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Ms. Katie Larsen <br />03/29/2019 <br />Page 4 <br />Lyngblomsten Preliminary Plat Engineering Review <br />b. In the HydroCAD model the applicant shall not include infiltration. The <br />HydroCAD model is for flood modeling verses water quality. Water quality is <br />calculated separately. <br />The model has been updated. <br />c. The applicant shall update all HydroCAD results and HWL elevations on the <br />plan. <br />The plans have been updated. <br />We anticipate that the modifications required to meet City standards for to the <br />HydroCAD model and site design will increase the flood storage required for the site. <br />7. The applicant shall update the water quality section based on our attached redlines. At <br />the time of this review, no water quality design changes need to be made. The redlines <br />are intended to clarify the design and the requirements. <br />The dead storage calculations have been updated <br />a. The water quality design may need to be adjusted based on other comments in <br />this review. <br />b. The dead storage volume should account for the entire site. The pond needs to <br />over-treat the areas being directed to the pond to compensate for the areas <br />leaving the site without treatment. <br />The dead storage calculations have been updated <br />8. The Water Reuse system will be supplemented by municipal water in low conditions: <br />a. The applicant shall provide calculations demonstrating the amount of infiltration <br />provided. <br />Standard Rice Creek watershed district water reuse calculations nave been <br />provided. <br />The location of the re-use system pump and connection to city water shall be <br />shown on the utility plan with backflow prevention. <br />b. Provide an elevation (below the NWL) that the irrigation system will need to <br />switch to City water during dry periods. <br />The elevation has been labeled on the plan <br />The applicant shall submit their allowable pump down elevation. Please <br />identify where on the plan this is included. If a pond liner is being proposed <br />please include information on the grading plan or other. <br />c. With the final design additional detail will be required and reviewed. <br />This is noted <br />9. All storm sewer pipes that will be maintained by the City shall be concrete pipes per City <br />standard specifications. <br />Concrete pipes have been labeled <br />10. All storm sewer pipes that will be maintained by the City shall have a minimum diameter <br />of 15”. <br />Pipe size has been modified to the minimum 15 inch requirement within the City <br />11. The plan set shall show the storm sewer plan view and easement lines on the same <br />page. This will allow the City to verify all storm and utility easements are correct. <br />The plan sheets hare been modified <br />Easements will be reviewed with the final design submittal. <br />12. In the Storm Sewer Pipe Sizing spreadsheet, the applicant shall include the Hydrology <br />input values (area, C values, time of concentrations, intensities). <br />The calculation spreadsheet has been included. <br />13. The applicant shall verify the manhole sizes/storm sewer layout for: <br />a. CB 037, tight angle, consider storm sewer realignment. <br />b. CB 004, tight angle, larger structure needed. <br />c. CB 001, tight angle, larger structure needed. <br />d. CB 101, tight angle, larger structure needed. <br />e. CB 011, tight angle, larger structure needed. <br />f. CB 013, tight angle, consider storm sewer realignment. <br />g. CB 008, tight angle, larger structure needed. <br />h. Additional CB’s required between CB 1 & 2 at the road bend.