Laserfiche WebLink
COLORADO DEPARTMEM OF PUBLIC HEALT~I AND ENVIRONMEl~l; Water Quality Control Division <br />Rationale -Page 10, Permit No. CO-000022I <br />The term MtQt represents the Tota(~aximum Daily Load (IMDL) of a pollutant that can be carried by the <br />receiving stream without violming t e stream standards. ;!he term MrQI represents the pollutant load that a[r~ <br />exists instream above the discharge ~oim in quesrion. The' difference between the two loads, which is MyQi - <br />represents the loading that can be a{located to the discharge. <br />It may be appropriate in certain si ions to perform a more detailed analysis that would identify, quantify and <br />develop control strategies for additi nal individual polnuam sources that might exist above and below the <br />permiaee's discharge points. !n thi case, it was determined that limitations for these two discharge points om be <br />calculated independently from any o her pol[utam source. However, the two outfalls are considered as one cc mbined <br />source for this purpose. <br />This rationale and accompanying pe 't serve as a Total /Maximum Daily Load (TiI~L) under Section 303(d) of the <br />Clean Water Act, and this TMDL wi l be submitted to the US EPA Region V//1 jar review and approval. For this <br />facility, rota! recoverable iron is the only parameter of cascern. Values for effluent Jlow are shown in Table 17-8 in <br />section V/.3.d)4) and low flows (30 3) are shown in Table !fI-2. In this case, becatete the upstream backgro.tnd <br />concentration is significantly grease than the stream stamiard, the result is a negative number. The default is the <br />stream standard, which becomes the effluent limitation. <br />Table VI-6 - Sununary of TMDL Based Mass Balance Calculations <br />Upstream WQ,S/TMDLBased• _ , <br />Ambient Mean-. Stream Swndmd, Efjluent,'CancentmtJon; <br />Period Coneentrakon- Chronic Chioriia " <br />(MI) (M3) ' (M2) <br />_Total Recoverable /ton, mR/P 6.77 L0 -1.72 <br />Because of the mathematical relario hip between flow, pollutant concentration and pollutant mars, concemra <br />limitations calculated using this met~od implicitly limit irutream polluuant mars to the maximum allowable lere~ <br />Also, only flow and concemration li nations need to be specified in the permit. Mass limitations are not required. <br />3. Discussion of Eflluem Limitations: She basis jar the effluent limitations jar TSS, pIi and oil & grease is uncl wnged <br />from the previous permit. Please se~ previous rationale fire the discussion. <br />a) R~ulations for Effluent Limitations: The Regulations for Effluent Limitations (10.1.0), apply to the conventional <br />pollutants. For this facility the ~imitarions for Oi! and Grease are based on this regulation. <br />bj Aoolicable Federal Effluent Guidelines and Standards: The federal guidelines which apply to this type of (aciliry <br />are found under 40 CFR 434, tit{ed Coal Mining Point Source EfRuent Guidelines. The limitations which apply <br />are: I <br />Table L'I-7 -Federal Standards (40 CFR 434) <br />Parameter Limitations <br />30 Day Avg Daily Maz. <br />pH, s. u. (minimum -maximum) ---6.0 - 9.0--- <br />Total Suspended Solids, mg/P* 35 70 <br />Totallron, mg/P* <br />BAT*• 3.3 7.0 <br />NSPS*** 3.0 6.0 <br />Settleable Solids, mf/P* N/A 0.5 <br />• !hest parameters subjro ro Burde of Proof Requirements, set nrb secrion <br />'• Besr Available Technology - appGe ra (hare ponds already tonslrurred <br />••• New Sourn Prrformancr Smndard - applies to those ponds taurruned afar 5/4/84 <br />