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idequately <br />xomodate the <br />We believe <br />f provide <br />5 matter. On <br />ry this Septem- <br />f the population <br />20 Dunwoody Ave. <br />ayzata, Minn. 55391 <br />lonc 474-6587. <br />mm <br />■vv <br />JACK E GILL <br />THEODORE O. KEMNA <br />JOHN W. EMONO <br />KENNTH E. AOOLF <br />WILLIAM R. ENGELHAROT <br />R SCOTT HARRI <br />GERALD L. BACKMAN <br />R. MARK KOEGLER <br />8CHOELL & MAOSON.INC <br />ENGINEERS •SURVEYORS • PLANNERS <br />SOIL TESTING <br />(612)338-7601 • 50 NINTH AVE. SO. • HOPKINS. MN 55343 <br />June 29, 1983 <br />Design Two, Inc. <br />c/o Mr. Bert Haglund <br />684 Excelsior Boulevard <br />Excelsior, Minnesota 55331 <br />lS®[iOW[i <br />JUL -61983 ‘i <br />CITY OF OR^'^ <br />Subject:Drainage Calculations <br />Dalvary Memorial Church <br />Orono, Minnesota <br />Our File No. 11871 <br />Dear Mr. Haglund: <br />Enclosed are the drainage calculations you requested for <br />the above named subject. Based on the hypothetical hydrograph <br />for a 100-year frequency storm, the storage requirement after <br />development is 5,040 cubic feet. There appears to be adequate <br />room at the lowest end of the property for ponding. The pond <br />can be incorporated into the parking area if necessary. The <br />area of the pond can be determined once you determine the depth <br />or the other way around. <br />The storage requirement is based on an allowable discharge <br />of 9.3 cfs. This has been calculated as the discharge for the <br />existing site. The runoff coefficient used for hard surface <br />areas was 0.9 and 0.3 for grass areas. <br />The allowable discharge of 9.3 will have to be controlled <br />out of the pond area. We have enclosed a detail for a typical <br />baffled outlet. The outlet pipe will need to be sized but <br />additional field work will be necessary to determine the grade. <br />The outlet pipe can be determined if the City agrees to <br />the concept. We will, however, have to furnish the watershed <br />with the pipe size when a grading and drainage permit is applied <br />for. <br />; <br />'I <br />■,’ri ’rA'A A <br />V .-v/.v <br />.v’^ I..-; a'■ \-a 'a-: , <br />If <br />contact <br />WREngei; <br />enclosu