06-27-2016 Council Packet - Laserfiche WebLink

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Draft – 10/1/15 Functional Design and Performance Specifications: The project design is so conceptual in nature, the sizes, types, lengths, slopes and characteristics of the proposed infrastructure remain undefined. Only the sizes, types, lengths, slopes and characteristics of select pipes included in the model submittal have been defined. The following summarizes those physical features either described in the written submittals or the model submitted by WSB on September 11, 2015 (and reviewed by HEI), which related to project performance. Project performance is defined as the 2-year 24 hour, 10-year 24-hour and 100-year critical duration peak discharge and runoff volume or the timing of flood peak (i..e., the specific discharge hydrographs for these events). Pipe Infrastructure Outlet Pipe 72-inch RCP estimated length 4,116 feet @ 0.19% slope I 35E Culvert(s) 60-inch RCP Drainage Area Characteristics Total Land Area Served by the Outlet 1,430 acres total; 1,415 acres excluding I 35W Current Amount of Impervious Area (acres) Hugo region – 71 East region – 16 Central region – 11 West region – 10 Total – 108 Maximum Allowable Increase Impervious Area At Full Development (acres) Hugo region - ** East region – 290 Central region –170 West region –72 Total –532 acres Maximum Allowable Total Impervious Area At Full Development (acres) Hugo region - ** East region – 306 Central region –181 West region –82 Total –640 ** no more than existing conditions peak discharge for the 2-year, 24-hour; 10-year, 24-hour; and 100- year, 24-peak discharge from the City of Hugo to the City of Lino Lakes estimated at 35.4 cfs for the 100- year, 24-peak discharge. This discharges is based on adding the hydrographs for nodes CA55MTL_012, CA55MTL_013, CA55MTL_011, and CA55MTL_025A from the proposed WSB InfoSWMM model, submitted 9-11-2015