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December 23, 1999 Page 3 • 2.O GROUNDWATER MONITORING This groundwater monitoring plan presents detailed descriptions of the monitoring well layout, well completions, groundwater monitoring zones, water-quality parameters, monitoring schedules, and monitoring procedures. The Piceance Site has 25 monitoring well completions located in l8 boreholes. The Parachute Site will have at least one monitoring well. The groundwater monitoring procedures are described in Section 3.0. Two domestic wells near the Piceance Site are also included in the program. 2.1 Groundwater Monitoring Locations 2.1.1 Picemtce Site Groundwater Monitoring Locatio~rs The monitoring well layout for the Piceance Site is shown on Figure 1. Figure 2 is a generalized stratigraphic column showing aquifer locations and important stratigraphic horizons for the Piceance Site. Monitoring well completion diagrams are presented in Appendix A. A summary of the Piceance Site monitoring wells included in the groundwater monitoring plan is presented in Table 1. • The monitoring wells are positioned up-gradient, down-gradient, and cross-gradient of the 0-5 year mining panel. The monitoring well layout assumes a groundwater flow direction in both the Upper Aquifer and Lower Aquifer of southwest to northeast. This trend is in accordance with regional groundwater data (Weeks et al. 1974). Site-specific data from the Upper Aquifer suggests the flow direction is roughly west to east. Therefore, positions of the up-gradient and down-gradient wells, relative to groundwater flow direction, are based on an averaged flow direction of N65°E. American Soda has installed this well configuration for the 0-5 year mining panel to assure that potential impacts to groundwater and surface water will be detected. American Soda will use a network of 25 monitoring well completions (as detailed in Figure 1) to monitor groundwater quality and water levels at the Piceance Site for the 0-5 year mining panel. The Upper Aquifer will be monitored at 1 I locations, the Lower Aquifer will be monitored at 10 locations, and the Alluvial Aquifer will be monitored at 4 locations. Of the 25 well completions, 15 completions (10 well bores) are located outside the 0-5 year mining panel, and l0 completions (8 well bores) are located within the 0-5 year mining panel. • ~ Weeks, J. 6., G. H. Leavesley, (:. A. Welder, and G. J. Saulnier, Jr. (1974).,,"Simulated Hffects of Oil-Shale Development on the I lydrolooy of Piceance basin, Colorado," U.SG,S Pr•ojessiona! Paper 90R, 84 p. Agapi[o Associates, Inc.