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Ms. Katie Larsen <br />11/19/18 <br />Page 2 <br />Watermark 1st Addition Engineering Review <br />Noted. Buffer signs will be shot and shown on grading as-built. <br />2. The applicant shall label bench for Pond 100 <br />Labels added. <br />3. The applicant shall show silt fence around entire perimeter of ponds (until street & <br />utility construction is complete). <br />Silt fence revised. <br />4. SWPPP Plan to be reviewed by the City’s Environmental Coordinator and not included <br />here within. <br />Noted. <br />5. The applicant shall install an outlet control structure at the temporary pond prior to <br />outletting to Lake 20. <br />Per discussion, perforated riser added to temp. sediment basin. See sheet GE2. <br /> <br /> Stormwater Management <br /> <br />The stormwater management for the Watermark 1st Addition development includes a storm sewer <br />conveyance system to Pond 100, Pond 200, and Pond 300 for treatment and storage, with an <br />eventual outlet to Lake 20. <br /> <br />Comments: <br />1. The applicant shall provide storm sewer calculations for all of proposed piped systems. <br />Storm Sewer spreadsheet attached. <br />Engineering staff is still reviewing the storm sewer spreadsheet & calcs at this time. <br />2. The applicant shall clarify NWL for Pond 100. Detail OCS 100A shows Pond NWL at 901 <br />and orifice at 900.2, plan shows NWL at 900.2. Additionally, show location of OCS100A on <br />Storm Sewer plan. <br />Phase 1 Grading Pond 100 NWL set at 900.2. Ultimate NWL to be set at 901.0 and <br />temporary structures removed. All Interim pond data updated on final grading as well as <br />final street & utility plans (in Italics). See updated sheet 18 and 44 for OCS 100A. OCS <br />was mislabeled in details on sheet 44. <br />3. The applicant shall provide profile and detail for OCS between Pond 20 & Lake 20. OCS <br />is shown on the Storm Sewer Sheet Index, but not on a detailed plan sheet. <br />OCS added to plan and profile sheets. <br />4. The applicant shall label bench for Pond 300. <br />Bench labels added on grading plans at all ponds. <br />5. The applicant shall note that CB’s installed adjacent to ped ramps shall allow enough <br />space for ADA curb transitions. <br />Reviewed structures and revised location of CBMH 270 & 271. <br />6. The applicant shall limit storm sewer crossings underneath sidewalk when feasible. <br />Per discussion with city, storm sewer to remain in order to avoid structures in wheel path. 3 <br />locations in phase 1 will be underneath ped ramps. <br />7. The applicant shall add a CB on Crane Drive, approx. Sta. 0+50, 20’ LT. <br />CB 359 added. <br />8. The applicant shall add a CB on Cass Drive, approx. Sta. 0+50, 15’ LT. <br />Per discussion, CB on 21st ave. has the capacity to pick up Cass Drive intersection. A 3% <br />grade is shown along radius from Cass Drive to 21st Ave. See sheet 28. <br />9. The applicant shall provide narrative regarding re-use system, connections to City supply <br />(if necessary), specific areas watered by re-use system, irrigation used for wetland buffer <br />establishment (if applicable), and why the irrigation area appears to be slightly greater <br />than what was analyzed for the feasibility report. Option 2 from that report included the <br />berm, townhomes, and park. This plan includes additional area from streetscaping. <br />The re-use system will be the primary source for water in the irrigation system. The <br />secondary city water connection should only be needed if there is an issue with the <br />primary pump system. The connection to the city water supply shall include a “Double <br />check backflow device” that will make certain that the potable water supply is not <br />hampered with.