|
and concentrations of some pazameters was noted on June 26, 1995. Mine water elevation
<br />measurements indicated that the No. 3 Mine had flooded to the portal elevation. The
<br />dischazge (combined spring and mine overflow) jumped to 67.5 gallons per minute. Iron
<br />concentrations rose significantly from 0.055 mg/1 on May 16, 1995 to 6.21 mg/1 on Jun
<br />26, 1995. TSS rose from <IO to 55 mgfl, and TDS from 845 to 1150 mgll. By July 25,
<br />1995, flow had dropped to 34.7 gallons per minute, TSS fell to 35 mg/1, but TDS rose to
<br />1235 mgJl and total iron to 6.82. These values exceeded CDPS standazds established for
<br />Mine No. 1 dischazge. Outfa11007 dischazge was conveyed to the water treatment systems
<br />established at Mine No. 1 for treatment effective August 11, 1995. Except for one known
<br />date (inspection of Apri126, 2001), there has been Mine No. 3 discharge reported in
<br />periodic inspections since the 1995 event. Dischazge from Mine No. 3 of October 12,
<br />2002, had a total iron concentration of 0.88 mg/1, which is below the current CDPS
<br />pemut maximum of 0.957 mg/1. However, the current CDPS permit now includes a
<br />maximum potentially dissolved iron parameter of 0.431 mg/1. Mine No. 3 dischazges of
<br />September 8, 2002 at a potentially dissolved iron concentration of 1.29 mg/1 and October
<br />12, 2002, at 0.78 mg/l, are above the maximum permitted. By dilution, combined
<br />untreated dischazges from Mine No. 3 and Mine No. 1 aze in compliance with the current
<br />CDPS permit parameter limits. However, the combined dischazges aze currently treated
<br />and discharged to North Thompson Creek at the permitted location of Outfa11001.
<br />Since August 11, 1995, Mine No. 1 and Mine No. 3 portal dischazges have been
<br />combined and treated. The dischazge (Outfa11001) to North Thompson Creek from the
<br />water treatment system is subject [Rule 4.05.1(4)(d)] to the CDPHE CDPS Pernut No.
<br />CO-0029599. There is no known incident where Outfal1001 dischazges failed to meet
<br />CDPS discharge requirements.
<br />Flow and whole effluent toxicity have CDPS reporting requirements, and in some cases
<br />these aze limitations.. Oil and grease, at 10 mgll, is a CDPS limit, but none have been
<br />detected (reported) in monitoring reports. Flow rates at Outfa11001 have, from 1996
<br />through 2002, ranged from 30 (winter of 1996) to 160 (May 1997) gallons per minute.
<br />Average flows have been, for 1996, 36.8; 1997, 52.0; 1998, 69.0; 1999, 42.1; 2000, 36.8;
<br />2001, 25.5; and 2002, 22.4. On May 20, 2003, the flow was 21.4 gallons per minute.
<br />(c) Flows From Other Sources
<br />There are a number of inflows, other than from the portals of Mine No. 1 and Mine No. 3,
<br />to North Thompson Creek between the upstream and downstream monitoring stations of
<br />the mining permit. These include dischazges from Mine No. 2, four known springs and
<br />seeps, runoff from reclaimed disturbed and undisturbed azeas of the contributing
<br />watershed, and, perhaps, chazge to surface flows from alluvial aquifers, including that
<br />section located at the foot of the mine waste refuse pile.
<br />The North Thompson Creek Mine No. 2 is abandoned and "pre-law". It was not,
<br />historically, a part of Permit C-1981-025, and it is not proposed to be reopened or
<br />permitted under this renewal action. A detention pond prior to discharge into North
<br />21
<br />
|