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?s <br />constituents and values between -10 and 10 are considered good. <br />Field pH is an important parameter to measure because some coal spoils have <br />the potential to increase acidity of the ground water which increases the mobility <br />of most heavy metals. A pll of less than 5 would generally be needed to greatly <br />increase the mobility of most heavy metals. Available pH data is tabulated in Table <br />4.8-10a. <br />The sodium-absorption ratio (SAR) is tabulated on the second series of pages <br />in Table 4.8-10a. <br />The major constituents, other than the carbonates, are presented on the <br />remaining pages of Table 4.8-10a. The heavy metals with an asterisk by their symbol <br />• are total measurements while the others are dissolved concentrations. Dissolved and <br />total concentrations are similar for most of the heavy metals, except for iron <br />concentrations where the total values are generally significantly greater. <br />TWENTYMILE AQUIFER <br />Well GD1 is the water supply well for the mine and is completed in the <br />Twentymile Sandstone. The TDS plot (Figure 4.8-30) for water from this well shows a <br />decline in TDS in 1981 and 1982 and an increase in the last four years, except the <br />1984 value. The 1984 value is significantly below the other values, but the DSSUM <br />value indicates that the TDS is a good measurement. The upward trend over the last <br />few years could be the result of increased usage of this well since 1985, but is not <br />thought to be caused by mining since mining does not penetrate this aquifer. Values <br /> <br />4-233v <br />REVISED FEB 13'87