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are extremely dramatic as is evident in the chemograph depicted in <br /> Figure 3. The mean TDS concentration for the period of record is <br /> 1189 mg/l , fluctuating between approximately 600 mg/l during <br /> mid-summer and 1800 mg/l during mid-winter. <br /> Comparison of the data from year to year indicate that the <br /> quality of this water has remained essentially unchanged since <br /> monitoring began in October 1979. Comparison of October 1979 <br /> water quality to that of October 1985 (see Table 9 of Section <br /> V.B.2.d. ) indicates that the quality of water on Tuttle Draw at <br /> SW-N1 has not changed within the past six years with respect to <br /> virtually all of the reported parameters. <br /> 2. NPDES 002 and 003 <br /> NPDES discharge points 002 and 003 (Permit No. CO-0000213; see <br /> Appendix 7-6) are located along the southern edge of the <br /> scraper area on the northside of Tuttle Draw. To date, neither <br /> of these discharge points have been known to discharge. Discharge <br /> monitoring reports for the past three quarters of 1986 are provided <br /> in Appendix C. Because the present storage capacity and spillway <br /> configuration of the 002 pond are inadequate (see Appendix 7-1 of <br /> the Nucla Mine Permit Revision) , this pond has been redesigned. Up <br /> until and upon reconstruction, the pond will continue to be <br /> monitored for flow and quality according to the requirements of the <br /> NPDES permit. Regarding the 003 pond, PCC has requested an <br /> exemption from the requirements of the sedimentation pond <br /> regulations. The existing structure drains a very small drainage <br /> area including a reclaimed haul road, the immediate reclaimed area, <br /> and the area around the existing sedimentation structure. No new <br /> mining disturbance is planned in this watershed. The existing <br /> structure has a capacity of 261 cubic feet and would continue to <br /> perform the function of a sediment trap until bond release is <br /> approved for this area. Any new excavation and remedial work on <br /> the existing structure could possibly disrupt the overall <br /> hydrologic balance of the watershed more than leaving the present <br /> conditions undisturbed. <br /> 20 <br />