01/12/2022 Item 6A, NorthPointe Garden Estates FP & Site Plan

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Ms. Katie Larsen 1 /5/2022 Page 2 2. Applicant to consider moving the proposed pedestrian ramp by the two handicap stalls off the southeast corner of the building to are area between the proposed stalls or adding an additional pedestrian ramp. • Grading & Stormwater Management The NorthPointe Garden Estates will require site grading for the proposed apartment building, retaining wall, utilities, patio area, and parking lot. The minimum elevation for the building pads is dependent on the groundwater elevation and the design of the stormwater facilities. The proposed project is within the Rice Creek Watershed District (RCWD). Stormwater BMPs are needed to meet City stormwater requirements. The applicant is proposing to meet City stormwater requirements by utilizing ponds previously constructed with earlier additions of the NorthPointe development. The design of the ponds shall meet the requirements of Table 6 of the City's Stormwater Management ordinance. Comments: 1. Retaining walls over 4-ft in height will require a structural engineering design to be submitted prior to approval of the final plat. 2. Applicant to submit verification that a retaining wall of that height can be as close to the building as proposed. 3. Applicant to clarify the type of material being used for the 27" diameter storm structures (i.e. PVC, concrete, etc.). 4. Staff has concerns about the run of storm sewer from CB 109 to STMH 106 being too close to the proposed retaining wall and building. Staff concerns are summarized below: a. Weight of the structures and possible surcharge behind the wall b. Seepage at pipe to structure connections c. Issues with maintenance and future replacement access d. Storm pipes and structures should be above the building footing in this area 5. Stormwater from the parking lot should not drain directly into the city -maintained, existing stormwater pond closest to Chestnut Street. Applicant to provide pretreatment via a basin or structure prior to discharging to the pond. 6. Applicant to provide additional details on the time of concentration calculation, specifically for sub -catchments 20S and 30S, including the assumed flow paths. 7. The outlet pipe from OCS 116 is shown to have an invert of 910.64 on Sheet C7 but is modeled with an invert of 910.50. Applicant to verify which is correct and update the plans and report. • Water Supply There is currently an existing 8-inch diameter ductile iron pipe (DIP) water main along Chestnut Street. There is an 8-inch DIP stub to the property. The applicant is proposing to extend the 8-inch DIP pipe to serve the building. One hydrant is proposed in the parking lot. Comments: NorthPointe Garden Estates Final Plat Engineering Review