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• Pine Glen Page 2 November 8, 2005 Drainage Review Responses City of Lino Lakes, Minnesota Based on the updated location of infiltration area #2, Lots 18 -20, Block 4 have low floor elevations less than 2 feet above the 100 -year elevation. 6. Based on current HydroCAD model results, lot 33, block 1 has a low floor elevation less than 2 feet above the 100 -year elevation for Pond #3. Please clarify. 7. Based on current HydroCAD model results, lots 13, 16, and 18, block 1 have low floor elevations less than 2 feet above the 100 -year elevation for Infiltration Pond #4. Please clarify. Lots 12 -16, Block 1 have low floor elevations less than 2 feet above the 100 -year elevation for infiltration area #4. 8. Based on current HydroCAD model results, lots 3 -6, block 3 have low floor elevations less than 2 feet above the 100 -year elevation for Pond #6. Please clarify. 9. Based on current HydroCAD model results, lots 1 -9, block 4 have low floor elevations less than 2 feet above the 100 -year elevation for Infiltration Pond #7. Please clarify. Lots 1 -9, Block 4, have low floor elevations less than 2 feet above the 100 -year elevation for infiltration area #7. Please provide a copy of the analysis of this pond from STS Consultants when completed. Based on existing contours in the development south of Pine Glen, there seems to be a possibility of infiltration area #7 overflowing off -site to the south. Verify that the positive overflow will remain on -site. It is recommended that the ground elevation for Lots 9 -12, Block 4 be a minimum of 1 foot above the positive overflow for infiltration area #7. Determine the 100 -year elevation for the low area upstream of the culvert draining subcatchment Pl- OFF. • 10. 11. Provide low opening and low floor elevations for the existing houses along James Street, and houses adjacent to infiltration Pond 2 and the existing low area draining subcatchment P1 -OFF. Please submit final plans with elevations when survey is completed. 12. Submit the geotechnical report with anticipated high ground water table. Low floor elevations are typically required to be four feet above the high ground water table. A geotechnical report has not been submitted. 13. Provide test results confirming the infiltration capacity of the proposed infiltration basins. If an infiltration test is not performed, it is recommended that an infiltration value of 0.5 inches per hour (.00069 feet per minute) be used for design as per the RCWD design aide standards for Type A soils. Design the infiltration basin such that the infiltration volume below the outlet, at a minimum, is equal to the runoff volume from a 2.5 -inch stoini, and limit the draw -down time to a maximum of two days. 14. The lag /CN method is used to determine the time of concentration based on the hydraulic length and average land slope for an entire watershed. Therefore, it is not recommended that the lag /CN method be used in combination with the TR -55 method for the determination of subcatchment curve numbers. 15. A time of concentration calculation for existing subcatchment 2E -OFF is not included in the • submittal. Please submit time of concentration calculations for subcatchment 2E -OFF. 16. Assume Type B soils for all disturbed pervious areas (CN =61).