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not contribute additional suspended solids above natural conditions 58. Materials available for seedbed preparation were determined to be nontoxic 59and valuable as plant rooting media 60. Therefore, there is little probability of leaching of toxic topsoil. No record was found of discharge from the remaining two sedimentation ponds in CDPHE discharge monitoring reports (CDMR)(1989 to present), monthly inspection by the Division (1991 to present), or Annual Hydrologic Reports (1989 to present). A number of other authorized sedimentation ponds have been previously reclaimed. With the exception of one stabilized rill, there was no evidence of surface erosion at the time of the Phase II Bond Release Inspection by the Division. Mine water currently discharges from both the Mine 1 and Mine 3 portals. These discharges aze directed into treatment ponds, and the last treatment pond discharges into North Thompson Creek. A review of CDPHE discharge monitoring reports (ls` Quarter 2000 to present) found no incident where discharges exceeded permitted values. The probable hydrologic impact to North Thompson Creek, at low flow, is a 5% increase in conductivity 6t and, throughout the year, a discharge of approximately 0.9 tons of salt per day 6z. There is mine water discharge from Portal 2. This portal was reclaimed by the Division's Inactive Mines Program. This portal and its mine water discharge aze not a part of Permit C-81-025, and aze not a part of this bond release (SL-04). Discharges from this portal are treated by a passive detention pond, and are then discharged to North Thompson Creek between Portals 1 and 2 of the Permit C-81- 025 mine site. There are two shallow groundwater monitoring wells in the vicinity of the Mine Waste Refuse Pile (refuse pile). Well D-1 A is located directly below the refuse pile and well D-2A is located west of well D-lA, outside the probable plume of any groundwater contamination from the refuse pile. Conductivity of water samples from well D-lA rose from 3000 umhos/cm (when installed) to 4000 umhos/cm in 1989, and has stabilized in the vicinity of 4000 umhos/cm to the present 63. The conductivity of water samples from well D-2A appeazs to be dropping from a initial 2,500 to 1,000 umhos/cm in yeaz 2000. The impact of groundwater below the refuse pile to North Thompson Creek is unknown. Annual measurements have been taken, in May and September, on North Thompson Creek, above and below the mine. Samples from below the mine aze used to determine the quality of the creek water is as it leaves the mine site. The average conductivity measured in September (low-flow condition) over [he past five years above the mine is 177 umhos/cm ~, and below the mine is 258 58 see Soils Loss Comparison -North Thompson Creek Mine Sites, pages 4-19i through 4-19iii of the PAP s9 PAP page 4-v 5/O1 60 Proposed Decision, Partial Bond Release Request, March 9, 1988, Page 3 61 2000 Annual Hydrology Report, pages ez PAP page 4-122 6J 2000 Annual Hydrology Report, Appendix II 612000 Annual Hydrology Report, Appendix I SL-04, C-81-025 November 13, 2001 Page 14 of 16 Pages