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___,~ <br />(~ISGL111G ESGlSEEItS <br />1326 Energy Pork Drive <br />St. Pad, MN 55108 <br />612.644.4389 <br />1.800.868.2923 <br />Fax: 612.644-9446 <br />CIVIL ENGINEERING <br />ENVIRONMENTAL <br />UNICiPAL <br />~iANNING <br />soup WASTE <br />STRUCTURAL <br />suRVEnNG <br />TRAPPIc <br />TRANSPORTATION <br />ELECTRICAUMECHANICAL <br />ENGINEERING: <br />HVAC <br />POWER DISTRIBUTION <br />SCADA <br />SYSTEM CONTROLS <br />FFICESIN: <br />INNEAPOLlS <br />PRIOR LAKE <br />ST. PAUL <br />June 22, 1995 <br />File: 230-179-11 <br />Mr. Gary Schmitz <br />Planning Assistant <br />City of Ellc River <br />13065 Orono Parkway <br />P.Q. Box 490 <br />EIk River, MN 55330 <br />RE: DICKENSON BUS GARAGE DRAINAGE PLAN <br />Dear Mr. Schmitz: <br />As requested, we have reviewed the drainage calculations for the revision to the Dickenson <br />Bus Garage drainage system. These calculations were prepared by .John .Oliver and <br />Associates, and dated June 8, 1995. Essentially,. the proposal is to eliminate one of the on- <br />site ponding areas to allow for additional paved parking area on the site. As you recall, the <br />original drainage system had a pond in the .north part of the site and one in the south part <br />of the site to detain and treat the runoff prior to discharging to the wetlands in the area. <br />The proposed change is to eliminate the most northerly pond and to .treat all runoff in the <br />southerly pond. <br />In reviewing the calculations, we find that they are all appropriate, and we would <br />recommend approval. We would suggest two minor changes. First, the outlet proposed <br />from the pond to the south is a 12" pipe with a flared end section. The existing outlet is <br />a vertical standpipe type of arrangement. We suggest that the additional new outlet be of <br />the same type as the existing outlet. The second item I would point your attention to is the <br />paved flumes which take the runoff off of the parking area to this pond. These have the <br />potential of ongoing erosion problems. We suggest that catchbasins and small diameter <br />pipe be utilized to collect the water from the paved surfaces and discharge it to the pond <br />to eliminate potential erosion problems. <br />If you have any questions regarding these comments, please call. <br />Sincerely, <br />MSA, CONSULTING ENGINEERS <br />~- <br />Terry J. curer, P.E. <br />TJM: tw <br />179-2231.jun <br />WASECA <br />