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Lake <br />Kell , <br />Gervcnis <br />Elevation <br />862.5 <br />862.3 <br />862.9 <br />862.0 <br />862.3 <br />860 + <br />Remarks <br />Storage shed <br />Summer house <br />Elevation at walkout basement <br />Elevation at walkout basement <br />Ground elevation at house with basement <br />House under construction <br />Kohlman 861.4 Elevation at walkout basement <br />862.9 Elevation at walkout basement <br />860.8 Shed <br />It should be noted that substantial portions of the total watershed <br />tributary to this area are presently undeveloped. In_addition, many areas <br />are presently landlocked which will ultimately outlet through this area. De- <br />a <br />spite <br />this fact, some flooding has presently been experienced on Lake Phalen.- <br />After ultimate development, <br />the severity of flooding will increase. With the:,- <br />existing outlet, the maximum discharge is 220 cubic feet per second <br />critical 100 -year, 10-day storm. This discharge requires <br />storage and results in a regional flood level o <br />cause <br />tions <br />some <br />for the <br />3,895 act. .ex_..nf,.__': <br />flood level will. <br />solu- <br />This <br />flooding of houses located within this drainage area. Alternate <br />to this problem include improving the outlet from Phalen Lake; diverting +: <br />of the drainage area into other systems; and providing for separation <br />storm and sanitary sewage beginning at Lake Phalen. <br />Improving the outlet will not materially lower the flood level. This <br />would increase the maximum discharge to approximately 240 cubic feet per secop6 <br />and require 3,560 acre -feet of storage with a resulting regional flood level,* <br />of 863.3. <br />By diverting the overflow from the Vadnais Lake system for the critical":::r <br />100 -year storm into the Trout Brook system, the peak discharge from this area.:': <br />would be reduced to 200 cubic feet per second and the stormwater storage <br />requirement would he reduced to 3,150 acre -feet. This would result in a <br />flood level of 862.9 in the chain of lakes. <br />By separating the storm water completely from the existing beltline <br />setiv <br />system and installing a 300 cubic feet per second outlet, the storage require''- <br />ment would be reduced to 2,360 acre -feet, resulting in a regional flood lever <br />6 <br />