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Each borehole is capable of discharging up to 500 or 600 gpm of mine water. Dischazge through the boreholes will occur on an alternating basis, with the potential of discharging simultaneously. The chemistry of the mine discharge has changed so that the primary focus of the treatment is for iron removal. In order to accomplish this, . the pH of the mine discharge must be raised to a range of 8.8 to 9.0. Sodium hydroxide was used for several years to raise the pH and drop-out the iron in settling ponds, in order to meet the 0.5 mg/1 total recoverable iron limit in CDPS Permit No. CO-0042161. The as-built drawing for the system is presented in Exhibit 8K and based upon the survey data. The storage capacity of each cell was calculated. Pond 1 (west cell) has a capacity of 374,728 gallons, Pond 2 has a capacity of 348,533 gallons and Pond 3 (east cell) has a capacity of 277,008 gallons. The total capacity of all three ponds is 1,000,269 gallons. The flow rate for varying detention time is as follows: TIME (hrs) • FLOW RATE (gpm) POND 1 (374,728 gallons) POND 2 (348,533 gallons) POND 3 (277,008 gallons) TOTAL DETENTION 300 20.8 19.4 15.4 55.6 350 17.8 16.6 13.2 47.6 400 15.6 14.5 11.5 41.6 450 13.9 12.9 10.3 37.1 500 12.5 11.6 7.2 31.3 750 8.3 7.7 6.2 22,2 1000 6.2 5.8 4.6 16,6 1250 5.2 4.8 3.8 13.8 ACZ Laboratories, Inc. conducted a titration study on the mine discharge and showed that raising the pH to 9 would provide an effluent concentration of 0.63 mg/1 of the total recoverable iron after 12 hours and a concentration of 0.21 mg/1 at 24 hours. TCC has operated the system and has achieved compliance with its discharge permit for total recoverable iron by maintaining the pH at 8.8 to 9.0 in the discharge. At a pH of 10, the total recoverable iron was reported at 0.01 mg/1 after 12 hours and at 0.01 mg/1 at 24 hours. This shows that by elevating the pH, the iron will precipitate at a faster rate. TCC used this information as a starting point and then fine-tuned it at the site. At higher flows, TCC would be required to apply additional sodium hydroxide to achieve the same pH level. The settling cells (impoundment) were constructed prior to discharge of underground mine water at the Fish Creek Borehole Area. It consists of three adjacent cells, each measuring 123 feet by 37 feet, with a final depth of eight (8) feet. Typically, a I S foot light duty road courses around the entire structure and on the berms separating the cells. The sodium hydroxide is presently housed in the Electrical Control Building along with the metering pumps used to inject the sodium hydroxide into the mine discharge. A third portable structure will be located adjacent to the Electrical Control Building for more efficient storage and handling of the NaOH a chemical feed line extends from the metering pumps in the Electrical Control Building to the east cell of the impoundment, near the outlet of the borehole pump discharge line. An aerator has been placed downstream of the inlet into the pond so that the sodium hydroxide is dispersed throughout the cell, promoting the precipitation of~ron from the mine dischazge water. The water flow through the cells was modified to take advantage of additional retention time in the system. The original flow path focused on using two of the three cells at any one time. Presently, all three cells are used and this required installation of a new inter-pond line between the center and western cell. The baffles in the cells reduce • the potential for short-circuiting, increasing the efficiency of the ponds. The final component added to the system MR06-207 2.05-77 04/25/06