C150104 Feasibility Study - Laserfiche WebLink

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I I I I I I I I I I I I I I I I I I I However, this configuration will probably require more annual maintenance than a riprapped shore. The entire dam would be constructed from on-site materials to eliminate the haul costs associated with select materials. The downstream toe of the dam would be constructed from the sand and gravel alluvium excavated for the key trench. The embankment would use the clay overburden that overlays the entire property. The proposed reservoir design is based on not excavating into the ground more than 2 feet. The remaining clays would be scarified and re-compacted to keep the reservoir bottom relatively leak free. This property has an underlying sand and gravel valley fill alluvium that is part of the old South Platte River stream channel. This alluvium is highly permeable. If it is penetrated, it will create a leaky bottom in the reservoir that will not effectively hold water. The shallow depth of construction will also eliminate groundwater pressure against the bottom of the reservoir which could compromise the integrity of a liner. The reservoir capacity based on site constraints will be approximately 2000-2300 acre-feet. Delivery of water to the reservoir will be supplied from a combination of gravity diversions from the Peterson Ditch and from pumping water from the GASP "Ovid Wells". C. Project Goals The primary goal of the reservoir project is to divert and store water during times of available flow from the South Platte River. An off stream reservoir site would allow strategic releases to increase flows in the river during periods between April 1- October 15 when the flow of the South Platt River at the State line are below 120 cfs. This re-regulation of flows in the South Platte River is intended to reduce the potential for curtailment of diversions from the lower sections of the South Platte River. 3