2002-03-04_REVISION - M1986015 (8)

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WATER INFORMATION Exhibit G Water Information This exhibit presents an inventory of the existing water resources at the Puebla East Pit and a discussion of water requirements of the mining plan and how those requirements will be met. The water resources at the Pueblo East Pit include two main components, surface water and ground water. The surface water system in this area consists solely of the Arkansas River. No appreciable tributaries join the river as it passes through the permit area, although the St. Charles River joins the Arkansas about three or four miles downstream of the permit area. The Arkansas river is a broad, swift flowing and meandering river at this location. Based on 10 years of stream gage data (1989 - 1999) from the USGS, the average annual flow in the River is over 630,000 ac-fUyr at this location. The ground water system is connected to the surface water system, yet it also has its own distinct characteristics. The ground water system consists of the alluvial aquifer associated with the Arkansas River. On average, the alluvium is approximately 4,920 feet wide in the permit area. The aquifer is essentially shaped like a trough with the thickest areas occurring near the river and thinning away from the river. The base of the aquifer (which is also the top of the underlying shale bedrock unit) is fairly irregular resulting in varying saturated thickness across the aquifer. The amount of ground water flowing through the aquifer can be estimated using the Darcy equation, which is written: Q = KiA; where Q =flow rate, K =hydraulic conductivity, i =gradient (based on topography), and A =the cross-sectional area of the aquifer. Using an estimated hydraulic conductivity of 3,000 gpd/ft2, the estimated underflow in the alluvial aquifer is approximately 1,000 ac-ftlyr at this location. Several production wells are completed in the alluvial aquifer in and near the permit area. Based on a review of the State's master well list, a review of property records and site visits to the area, the following five wells were identified that appear to be within 600 feet of the affected area of Phase I of the mining plan (shown on Exhibit C-2). Only the Helmsing and Prijatel wells are within 200 feet of any land that will be used in a way that could potentially affect the integrity of the well. The Helmsing well, by prior agreement, will be moved and the Prijatel well is no longer in use, Pueblo East Pit Amendment Exhibit K Page 1