Laserfiche WebLink
0.1~JO/99 FRI 15:40 FAS JOJ 7820J90 CDPHE/WgCD fth005 <br />COLORADO DEPARTMENT OF PUBU[ HEALTH AND ENV/RONMENT, Water Quality Control Division <br />Amendmnu No. 3-Rationale. Page 4, Permit No. CO-0000132 <br />Where: <br />Q, = Upstream low flow (41 cfs) <br />Qt =Maximum discharge flow (0.45 cfs or 0.288 MGD) <br />Q, = Cotnbrned downsfream flow (Q, + Q,) <br />M1 = Upsfream background pollutant concentration -represents the mean of qursrterfy samples collected in 1998 <br />by t/u permittee as required by the Colorado Division of Minerals and Geology <br />Mt = Utilaawn; Maximum allowable effluent pollutant concentration calculated using mass balance equation <br />M, =Maximum downstream allowable pollutant concentration (WQS for segment 3) <br />The teen M,Qt, represents the mass of a polltuant that tan be carried by the receiving stream without violaring stream <br />,standards. The terns M,Q, represents the pollurani load that already exists incneam above the discharge paint in <br />question. The difference benveen the two Inads, which it ibfiQJ - M1Qt, represenus the loading rlwt can be allocated to <br />the discharge. <br />The Division will authorize this durharge. AU terms and conditions, including ef)`luent limitations and monitoring <br />requirements, that currently apply to outfaU 011 will apply to this temporary disehasge point. Additionally, ro verify <br />that the discharge metals conrnurations are insigniflrnnt, the Division will require, by separate letter, a second metals <br />analysis using the lowest method detection level. These results will be reviewed. If there is reason for concern that <br />the discharge may exceed potential limitations, the Division will work with the perndttee ro assure that adequate <br />treatment rs occurring, and may reopen the permit to rake appropriate action. <br />Additionally, since whole e,(jluent toxicity (DVE17 testing is required for ourfall 011 an a quarterly basis and no <br />discharge has occurred from the permanent discharge location during the second ralendar quarter of 1999, the <br />Division requests that the permittee tolled a sample for this purpose from this temporary outfall during the first week <br />of discharge. This will provide an additional measure of the quality of this discharge. This sample will count as the <br />routine sample for the second quarter that is required under Parr I. B.I. (b) of the permit. <br />This authorization is for aone-time short-term activity only. The permittee prajeds that when the mine reopens. <br />pumping will resume and discharge will ocder at the authorized mine water discharge point, outfall 011. Ij the <br />permittee determines char this inflow ro the mine will be chronic and this water will need ro be discharged on a long- <br />term basis, they will need to submit a request for a permanent amendment to authorize it. <br />Figure 4 is being added to the permit to show the location of ttmpomry outfaU 011. T7us figure is added as page 21a <br />of the permit. <br />Because this action doer nor change any permit conditions, it is nor subject ro public notice provisions. <br />Jon C. Kubic <br />April 30. 1999 <br />