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� <br />' <br />' <br />� <br />� <br />� <br />' <br />� <br />' <br />� <br />I. Overview <br />The water augmentation reservoirs are located in Section 15, Townhship 9 South, <br />Range 74 West in Park County, Colorado. The augmentation reservoirs are located in <br />Filing No. 2 in the Lost Park Ranches Subdivision and are included in a dedicated <br />easement identified as Outlot A(14.35 ac.). The existing reservoirs (2), were originally <br />constructed in 1976 and are currently in a state of disrepair. The outlet culverts are <br />both experiencing structural failure in varying degrees. Infiltration into the culverts has <br />been observed from the CCTV televised inspections as well as debris accumulation <br />inside the conduits. Water migration (piping) adjacent to the culverts has been <br />observed creating sink holes in the reservoir dams which may ultimately lead to dam <br />failure. Currently, the upper pond has been drained with the lower pond continuing to <br />impound some water. The reservoir dams (2) have been inspected by the Office of the <br />State Engineer/Dam Safety Branch with a State mandate to replace the existing outlet <br />culverts and reconstruct the reservoir embankments. <br />Historically, water has been released from the upper reservoir once a year, primarily in <br />the fall. An existing valve in the upper reservoir, normally closed to provide a full <br />reservoir, is opened and the pond is drained. The Park County Water Commissioner <br />has expressed a desire to be able to regulate the release rates in a measured form to <br />more closely monitor the volume of water being released for augmentation purposes. <br />II. Dam Classification <br />In 1986, the upper and lower reservoirs were inspected by the Office of the State <br />Engineer and subsequently inspected by the State in January and March, 2010. Per <br />the inspections performed in 1986 and the subsequent reports in 2010 the reservoirs <br />have been classified: <br />� A. Upper Reservoir: The upper reservoir has been classified as a minor Class <br />IV jurisdictional dam. Per the 1986 inspection reports, the reservoir impounds <br />10.4 ac.ft. of water with a surface area of 3.25 acres. The crest length was <br />� measured at 390 feet with a crest width of approximately 5 feet. <br />� <br />� <br />, <br />, <br />C <br />B. Lower Reservoir: The lower reservoir has been classified as a minor, low <br />hazard non-jurisdictional dam. Per the 1986 inspection reports, the reservoir <br />impounds 3.25 ac.ft of water with a surface area of 1.35 acres. The crest <br />length was measured at 180 feet with a crest width of approximately 5 feet. <br />III. Design Rationale <br />Proposed improvements to both reservoirs include the removal of the existing CMP <br />outlet culverts and replaced with new 18-inch HDPE culverts. New in-line water level <br />control vaults, with stoplogs, will be instalted and the existing gate valves removed. The <br />water level control vaults will allow the Water Commissioner to release water at pre- <br />determined discharge rates. Staff gages will be installed in the vaults to provide for a <br />visual observation of the water level in the reservoirs. New overflow spillways wilt be <br />� <br />