Laserfiche WebLink
COLORADO DEPARTMENT OF HEALTH, Water Quality Contra! Division <br />Rationale -Page 16, Permit No. CO-0043648 <br />The mass balance equation u: <br />M3Q3 - M~Qt <br />Mz = <br />Qt <br />Where: <br />Qt = Upstream low flow (IE3 or 30E3J from section III.B.2 <br />QZ = Average daily a-Qluem flow (design capacity) <br />Q3 = Combined downstream flow (Qt + QtJ <br />Mt = Upstream background pollutam concentration from 1/LB.1 <br />M= = Unbtown; Maximum allowable ejJluent pollutant concentration calculatrd using mass <br />balance equation <br />M3 = Maxinutm downstream allowable pollutant concentration (stream standard) <br />Ordinarily, because of the mathematical relationship between flow, pollutant concentration and pollutam <br />mass, concentration limitations calculated using this method implicitly limit instream pollutant mass to a <br />maximum allowable Itvel. Therefore, under normal circumstances, only flow and concentration limitations <br />need to be specified in the permit and mass limitations are not required. <br />In this case, it will be necessary to monitor pollutant loadings in order fully characterize instream <br />pollutant conditions, examine long term trends in pollutant conditions, and assess the impact of pollutants <br />upon downstream segments. The information gathered will likely be used help determine whether or not <br />unauthorized discharges have occurred. In addition, instream concentrations will be monitorrd in order to <br />determine whether or not stream standards are being maintained. Therefore, while numeric limits will be <br />expressed only as pollutant concentrations, the permit will require that both concentrations and mass <br />loadings be reported. <br />3. Discussion of Effluent Limitations -Regulatory Basis <br />a. "No DischarPe" Limitation <br />The entire Cresson Mine Project has been designed with the intention ojavoiding any point source <br />discharge of pollutants. Correspondingly, the terms and conditions of this permit have been developed <br />in accordance with this basic premise. Monitoring conditions have been developed in order to detect <br />any discharge that migh[ occur, and e,Qluent limits have been developed in order to insure, at the very <br />least, that applicable stream standards wit! not be violated if anv discharge does occur. However, it <br />should be noted that the limits initially !(sled in the permit do not account for some additional <br />restrictions which antidegradation considerations would impose upon discharges. Therefore, should <br />any discharge be detected, the permit may be opened arui effluent limitations revised. <br />b. Regulations for ERTuent Limitations: The Regulations for EJJluent Limitations (/0. LOJ, apply to the <br />conventional pollutants - BOD3, TSS, pH, oil and grease, and total residual chlorine. For thic <br />facility, the only pollutants of concern are TSS and pH. For pH, water quality standard based limits <br />are more stringent than the effluent regulation limits. For TSS, federal effluent guidelines supersede <br />State e,Qiuent regulations. Therefore, for this facility, no limits are based upon the State effluent <br />regulations. <br />Applicable Federal ERluen[ Guidelines and Standards: The federal guidelines which apply to this type <br />of facilin~ are found under 40 CFR Part 440. Subnnrt J, titled Conner. Lend. Zinc. Gold, Silver and <br />Molvbdemmt Ores Subcateeorv. The linututions which apply are.• <br />