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COLORADO DEPARTMENT OF PUBLC HTALTli AND ENVIRONMENT, Water Quality Control Division
<br />Ratiomle -,Page 7, Permit No. CO-0045161
<br />reasonable potential depending on the amount of available data.
<br />The /t'rst step, determining thepollutants ofconcern, thepermit writer, with the cooperation ofthe permittee, must
<br />use best professional ~udgmenttodeterminethepollutantsofconcern("POC's ). POC'sarepollutantsthatmight
<br />be expected to the eff~uen[. POC"s may be: pollutants that have been detected in [he effluent (through comp Hance
<br />monitoring, priority pollutant monitoring, optional monitoring, or other monitoring) in the last 5 years; pollutants
<br />with known sources; pollutants Chat are known to commonly occur in similar effluents; pollutants that are present in
<br />the influent or at other sampling points in the treatment ar collection systems; pollutants that are present in the
<br />bioso ids or other treatment rest uals; other pollutants which, in the permit writer's best professional judgment,
<br />may be found in the effluent.
<br />The permitteepravided upstream and downstream data from their facility, which represents instream quality before
<br />and after the discharge s). This data was compared wish additional ambient data provided in the water quality
<br />assessment (Appendix A, Table A-5 ,and com aged with the WQBELs to determine the POC's. Additionally, with
<br />the development ajELGs for the Western Arline Coal Mining Subcategory, there was a consideration of what
<br />potential pollutants were pollutants of concern. It was determined that total iron was the onlypollutantofconcern.
<br />The limitations (or total recoverable iron are lower than some effluent monitoring results summarized in Table VI-1
<br />for total iron. For this reason, a compliance schedule is included in thepermit (see Part LA.B.) to give thepermittee
<br />an opportunity to assess their treatment system's capability ofineeting these limitations, and design and construct
<br />addrtionaltreatmentfacilities,iftheyaredeemednecessary. ThepermitteewillberequiredtosubmitaPreliminary
<br />Report by June 30, 2005, detailing their plan for bringing the discharge into compHancewith the final limitations
<br />that become efff(ective January 1, 2008. !n the interim, the ELGJor total iron will be applied. The WQBEL-based
<br />limitation wilfbe used as the final limitation. This compliance schedule applies to all outfalls.
<br />ii. Benzene Ethvlbenzene Toluene and Xvlene ("BETX")- Because of the nature o vehicle washwater containing
<br />rest ues ofgaso ine, the permittee wit monitor and meet the limitationjor BT at outfa11002A.
<br />iii. Water Su 1 ; Colowyo discharges to Segment 3e ofthe Lower Colorado River Basin, Yampa Sub-basin, which is
<br />casstte orwatersupply. Thereasonforthisclassi~tcationistha[Colowyowithdrawssurfacewaterfordomesdc
<br />use tom Goodsprings Creek, MiJI Creek, and Taylor Creek. These water intake structures are upgradient of
<br />Colowyo's process water outfalls, where they will not be influenced by these downgradient discharges.
<br />d) Antide radation: Since the receiving waters are desi Hated as UseProtectetl, an antidegradakon review is not required
<br />for the~rges pursuant to section 31.8(1)(6) ogfThe Basic Standards and Methodologies for Surface Water.
<br />e) Colorado Mixin Zone Re lotions: Pursuant to section 31.10 ofThe Basic Standards and Methodolo ies for Surface
<br />ater a mixing zone etermination is required for this permitting action. The Co ora o Mtzin one m ementation
<br />G~nce dated Apri12002, identifres the process jot determining the limit on the area impacted y a ischarge to
<br />sur ace water where standards maybe exceeded (i. e., regulatory miring zone). This guidance document provides for
<br />certain exclusions from further analysis under the regulation, based on site-spec fc conditions.
<br />The guidance document provides a mandatory, stepwise decision-makingprocessfor determining ifthe permis limits will
<br />not be affected by Yhis re lotion. Exclusion, based on Extreme Mixin Ratios, maybe ranted ifthe ratio of the design
<br />flow to the chronic low f~w (30E3) is greater than 2.1 or if the ratio of the chronic low flow to the design flow rs eater
<br />than 20: I. Since the ratio of{the design flow to the chronic low flow is greater than 2: I or discharges to Goodpring
<br />Creek, Wilson Creek, and their tributaries, the permittee is eligible for an exclusionJf m further analysis under the
<br />regulation.
<br />fl Salinity Re lotions: An evaluation of the discharge of total dissolved solids indicates that the Colowyo's facility
<br />excee the thresho d o 1 ton/d or 365 tons/year o(sahmryry as set orth in the Colorado River Salinity Standards. n
<br />conformance with section 61.8(~(1)(i)(A) of the Colorado Dischar e Permit S stem Re~ations~te permittee must
<br />submit a repport that documents whethher it is feast !e to treat to these evels. T e alinity egulations allow for the
<br />waiver ofTDS limitations upon submittal of a report that demonstrates that achievement ofzero salt loading or, in the
<br />event that is not achievable, discharge ofless than one ton per day, is not economicallyfeasible. There is no record that
<br />Salinity requirements are included in Parts LA. S., /.B.2. and LD.3. of the permit. As part of these requirements, the
<br />facility must submit a Salinity Study campn'sed ofthe following information:
<br />• Exisrin annual tonnage ofsalt discharged and seasonal effluent dischar e flowrares.
<br />• Cost of modifying an industrial water treatment plant, if any, to provider no salt discharge.
<br />• Cost ofsalt minimization.
<br />• Description ofthe quantity and salinity of the water supply.
<br />• Descnptionofwaterrights,tncludingdiversionandconsumptiveusequantitiesandthecompatibilityofColorado
<br />water laws with either the complete elimination of a salt discharge or any plan for minimizingg a salt discharge.
<br />• Alternative plans that could reduce or eliminate salt discharge. Alternative plans shall include.•
<br />• Description of alternative water supplies, including provisions far water reuse, ifany.
<br />• Description of the quantity and the quality of the proposed dischar,ge.
<br />. Description ofhow salts removed from discharges shall be disposed of to prevent such salts from entering surface
<br />waters or ground water aquifers.
<br />Costs of alternative plans in dollars per ton ofsalt removed.
<br />• Ofthe alternatives, astatemenf as to the one plan for reduction ofsalt discharge that the applicant recommends be
<br />adopted.
<br />• Such other information pertinent to demonstration of nonpracticability as the Division may deem necessary.
<br />Revised 1/24/1005
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