|
~OLORADO DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT, Water Qaaliry Contro(Division
<br />4ationa(e -Page 5, Permit No. CO-0038176
<br />For rainfall, to waive TSS and total iron [imitations, it is necessary to prove that discharge occurred within 48 hours after
<br />measurable precipitation fias stopped. In addition, to waive settleable solids limitations, it is necessary to prove that
<br />discharge occurred within 48 hours after precipitation greater than the 10 year, 24-hour event has stopped.
<br />For snowmelt, to waive TSS and total iron limitations, it is necessary to prove that discharge occurred within 48 hours
<br />after pond inflow has stopped In addition, to waive settleable solids limztations, it is necessary to prove that discharge
<br />occurred wit zn 48 hours after pond in, flow volume greater than the 10-year, 24-hour event has stopped.
<br />Documentation that the treatment facilities were properly operated and maintained prior to and durin the storm event
<br />must be submihed with any request for relief The Dtvtston shall determine the adequacy of proofg As part of thfs
<br />determination, the Division shall evaluate whether the perrnitiee could have controlled the discharge to such a manner that
<br />primary limitations could have been met, whether proper sediment storage levels were maintatned and the ponds had
<br />su~czent water and sediment capacity for the storm event plus other relevant factors. All manual pond dewatering must
<br />meet TSS and total iron limitations unless previous approval has been granted for ponds that have no other method of
<br />dewaiering.
<br />Post~-Minin~Ar~eas: In conformance with 40 CFR 434.50, commencing at the time acrive mining has ceased and all surface
<br />areas served by a sedimentation pond have been returned to the required contour and reveggetarion has commenced,
<br />applicable discharges may be eligtble for limitations other than those sped~z'ed in Pan LA.1. In most cases, these post-
<br />mtntng limitations shall remain in eryect until bond release. The permittee shall notififi,, the Division at the ap ropriate ttme
<br />so that consideration ofpermit modifications can be made. Prior to notification andsubsequent permit modification, active
<br />mining limitations will! apply regardless of actual mine status.
<br />e. Pollutants Limited b Water uality Standards: The water quality assessment in Appendix A contains the evaluation of
<br />po utants invite y water qua ity Stan ar The mass balance equation shown in Seaton IV ofAppendix A was used for
<br />pollutanu. to calculate the maximum allowable efluent concentration, Mz that could be discharged without cousin the
<br />water quality standard to 6e violated. A detat ed discussion of the calculations for the maxtmum allowable a uent
<br />pollutant concentrations for fecal coliform, total residual chlorine, ammonia and metals is provided in Section of the
<br />water gtialiry assessment contained in Appendix A. The maximum allowable a wentpo/lutant concentrations determined
<br />as part of these calculations represent the calculated a uenl limits that woul~be protective of water quality. These are
<br />also known as the water quality-based effluent limits (W~BELs).
<br />The Permits Unit evaluated the calculated WQBELs and has made a determination as to whether there is a reasonable
<br />potential for the facility discharge to cause or contribute to an exceedance of a stream standard. If there is a reasonable
<br />potential for the discharge to contribute to an exceedance, effluent limits are tncluded in the permit.
<br />i. Fecal colt orm total residual chlorine. and ammonia: For ecal coliform and total residual chlorine, the previously
<br />discus imits are more stringent t an ca ctt a7 led WQB Ls and therefore are applicable. Thus, a reasonable
<br />potential analysis was not performed and no further discussion of these pollutants is provtded.
<br />For ammonia, ancillary and/or additional treatment technologies are often employed to reduce the ammonia
<br />concentrations. A facility may currently discharge ammonia at [ow-level concentrations to meet e/~uenr limitations
<br />and therefore their ef}Iuent discharge shows no reasonableppotential to cause or contribute to ezceedances ofinstream
<br />standards. However, absent limitations, a facility may no ton er continue such pollutant reductions and therefore the
<br />discharge will have_reasonablepotential. For this reason, the Permits Unit performs a qualitative determination of
<br />ii.
<br />the pollutants of concern, the
<br />t to determine the pollutants
<br />POC's may be: •pollutants t
<br />ant monitonng; optional mos.
<br />'ants that are Imown to comm
<br />mt or at other son
<br />or other treatment
<br />in the effluent.
<br />ng, or orner monuor
<br />occur in similar efflu
<br />r collection systems;
<br />h, in the permit write
<br />~ermitiee, must use
<br />'ants that might be
<br />trough comp/iance
<br />years; pollutants
<br />that are present in
<br />are present in the
<br />~nalludgment, may
<br />The permittee provided upstream and downstream data from the West Elk Mine, which represents instream quality
<br />before and after the discharge(s). This data was compared with additional ambient data provtded in the water quality
<br />assessment (Appendu A, Table A-6), and compared with the W BELs to determine what the POC's were.
<br />Additionally, mth the development of ELGs for Ehe Western Alka~ine Coal Mining Subcategory, there was a
<br />consideration of what poterstia[ pollutants were pollutants of concern. Whereby, it was determined thae total iron was
<br />the only pollutant of concern.
<br />T7te limitations for total recoverable iron are lower than same a uent monitoring results summarized in Table V-3.
<br />For this reason, a compliance schedule is included in the permit ~ee Part LA.8.1 to give the permittee an opportunity
<br />to assess their treatment system's capability of meeting these limitations, and deszgn and construct additional treatment
<br />facilities, if they are deemed necessary. The permitiee will be required to submzt a Preliminary Report by December
<br />31 2004, detailing their pion for bringing the dzscharge into compliance with the final limitations that become
<br />ef~ective January 7, 2007. Because the previous permit had no limitations for these metals, none will be applied
<br />durinz the inserim period. The reallocated limitations will be used as the final limitation. This compliance schedule
<br />to
<br />Last Revised. 4/79/1004
<br />For total ammonia, the assimilative capacities shown in Appendix A are much greater than levels achieved by current
<br />treatment technology. Thus, total ammonia limitations are not imposed and no monitoring is required.
<br />
|