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GENERAL44767
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Last modified
8/24/2016 8:13:28 PM
Creation date
11/23/2007 1:17:33 PM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
C1981025
IBM Index Class Name
General Documents
Doc Date
8/26/1988
Doc Name
Proposed Decision & Findings of Compliance for RN1
Permit Index Doc Type
FINDINGS
Media Type
D
Archive
No
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<br /> <br />VIII. Probable Hydrologic Consequences of Mining and Cumulative <br />Probable H drolo is Conse uences of North Thom son Creek Mine - <br />roun ater <br />The probable hydrologic consequences of mining at the North <br />Thompson Creek Mine Complex have changed very little since the <br />original Findings were written. However since reclamation of the <br />No. 1 Mine Portal area, seepage has occurred that is high in iron. <br />Also, more details have been supplied as to possible stream <br />depletion due to mine flooding. This issue needs to be addressed <br />in the probable hydrologic consequences (PHC) section of this <br />document. <br />During a site inspection on April 28, 1988 seeps were noted in the <br />vicinity of the No. 1 Mine Portal. The seeps were obviously high <br />in iron content and were surfacing along the riprap bank of North <br />Thompson Creek and running into the creek. Since that time, the <br />iron rich seeps have been collected in a French drain system and <br />culverted across the river into two new treatment ponds. In order <br />to assure that all the seepage was collected in the French drain <br />system, a bentonite field trench was constructed between the French <br />drain and the creek. <br />The seeps were emanating from portal seals of the No. 1 Mine which <br />had been constructed in the face up. Iron rich discharges have not <br />been noted to come from the developed A seam. However, the B Seam, <br />in which the old No. 2 Mine was developed, is acid and high in <br />iron. The high iron content water emanating from the No. 1 portal <br />seals is believed to came from returns developed in the B Seam for <br />the No. 1 Mine. Water emanating from this portal and the B Seam <br />area had previously been a problem at this discharge point for the <br />No. 1 Mine. The B Seam is noted to have a thick (up to 1 foot) <br />pyrite rich split in the middle of the coal seam. <br />The seepage water has a pH of 6.8 with total dissolved solids of <br />2,810 mg/1 and a recoverable iron of 121 mg/1. The flow at the <br />measured maximum was 40 gallons per minute. The company has <br />committed to perpetual treatment of this discharge. A tank <br />containing sodium hydroxide has been placed just upstream of the <br />first treatment pond. A drip system feeds a low amount of the <br />chemical to the mine water thereby elevating pH and allowing the <br />iron to drop out. Results of the analysis of the treated water <br />after a 24 hour settling period were a pH of 8.24, dissolved solids <br />2,715 mg/1, and recoverable iron of .63 mg/1. <br />-5- <br />
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