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2025-18 1531 Camden Ridge Dr. Lot Cover Variance Memorandum To: Rachel Arsenault, Associate Planner Eric Maass, Community Development Director From: Joe Seidl, Water Resources Engineer CC: Charles Howley, Public Works Director/City Engineer George Bender, Assistant City Engineer Mackenze Grunig, Project Engineer Date: 11/25/2025 Re: Variance Review at – 1531 Camden Ridge Drive, Planning Case #2025-18 The Water Resources Department has reviewed the variance submittal for 1531 Camden Ridge Drive. These comments are organized into two categories: general comments & findings and proposed conditions. General comments are informational and provide the basis for findings or guidance during preliminary planning. Proposed conditions are requirements that Water Resources recommends for inclusion in the final order if any variance were to be approved. References to the “City Standards” refer to the City of Chanhassen Standard Specifications and Detail Plates. The plans submitted with this application have been reviewed solely to evaluate the feasibility of the project relative to the requested variances and the proposal’s general conformance with City Standards. A recommendation regarding variance feasibility does not constitute final approval of any alignments, materials, access points, grading, or utility connections shown or implied in the submittal. Detailed construction drawings will be required and reviewed for compliance with City Standards, the Chanhassen Code of Ordinances, the final variance order, and the professional judgment of the City Engineer. General Comments and Findings 1. It is the opinion of the Water Resources Department that the requested variance could only be developed in conformance with the Chanhassen Code of Ordinances and City Standards if all comments and conditions in this memo are addressed. However, as outlined below, staff does not support the requested hard cover variance. 2. The applicant requests a hardcover variance in the Shoreland Management District to build a garage and home addition on the property. 3. Properties within the Shoreland Management District are restricted to a maximum lot coverage of 25%, unless the lot was platted prior to January 1, 1976. Because the parcel at 1531 Camden Ridge Drive was not platted prior to this date, it does not qualify for any increased lot coverage allowance and cannot exceed the 25% maximum, even with offsetting stormwater BMPs or shoreline buffers. City Code does not permit trading additional impervious surface for BMP installation in these circumstances. 4. Both the Minnesota Department of Natural Resources (DNR) and Riley Purgatory Bluff Creek Watershed District (RPBCWD) do not support increases in impervious surface especially within Shoreland areas where runoff directly drains to high-value water resources. 5. The property has a lot area of approximately 14,810 square feet. o The existing hardcover as outlined in the original survey is approximately 3076 square feet which equates to hardcover percent of 20.8% o The proposed hardcover as outlined in the submitted plans is approximately 4054 square feet which equates to hardcover percent of 27.4% Based on the submitted plans, the project results in a net increase in impervious area of approximately 978 square feet. The increase in hardcover over the allotted 25% limit which contradicts the intent of the City’s Local Surface Water Management Plan, the Shoreland Ordinance, and state and watershed district guidance for shoreland redevelopment. 6. There are no existing stormwater BMPs onsite or directly downstream of the property. Runoff from the property flows untreated into Bluff Creek which is on the MPCA’s list of impaired waters for turbidity and fish biodiversity. Increasing the amount of hardcover increases the volume and rate of stormwater runoff and the load of pollutants such as phosphorus, nitrogen, and sediment entering the receiving waterbody. 7. Increased impervious area is especially harmful near adjacent and downstream water resources because it: o Increases nutrient-laden runoff, driving algal blooms and degrading water clarity. o Accelerates shoreline erosion and destabilizes slopes. o Reduces infiltration, groundwater recharge, and baseflow to downstream streams, lakes, and wetlands. o Increases thermal pollution, affecting aquatic habitat. This is a key reason both the DNR and watershed district do not support increased hardcover in situations like this, and why the City’s 25% lot cover limit exists. 8. The City of Chanhassen’s Local Surface Water Management Plan, Policy 2.14, states: “Protect shorelands and water resources. All properties are required to have native vegetated buffer adjacent to wetlands, storm ponds, and water resources. Non- conforming properties and lots of record shall be brought into compliance when applying for permits or variances. The minimum non-conforming buffer width shall be 10 feet.” City Ordinance - Shoreland Management District Section 20-490 states: In evaluating all variances, zoning and building permit applications, or conditional use requests, the zoning authority shall require the property owner to address, when appropriate, stormwater runoff management, reducing impervious surfaces, increasing setback, restoration of wetlands, vegetative buffers, sewage treatment and water supply capabilities, and other conservation-designed actions. 9. Lot coverage limits protect water resources by: • Restricting runoff volume and pollutant loads • Maintaining natural infiltration and groundwater recharge • Preserving shoreline stability and ecological function For these reasons, BMPs cannot be exchanged for additional impervious area. Reducing the size of the home, garage, or driveway is the appropriate method for complying with ordinance requirements. 11. The applicant requests a hardcover variance to exceed the 25% allowed. Staff finds that the site can be redeveloped in a compliant manner without increasing impervious surface beyond the 25% limit. The size and configuration of the proposed addition and driveway appear to be design choices, not site constraints. As such the Water Resources Department does not support the requested variance. 12. If any variance were approved by the Planning Commission, staff strongly recommends applying City Ordinance Sec. 20-490 and Policy 2.14 to establish permanent native buffers and implement stormwater practices in an attempt to mitigate impacts. Proposed Conditions 1. 1 A permanent 10 - foot native vegetated buffer adjacent to the trail with permanent buffer signs must be installed along the upstream side using species native to the ecotype. The buffer design may be configured around the path and stairs. Design plans must be approved by the Water Resources Engineer. 2. A buffer agreement describing the precise location and extent of the buffer strip, as well as the restrictions and maintenance for activities within the buffer strip and shall be signed by the property owner and the city and shall be recorded against the property at the county recorder's office. The property owner shall be responsible for all costs and fees associated with the buffer strip dedication. 3. The installation of any improvements on the Site shall meet all applicable jurisdictional requirements, including but not limited to the Minnesota Department of Natural Resources and the Riley Purgatory Bluff Creek Watershed District, and all applicable permits shall be obtained prior to any site improvements.