2004-02-27_REVISION - M1977424 - Laserfiche WebLink

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Logan Wash Mine TR No. 4 Pollution Discharge Elimination System (NPDES) permit (No. COG600452) with the Colorado Department of Public Health and Environment (CDPHE). OOSI has monitored flow from the Reseazch Mine since 1993. Discharge consisted of flows ranging from 1 to 3 gallons per minute (gpm) during the months of April through July. Annual volumes of flow range from zero to 288,500 ft3, for the period of record from 1993 through the 2003. The average volume of dischazge for this period is 73,740 ft3. The dischazge of 288,500 ft3 was in 1997, an abnormally wet year for western Colorado. The average flow from the portal during flow periods is 1.0 gpm (1993-2003 data). Discharge emanated from a 6-inch diameter meta] pipe that originates from inside the portal behind a small earth/bentonite dike constructed inside the main drift approximately 45 feet from the portal. The Research Mine workings consist of two subparallel drifts with various side drifts and rooms (see Attachment B). The two drifts have separate portals that daylight on the south-facing outcrop, separated by a distance of approximately 200 ft. The drifts are joined underground by a side drift approximately 80 feet inside the east portal. The west portal is approximately the same elevation as the east portal and was sealed with an earth plug during previous reclamation activities in the early 1990's. During construction of the adit plug, a small bentonite dike was placed in front of the underground face of the plug to limit potential water contact with the plug. The west drift inclines with an 11 % grade (as shown on mine maps) and therefore lies above the workings in the east drift. A summer inspection of the upper (west drift) workings showed the accumulation of water in some locations and the incline portion of the west drift was contributing a small amount (estimated to be less than 0.5 gpm) to the lower workings near the cross drift. On the basis of mine maps (Attachment B), the east or lower drift is 1,300 ft long and 10 ft wide. An underground inspection showed the drift to be 8 to 9 ft high. The east drift declines with distance. It is the east drift that floods dwing spring runoff and, in some cases, discharges water from the portal. The incised gulley located immediately the east of the east portal typically exhibits spring runoff, some of which emanates from strata bedding or other spring openings on the swface. It is likely that some of this swface water infiltrates the outcrop and contributes to flooding of the mine workings. Mine-Water Management The permanent management of mine water in the Research Mine is being investigated. Options to manage potential discharging mine water include 1) allow potential discharge to continue under and continue the sampling program required under the existing NPDES permit, 2) allow potential discharge to occur, but combine (reroute) the discharge with discharge from Outfall 001, now located in upper Dry Wash northwest of the main L-I Portal, and 3) plug the adit and prevent discharge from occurring. An additional option is to conduct a local water quality survey of springs in the area with the intention of comparing these data with mine water discharge quality. If the data are comparable, a defendable azgument would be proposed to allow discharge of the mine water without a NPDES permit. In the interest in reducing sampling and analytical costs associated with the NPDES permit, OOSI decided to investigate the option of confining the mine water in the mine. This Western Water 8. Land, Inc. 10