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PERMANENT IMPOUNDMENT DOCUMENTATION FOR POND F <br />In conjunction with Technical Revision TR-22, submitted February 14, 2006, the status of <br />Sedimentation Pond F was recommended for revision to permanent status. The revision <br />supports the postmining uses of rangeland and wildlife habitat Under applicable provisions of <br />Rule 4.05.9(13), permanent impoundments must meet the criteria described in items a). through <br />f), which are described below. <br />A. Quality of impounded water is suitable on a permanent basis for its intended use, water <br />quality at the discharge meets state and federal water quality standards and the discharge <br />is not degrading to the receiving stream. <br />Pond F water quality is represented by discharge sample point no. 321 (CDPHS no. OO6A). <br />Monitoring has been conducted on a weekly basis during the spring months anticipating <br />discharges due to snow melt and spring rains. Historically, Pond F has discharged for only 2 or <br />3 weeks and then usually dries up by mid-July. This is based on pre-2000 records. There has <br />been no observed discharge in 2000, 2001, 2002, 2003 or 2004 indicative of the recent drought <br />conditions in northwest Colorado. However, in 2005 there were discharges in April and June. <br />There is no water quality data to compare with state or federal water quality standards. With the <br />renewal of the GDPS Discharge Permit in July 1997, discharge monitoring requirements were <br />reduced to flow, pH and settleable solids, The water quality data for 1995 through 1999 was <br />included on Table 1 in Exhibit 42B, Post-mining Drainage Permanent Impoundment <br />Documentation. For 1996 and 1997, the maximum Total Suspended Solids (TSS) value for <br />point no. 321 was 186 mg/L, for Total Dissolved Solids (TDS) 410 mg/L and for total iron 4.55 <br />mg/L These are the most recent measurements for these parameters. In all cases, discharge <br />water quality was in compliance with the applicable effluent standards. In accordance with the <br />discharge permit for the mine, field parameters incuding temperature, conductivity and pH are <br />currently measured for each discharge. Monitoring records for 1991, 1996 and 2005 were <br />reviewed. The pH has ranged between 7.5 and 8.8 and conductivity has ranged from less than <br />100 to 300 umhos/cm. For the most recent discharges, in 2005 the measured settleable solids <br />have been 0.2 mL/L/h or Tess, pH has been 8.0 and electrical conductivity (measured in the <br />field) has been 200 umho/cm or less. <br />These data indicate the quality of the discharge water has been good historically with low solids <br />(settleable, suspended and dissolved). Typically water quality from runoff improves as <br />vegetation is reestablished as reported in the Hydrologic Reclamation Evaluation submitted in <br />Appendix E. This plays a minor role for this pond because only about one-half of the watershed <br />for Pond F is native and undisturbed assuming the ditch PD-3 is retained. Available water <br />quality data, including field and laboratory testing since 1995, in combination with a history of <br />use for livestock (without incident) suggest the water quality is typically adequate for the long <br />temt intended use, which is limited to livestock watering and for wildlife. Historically this pond <br />typically has very limited discharge (a few weeks a year). Therefore, it is unlikely that any <br />degradation will occur to the receiving stream, Bush Draw. In addition CDPS effluent limits are <br />based, in part, on receiving stream standards, degradation of the receiving waters is not likely to <br />occur in the future. <br />Permanent Pond FDocumentation -Exhibit 42C Page 2 <br />