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Ms. Katie Larsen <br />10/03/2025 <br />Page 6 <br />Erickson Property Development - Engineering Review <br /> <br />8. Provide calculations demonstrating spread at the catchbasin low points is 10’ or less <br />for the 3-year storm event. <br />Landform Response (8/11/25) – See storm Calcs. <br /> <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 />Landform Response (8/11/25) – Updated. See storm calcs. <br />WSB Response (9/3/25) – Pipes from CB-202 to FES-200 must be upsized to the 15” <br />minimum. <br />Landform (8/11/2025) Pipe will be up sized to a 15" RCP. See sheet C5.1. <br />WSB (9/26/2025) Pipe from CBMH-201 to FES-200 must be upsized to 15” RCP. <br />Current design would result in flow constriction of pipe going from 15”to 12” diameter. <br />Landform (9/30/2025) Updated. See sheet C5.1. <br />WSB (10/3/2025) Complete <br /> <br />10. The storm sewer draining to the pond must be raised to outlet at the pond NWL of <br />904. <br />Landform Response (8/11/25) – Updated. <br /> <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 />Landform Response (8/11/25) – Updated. See storm calcs. <br /> <br />12. Confirm constructability of MH-119 as a 2x3 structure based on proposed pipe sizes <br />and alignments. <br />Landform Response (8/11/25) – Structure is now a 48" CBMH. <br /> <br />13. Mesic prairie seeding should continue down to the BMP NWL instead of southern <br />boulevard. <br />Landform Response (8/11/25) – The BWSR Mesic prairie seeding and the MN DOT <br />Southern Boulevard see hatches were flip flopped. See revised plans showing Mesic <br />prairie seeding down to the NWL. <br /> <br />14. WSB Response (9/3/25) – How will CBMH-201 and -202 be paved over with the <br />temporary cul de sac? How will road drainage be routed during those conditions? <br />Landform (8/11/2025) Roadway pavement and curb and gutter will be extended <br />into cul-de-sac. See sheet C2.1, C3.1 and C5.1. Also see detail 3 on sheet C7.6. <br />Neenah drive over casting R3501-T to be used. <br />WSB (9/26/2025) Complete <br /> <br /> <br />• Water Supply <br /> <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 /> <br />Comments: <br />Page 125 of 145