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, � <br />EN HILLS <br />MEMORANDUM <br />DATE: November 14, 2011 <br />TO: Honorable Mayor and City Councilmembers <br />Patrick Klaers, City Administrator � <br />� � <br />FROM: Terry Maurer, Public Works Director <br />SUBJECT: Drainage Report for Townhouse Villages North and <br />Townhouse Villages at Arden Hills <br />Background <br />On Saturday, July 16, 2011, the City experienced a large rainfall event which caused <br />flooding in several areas. The flooding caused property damage to some of the <br />townhomes on Arden View Court and Arden View Drive. <br />Because of the drainage issue in this area, staff engaged Bolton and Menk to review the <br />drainage system to attempt to identify potential improvements. Representatives of Bolton <br />and Menk were in attendance at the October 10, 2011, Work Session to present their <br />initial findings. At that meeting they were asked to look at one additional option; taking <br />a portion of the townhome drainage area to the north to the Old City Hall site in an effort <br />to increase storm water capacity in the southern townhome area. <br />Attached is a copy of the final Drainage Report prepared by Bolton and Menk. You will <br />note that when the additional option of taking drainage to the north was analyzed it did <br />not significantly reduce the flood' elevation in the southern townhome area. This <br />indicates that the limiting point in the existing storm sewer pipe system is downstream <br />where all the flow from both the north and south areas combine. Bolton and Menk did <br />analyze increasing this pipe (Option 6) and found 825 feet of existing 27 inch storm <br />sewer pipe would have to be increased to at least 33 inch capacity in order to have a <br />significant effect on the flood level in the southern townhome area. � <br />Staff believes the key finding in the study is stated in the last paragraph on the first page <br />under Existing Condition Analysis. That paragraph states: <br />City Council Meeting <br />P:�,Admin\Council�Agendas & Packet Information�2011\l 1-14-11 Regular�Packet <br />Information\TownhouseDrainageReport. doc <br />Page 1 of 2 <br />