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In the 1989 AHR, Peabody modified the nomenclature of the wells at the Seneca II site by adding a suffix to each, thereby designating which aquifer the well monitors. For example, GW-s17 was renamed GW-s17-W to indicate that it monitors the Wadge coal seam aquifer. The other suffixes follow: A = ALLUVIUM LO = LENNOX OVERBURDEN LWI= LENNOX/WADGE INTERBURDEN W = WADGE COAL SEAM U = WADGE UNDERBURDEN WCO= WOLF CREEK OVERBURDEN WC = WOLF CREEK COAL SEAM TC = TROUT CREEK SANDSTONE S = SPOILS Aquifer Quantity and Oualitv All variant well levels, indicative of water quanity, reported by Peabody are reasonably explained by failed plunging techniques, resaturation of spoils piles and/or variability in regional precipitation amounts. For example, the levels in many of the wells were at the .lowest levels in permit history during 1990. This was primarily the result of drought like conditions in the region since 1986-87. Levels did not rise significantly in 1991, a normal precipitation year, but are expected to rise with time. Five potentially significant aquifers have been identified at the Seneca II mine: Trout Creek Sandstone, Wadge Overburden, Alluvium, and Reclaimed Spoil. Of the five listed only the Trout Creek Sandstone member is considered a regional aquifer. The Trout Creek Sandstone lies 70 feet below the Wolf Creek member, the lowest coal bed to be mined, and is separated from the Wolf Creek coal by a confining unit of interbedded sedimentary units which has prevented and should continue to prevent the vertical migration of water. This aquifer has historically exhibited high sulfate levels (> 1000 mg/1), is monitored by well GW-s5-TC, and is used only by the Seneca II shop for domestic related purposes. We should note that 504 type waters will have noticeable laxative effects when concentrated at levels greater than 600 mg/1. The other four aquifers are thought to be hydraulically discontinuous and because of low transmissivities and isolated nature, not of regional scope or importance. Each will be discussed separately in lithologic order from upper to lower members. Spoil aquifers form as a result of resaturated backfilled pits and discharge water at spoil springs when the elevation head of the spoil spring exceeds the ground surface elevation. Peabody monitors six spoils springs for water quality. In addition, Peabody monitored 10 spoils wells in 1989 and is now monitoring a total of five spoils wells for water quality.