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V_ ALTERNATE DRAINAGE SYSTEMS A. Alternate Development Policies The Alternative Drainage systems were developed in a cooperative effort with input from the City of Canon City, the Fremont County Sanitation District, the Hydraulic Ditch Company, and the local residents. Several additional variations on the presented alternates were also examined but are not included in this report. B. Alternate 1 This alternate investigates the existing flow conditions through the project area. It assumes that the Hydraulic Ditch is completely filled with stormwater and stormflows from tbe north would continue flowing across the canal. Based on this assumption nearly 1100 CFS would flow south between 19th Street and Diamond Avenue while approximately 1000 CFS would. flow between Cottonwood Avenue and Field Avenue. The flow from the area east of Field Avenue would continue easterly toward the Abbey Basin. The next assumption made is that the two (2) southerly flows will continue across SH 50 and the railroad and eventually empty into the Arkansas River. TIle total flow amounts Iba.! would reach the river would be 1259 CFS ,lOd 19570 CFS. Co Alternate 2 Because of the lack of downstream facilities, d(~tention facilities have been planned from the upper portion of the basin. A 41 acre foot detention basin is proposed for the area north of South Street to intercept the western portion of this basin. An improved channel is proposed from High Street to South Street on both sides of the detention basin with a new culvert under South Street. Thc channel reach from South Street to Central Avenue need only minimal improvements. A new 54" RCP trunk storm sewer is proposed from Central Avenue to SH 50 along Orchard Ave. This system would only handle about a lO-year stonn flow with the remainder of the flow confined to the north - south residential streets. From SH 50 to East Main Street a larger 72" RCP storm sewer to intercept the total 100-year flow. The remainder of this portion of the 1iystem would be built as an open channel to the Arkansas River. The central area of the basin currently drains through an undersized concrete channel through a residential area. An existing detention basin north of Elizabeth Street will be enlarged to an 18 acre foot basin. An improved channel will be built from the basin to Central A venue. A 60" RCP storm sewer is proposed to intercept the flow along Central Avenue th.E:reby relieving the undersizc concrete chane!. The proposed storm sl~wer will turn south along Stage Coach Avenue and then east to Cottonwood Avenue. From thi.s point a 66" RCP storm sewer will. carry most of the flow south to SH 50. A larger 78" RCP storrll sewer will be m:eded to intercept the lO()..year flow at SH 50 and transport it to a point below Fowler Street where an open channel will carry the flow to the Arkansas River. The eastern portion of the drainage basin, along Field Avenue, will drain into a new 16 acre - feet detention basin. This flow will then be transported to the Abbey Channel once the flow peak has been decreased by 75%. The estimated cost of Alternate 2 is $3,221.000.00. This cost does not include land or easement purchase costs and is based on 1994 dollars. D. Alternate 3 This alternative contains the same detention alu:rnatives as Alternate 2 as well as the same improvements north of the Hydraulic Ditch.