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The Consolidated Mutual Water Company <br />11/25/2013 <br />6. WATER STORAGE EVALUATION AND OPINIONS <br />To evaluate the water storage potential for the Ralston Quarry, the quality and quantity of fractures within the <br />rock was determined and water pressure tests were performed at the proposed elevations for the reservoir <br />walls and bottom. Additionally, three dimensional computer modeling of the probable final reservoir slopes was <br />conducted to evaluate potential storage volume. <br />6.1 Analysis of Hydraulic Conductivity <br />Brierley was able to conduct eight of eleven borings to a depth 50 ft below the proposed final pit floor elevation <br />of 6,000 ft. The rock core retrieved from the borings was observed for indications of how it would respond with <br />respect to water storage. Rock fracture frequency, RQD, openness, and infill were observed and recorded on the <br />Rock Core Boring Reports provided in Appendix A. The RQD ranged from 41 to 100 percent within the planned <br />reservoir zone. Low RQD is an indicator of fractured rock. The fractures within the cored bedrock generally had <br />variable spacing between fractures, fracture openings typically less than 1 /101" of an inch, with mineral infilling. <br />In -situ permeability testing was performed in boreholes LH -01, LH -02, BA -4, and BA -8B utilizing a single packer <br />system for the purpose of evaluating the hydraulic conductivity within the rock mass. Packer testing was <br />performed in general accordance with ASTM D4630. Depth intervals were selected based on the proposed <br />bottom elevation and surface water elevation of the reservoir. Two single packer tests were performed on each <br />boring. For borings LH -01, LH -02, and BA -4, the first test interval was located 50 ft above the bottom of the <br />boring and was tested to evaluate the bottom of the reservoir. The second test interval was located 50 ft above <br />the top of the first test interval and was tested to include the reservoir walls within the test interval. BA -BB's <br />two intervals were similar but in 30 ft increments. The results of the first test interval (lower) was subtracted <br />from the second (higher) test interval to give an indication of the hydraulic conductivity for the bedrock walls of <br />the filled reservoir. The basalt /shale contact was located in borings LH -01 and BA -86, the lower packer test in <br />this boring evaluated only the shale while the upper packer results revealed the hydraulic conductivity at the <br />basalt /shale contact. <br />The hydraulic conductivity of the bedrock ranged from 9.3 x 10 -7 centimeters per second (cm /sec) to 2.4 x 10 -5 <br />cm /sec when measurable by water pressure testing. For some intervals of the water pressure tests, the <br />apparent hydraulic conductivity of the bedrock was below the sensitivity of the water pressure tests, as <br />indicated by no measurable flow, or negative flow, during the test. A summary of the measured hydraulic <br />conductivity for the bedrock was presented in the Phase I report. Based on the results of the packer testing, <br />Brierley has concluded that the bedrock will provide water retention consistent with use as a water storage <br />reservoir. <br />6.2 Evaluation of Water Storage and Seepage Losses <br />Brierley performed an analysis of groundwater seepage for the water in the planned reservoir into the <br />surrounding rock. SEEP /W (GEO -SLOPE International) uses finite element modeling to evaluate the seepage and <br />excess pore -water pressure dissipation. <br />BRIERLEY 12 <br />ASSOCIATES <br />creL mnq $thlCe unaergruuad <br />