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Ms. Katie Larsen 02/07/2019 Page 3 Lyngblomsten Preliminary Plat Engineering Review 7. The applicant shall update the water quality section based on our attached redlines. At the time of this review, no water quality design changes need to be made. The redlines are intended to clarify the design and the requirements. a. The water quality design may need to be adjusted based on other comments in this review. b. The dead storage volume should account for the entire site. The pond needs to over-treat the areas being directed to the pond to compensate for the areas leaving the site without treatment. 8. The Water Reuse system will be supplemented by municipal water in low conditions: a. The applicant shall provide calculations demonstrating the amount of infiltration provided. b. Provide an elevation (below the NWL) that the irrigation system will need to switch to City water during dry periods. c. With the final design additional detail will be required and reviewed. 9. All storm sewer pipes that will be maintained by the City shall be concrete pipes per City standard specifications. 10. All storm sewer pipes that will be maintained by the City shall have a minimum diameter of 15”. 11. The plan set shall show the storm sewer plan view and easement lines on the same page. This will allow the City to verify all storm and utility easements are correct. 12. In the Storm Sewer Pipe Sizing spreadsheet, the applicant shall include the Hydrology input values (area, C values, time of concentrations, intensities). 13. The applicant shall verify the manhole sizes/storm sewer layout for: a. CB 037, tight angle, consider storm sewer realignment. b. CB 004, tight angle, larger structure needed. c. CB 001, tight angle, larger structure needed. d. CB 101, tight angle, larger structure needed. e. CB 011, tight angle, larger structure needed. f. CB 013, tight angle, consider storm sewer realignment. g. CB 008, tight angle, larger structure needed. h. Additional CB’s required between CB 1 & 2 at the road bend. 14. On Sheet C1.51, in section D of the “General Construction Sequence”, the applicant shall add the following note prior to note 3 “Locally Strip topsoil…” a. “Prior to site disturbance, construct a construction detention pond (in the location of the proposed pond) to help treat soil runoff during construction.” 15. On Sheet C1.51, in section D of the “General Construction Sequence”, the applicant shall add the following note prior to note 11 “Complete stabilization of the…” a. “Prior to final stabilization, verify the proposed pond is constructed to final grade. Clean out any accumulated deposited sediments during construction.” 16. On Sheet C1.51, in section G of the “General Construction Sequence”, the applicant shall add the following note. a. “Street Sweeping (with a pickup broom only) will be provided as needed or at the direction of the owner/engineer.” 17. On Sheet C1.51, the applicant shall include erosion control blanket on the pond slopes above the NWL. 18. On Sheet C1.51, the applicant shall include erosion control blanket on all back-yard swales and 50’ around all back-yard catch basins. 19. At the 24 inch diameter westerly pipe outlet we recommend connected the pond outlet to the existing pipe via a manhole with and open grate. • Water Supply The proposed site is currently not served by municipal water and on site wells shall be abandon per MDH. This area of the City, Woodridge Estates, is currently a low pressure area. The City’s Comprehensive Plan and water system model identifies the need for a 12-inch diameter trunk watermain to be looped through the Lyngblomsten development site to serve the fire flow needs for