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B <br />DEWAYNE C. OLSON CONSULTING ENGINEERS INCORPORATE <br />February 9, 1987 <br />M.. William Sikora <br />C. G. Rein Company <br />949 Sibley Memorial Highway <br />St. Paul, Minnesota 55118-3698 <br />Dear Mr. Sikora: <br />At your request we have conducted a preliminary drainage <br />analysis for the proposed shopping center in Roseville (S..-E. <br />of the Intersection of County Road D and Long Lake Road). <br />Runoff from this site is to County Ditch 5 and ultimately Rice <br />Creek. Accordingly, the site runoff rate and quality must be <br />maintained at the.predeveloped level. The existing runoff <br />from the site in a 100 year frequency storm event is approxi- <br />mately 7.75 cfs. In order to maintain this rate, we propose <br />to construct two dry ponding areas; one ponding area adjacent <br />to the sag point on County Road D and one ponding.­area restricting' <br />the runoff rate at the existing drainage swale at the N.E. corner <br />of the site. The combined volume of these ponding areas would <br />be approximately 0.65 ac. ft. resulting in a developed maximum <br />runoff rate of 7.5 cfs. <br />Ramsey County has installed a storm sewer outlet from the swale <br />at the N.E. corner of the site. We.propose.to extend this <br />pipe to the curb line of the drive and install an inlet <br />structure. From this structure two new pipes would be extended <br />to provide outlets to the ponding areas outlined above. Baffled <br />weir structures would be installed at both pond outlets in order <br />to maintain runoff quality. <br />We will submit final calculations and a drainage plan to you <br />when they are completed. If you have any questions, please call <br />me at 780-1540. <br />Sincerely, <br />r <br />Derrick J. Passe, E.I.T. <br />DJP/cv <br />X. Mr. Charles Honchell - City of Roseville <br />1611 Highway #10 N.E., Minneapolis, Minnesota 55432 (612) 780-1540 <br />