2013-10-07_REVISION - C1981025 (8)

Home Browse Search

elevation. The discharge (combined spring and mine overflow) jumped to 67.5 gallons per minute. Iron concentrations rose significantly from 0.055 mg/1 on May 16, 1995 to 6.21 mg/1 on Jun 26, 1995. TSS rose from <10 to 55 mg/1, and TDS from 845 to 1150 mg/l. By July 25, 1995, flow had dropped to 34.7 gallons per minute, TSS fell to 35 mg/1, but TDS rose to 1235 mg/1 and total iron to 6.82. These values exceeded CDPS standards established for Mine No. 1 discharge. Outfall 007 discharge was conveyed to the water treatment systems established at Mine No. 1 for treatment effective August 11, 1995. Except for one known date (inspection of April26, 2001), there has been Mine No. 3 discharge reported in periodic inspections since the 1995 event. By dilution, combined untreated discharges from Mine No. 3 and Mine No. 1 were in compliance with the prior approved CDPS permit parameter limits (measuring 0.03ppm on December 5, 2005, the last sample taken prior to the termination of the CDPS Permit). On or around April 20, 2006, The CDPHE Water Quality Control Division (WQCD) terminated the Colorado Discharge Permit No. C0-0029599. WQCD subsequently wrote a letter to MINREC stating that the CDPS permit should not have been terminated and requested that MINREC submit an application for a new CDPS permit. The reason WQCD requested a new permit at the North Thompson Creek Mine is because of the passive water treatment system treating the No. 1 and No. 3 Mine Portal discharges. WQCD requires a discharge permit on all water treatment systems. The issue of concern is that the discharge from the No. 3 Mine Portal has an iron concentration that exceeds the receiving stream standard. However, after the No. 1 Mine and the No. 3 Mine discharges mix and flow through the passive treatment system, the majority of the iron is removed and the resulting discharge is in compliance with receiving stream standards. The new permit, CO-048233, was issued on February 1, 2010. After the passive treatment system, the water flows through the NPDES discharge point. This is the point where the water quality is measured. North Thompson- Four Mile Mineral and Land Corporation (NTFM) has been active in diverting the treated water from this point away from North Thompson Creek back on to their property into storage ponds for private use. (c) Flows From Other Sources There are a number of inflows, other than from the portals of Mine No. 1 and Mine No.3, to North Thompson Creek between the upstream and downstream monitoring stations of the mining permit. These include discharges from Mine No. 2, four known springs and seeps, runoff from reclaimed disturbed and undisturbed areas of the contributing watershed, and, perhaps, charge to surface flows from alluvial aquifers, including that section located at the foot of the mine waste refuse pile. The North Thompson Creek Mine No. 2 is abandoned and "pre-law". It was not, historically, a part of Permit C-1981-025, and it is not proposed to be reopened or permitted under this renewal action. A detention pond prior to discharge into North Thompson Creek treats the discharge from this mine. No record of 18