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COLORADO DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT, Water Quality Control Division
<br />Rationale, Page 8, COG - 0850000 Coal Mining General Permit
<br />Alternate Limitations For Acid Or Ferruginous Mine Drainage From Coal Refuse Piles And From Steep Slope Areas Or
<br />Mountaintop Removal Operations — Table III -5e contains limitations for any discharge or increase in the volume of a
<br />discharge caused by precipitation within any 24 hour period greater than the 1-year, 24- hourprecipitation event, but less
<br />than or equal to the 10-year, 24 -hour precipitation event (or snowmelt of equivalent volume) may may substitute the
<br />following limitations for these specific parameters only, subject to burden of proof requirements described in Part LB.4
<br />Table III -Se: AlternateEf uent Limitations and Monitorin_ Re ' uirements —Acid or Ferru inous Mine Draina_ e
<br />Total Suspended Solids, rng/1
<br />Total Manganese, nrg/l
<br />Total Iron, mg/l
<br />Existing Sources (before5 /4/84)
<br />New Sources (after 5/4/84)
<br />Settleable Solids, mill
<br />Federal Effluent Limitation Guidelines`-
<br />Report NA. Report Federal ELG
<br />Report NA Report Federal ELG
<br />Report
<br />Report
<br />Report
<br />NA
<br />NA
<br />NA
<br />Report Federal ELG
<br />Report
<br />0.5 Federal ELG
<br />Weekly Grab
<br />Weekly Grab
<br />Weekly Grab
<br />Weekly Grab
<br />IV. OTHER PERMIT CONDITIONS
<br />a. Regulations for Effluent Limitations (Regulation No. 62) — Section 62.4 of the regulations includes effluent limitations that apply
<br />to all discharges ofwastewater to State waters. These regulations are the basis for the oil and grease limitations in the tables
<br />above. Note that the limitations for TSS are not included in many cases due to the presence offederal ELGs.
<br />b. Technology -Based Limitations (Federal Effluent Limitation Guidelines) — Federal Effluent Limitation Guidelines (ELG's)
<br />guidelines have been peon ulgated for these facilities and must be applied to these discharges, unless a more stringent Water
<br />Quality Standard exists. The Water Quality Standards in many areas of the state are often more stringent than the federal
<br />ELGs, and therefore may be substituted in a certification.
<br />c. Water Quality Standard -based Limitations (Discharges to Surface Waters)- Water quality -based limits are imposed for pH.
<br />Water quality -based reporting may also be imposed for other pollutants of concern based on the discussion that follows.
<br />1. j — This parameter is limited by Water Quality Standards as the water quality standards of 6.5 -9.0 s.u. range are »tore
<br />stringent than those specified under Regulations for Effluent Limitations.
<br />2. Metals — The permit writer will review the application 'and determine if any metals parameters must be limited and/or
<br />monitored to protect the classified use assigned to the receiving water. If required, the permit writer will set these
<br />limitations equal to the appropriate water - quality standards. • As many Water quality standards for metals are listed as
<br />TVS, and based upon an'equation dependent on the hardness of the receiving stream, the permit writer Will obtain
<br />hardness data 16 the appropriate metals limitations where appropriate. If a water quality based limitation for
<br />metals is considered in the permit, the more stringent of the federal ELG and the water quality based limit will be
<br />applied.
<br />3. Organics - The permit Writer will review the application and determine if any organic parameters must be limited and /or
<br />monitored to protect the classified uses assigned to the receiving water. If required, the permit writer will set these
<br />limitations equal to theappropriate water - quality standards.
<br />- 4: Chemicals -:The addition of chemicals (including release agents) to discharge is not allowed unless expressly authorized
<br />by the Division. If a uthorized, all chemicals must be used and stored in aecordance with the manufacturers'
<br />recommendations and in accordance with any applicable state or federal regulation.
<br />d. Salinity Requireinents —All permit actions for discharges to surface waters in the Colorado River Basin must include salinity
<br />monitoring. Accordingly, the permit writer will perform an analysis, as set out in the paragraphs that follow, to determine
<br />which salinity requirements apply pursuant to the requirements of Section 61.8(2)(1) of the Colorado Discharge Permit System
<br />Regulations(Regulation No. 61). Multiple discharges covered from a single facility are subject to the limitation that would
<br />apply if there were a single discharge point.
<br />Based on the effluent data in the application from a new facility, the perznit writer will crake an assessment of the expected
<br />salinity load in the discharge from concurrent f ows at all outfalls) and if less than I ton/day or 366 tons /year, the calculation
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