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■ <br />.Aff <br />SEN <br />ENW ELTS•AR:Nm[CT!■RLANNER9 <br />222 EA511111LE L.ANADA ROAD, SJ PAU1, ONNESOrA 55117 0124R4.0272 .� j41•' <br />MEMORANDUM <br />i.. 'A ♦. :1 r 1 <br />TO: CITY OF MOUNDS VIEW <br />ATTN: DON PAULEYJ. <br />����//�,�/J��J <br />FROM: DAN BOXRUD fJl/ <br />DATE: SEPTEMBER 22, 3.987 <br />SUBJECT: GREENFIELD ESTATES DEVELOPMENT <br />SEH FILE NO. 87154 <br />You relayed to me a question about the ramifications of the <br />second (higher or overflow) outlet culvert being proposed under <br />Hillview Road. The concern you expressed related to whether or <br />not this would have an adverse effect on the downstream <br />_ properties. <br />There would potentially be two reasons for the second 24 inch - <br />culvert becoming operational. One would be that the existing <br />culvert could become plugged causing the second culvert to begin <br />carrying water under Hillview Road. Jf this is the case, then <br />little flow would have occurred during the earlier part of the <br />storm so that the outflow rate and indeed the outflow volume <br />would not be any difforent- and, in fart, would probably be less. <br />The second reason for the second culvert to operate would be if a <br />"Noah's Ark" event occurred. The first culvert would begin <br />operating as planned, but the second 'culvert would start <br />operating because the storm was greater in intensity or duration <br />than the design storm. Additional flow could be conveyed down- <br />stream under this condition. However, it is likely that the <br />downstream properties would he also receiving such amounts of <br />water that the water would backup to Hil risw Road. Everybody <br />would be in trouble under such an event. <br />In summary, I don't see any adverse effect on any properties due <br />to the emergency overflow culvert. <br />DRB/jcj <br />5r PAIII, anmcwA: ALL$ <br />wND RICkSON INC. E1LIONINNES0IA WK(W&N <br />NENU <br />