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Ken• Coal Co. Marc Mine -Permit C-80-006 Fetrruary 14, 2006 TR-22 - Pond F Permanent Pond Demonstration • Footprint is approximately 3 acres • Storage capacity of 4.8 acre-feet (af, active) and 1.8 of (dead) • Crest Elevation 8156.0 feet • Primary outlet -Type 3 riser pipe designed for 10-year, 24hour flood - hole elevation 8149.3 feet • Emergency spillway designed for 25-year, 24hour flood • Spillway elevation is 8153.4 feet • Dam length 400 feet • Dam height 10.4 ft; OSM height 8.8 feet • 3H:1V slope down stream embankment and 2.5H:1V up stream embankment • Natural topography along the pond shores - i0°k to 14% slope Any discharge flows ultimately are tributary to Bush Draw (800 feet to the north}, which is tributary to the Canadian River (2 miles to the northeast), which is tributary to the North Platte River (16 miles to the northwest). This area is considered Segment 4 for the North Platte River Basin with wafer quality classthcations that inGude Aquatic Life Cold 1, Recreation 1a, Water Supply, and Agriculture. The unnamed drainage, as well as Bush Draw, has intermittent (tows typically associated with snow melt or large storm events. The following is the demonstration for beneficial use as required by the regulations for a permanent impoundment status for Pond F. The information is provided consistent with Rule 4.05.9 (13) of the Regulation. A. Quality of impounded water is suitable on a permanent basis for its intended use, water quality of the discharge meets state and federal water quality standards and the discharge is not degrading to the receiving stream. Pond F water quality is represented by discharge sample point no. 321 (CDPS No. DO6A. Monitoring has been conducted on a weekly basis during the spring months anticipating discharges due to snow melt and spring rains. Historically, Pond F has discharged for only 2 or 3 weeks and then usually dries up by mid-July, based on pre-2000 records. There has been no observed discharge in 2000, 2001, 2002, 2003 or 2004 indicative of the recent drought conditions in northwest Colorado. However, in 2005 there were discharges in April and June. There is no water quality data to compare with state or federal water quality standards. With the renewal of the CDPS Discharge Permit in Juiy 1997, discharge monitoring requirements wen: reduced to flow, pH and settleable solids. The water quality data for 1995 through 1999 was included on Table 1 in Exhibit 42B, Post-mining Drainage Permanent Impoundment Documentation. For 1996 and 1997, the maximum Total Suspended Solids (TSS) value for point no. 321 was 186 mglL, for Total Dissolved Solids (TDS) 410 mg/L and for total iron 4.55 mglL. These are the most recent measurements for these parameters. In all cases, discharge water quality was in compliance with the applicable effluent standards. In accordance with the discharge permit for the mine, field parameters inGuding temperature, conductivity and pH are currently measured for each discharge. Monitoring records for 1991, 1996 and 2005 were reviewed. The pH has ranged between 7.5 and 8.8 and conductivity has ranged from less than 100 to 300 umhoslcm. For the most recent discharges, in 2005 the measured settleable solids have 6371 TR-22 Pond F demo NWCC IIIC. Page 2