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of NPDES Permit No. CO-0000221 (Appendix 15-51. NPDES Sites 005, 006, and 009 are currently incorporated in the NPDES permit, and are located at the outfalls of each • sedimentation pond. Pond 006 was completed in October, 1989 and it started discharging affluent in March, 1990. NPDES 005 was completed in July of 1992 and started discharging in April, 1993. NPDES 009 was completed in October of 1991 and started discharging in April, 1996. Proposed NPDES Sites 015, 016, and 017 are all part of the II-W South Expansion area. Monitoring at NPDES sites will adhere to the requirements of NPDES Permit No. CO-0000221. Tri-annual full-suite water samples will be collected at all NPDES sites. Ground Water Monitoring Ground Water Monitoring Site Numbering System. An example of the format used to identify ground water sites is "GW-S2W-19A". The "GW" prefix indicates ground water; the "S2 W" refers to the Seneca II-W Mine; the number "19" refers to the site number; and the "A" refers to the aquifer code, which in this case is the alluvium. Other aquifer codes include: "OV" _ Wadge Overburden; "W" = Wadge coal; "WC" = Wolf Creek coal; and "I" = Wadge/Wolf Creek interburden. The addition of en "E" prior to these aquifer codes at Well Site A'3 denotes an eastern set of water level observation wells. For the sake of brevity in the text, the GW- S2W prefix is usually omitted. Thus, for example, Site GW-S2W-19A is referred to as simply "Site 19A". Ground Water Monitoring Well Construction and Testing. Well construction summaries and lithologic logs are found in Appendix 7-1. No well development activities were documented for wells drilled in 1979 (Well Sites 1-91. Wells GW-S2W-lOW to 13W were developed in August, 1982. Development procedures consisted of water injection followed by air surging. Air is injected into the well forcing water, sediment, and contaminants out of the top of the casing. The air supply is periodically shut off, allowing the aerated water column to fall back down the well bore which effectively back surges the gravel pack. Development information for wells drilled in 1987 (Well Sites 14 through 191 may be found with their respective well construction summaries (Tab 7, Appendix 7-11. In general, these development activities included a combination of hailing, pumping, and air surging. Aquifer tests were attempted on all wells drilled in 1987 (Wells GW-S2W-14OV to 19A1. Tests conducted at Wells 14OV and 16OV were unsuccessful. Accurate water level measurements could not be obtained in 14OV, and 16OV was dry at the time the aquifer tests • 10 Revised 9/98