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16 <br />Based upon the Department of Public Health and Environment, Water Quality Control <br />Commission. Basic S[crndards for Groundtirater (d CCR 1002-41), bedrock ground water in the <br />vicinity of Mine No. 3 is classified as "Potentially Useable Quality" for the following reasons: <br />a) ~ TDS levels are less than 10,000 mg/I, <br />b) Ground water is not used for domestic or agricultural uses, <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 that 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 Standazds, were not considered for two reasons. First, sulfate <br />exceeds the standazd of 250 mg/1, 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 1998 data to background levels (existing as of January 31, 1994) indicate TDS <br />values have increased by a factor of 1.15, which meets the Table 4 standard of a maximum <br />allowable increase of 1.25 times the background value. pH falls with the acceptable range of 6.5- <br />8.5. Primary metals such as lead, cadmium, mercury, and selenium, as well as nitrite, were not <br />detected in the latest sampling. <br />In conclusion, with regard to Basic Standards for Groundwater (5 CCR 1002-41), Energy Ivfine <br />No. 3 has met the appropriate standazd for ground water and has protected current and future uses <br />of the ground water in the locale of the reclaimed mining operation. <br />2. Bedrock Water Quantity <br />Figure 4 of the ] 997 Annual Hydrology Report for Energy Mine No. 3 indicates the water level <br />in well 008-79-58 has recovered to the early 1979 elevation of 6716 feet M.S.L. and shows a <br />seasonal variation of ~ feet. Figure 5 of the report indicates the water level in we11008-79-6, <br />2500 feet northwest of 008-77-58, has been nearly static at approximately 6660 feet M.S.L. with <br />a variation of about 5 feet seasonally. Water level at the time of installation of this well indicates <br />the formation was likely already dewatered to some degree by mining activities, so direct <br />correlation to true baseline conditions is not possible. Water levels in both wells are currently <br />between 4-16 feet from the surface on average, which indicates nearly complete recovery for this <br />portion of the Twentymile Park ground water basin. <br />Colorado Yampa Coal Company sealed wells 008-SP-SA, 008-SP-4B, and 008-79-6 on February <br />19, 1999 in accordance with Rule 4.07.3(3). All remaining wells on the Energy Mine permit area <br />Colorado Yampa Coal Company: Mine No. 3. SLO? Findings 6/99 a:\C08406?\SL02(nd.doc <br />