2019-01-18_REVISION - M1974086 (17)

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i The Consolidated Mutual Water Company 11/25/2013 The computer model assumed a theoretical east-west cross section for the proposed quarry.The material was assigned a hydraulic conductivity of 2.7E-05 cm/sec,the midrange combined value from the in-situ permeability testing(Table 11),to evaluate the maximum potential seepage loss.The model assumed three different groundwater conditions;25 ft above the proposed reservoir level,at the midpoint of the reservoir(25 ft below the water surface),and 25 ft below the bottom of the reservoir floor(75 ft below the water surface).Seepage results were considered in cubic ft per day per square foot of reservoir(ft3/day/ft'),the same measurements considered by the Office of the State Engineer.Seepage for the first groundwater scenario reported inflow into the reservoir,while the other two scenarios reported outflow from the reservoir. The results of the flow into or out of the reservoir perimeter and bottom were generally small(t E-03 W/day/ft= or smaller). An equivalent volume loss of up to about 80 gallons per day can be considered for a 10-foot wide section through the middle section of the proposed central reservoir. These results of this assessment are considered consistent with the use of a quarry pit as a water storage reservoir in Colorado. 3 From a geological perspective,water losses due to seepage are unlikely. The intruded basalt is surrounded by relatively impermeable shale. Due to this geologic setting,the basalt will act as a "closed" local system and will be isolated from the larger regional system. During initial filling of the reservoir,some losses should be expected as the basalt becomes fully saturated. After saturation,the shale will act as an aquatard and the water will be trapped in the basalt and the system will reach a steady-state where an insignificant amount of flow will occur through the bedrock. Quantification of the initial loss during filling of the reservoir with the current amount of data is not possible without making significant assumptions and extrapolations; however,we believe that this initial loss will also be insignificant when compared to losses due to other mechanisms such as evaporation. Water level readings on borings and monitoring wells after drilling was complete showed artesian conditions in two locations in the form of water exiting the top of casing or monitoring well. Artesian conditions occur when the water pressure in the formation is greater than the pressure due to elevation head. The most common reason for artesian conditions is a hydraulic connection between a formation and a source of water at a significantly higher elevation with an impermeable layer acting as a hydraulic barrier or"cap"overlying the formation. �. Observations from the Brierley staff taking the water measurements noted that there was a pool of water in the quarry where runoff collected which was located at a higher elevation than the two locations where artesian conditions were observed. Brierley believes that this pool is the source of the artesian conditions observed. If correct,the observed artesian conditions are additional evidence that the basalt plug is a "closed"system as the water pressure has not significantly decreased since first noted after drilling. BRIERLEY 13 ASSOCIATES C�rorng Space Ur,�tegrowr.: