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PERMFILE55703
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PERMFILE55703
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Entry Properties
Last modified
8/24/2016 10:58:28 PM
Creation date
11/20/2007 4:42:44 PM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
C1982056A
IBM Index Class Name
Permit File
Doc Date
6/28/2006
Doc Name
pg 2.05-65 to 2.05-122.1
Section_Exhibit Name
2.05 Operation and Reclamation Plans Part 2
Media Type
D
Archive
Yes
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the dewatering wells immediately above the top of the coal seam in sealed mine workings in the Western Mining <br />District. Electricity will be supplied by the 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 boreholes will <br />occur on an alternating basis, with the potential of dischazging simultaneously. The chemistry of the mine <br />dischazge has changed so that the primary focus of treatment is for iron removal. hi order to accomplish this, the <br />pH of the mine dischazge must be raised to a range of 8.8 to 9.0. Sodium hydroxide is used by TCC to cause the <br />upward pH adjustment. TCC's experience shows that when the pH is in this range, that iron is dropped out at a rate <br />to meet the 0.5 mg/1 total recoverable iron limit in CDPDS permit number CO-0042161. <br />The as-built drawing for the system, based upon the survey data, is presented in Exhibit 8K. The storage capacity <br />of each cell was calculated. Pond 1 (west cell) has a capacity of 374,730 gallons, Pond 2 has a capacity of 348,530 <br />gallons, and Pond 3 (east cell) has a capacity of 277,000 gallons. The total capacity of al] three ponds is <br />approximately 1,000,260 gallons. The flow rate for varying detention time is as follows: <br />DETENTION TIME (hrs) <br />• <br />FLOW RATE <br />(gpm) POND 1 <br />(374,730 gallons) POND 2 <br />(348,530 gallons) POND 3 <br />(277,000 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 37.1 <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 16.6 <br />1250 5,2 4.8 3.8 13.8 <br />ACZ Laboratories, Inc. conducted a titration study on the mine discharge and showed that raising the pH to 9 would <br />result in an effluent concentration of 0.63 mg/1 of the total recoverable iron after 12 hours, and a concentration of <br />0.21 mg/1 at 24 hours. TCC has operated the system and has achieved compliance with its dischazge permit for <br />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 <br />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 <br />will precipitate at a faster rate. TCC used this information as a starting point and then fine-tuned it at the site. At <br />higher flows, TCC would be required to apply additional sodium hydroxide to achieve the same pH level. <br />The settling cells (impoundment) ware constructed prior to dischazge of underground mine water at the Fish Creek <br />Borehole Area. This installation consists of three adjacent cells, each measuring 123 feet by 37 feet, with a final <br />depth of eight feet. A 15-foot light-duty road runs around the entire structure and on the berms separating the cells. <br />The sodium hydroxide is presently housed in the Electrical Control Building along with the metering pumps used to <br />inject the sodium hydroxide into the mine dischazge. A third portable structure will be located adjacent to the <br />Electrical Control Building for more efficient storage and handling of the NaOH. A chemical feed-line extends <br />from the metering pumps in the Electrical Control Building to the east cell of the impoundment, neaz the outlet of <br />the borehole pump discharge line. An aerator has been placed downstream of the inlet into the pond so that the <br />sodium hydroxide is dispersed throughout the cell, promoting the precipitation of iron from the mine discharge <br />water. <br />TR06-52 2.05-77 05/16/06 <br />
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