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C: <br />i <br />c) Background levels are not adequate to assure compliance with the Human Health and <br />Agricultural Standards, and <br />d) Domestic or agricultural use of ground water can be reasonably expected in the future. <br />The numeric standards that would apply are those which are appropriate based on the factors listed <br />for "Potentially Useable Quality". The Division finds that the appropriate standards would be <br />found in Table 3, Agricultural Standards, and Table 4, TDS Water Quality Standards. Table 2, <br />Secondary Drinking Water Standards, were not considered for two reasons. First, sulfate exceeds <br />the standard of 250 mg/I, with measured values in 1979 and 1993 of 439 and 530 mg(1 <br />respectively. Secondly, use of bedrock ground water in the Twentymile Park basin is extremely <br />limited due to inherent poor quality, low yield, and availability of alluvial aquifers. <br />Comparison of 1999 data to background levels (existing as of January 31, 1994) indicate TDS <br />values have decreased, which meets the Table 4 standazd of a maximum allowable increase of 1.25 <br />times the background value. pH falls with the acceptable range of 6.5-8.5. Primary metals such as <br />lead, cadmium, mercury, and selenium, as well as nitrite, were not detected in the latest sampling. <br />In conclusion, with regard to Regulation No. 41, The Basic Standards For Ground Water, Area 41 <br />in Eckman Pazk has met the appropriate standard for ground water and has protected current and <br />future uses of the ground water in the locale of the reclaimed mining operation. <br />Bedrock Water Ouantity <br />Figure 6 of the 1993 Annual Hydrology report shows a stable water level for well 026-79-6 of <br />about 7138 feet MSL. Replacement well 94M002 water level in 1999 was measured at exactly <br />7137.57 feet MSL indicating no change to baseline water levels down gradient of mining. <br />Surface Water Ouality <br />No spoil springs have been currently or historically identified in Area 41 in Eckman Pazk. Any <br />spoil spring seepage intercepted by the south tributary of Foidel Creek would pass through Pond <br />A, a large sediment pond that will remain permanently. Discharge of spoil spring water through <br />the Pond A in Eckman Park does increase the salinity in Foidel Creek and Trout Creek <br />downstream of the mine. However, there is no evidence that Area 41 individually causes the <br />exceedance of receiving stream standards for Foidel Creek, the receiving stream. <br />Surface Water Quantity <br />Mining modifies the character of the landscape and has the potential to increase runoff from the <br />reclaimed areas. The disturbed areas of Area 41 were altered from apre-mining vegetative <br />community of an aspen forest to a post-mine condition of grassland. It is likely that runoff from <br />the reclaimed areas increases the amount of water to the surface water system below the mine. <br />Seasonal variation from one year to the next can be dramatic, based mainly on the amount of snow <br />pack each season. No identifiable increase or decrease in surface water quantity is apparent from <br />Colorado Yampa Coal Company: SL07 Findings I I/UO page 12 c ~jhb\C081071\SL07fnd.doc <br />