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COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division <br />Rationale - Page 3. Permit No. CO-0042161 <br />APPLICABLE RULES AND REGULATIONS: <br />A. Federal <br />At the federal level, New Source Performance Standards (NSPS) are <br />applicable to this facility. "These regulations are taken from the Coal <br />Mining Point Source Category, 40 CFR 434. The applicable sections within <br />this regulation are Part 434.45 for active mining areas, and Part 434.55 <br />for post-mining areas. Since this is a ^ew source and does not include <br />any discharge of surface runoff, the post-mining limits will be the same <br />as the active mining limits. <br />B. State <br />State Effluent Standards (SES) C10.1.0) apply to all discharges in the <br />state for parameters not superseded by Federal Effluent Guidelines or <br />Stream Standards. The SES apply to the more conventional pollutants. In <br />addition to these standards, the State also must apply the receiving <br />stream Water Quality Standards (WQS) which are appropriate for this <br />facility. An antidegradation review must also be performed for all new <br />facilities (see Discussion, paragraph G). <br />The WQS are applied based on a mass balance for each pollutant in • <br />question, to allow for the effect of any dilution provided by the <br />receiving waters. The variables used Sn the calculation are the allowable <br />in-stream level (WQS), the chronic stream low flow (30E3), the effluent <br />flow COeff), and the background concentration (Comb), as shown in <br />Appendix C. The mass balance equation is also shown in Appendix C. <br />LIMITATIONS AND RATIONALE: <br />Table 1 presents a comparison of appropriate limitations for active mining <br />(and post-mining). Table 2 shows limitations selected as being the most <br />stringent of those in Table 1, with the exception of Total Suspended Solids <br />(TSS). In the case of TSS, the federal limits are overriding. <br />Table 1 <br />Comparison of Regulations <br />Discharge point 001 <br /> Parameter SES WQS NSPS Antideg. <br />pH, s.u. 6.0 - 9.0 6.5 - 9 .0 6.0 - 9.0 NA <br />Oil and Grease, mg/1 10 NA NA NA <br />Total <br />Total Suspended Solids, <br />Iron, mg/1 mg/1 30/45 <br />NA NA <br />NA 35/70 <br />3.0/6.0 NA • <br />NA <br />Total Recoverable Iron, mg/1 NA 1.0 NA 0.066 <br />Total Dissolved Solids, mg/1 Monitor per Colo. Salinity Regulations <br />