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region), a more appropriate standard would be 10 mg/l (EPA, 1976). This <br />year, none of the Seneca II-W wells displayed a value higher than 1.82 <br />mg/1. <br />At the Seneca II-W shop well, Well 201TC, CDPHE drinking water standards <br />were used to determine its suitability. No human health standards were <br />exceeded. The secondary standard for iron (0.3 mg/1) was exceeded with a <br />value of 0.50 mg/1. The secondary standard for manganese (0.05 mg/1) was <br />exceeded with a value of 0.072 mg/l. Both of the standards are normally <br />exceeded at this well. However, bottled water is consumed at Seneca II- <br />W. Also, since the aquifer for the shop well (Trout Creek Sandstone) <br />starts at 280 feet below the Wadge Coal and is separated by confining <br />shale layers, water from this well should not be affected by mining and, <br />therefore, reflects the natural characteristics of the aquifer. <br />Ground Water Points of Compliance <br />A GWPOC have been established in the Dry Creek alluvium for the Seneca <br />II-W Mine. Appendix 15-3B of the Seneca II-W PAP provides the details. <br />The ground water standards for Dry Creek Alluvial Well DCAL-02 are <br />provided in this AHR on Table 7. The only exceedance of these standards <br />this year was iron. The standard is 8.06 mg/l, while a value of 11.00 <br />mg/l was observed this year. The iron standard established for this <br />alluvium was the highest of the pre-1994 values noted in the Dry Creek <br />alluvium. This particular well was drilled in 1998 for Peabody's Big Elk <br />Project, therefore no pre-1994 data exists at this well. It is unlikely <br />that the elevated values of iron are attributed to mining since, 1) the <br />iron value this year at the next alluvial well upstream, WHAL7-2, was <br />5.53 mg/1, 2) the high NPDES pond iron value this year was 1.95 mg/1, 3) <br />the highest spoil spring iron value this year was 1.18 mg/l and 4) this <br />well displayed high iron values (6.96 and 11.1 mg/1) as soon as it was <br />drilled. High levels of iron may be the result of organic matter and <br />plant debris present in the alluvium (Hem, 1989, pg. 77). Only four <br />samples at this well have been collected by SCC, so no TDS trend can be <br />discerned. 0 <br />8