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10/04/96 10:51 FAX 9709295177 0%BOW SANBORN ~{J 004 Antony Waldron Page 3 September l;i, 1991 "Streamflow may be diminished by a reduction in spring discharges. Decreases i^ spring basefLow to streams would be caused by interception of ground water sources by subsidence features. The intercepted water would remain within the Vorth Fork of tite Gunnison drainage basin, but the location of surface contributions could be altered. Three mines in the CHIS area monitor springs and seeps for possible subsidence impacts from mining - Hswlc's Nest, the West Elk vine, and Orchard Valley. Hawk's Vest recorded no changes in flow while they were operating, and currently they do not monitor flow." Dtie in part to a change in personnel at SMC, the practicable beginning of the 1993 spring monitoring commenced at the end of June. In order to make up for this oversight, the required spring monitoring was extended through June of 1991, as included in Technical Revision No. 18. During the review for Technical Revision No. 18, the Division required the baseline analysis to be conducted, submitted, and approved prior'to mining within the angle of draw of Springs 1-11. SMC agreed not to perform secondary mining under Springs 1-11, and subsequently agreed not to mine within the angle of draw oi' Springs 1-fi or Springy 10 &~ 11 until the baseline monitoring and interpretation of data is complete and approved by the Division. Spring monitoring data for Springs 1-11 are included in this report. When the present spring monitoring was bevun in June 1993, effort was made to locate the springs as marked on the Monitoring Location yap from Western Slope Carbon Hawk's Nest Mine included in the permit documents as pae'e 'L.0~1-50sviii. The legend indicates the marking to be Approximate Spring Location. Actual monitoring locations have been marked on the ground, and monitored at the same locations since. Spring 1 is a depression near a grove of depression may have contained water when previous to 1993. Data have not recorded a Field parameters, pH, conductivity, and indicate previous monitoring of surface Ovate depression. aspen trees. The it was monitored flow. The other temperature would r collected in the Spring 2 is possible re-emergence of water in a small ephemeral drainage channel. Flows, if any, are recorded in the spring and summer. Other than the high pH measurements for 1993, which are suspect, the field parameters are similar to surface water. Springs 3, ~, 5, & 6 are also passible re-emergence of surface water in a small ephemeral drainage, with similar characteristics of flow diminishing from spring to summer, moderate pH, low conducti~-ity, and variation in temperature. The only unusual data are the high conductivity measurements for Springs 2 & 3 in August 1983.