PROJ00206 - Laserfiche WebLink

Home Browse Search

I I I I I , I , I I I I I I I I I I I PROJECT SUMMARY The City of Longmont has numerous sources of water available to meet munici- pal demand including direct flow decrees, storage water, groundwater and project water. Future projected "water demands dictate that the City utilize all existing sources to their fullest capacity and that all the storage vessels be utilized. McCall Lake is one of 14 reservoirs owned or partially owned by the City of Longmont. The decreed capacity of McCall Lake is 506 acre-feet. The State Engineer's Office (SEO) has noted several deficiencies of McCall Lake in its 1986 and 1987 dam inspection reports. These deficiencies include: 1) erosion of the embankment, 2) erosion of the spillway, and 3) nonoperable outlet works. To comply with the SEO and to increase options for using McCall Lake water the following measures are required: 1. Reconstruct approximately 1800 feet of the upstream face embankment by flattening from the existing 1:1 slope to a 3:1 (horizontal to vertical) slope and providing riprap protection of the embankment, 2. Replace the existing spillway with a nonerodible concrete spillway and provide upstream and downstream riprap protection for the concrete spillway, 3. Replace the existing outlet works with i) a new trash rack-headwall structure, ii) new water tight gate on the lake side, iii) a hydraulic operator for the gate, iv) an in-line pipe flow meter, and v) 1750 lineal feet of 18" RCP (if needed), 4. Extend the existing toe drain in an 8 inch diameter PVC pipe to Independent Reservoir which is located south and east of McCall Lake, 5. Clean all brush, stumps and vegetation from the embankment and fill-in all rodent holes around the lake, 6. Construct a diversion structure from the Longmont Supply Ditch to the Oligarchy Ditch so releases from McCall Lake can be utilized by the City in the Oligarchy Ditch as well as the Longmont Supply Ditch.