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• <br /> '.'August 21, 1987 <br /> Mr. Larry Hamer. <br /> St. Anthony Village <br /> 3301 -Silver Lake'Road <br /> St. Anthony, MN <br /> RE: Proposal for Professional Engineering Services <br /> St. Anthony Drainage District No. 6 <br /> Feasibility Study <br /> Dear Mr. Hamer: <br /> This letter is in response to your recent request for a proposal for a <br /> drainage feasibility study for drainage district No. 6 in St. Anthony. <br /> The City wishes to consider drainage system improvements which might <br /> reduce flooding problems in the area. <br /> The City officials: need information on improvement feasibility so they <br /> ETM can decide on a proper course of action. In order to provide you with <br /> this information, we propose the following: <br /> Development of a computer analysis of the runoff hydrology in <br /> rieke District 6 so that volumes• and rates of runoff for various <br /> Carroll rainfall events can be estimated and projected for the existing <br /> �rr <br /> oc <br /> associates, inc. storm sewer system and for the system with future improvements. <br /> architects <br /> engineers Determination of storm sewer conveyance requirements and <br /> land surveyors runoff storage requirements for the district. <br /> Estimation of costs for construction of public improvements to <br /> the -drainage system to handle runoff events of different <br /> magnitudes. <br /> In conducting the analysis it will be necessary to establish subdrainage <br /> boundaries within District 6. This can best be done using 2-foot <br /> contour maps prepared by an aerial mapping firm such as Markhurd or <br /> Horizons, Inc. We have checked with Horizons, Inc. and they estimate <br /> that preparing a 2-foot contour map for the approximately 500 acre <br /> area would cost the City about $4,500. Without such a map, we would <br /> have to use existing information that may be available from existing <br /> street and utility plans. The accuracy of estimates of the drainage area <br /> and runoff could be expected to be less with this latter technique. <br /> We propose to estimate runoff discharges in the system for events with <br /> 10-year, 50-year and 100-year recurrence intervals. However, if you <br /> desire, we can substitute other recurrence intervals at no additional cost <br /> or consider additional recurrence intervals at a slightly increased cost. <br /> We propose to use a computer based hydrologic model called Illudas, <br /> which was developed by the Illinois Geologic Survey for urban runoff <br /> hydrology. <br /> • <br /> 10901 red circle drive <br /> box 130 <br /> ni nnetonka. minnesota 55343 <br /> 61?-935-6901 <br />