04-13-26 Planning Commission Meeting Packet

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Page: 4 6. Approval of the preliminary grading and storm sewer plans for the development is contingent upon all grading plans being reviewed and approved by the City Engineer prior to the start of any grading or construction.  The proposed culvert from FES 10 to FES 9 should be revised to remain perpendicular to the street and/or perpendicular to the overhead power easement.  The 100-year HWL for the ditch from FES 9 to Pond 3 must be determined and shown on the plans with the 100-year HWL fully protected by drainage and utility easement. No runoff can be permitted to encroach the L5B1 septic system area.  Design calculations must be provided with the Final Plat application, to include culvert size and slope for each lot, together with approximate 100-year HWL elevations along the road ditch. This design information is necessary to review the proposed subdivision drainage system at full build-out. 7. All localized low points must be protected within a drainage easement, including the localized 100- year HWL. Plan revisions may be needed as the construction plans are finalized.  Revise the plans to show the 100-year HWL at FES-10. 8. The storm sewer system shall be designed to meet all city design standards including RCP pipe materials and maintaining the minimum pipe cover of 3 feet for paved surfaces and 2.5 feet in green space.  The Pond 2 outfall pipe (OSC-2) makes a direct connection to the existing County culvert (24- inch RCP) across CSAH 13. A pipe condition assessment must be completed to verify that the connection can be made with no culvert maintenance or replacement. The County culvert inverts must be revised to be legible.  All drainage swale inlets require Type 402 structures with R-4342 casting. No flared end section inlets are permitted. Revise structures 10, 16, N4, and N6.  Revise all green space storm sewer pipe materials from HDPE to the city standard RCP. 9. Drain tile is required as part of the city standard street section at all localized low points in the street. For a rural section street, all drain tile discharge locations must terminate by connection to a storm sewer structure, if available, or terminating to the ditch using MnDOT Standard Plate 3131. The final construction plans must include all drain tile design details. 10. Per city requirements all storm sewer pipe easements must be a minimum 30-feet in width. When not located within the public right-of-way, minimum 30-foot easements centered over all storm sewer pipe and structures are required without encroachments from retaining walls, trees, or other small/dry utilities. Storm sewer easements must be shown on all site, grading, utility, and landscape plans. MUNICIPAL WATER SUPPLY 1. Connection to the municipal water system is available near the proposed development in two locations. The subdivision improvements will be required to connect to the existing 16-inch trunk watermain located along Inwood Avenue (CSAH 13). An 8-inch watermain will need to be extended along the new streets into and throughout the subdivision at developer’s sole cost, and to serve each proposed parcel in the subdivision. 2. A second connection point is required to create a looped watermain system, connecting to the existing 8-inch watermain located along Imperial Avenue in the adjacent Lake Elmo Heights neighborhood. This secondary connection will require the installation of a pressure reduction valve (PRV) as the Lake Elmo Heights neighborhood is located in the intermediate pressure zone while the proposed subdivision is located in the high-pressure zone. 3. The Preliminary Plans depict the general watermain improvements as required. The developer will be responsible to place hydrants and water system valves internal to the site as determined by the Public Works Director and Fire Department, and the PRV site layout will be prepared by