Agenda - Council - 08/12/2003 - Laserfiche WebLink

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B. Water System The subdivision has individual wells for each developed lot. There are two stub outs for connection to the City's 8" water main in the service road west of TH47. C. Sanitary Sewer System The subdivision has individual septic tanks for each developed lot. There are two stub outs for connection to the City's 8"sanitary sewer in the service road west of TH47. 4.0 PROPOSED IMPROVEMENTS A. Streets and Storm Drainaqe The City's existing aerial topography was used to develop existing and proposed profiles of the streets and identify the current drainage patterns. Existing conditions, includi'n§, location of existing storm drainage culverts, were verified in the field. The relative locatiOn, elevation and gradient of existing driveway connections were noted Jn the field. Under Option 1, the proposed street pavement is a seven (7) ton class with mountable concrete curb and gutter, thirty two (32') feet width to back of curbs. The underground storm drainage system will be designed to carry the 10-year storm flowing full. Under Option 2, the proposed street would be 4" of Class 5 crushed base, 24' wide, 4' wide shoulders and 4:1 ditch slopes to an 18" deep ditch on both sides. Driveway culverts would~' be needed at each driveway. The underground storm drainage system that will collect drainage from roadside ditches and carry the runoff to the detention pond will be designed to carry the 10-year storm flowing full. It is proposed to install environmental sump manholes at the culvert junctions. The Lower Rum River Watershed Management Organization will require storm water runoff from the subdivision and other contributing areas to be pre-treated prior to discharging to the adjacent wetland and eventually to the Rum River. To achieve the water quality goals for the contributing area, storm water will be routed to a proposed detention basin to be located on the rear of one lot south of 152nd Ave. In addition, to pick up the drainage from the Brandseth Subdivision to the north, it is proposed to install a 12" storm sewer and catch basin north of 152n.d Ave. as shown on EXHIBIT A. A large portion of the storm runoff from the adjac~,nt "Helium Street Extension Project, C.O.R. Project No. 02-20" is proposed to be discharged to the new detention basin being built in this project. The storm drain culverts and detention basin volume were increased in size to handle this additional runoff. Therefore, it Page 4 G:\MunicipaI~ARAMSFY\633\RA633FSR2.doc -205-