Laserfiche WebLink
powerlines shown on map 39, Powerline Location. <br />Each borehole is capable of discharging up to 500 or 600 gpm of mine water. Discharge through the <br />boreholes will occur on an alternating basis, with the potential of discharging simultaneously. The chemistry <br />of [he mine discharge has changed so [hat the primary focus of [he treatment is for iron removal. In order [o <br />accomplish this, the pH of the mine discharge must be raised to a range of 8.8 to 9.0. Sodium hydroxide is <br />used by TCC to cause the upward pH adjustment. TCC's experience shows that when the pH is in this range <br />that iron is dropped out at a rate to meet the 0.5 mg/I total recoverable iron limit in CDPDS permit number <br />CO-0042]61. <br />The as-built drawing for the system is presented itt Exhibit 8K and based upon the survey data. The storage <br />capaciq~ of each cell was calculated. Pond 1 (west cell) has a capacity of 374,728 gallons, Pond 2 has a <br />capacity of 348,533 gallons and Pond 3 (east cell) has a capacity of 277,008 gallons. The total capacity of all <br />three ponds is 1,000,269 gallons. The flow rate for varying detention time is as follows: <br />DETENTION TIME (hrs) <br />C~ <br />FLOW RATE <br />(gpm) POND I <br />(374,728 gallons) POND 2 <br />(348,533 gallons) POND 3 <br />(277,008 gallons) TOTAL <br />DETENTION <br />300 20.8 19.4 15.4 55.6 <br />350 17.8 16.6 13.2 47.6 <br />400 15.6 14.5 11.5 41.6 <br />450 13.9 12.9 10.3 37.] <br />500 12.5 11.6 7.2 31.3 <br />750 8.3 7.7 6.2 22.2 <br />1000 6.2 5.8 4.6 ] 6.6 <br />1250 5.2 4.8 3.8 13.8 <br />ACZ Laboratories, lnc. conducted a titration study ott [he mine discharge and showed that raising the pH to 9 <br />would provide an effluent concentration of 0.63 mg/I of the total recoverable iron after 12 hours and a <br />concentration of 0.21 ntg/I at 24 hours. TCC has operated the system and has achieved compliance with its <br />discharge permit for total recoverable iron by maintaining the pH at 8.8 to 9.0 in the discharge. At a pH of <br />10, the total recoverable iron was reported at 0.01 mg/I after 12 hours and al 0.01 mg/1 at 24 hours. This <br />shows that by elevating the pH, the iron will precipitate at a faster rate. TCC used [his information as a <br />starting point and then fine-tuned it at the site. At higher flows, TCC would be required to apply additional <br />sodium hydroxide [o achieve the same pH level. <br />The settling cells (impoundment) were constructed prior to discharge of underground mine water at the Fish <br />Creek Borehole Area. It consists of three adjacent cells, each measuring 123 feet by 37 feet, with a final <br />depth of eight (8) feet. Typically, a 15 foot light duty road courses around the entire structure and on the <br />berms separating the cells. <br />• The sodium hydroxide is presently housed in the Electrical Control Building along with the metering pumps <br />used to inject the sodium hydroxide into the mine discharge. A third portable structure will be located <br />adjacent to the Electrical Control Building for more efficient storage and handling of the NaOH a chemical <br />APPROVED APR 1 ~ 2000 <br />TR 00-35 2.05-77 03/28/00 <br />