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State Reg. <br />well design and lithology. The ground wafer monitoring plan is discussed • <br />in detail later in the section titled "Protection of the Hydrologic <br />Balance". <br />The wells are sampled semi-annually using standard U.S.G.S. recom- <br />mended methods. Each well is sampled using i submersible pump or <br />thief-type sampler until the pH, conductivity, and temperature stabilize, <br />thus indicating that the sample truly represents water present in the <br />aquifer. Samples are then field filtered using a nitrogren pressurized <br />Skougstad plastic filter barrel with a 0.45 micron filter membrane. Four <br />aliquots of sample wafer per sample are taken; one non-acidified and <br />non-filtered, one non-acidified and filtered, one acidified with HNO3 and <br />filtered for metals, and one acidified with HZSO4 and filtered for vitro- <br />gen compounds. Preservation techniques for nitrogen compounds have <br />been recently changed to use H3BO3 as the preserving agent in favor of <br />the more corrosive HZSO4. Samples are placed in coolers with ice and <br />shipped immediately to Peabody Coal Company's Central Lab in <br />Freeburg, Illinois for analysis according to procedures in Appendix 7-2. • <br />These samples are analyzed for the laboratory parameter list given in <br />Table 7-30. Field measurements of static water level, pH, conductivity, <br />and temperature are also recorded. <br />The results of the chemical analyses which are presented in Tables 7-7 <br />through 7-13 and are illustrated in Figure 7-3 by a Trilinear (Piper) <br />Diagram suggest that ground water quality in the permit area is ex- <br />tremely complex. Many samples contain undesirable concentrations of <br />dissolved solids, sulfate, fluoride, iron, manganese, and hardness, thus <br />rerxling these ground waters unsuitable for human consumption based on <br />drinking water standards listed in Table 7-4. The wide range in water <br />types can be expected since ground waler quality usually closely resem- <br />bles the chemical characteristics of its porous medium with considera- <br />tion given to the very low solubilities of most trace elements in water of <br />normal and alkaline pH (Hem, 1970). Other factors such as surface water <br />recharge will also influence ground water quality. A brief description of <br />water quality for each set of strata at the Seneca II Mine is provided • <br />below. <br />7-20 Revised 5/27/81 <br />