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TABLE 1 <br />Pond Invert Elevation Com orison <br />Pond 001' Pond 002 <br />Year 1992' 1996' 1992 1996 <br />Invert &levation 93.51 93.48 7538.97 7538.52 <br />Notes: I) Survey datum for Pond 001 is based on assumed datum. The survey observations for the survey done May <br />1996 were translated to conform with the datum of August 1992. <br />2) Data from August, 1992 Pond As-Built Surveys. <br />3 Data from Iv1a , 1996 Pond Sediment Surv s. <br />Table 1 suggests that there has been no change in the invert elevation which implies that the drainage <br />from the reclaimed Explosive Storage Area and Landfill Area watersheds, which contributes runoff <br />and sediment to ponds 001 and 002, respectively, do not contribute suspended solids above <br />background conditions. While a slight discrepancy in the invert elevations and pond areas exist <br />between the survey data from the two yeazs, which can be attributed to water in the ponds during the <br />1996 survey, the stage storage data suggests that minimal, if any, sediment has accumulated over the <br />four year period since the as-built survey. The lack of any sediment accumulation in the ponds <br />indicates that the established revegetation is currently the primary sediment control technology for <br />the reclaimed areas which drain to ponds 001 and 002. <br />Pond discharge at the Hayden Gulch Mine is permitted under the Colorado Wastewater Discharge <br />Permit System (CDPS), Permit No. COG-850018. Monitoring results indicate that all pond <br />discharges have been in compliance with the CDPS permit requirements. The Hayden Gulch Mine <br />received above normal precipitation during the 1994/1995 and 1995/1996 winters. During May <br />1995, the Hayden airport climatological station (which is located 1 l miles north of the mine site) <br />reported in excess of rune inches of precipitation. The discharge monitoring also indicates that <br />sedimentation ponds 001 (Explosive Storage Area pond) and 002 (Landfill Area pond) have never <br />experienced a discharge event, including 1995 with the heavy runoff/wet spring. <br />The Hayden Gulch Mine Annual Reclamation Reports since 1988 provide results of water quality <br />monitoring for the Upper Hayden Gulch surface water site (LTHG), located downstream of ponds 001 <br />and 002. Reclamation monitoring at the UHG site indicate TSS concentrations range from 2 mg/L <br />to 104 mg/L. Baseline sampling conducted as part of the Hayden Gulch Mine Permit Application <br />indicate that the maximum pre-mining TSS concentration measured at the Upper Hayden Gulch <br />surface water site was 543 mg/L. Results of TSS analysis for UHG samples are included in Table 2, <br />Upper Hayden Gulch Surface Water Monitoring Site, TSS Results. <br />The pond invert elevation comparison results for ponds 001 and 002 indicate that runoff from the <br />reclaimed areas do not presently contribute significant suspended solids to either pond 001 or 002. <br />The lack of change in the invert elevations, implying no sediment accumulation, indicates that runoff <br />from the reclaimed azeas should not contribute suspended solids to runoff outside the permit area in <br />excess ofpre-mining levels. The TSS monitoring conducted by HGCC at UHG support the results <br />Fik <'1BTl~pAuQ~mnovel.dem 628/AS 3 <br />