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COLORADO DEPARTMENT OF PUBL/C HEALTH AND ENV/RONMENT, Water Quality Control Division <br />Amendment No. 4, Rationale -Page 3, Permit No. CO-0027154 <br />Total Dissolved Solids, mg/P Report Report Salinity Regulations <br />WET, Chronic Lethality N/A Statistical State Permit Regulations <br />Difference <br />2. Discussion of Effluent Limitations <br />Tile Division determined effluent limitations applicable to continuous mine water and similar discharges <br />during drafting of the rer:ewal permit. The detailed explanations can be found in [he renewal rationale dated <br />February 5, 1993. The permittee indicated in the amendment request that e~Zuent quality is expected !o be <br />si»rilar to that oJlhe existing outjalls at this facility. On this basis, the same limitations that apply to of/ter <br />ortfalls have been imposed. Since this discharge goes to the same receiving water, all water quality based <br />limitations are appropriate. The federal effluent guidelines for coal mining facilities, 40 CFR Parr 434, are <br />the basis for the TSS limitations. Additional speciftc rationales continue below. <br />a. Total Dissolved Solids: Existing outfalls have limitations jot conductivity. These [imitations were <br />determined tJtrough n correlation study perforated by the permittee. Since no such study has been <br />performed jot this new outfall, rite permittee will 6e required to perform TDS monitoring until such time as <br />they cart submit an acceptable correlation for conductivity for tltls orttjall. <br />b. Whole ERiuent Toxicity: As determined jot the other continuous discharges, chronic WET limitations and <br />testing apply to this new outfall. The rationale jot this determination can 6e found in the rationale jot <br />antendnrent no. 2 dated April 25, 1994. Because this is a new source, in conjormartce with Division <br />policy, it roust meet the WET limitation immediately. <br />c. Antidegradation: The Division performed an antidegrndation review and determined r/tat effluent <br />limitations must meet water quality standards. This is consistent with limitations for of/ter outfalls in this <br />permit. !, np // II <br />/00 i t ~ ~ Iv~fkr, - n,o rem iP....) J oh ~s FteT Oro 1T, e I SR <br />B. Monitoring .~ fo% ~okt" ~ no rEvfu>J ~[s <br />'~""7 <br />1. Effluent Monitoring: Effluent monitoring will be required as shown in Table V-2. These frequencies are <br />similar to existing mine water or similar discharges. Refer to the permit for the location of the monitoring <br />point. <br />Table V-2 -- Monitoring Requirements for Oulfall 020 <br />Parameter Monitoring Frequency Sample Type <br />Flow, MGD Weekly Instantaneous <br /> or Continuous <br />TSS, mg/P Three/Month Crab <br />TR /ton, mg/P Three/Mono: Grab <br />TR Manganese, mgP Three/Month Crab <br />PD Copper, ntg/P Three/Mono: Grab <br />PD Silver, mg/P Three/Month Grab <br />Oil and Crease, mg/P Weekly Visual <br />pH, s. u. (Minimum- Weekly Grab <br />Maxtmum) <br />Total Dissolved Solids, ntg/P Three/Month Grab <br />WET, Chronic Lethality Quarterly 3 Grabs/Test <br />