1987-12-01_PERMIT FILE - C1981017 (188)

Home Browse Search

COLORADO DEPARTMENT OF HEALTH Water Quality Control Division Rationale - Page 6 PERMIT NUMBER: CO-0000396 Table 5 below shows the effluent limitations for discharge points 002, 003, 004 and 005. These limitations are based on the most stringent numbers that are found in Table 3. For total iron , the state water quality standard is selected over the federal technology based limitations because the discharges are of a more continuous nature (mine dewatering) than 001 and 006 thru 018 (surface runoff) . Therefore, a greater range of stream flows will be encountered during discharge and the more stringent limitations will insure adequate protection of water quality. For TSS, technology based limitations are used instead of state effluent standards pursuant to 10. 1 . 3 (3) of the WQCC Regulations. TABLE 5 EFFLUENT LIMITATIONS FOR DISCHARGE POINTS 002,003, 7004 and 005 Parameter Limitation Rationale Flow N/A Monitoring Total Iron (mg/1 ) 1 .0/2.0 WQS Total Suspended Solids (mg/1 ) 35/70 BPT, 1/ Oil and grease (mg/1 ) <10.0 SES — pH (su) 6.5-9.0 WQS Salinity 2/ Monitoring Colorado River Salinty Regulations 1/ Federal Best Practicable Control Technology for Coal Mines. 2/ See the Discussion and Special Conditions Section of this summary for a discussion of salinity. DISCUSSION AND SPECIAL CONDITIONS: Monitoring frequencies for parameters in this permit are given below. Flow, pH and . oil and grease will be monitored on a weekly r basis for all discharge points 001 thru 018. Total Iron and Total Suspended Solids wit-) be monitored on a monthly basis for discharge points 001 thru 018. This monitoring frequency is an increase over the previous permit which was quarterly. A review of the previous monitoring reports (Table 2) shows that the effluent quality is relatively constant and well below the effluent limitations. Therefore, the monthly monitoring frequency is justified both for the semi continuous discharges 002 thru 005 (CONTINUED)