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Pine Glen <br />Drainage Calculation Review <br />City of Lino Lakes, Minnesota <br />• <br />Page 2 August 2, 2005 <br />10. Provide low opening and low floor elevations for the existing houses along James Street, and houses <br />adjacent to infiltration Pond 2 and the existing low area draining subcatchment P 1 -OFF. <br />11. Submit the geotechnical report with anticipated high ground water table. Low floor elevations are <br />required to be 4 feet above the high ground water table. <br />12. Provide test results confirming the infiltration capacity of the proposed infiltration basins. If an <br />infiltration test is not performed, it is recommended that an infiltration value of 0.5 inches per hour <br />(.00069 feet per minute) be used for design as per the RCWD design aide standards for Type A soils. <br />Design the infiltration basin such that the infiltration volume below the outlet, at a minimum, is equal <br />to the runoff volume from a 2.5 -inch storm, and limit the draw -down time to a maximum of two days. <br />13. The lag/CN method is used to determine the time of concentration based on the hydraulic length and <br />average land slope for an entire watershed. Therefore, it is not recommended that the lag/CN method <br />be used in combination with the TR -55 method for the determination of subcatchment curve <br />numbers. <br />14. A time of concentration calculation for existing subcatchment 2E -OFF does not appear to be included <br />in the submittal. Please submit time of concentration calculations for subcatchment 2E -OFF. <br />15. Assume Type B soils for all disturbed pervious areas (CN =61). <br />16. Pond 6 is designed as a wet pond. Therefore, it is preferred that an exfiltration rate not be included in <br />41) the HydroCAD model. <br />17. It is recommended that Pond 5 be a minimum of 4 feet deep. <br />P <br />18. The proposed 3" orifice in the Pond 1 outlet structure is not feasible due to a high potential for <br />clogging. It is preferred that a minimum 4" orifice be used. <br />19. Pond skimmer pipes are required to be a minimum of 12" RCP. <br />20. It appears that pond outlet 6 is not buildable as depicted. <br />21. Verify capacity of existing storm sewer along CSAH No. 23. <br />22. Storm sewers and culverts are required to be a minimum of 15" RCP. <br />23. A minimum of 2 feet of cover from top of storm sewer pipe to rim of catch basin/manhole is <br />recommended. <br />24. Pond 1 dead storage volume for elevation 894.5 seems inconsistent with the volume depicted in the <br />HydroCAD model. Please clarify. <br />25. Will a culvert be required under the trail to drain subcatchment P7 -OFF? <br />26. Should the note on the Grading Plan for Pond No. 4 read "897.5 place 1 -1/2" rock "? <br />27. Is Pond 1 contour designations in the Grading Plan correct? <br />28. Is Pond 6 elevations correct in the `dead storage provided' sheet? <br />29. Should the area for elevation 894 in the dead storage calculation read 1,800? <br />• <br />