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Description of Proposed Improvements: Sheet 7 Estimated Cost of Proposed Improvements: A storm sewer system is planned between Garland and Garrison Streets which will convey the 10-year flood. A portion of this flow will be carried in the existing system, which will join with the new pipe east of Garrison. A portion of the lOO-year flow will continue to be carried on the surface to the inter- section. The surface flow will diverge at this point. Part of the flow will proceed eastward on the north side of Colfax and enter the North Dry Gulch sub-basin. This situation occurs to a greater degree at present. Item Description Quantity CONSTRUCTION 9011 Storm Sewer Twin SiX? Box Culverts 5'x81 Box Culvert Asphalt over Twin SiX?' Box Asphalt over 5'x8' Box Manholes Inlets Inlet Pipe Asphalt over Inlet Pipe Curb and Gutter Replacement Inlet Apron Outlet Headwall Overflow Spillway from Ditch Excavation for Open Channel Concrete Low Flow Channel Maintenance Roadway Drop Structure Construction Sub-total 1511 Engineering 10% Contingencies Tbtal Construction 50 270 770 220 770 4 12 370 370 195 1 1 1 5,400 100 580 2 From Garrison St. to Estes St. a series of lined channels, bridges and culverts have been either planned or constructed by individual developers. These facilities in general convey at least a lO-year flood and protect the buildings from damage ln a lOO-year flood. Maintenance access is provided either by roadways or permission to use parking lots. New twin 5'x7' box culverts are proposed under Estes St. and l4th Avenue, parallel to the existing 3.2'xlO' box culvert. An over- flow structure exists at station l82+50 to discharge storm flows carried by the Rocky Mountain Ditch into the Dry Gulch channel. Downstream from l4th Avenue an open channel with 4:l sideslopes, a concrete low-flow channel and erosion control structures is proposed. The channel would be constructed to keep flow veloci- ties below 7.5 feet per second in a lO-year flood. The channel will connect with a downstream detention pond and provides an opportunity for a greenbelt or park environment if additional right-of-way is acquired. LAND ACQUISITION Right-of-way Acquisition Easements along Pipelines Land Acquisition Sub-total 10% Contingencies 5% Legal Total Land Acquisition TOTAL COST Sheet 7 Costs in Each Reach Reach D Reach E 1.5 790 Total Canst. $ 244,162 $392,638 Sheet 7 (Reaches D & E) Unit L.F. L.F. L.F. L.F. L.F. Ea. Ea. L.F. L.F. L.F. L.S. L.S. L.S. C.Y. C.Y. L.P. Ea. Unit Price $ 270 425 325 46 27 1,000 1,000 30 18 10 3,000 3,000 3,000 3 210 14 5,000 A 25,000 L.F. 15 Land Acquisition $ 44,505 $ 12,248 Cost $ 13,500 114,750 250,250 10,120 20,790 4,000 12,000 11,100 6,660 1,950 3,000 3,000 3,000 16,200 21,000 8,120 10,000 $ 509,440 76,416 50,944 $ 636,800 37,500 11,850 $ 49,350 4,935 2,468 $ 56,753 $693,553 Total $ 288. 667 $ 404,886 I I I I I I I I I I I I I I I I I I I