1988-04-11_PERMIT FILE - C1981008A (21)

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wells actual yield. The type and amount of sediment (or lack thereof) after air lifting gives a good indication of the quality and integrity of the well . If a well yields little water, water is injected into the well to facilitate in the removal of sediment and contaminants. The next stage of development consists of bailing and/or overpumping. At least three casing volumes are bailed or pumped from the well, further removing sediment and contaminants. The bailing process effectively surges the well bore. At this time, a well is ready to be evaluated for incorporation into Peabody's long term monitoring program. Monitor Well Placement and Site Numbering System The monitoring wells were installed as single wells or in bedrock clusters.. The bedrock cluster sites consist of three monitor wells (overburden, Dakota coal, and underburden) placed in a line approximately ten feet from each other. At one of the monitor well cluster sites (GW-N16, GW-N17, and GW-N18), observation wells were installed (GW-N16P1 , GW-N17P1, and GW-N18P1) to aid in aquifer testing. Figures 15-1 through 15-5 show generalized schematics of a bedrock cluster site and well construction schematics. Similar to the surface water data, the ground water data is stored and managed on Peabody's mainframe computer. To manage the different types of data collected from each monitoring site, there is a unique alpha numeric number assigned to each monitor well . The alpha numeric number system is explained on Table 15-6. Ground Water Quality Sample Handling, Preservation, and Analysis The ground water quality parameter list for which water samples at Nucla and Nucla East are analyzed is contained in Appendix 15-1 . The following parameters (Ag, Ba, Cr, Ni, and sulfide) have been added to the parameter list in 1987. As previously mentioned, Peabody has asked for a variance from further analysis of chromium (Cr). Table 15-4 indicates the sample type, preservation, and the bottle type necessary for analysis of the particular constituents shown. All sample bottles are appropriately labeled and placed into ice coolers prior to delivery to Peabody's contract laboratory (ACZ Laboratories, Steamboat Springs, Colorado). Preparation and analysis of all water samples is done in accordance with USEPA Manual of Methods for Chemical Analysis of Water and Wastes (1983). All water samples are field tested for pH, temperature, and specific conductance at the time they are collected. 15-12 Revised 04/11/88