 25-10 Memorandum To: Erik Maass, Planning Director From: Mackenze Grunig, Project Engineer Joe Seidl, Water Resources Engineer CC: Charles Howley, Public Works Director/City Engineer George Bender, Assistant City Engineer Charlie Burke, Public Works Operations Manager Mackenze Grunig, Project Engineer Date: 8/25/2025 Re: Eden Springs Senior Living Preliminary Plat and Site Plan Review - City Planning Case No. 2025-10 PROJECT OVERVIEW The Applicant is requesting preliminary plat approval and site plan review of an assisted living facility with memory care at a 3.5 acre site. The submittal proposes building two 13,000 square foot custom buildings in two phases. Each building is planned to accommodate 17 senior residents. Construction plans and Stormwater Reports developed by Civil Site Group dated August 13, 2025 were reviewed by staff. ACCESS The development fronts on W 78th Street near the intersection of Audubon Road and TH 5 and proposes one access driveway on the far west side of the site, and another access on the east side of the site as a right-in right-out. The Minnesota Department of Transportation (MnDOT) was provided with plans for review due to the proximity of TH 5 and had no comments or subsequent conditions based on the provided plans. SANITARY SEWER AND WATERMAIN Water service is available off W 78th Street via a 12 inch DIP watermain. The applicant is proposing to wet tap two services for the building at the public watermain, one on the east side of the lot and the other on the west side of the lot. This approach is not approved. The City’s sanitary sewer network is not available near the subject property, however the “Chanhassen Interceptor” sanitary main owned and operated by the Metropolitan Council Environmental Services (MCES) is directly adjacent to the property. The applicant is proposing to connect a private lateral directly to the MCES interceptor via a manhole located within the 1680 78th Street property. This connection would require an easement with the 1680 78th property owner. Based on feedback from the applicant, the adjacent property owner is not interested in providing an easement to construct the connection to the interceptor. Prior applications proposed a gravity sanitary sewer connection to the existing interceptor manhole within the City right-of-way. The applicant shall revise the sanitary sewer alignment prior to the City Council’s review of the preliminary plat application. WETLANDS A Notice of Decision of the wetland boundary and type was approved on 5/29/2025. The wetland delineation indicates the wetland is 0.08 acres of a Type 1/2, located adjacent to Riley Creek. While there is no direct impact to the wetlands on-site, the applicant is proposing to encroach into the proposed wetland buffer during construction activities. Additionally, the applicant is requesting wetland buffer averaging and a reduction in wetland buffer setbacks due to site conditions and constraints, such as dynamic topography, wetland location in relation to site boundaries, and adjacent street frontage treatments. While staff generally agrees that the site has inherent constraints due to the location of the wetland and the proposed structure and property lines, the applicant’s proposal is to have a minimum buffering average width of twenty (20) feet coupled with a five (5) foot setback one as illustrated below. / The proposed plans show a minimum buffer associated with a manage 2 wetland classification but show the building and sidewalks well within the 30 foot setback measured from the buffer edge which is a variance to city code. Building setbacks act to help preserve the wetland buffers and downstream water resources. To offset the adverse impacts anticipated from the close proximity of the building and walkways an enhanced buffer establishment plan is recommended by staff. During the TEP’s site review staff observed that the proposed buffer areas for both the wetland and Riley Creek were degraded and filled with debris and invasives including buckthorn. As such, the Water Resources Department recommends that the debris and invasives are removed and a native vegetation is established to protect the wetland and creek. As such the applicant shall work with staff to update and enhance the buffer establishment plan. GRADING & DRAINAGE The project site is located north of W 78th Street, west of Lake Ann Park Drive, and south of Lake Ann. It consists of a single parcel that is currently an open, grass-covered lot with woods and a wetland along its northern edge. Under existing conditions, most of the site drains north to Riley Creek, while a small portion within the right-of-way drains south to W 78th Street. Under the proposed conditions, the site will be mass graded to accommodate a senior assisted living facility with an impervious footprint of approximately 58,000 square feet. Stormwater runoff from the facility will be directed to a water reuse basin and a filtration basin. A small portion of the site within the right-of-way will continue draining to W 78th Street, while the remainder will flow north to Riley Creek. Due to site constraints, the applicant proposes grading up to the minimum wetland buffer. EROSION CONTROL The proposed development will impact one (1) acre of disturbance and will, therefore, be subject to the General Permit Authorization to Discharge Stormwater Associated with Construction Activity Under the National Pollution Discharge Elimination/State Disposal System (NPDES Construction Permit). The applicant has submitted an erosion control plan and a Storm Water Pollution Prevention Plan (SWPPP), however revisions and updates to the plans and SWPPP are required in order to meet the requirements of the NPDES Construction Permit and Sec. 19-145 of City Code. The location of stockpiles for grading and for topsoil must be noted. The SWPPP will need to be updated as the plans are finalized, when the contractor and their sub-contractors are identified and as other conditions change. An approved SWPPP shall be submitted prior to recording the final site plan agreement. All erosion control shall be installed and inspected prior to initiation of site grading activities. STORM WATER MANAGEMENT Article VII, Chapter 19 of City Code describes the required storm water management development standards. Section 19-141 states that “these development standards shall be reflected in plans prepared by developers and/or project proposers in the design and layout of site plans, subdivisions and water management features.” These standards include abstraction of runoff and water quality treatment resulting in the removal of 90% total suspended solids (TSS) and 60% total phosphorous (TP). The proposed project is located in Riley Purgatory Bluff Creek Watershed District and therefore subject to the watershed’s rules and regulations. A Stormwater Management Report was submitted for review to confirm all applicable stormwater management requirements are being met. This includes rate control, volume abstraction and water quality requirements among others. All comments on the proposed design from both the city and RPBCWD