2012-06-20_PERMIT FILE - C2010089 (84)

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Murari P. Shrestha, P.E. August 25, 2010 Page 3 To determine aquifer characteristics for the Brushy Basin Formation, we relied on the pump test information from the permit files available from the State Engineer's Office. From this information, we determined a transmissivity of approximately 530 gallons per day per foot (gpd/ft) for the bedrock material. We also determined a storage coefficient of 0.0001 based on the characteristics presented in the mine permit documents and our experience with ground water pump testing and characteristics. We relied on the estimated potable water requirements presented above. Based on an annual demand of approximately 0.61 af/yr, the annual average pumping rate for wells at each mine location is approximately 0.38 gallons per minute. This amount is consistent with the expected annual demand for a single family home. We determined centroid locations for the New Horizon North and Cyprus Block mine properties based on the well field areas claimed in the client's recent water court application and locations where Western Fuels indicates wells may be constructed. The analytical approach was identical for both the Cyprus Block Property and New Horizon North because water supply wells will produce from the Brushy Basin Formation at both locations and the Brushy Basin Formation is present at similar depths at each of the two mine locations. Distances from these centroid locations to nearby wells were measured using GIS methods and the well locations for nearby wells, as indicated in the State's Master Well List database. Existing neighboring production wells were identified from the Master Well List, as summarized in Table 2 and Figure 1. For wells located within 1000 feet from the mine boundary, a distance of 600 feet was conservatively assumed, which is the distance used by the State Engineer's Office to determine whether or not the applicant for a new well permit needs to pursue a 600 -foot spacing waiver. Projected drawdowns at the identified neighboring wells were calculated using the aquifer characteristics identified above, the measured distances and the Theis equation. A pumping period of 20 years was assumed for this analysis. The pumping was modeled such that all of the demand was supplied from one well located at the centroid location, although up to five wells may be constructed at each mine property. Based on our analysis, new wells constructed and operated at the New Horizon North and Cyprus Block mine properties may cause a small change in water level in neighboring wells. The change in water level resulting in neighboring wells resulting from wells used to meet the demand at the New Horizon and Cyprus Block properties is quite small, on average approximately 0.53 feet with a maximum change of approximately 0.85 feet. Where data are available to analyze available water level drawdown in the neighboring wells, the projected change is on average approximately 0.11% of the available drawdown at the Cyprus Block location and 0.45% at the New Horizon North location, with a maximum projected change of 1.29% of the total available drawdown occurring in permit number 39696, resulting from well pumping at New Horizon North. A summary of the neighboring wells and the water level change calculations has been presented in Table 2. The analysis assumes full connection across the aquifer between the Western Fuels wells and all of the wells indicated in Table 2, which is a conservative assumption. As indicated, the change in water level resulting from the operation of up to five potable www.bbawater.