11/28/2005 Council Packet (2) - Laserfiche WebLink

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Pine Glen Page 3 November 8, 2005 Drainage Review Responses City of Lino Lakes, Minnesota 17. Pond 6 is designed as a wet pond. Therefore, it is preferred that an exfiltration rate not be included in the HydroCAD model. 18. It is recommended that Pond 5 be a minimum of 4 feet deep. Pond #5 is required to be a minimum of 4 feet deep. 19. The proposed 3" orifice in the Pond 1 outlet structure is not feasible due to a high potential for clogging. It is preferred that a minimum 4" orifice be used. 20. Pond skimmer pipes are required to be a minimum of 12" RCP. Pond #1 sediment control structure drawing depicts an outlet pipe larger than what is modeled in HydroCAD. Please update the drawing to reflect the model. 21. It appears that pond outlet 6 is not buildable as depicted. 22. Verify capacity of existing storm sewer along CSAH No. 23. 23. Storm sewers and culverts are required to be a minimum of 15" RCP. 24. A minimum of 2 feet of cover from top of storm sewer pipe to rim of catch basin/manhole is recommended. 25. Pond 1 dead storage volume for elevation 894.5 seems inconsistent with the volume depicted in the HydroCAD model. Please clarify. 26. Will a culvert be required under the trail to drain subcatchment P7 -OFF? r27. Should the note on the Grading Plan for Pond No. 4 read "897.5 place 1-1/2" rock "? 28. Is Pond 1 contour designations in the Grading Plan correct? 29. Is Pond 6 elevations correct in the `dead storage provided' sheet? 30. Should the area for elevation 894 in the dead storage calculation read 1,800? The area for elevation 894 is larger than the area for elevation 894.5 for the pond #1 dead storage calculation. Please clarify. Additional Comments The proposed development meets rate control for the 10 -year and 100 -year storm events, but not the 1 -year event. The existing rate for the 1 -year event is 0.03 cfs, and the proposed rate is 0.48 cfs. Approximately half of the proposed discharge flows to the wetland and half to the county road. It is not reasonable to restrict a site to essentially zero discharge; therefore, the proposed rate for the 1 -year event presented in the model is acceptable. Provide easements around pond #1 and infiltration area #2 and indicate on the plans. Lots 2 -5, Block 5, have low floor elevations less than 2 feet above the 100 -year elevation for infiltration area #11. Tie ends of berms into slope for infiltration areas #10 and #11 to ensure that runoff is captured within the berms. Approval is required from Rice Creek Watershed District.