1987-12-01_PERMIT FILE - C1981017 (187)

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COLORADO DEPARTMENT OF HEALTH Water Quality Control Division Rationale - Page 3 Permit No. CO-0000396 EFFLUENT LIMITATIONS, RATIONALE AND MONITORING FREQUENCIES: The limitations shown below were chosen for outfall 009. They represent the more stringent (with noted exceptions) of those in Table 1. Monitoring Parameter Limitation Rationale Frequency Flow, MGD N/A Monitoring Weekly pH, S.U. 6.5 - 9.0 WQS Weekly Oil and Grease, mg/l 10 SES Weekly BODS, mg/l 30/45/60 1/ SES Monthly TSS, mg/l 35/70 2/ BAT Monthly Total Iron, mg/l 3.5/7.0 2/ BAT Monthly Fecal Coliform, No/100ml 6,000/12,000 SES Monthly Settleable Solids, ml/l 0.5 3/ BAT Monthly Salinity N/A Salinity Standards Quarterly 1/ SES - 30/45 (30-day/7-day average). A daily maximum limitation of 60 is included to facilitate monitoring. 2/ These limitations do not apply to storm-related discharges (see permit). TSS limitations based on BAT were chosen over SES because 10.1.3(3), State Regulations for Effluent Limitations, states that where federal technology based guidelines exist they shall take precedence over SES. 3/ This limitation applies to discharges caused by precipitation less than the 10-year, 24-hour event. Influent Monitoring In order to assess the significance of the bath house flow, the permittee will be required to sample the flow prior to entering the pond. Required parameters and monitoring frequencies are shown on page 5 of the permit. This influent monitoring will be required for one year, beginning on the effective date of the amendment. At the end of all monitoring, the division will analyze the results. At that time the division may determine that limitations are necessary at the point where the flow enters the pond or that further monitoring is needed. It may be determined that no action is needed. Each facility is different and without a sufficient data base no course of action can be determined. The one-year monitoring program will provide this data base. It should be noted that if additional limitations or other permit changes become necessary, the permit modifications will be subject to public notice.