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Ms. Katie Larsen <br />06/04/2025 <br />Page 3 <br />9. Rational method pipe capacity calculations must be provided showing storm sewer is <br />sized to convey the 10-year storm event. The minimum pipe diameter is 15". <br />10. The storm sewer draining to the pond must be raised to outlet at the pond NWL of <br />904. <br />11. The pipe between the catchbasins is 18" diameter, but the pipe to the pond is 15" <br />diameter. Resize one or the other to avoid flow constriction. <br />a. This pipe sizing also does not match the pipes modeled in HydroCAD. <br />12. Confirm constructability of MH-119 as a 2x3 structure based on proposed pipe sizes <br />and alignments. <br />13. Mesic prairie seeding should continue down to the BMP NWL instead of southern <br />boulevard. <br />• Water Supply <br />The proposed Erickson Property water system extension is consistent with the original <br />Watermark preliminary plat. This development will be served by 8- inch diameter ductile iron <br />pipe (DIP) water main which was stubbed with the Watermark 5th Addition and with 1-inch <br />Type K copper services being extended to each lot. A future 8" stub will be provided on the <br />north end to connect to the 8" water stub provided on Osakis Street with the Watermark 6th <br />Addition in the future. <br />Comments: <br />1. Provide utility profiles <br />2. Call out all utility crossings <br />a. Maintain minimum 18" separation <br />b. Insulate when separation between water (services/main) and storm sewer is <br />less than 36" <br />3. Show existing watermain along Norway Ln <br />4. Test the existing gate valve in Norway Ln <br />a. If holding, utilize the existing gate valve in Norway Ln for testing <br />i. Do not connect to existing with a gate valve <br />b. Otherwise, remove watermain back to and including existing gate valve <br />i. Connect to existing with new 8" gate valve at that location <br />5. Utilize current utility as-builts/plans for Watermark 51h and 61h Additions <br />• Sanitary Sewer <br />The proposed Erickson Property sanitary sewer is generally consistent with the original <br />Watermark preliminary plat. Originally this street was to be served from the north with an <br />8" stub from Rainy Lane as part of the Watermark 6th Addition but, due to the northern <br />most property in the stretch not participating, the segment will now need to be served from <br />the existing sanitary sewer in Norway Lane which was installed as part of Watermark 5th <br />Addition. This development will be served by 8- inch diameter poly -vinyl chloride (PVC) <br />pipe along with 4-inch diameter Schedule 40 PVC service pipe to each lot. <br />Comments: <br />1. Provide utility profiles <br />2. Create a detail for connection to existing sanitary sewer main with sanitary manhole <br />a. Describe process for maintaining existing sanitary sewer, watermain, and <br />storm sewer service as well as vehicle access during construction <br />Erickson Property Development - Engineering Review <br />Page 33 of 46 <br />