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<br />Long Hollow Reservoir <br />Feasibility Study <br /> <br />grout curtain cut -off wall beneath the center of the dam. This grout curtain wall extends to a <br /> <br />depth of 100 feet and consists of angled grout holes spaced on 10 feet center to center across the <br /> <br />entire crest length of the dam. In addition, the overburden soil and rock beneath the dam are sub- <br /> <br />excavated to a depth of 10 feet and replaced with compacted fill consisting of the Lewis Shale. <br /> <br />Finally, a seepage blanket is placed on the slopes and the floor of the reservoir upstream from the <br /> <br />dam. The seepage blanket will be constructed by removing the natural fractured rock in the area <br /> <br />and replacing it with a compacted fill consisting of Lewis Shale. The final seepage control <br /> <br />features will depend on additional geotechnical investigation and final design. <br /> <br />An instrumentation program of surface survey monuments and piezometers to monitor water <br /> <br />pressure in the embankment at multiple levels is recommended for the enlarged embankment and <br /> <br />included in the cost estimate. <br /> <br />LHR is shown on Exhibit 3.1-1. The exhibit contains a table that shows the coverage and <br /> <br /> <br />acreage on affected land parcels resulting from the enlargement. <br /> <br />An opinion of probable cost for the 5,400-AF enlarged dam and reservoir is presented in Exhibit <br /> <br /> <br />6-1. The estimated cost for the reservoir is approximately $13,476,000. This estimate is <br /> <br />considered to be accurate within a range of "=15 percent. The cost per AF of storage will be <br /> <br />$2,496. The operation, maintenance, and repair costs for the LHR are estimated to be <br /> <br /> <br />approximately $22,000 per year for operation and maintenance and approximately $30,000 per <br /> <br />year for replacement reserve. These costs are based on extrapolations from the Red Mesa <br /> <br />Reservoir operated by the Red Mesa Ward Reservoir Company. <br /> <br />This report has been prepared in accordance with generally accepted engineering practices in this <br /> <br />area for use by the client for planning purposes. The conclusions and recommendations <br /> <br />submitted in this report are based upon the data described in the report text. Final design of the <br /> <br />dam and appurtenant structures will depend upon additional data, as described in section 7. <br /> <br />991-077.120 <br />March 2005 <br /> <br />Wright Water Engineers, Inc. <br /> <br />Page 5 <br />