will need to be addressed. The applicant shall provide final versions of all modeling (HydroCAD and MIDS) and Stormwater Management Report to address remaining comments and confirm rate, volume and water quality requirements are met as part of the final site plan submittal. Additionally conditional approval from the watershed district shall be provided with the final site plan submittal to confirm the design is meeting all applicable stormwater management requirements. The applicant proposes to meet stormwater management requirements through an irrigation system, a biofiltration basin, and a Jellyfish Filter. Runoff will be routed first to the irrigation system, then to the Jellyfish Filter, and finally to the biofiltration basin. The applicant must provide documentation to verify the pollutant removal rates assumed for the Jellyfish Filter. On-site infiltration is not feasible due to “Type D” soils, which are slow-draining and typically have an infiltration rate of about 0.06 in/hr. Site-specific testing confirmed an infiltration rate of 0.0 in/hr, limiting infiltration opportunities. As a result, the site qualifies as “restricted” under RPBCWD rules, reducing the required abstraction from 1.1 inches to 0.55 inches. The applicant modeled abstraction through the irrigation system and biofiltration basin in MIDS, which indicates compliance with the 0.55-inch requirement. The applicant must confirm the proposed irrigation area with a supporting figure. Freeboard requirements are met for the stormwater basins, with at least 1.0 foot of freeboard to be provided at site low points. An operation and maintenance (O&M) plan is required for all private stormwater BMPs. The O&M obligations apply in perpetuity and must be approved by the Water Resources Engineer (or designee) and recorded against the benefiting properties. The site is located within both the FEMA and RPBCWD floodplains. If grading alters floodplain elevations, the applicant must demonstrate compliance with all applicable floodplain regulations, including compensatory storage. WATER RESOURCES RECOMMENDATIONS: The applicant shall submit documentation demonstrating the removal percentage for the Jellyfish Filter with the final plans submittal. The applicant shall provide an operation and maintenance plan (O&M) for the private stormwater BMPs onsite. The O&M of private stormwater BMPs is required in perpetuity and must be approved by the Water Resources Engineer, or their designee, to be recorded against the benefiting properties, prior to building permits being issued. The O&M agreement shall outline the areas to be irrigated with the reuse system. The applicant shall provide 1.0’ of separation from the emergency overflow routes to the low floor elevation with the final plans submittal. The applicant shall submit storm sewer sizing calculations and catch basin drainage area map with the final plans submittal. The applicant shall secure conditional approval from the watershed district prior to submitting the final plans application to the City. It is the applicant’s responsibility to ensure that permits are received from all other agencies with jurisdiction over the project (i.e. MnDNR, Carver County, RPBCWD, Board of Water and Soil Resources, MnDOT, DNR, etc.) prior to the commencement of construction activities. The applicant shall confirm in the stormwater management report if there are any FEMA/RPBCWD floodplain impacts or not and update the design and plan to meet all applicable rules. The applicant shall work with staff to update and enhance the buffer establishment plan. An approved buffer enhancement plan shall be required before recording the site plan agreement. ENGINEERING RECOMENDATIONS: The developer shall enter into Encroachment Agreements for private improvements (e.g., retaining walls and monument signage) located within the 10-foot wide public drainage and utility corridor abutting 78th Street right-of-way prior to issuance of building permits. Any previously recorded easements located within proposed public right-of-way or proposed public drainage and utility easements must be vacated prior to or concurrently with the final plat. The applicant and their Engineer shall work with City staff in amending the construction plans, dated August 13th, 2025 prepared by Anders Melby with Civil Site Group, to fully satisfy construction plan comments and concerns. Final construction plans will be subject to review and approval by staff prior to recording of the final plat. All newly constructed streets and sidewalks will be privately owned and maintained. The developer shall provide for review and approval maintenance agreements for these improvements. Construction design elements associated with the street plans such as stationing, curb tables and alignments, centerline grades, and intersection details will be required prior to final plat approval. All sanitary sewer mains shall be privately owned and maintained and their connection to the MCES interceptor be permitted through MCES. Approval to connect directly to the MCES interceptor shall be provided to the City prior to Final Plat. The applicant will be required to enter into a maintenance agreement with the City for the proposed inside drop within MCES manhole prior to issuance of building permits. City owned utilities shall be covered by a Drainage and Utility Easement which shall be large enough for the owner to own and maintain. The applicant will be required to enter into a Development Contract with the City and all applicable securities and fees provided prior to recording of the final plat. It is the applicant’s responsibility to ensure that permits are received from all other agencies with jurisdiction over the project (i.e. MCES, Army Corps of Engineers, DNR, MnDOT, Carver County, RPBC Watershed District, Board of Water and Soil Resources, PCA, MDH, MPCA, etc.). Once permits are received, applicant shall provide copies to the City’s engineering office prior to start of construction. The developer shall incorporate the latest City Detail Plates and Specifications into the Final Plat application. Sidewalks must be a minimum of 5 feet wide, and City trails must be a minimum of 10 feet wide. City Standard Detail Plates shall be included in the construction plan set and displayed in a layout format of 2 rows by 4 columns for consistency with City expectations. Retaining walls shall be privately owned and maintained. Walls four feet in height and greater shall be designed by an engineer. Removal plans shall be updated to include the impacts into W 78th St in order to construct access off the street. Applicant shall construct a right-in/right-out at their eastern entrance, including medians, and install applicable signage within W 78th St median. The applicant shall loop the watermain within the site, and is only approved to complete one wet-tap on the existing city owned watermain. Provide a traffic control plan to construct the connections to 78th Street and the connection to the existing watermain. Final construction plans shall include a color-coded map identifying publicly owned improvements vs privately owned.