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<br />Concern: <br /> <br />'l <br /> <br />[ <br />~, <br /> <br />002H5 <br /> <br />2.1.10 Culverts at County Line Road <br /> <br />1 <br />, <br />During the high runoff this past spring, a larg~ volume <br />of water accumulated west of the County Line Road. If the road <br />and existing culverts had given away, Alamosa County and the <br />City of Alamosa would have been flooded extensively more than <br />actually occurred. The culverts should be replaced with an <br />open structure to help eliminate this volume of water being <br />held by the roadway. <br /> <br />Findings: <br /> <br />Two 60-inch diameter Corrigated Metal Pipe (CMP) <br />culverts are installed in the County Line Road embankment. <br /> <br />,. <br />i <br />I <br /> <br />'l'he ends of the culvert protrude beyond the embankmen't <br />which is hydraulically inefficient. During the 1985 flood, the <br />combined capacity of the culverts was less than 200 cfs under <br />about 6 feet of head. A concrete headwall would make a slight <br />improvement in the capacity of these culverts. <br /> <br />Cost Estimates: <br /> <br />~ <br />f <br />Ii <br />Ii <br />;1 <br />" <br />;i, <br />,I <br />1 <br />I <br />, <br />f, <br />" <br /> <br />Approximately 1,800 acre-feet of water were impounded <br />behind'the County Line which had a positive effect on reducing <br />the peak flood downstream in Alamosa County. However, the <br />release of this water is slow resulting in unnecessary damages <br />upstream in Rio Grande County. Willows and other vegetation in <br />the channel impede flow through the bridge opening, <br /> <br />To construct a concrete headwall. <br /> <br />$2,907 <br />$5,000 <br /> <br />To clear the channel, <br /> <br />Recommendation: <br /> <br />, <br />, <br /> <br />The entrance condition of the existing culverts should <br />be improved by constructing a concrete headwall, and the <br />conveyance capacity of th highway bridge should be improved by <br />clearing the channel of illows, mud and debris. This work <br />should qualify for the St te disaster assistance. <br /> <br />~,~, ~ ItS? <br /> <br />57 <br />