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John Powell <br />April 4, 2001 <br />Page 2 <br />4. Storm sewer calculations need to be provided for the site. <br />5. The minimum storm sewer size is 15" RCP. <br />Drainage <br />1. In the HydroCAD model, all Time of Concentrations were "Direct Entry ". Time of <br />Concentration computations need to be submitted. <br />2. The 2 and 100 -year storm events were submitted. The City requires rate control for the 1, <br />10, and 100 -year storm events. Please submit the 1 and 10 -year events. <br />3. The 2 -year computations used a 3.25" rainfall event. Typically, 2.8" is used for a 2 -year <br />event. How was this value determined? <br />4. The curve number for soybeans, straight row, good condition is 72, not 78. The <br />computations need to be revised to reflect the correct curve number. <br />5. The City Surface Water Plan does not allow for dry basins. All basins must be designed <br />to wet NURP basin standards: <br />2.5" dead storage volume <br />4:1 side slopes max. <br />15 feet of 10:1 bench at normal water level <br />4 feet minimum depth on dead storage <br />3:1 length to width ratio <br />6. Storm sewer computations need to be submitted. <br />7. Storm sewer pipe sizes and slopes are needed on the plan sheets. <br />Miscellaneous <br />1. Permits from the Rice Creek Watershed District and the Anoka County Highway <br />Department will be needed for this project. <br />If you have any questions or comments regarding this review, please contact me. <br />• <br />