5 Colo. Code Regs. § 1002-62.5
Current through Register Vol. 47, No. 20, October 25, 2024
Section 5 CCR 1002-62.5 - SPECIFIC LIMITATIONS FOR THE DISCHARGE OF POLLUTANTSThe following numeric limits shall apply where the Water Quality Control Division ("Division") identifies the pollutant as one that may, without treatment, be present in the discharge at a level approaching the relevant limit. Except as required under federal law, where the Division determines that a numeric limit is infeasible, the Division shall require implementation of best management practices as a condition of the permit as necessary to control or abate the discharge of pollutants to state waters. In no case will a discharge be held to be in compliance with any of the limitations set forth below where the discharge is diluted with other waters, unless such compliance would exist without such dilution.
(1)Numeric LimitationsPARAMETER | PARAMETER LIMITATIONS | PARAMETER LIMITATIONS | PARAMETER LIMITATIONS |
7-Day Average 1 | 30-Day Average 2 | Instantaneous Maximum 3 |
(a) Biological Oxygen Demand (BOD5) | 45 mg/l | 30 mg/l | N/A |
(b) Total Suspended Solids (TSS) | 45 mg/l | 30 mg/l | N/A |
(c) Carbonaceous Biological Oxygen Demand (CBOD5) | 40 mg/l | 25 mg/l | N/A |
(d) Residual Chlorine | 0.5 mg/l 3, 5 |
(e) pH | 6.0 - 9.0 s.u. 3, 4 |
(f) Oil and Grease | 10 mg/l 3, 6 |
1 7-Day Average: The arithmetic mean of all samples taken in a 7-day period.2 30 Day-Average: The arithmetic mean of all samples taken in a 30-day period.3 As determined by the results of any single grab sample.4 The pH shall remain at or between these values.5 This limitation shall not apply to discharges to irrigation ditches or to ground water6 A numeric effluent limit will be assigned in permits for discharges to surface waters, however, monitoring for a "visual sheen" will generally be required. Where a visual sheen is detected, the discharger will be required to collect a grab sample and have it analyzed for oil and grease. Monitoring for oil and grease may be required where there is a reasonable potential that oil and grease will be present in the effluent at concentrations at or above 10 mg/l. These numeric limits and sampling requirements have been set with the inherent variability of the analytical procedures taken into consideration.
(2) In addition to the above effluent limitations, the arithmetic mean of the values for effluent samples for CBOD5, BOD5 and TSS collected in a period of 30 consecutive days shall not exceed 15 percent of the arithmetic mean of the values for influent samples collected at approximately the same time during the same period (85 percent removal). (a) For domestic sources, where the permittee has demonstrated that the treatment facility is unable to meet the 85 percent removal requirement for a parameter and the inability to meet the requirement is not caused by excessive infiltration, as defined in 40-CFR 35.2005(b)(16), a lower percent removal requirement or a mass loading limit may be substituted provided that the permittee can demonstrate that the provisions of 40 CFR 133.103(d) can be met.(b) For industrial sources, the Division may, as it finds appropriate on a case by case basis, substitute a lower percentage removal requirement or a mass loading limit for the 85 percent removal requirements of this subsection (2). The Division may also determine, on a case by case basis, that the numeric limitations for CBOD5, BOD5, and TSS as listed in subsection (1), are sufficiently protective of the applicable designated uses, and in such case, the Division may exempt such industrial source(s) from the percentage removal requirements of this subsection (2).(3) The numeric limitations for TSS in section 62.5 , above, may be adjusted for waste stabilization ponds which treat domestic waste provided that (1) the waste stabilization ponds are the principal process used for secondary treatment; and (2) the facility is designed to achieve the solids removal possible with best waste stabilization pond technology. Best waste stabilization pond technology is defined as that design criteria for ponds currently in effect as adopted by the Commission or the Division. Since these criteria will be upgraded periodically, any permittee not in conformance with the approved design criteria will be given an opportunity to establish a reasonable implementation schedule given due consideration to design, construction, and financial capability of the permittee. The adjusted limitations shall be as described below: Treatment Type | 7-Day Average 1 | 30-Day Average 2 |
Non-aerated Waste Stabilization Ponds | 160 mg/l | 105 mg/l |
Aerated Waste Stabilization Ponds | 110 mg/l | 75 mg/l |
1 7-Day Average: The arithmetic mean of all samples taken in a 7-day period.2 30-Day Average: The arithmetic mean of all samples taken in a 30-day period. In addition, where adjusted TSS limitations are given, the 85 percent removal requirement for TSS shall be waived.
(4) The numeric limits for pH for domestic wastewater treatment facilities may be adjusted to values outside of the limits in section 62.5 , above, subject to limitations necessary to protect applicable water quality standards, where inorganic chemicals are not added to the waste stream as part of the treatment process and where industrial contributions do not cause the pH to be less than 6.0 s.u. or greater than 9.0 s.u.(5) Sampling of discharges, for the purpose of the effluent limitations for pollutants set forth in section 62.4 above, shall be made prior to any admixture of the discharge with state waters. All new discharges, except for on-site wastewater treatment systems with Division approval, shall be constructed so that a sample of the effluent can be obtained at a point after the final treatment process and before discharge to state waters. If samples for BOD5, CBOD5 or TSS are taken at the outfall of a final quiescent pond, with a detention time of at least 48 hours, the sample may be a grab sample. In all other plants which cannot meet this requirement, effluent samples shall be a composite sample, comprised of a minimum of four grab samples taken approximately two hours apart.
(6) Normally the numeric limits for BOD5 will be applied, however, they may be replaced with the numeric limits for CBOD5 in section 62.5 at the request of the permittee.(7) The permittee must be able to show proof at the request of the Division of the accuracy of any flow-measuring device used in obtaining data submitted in the discharge monitoring report. The flow-measuring device must indicate values within ten percent of the actual flow being measured.(8) If wastewater is returned to the source from which it was obtained, the numeric limitations specified in section 62.5 above, may be in addition to the measured values of the same parameter(s) in the incoming water except where an exceedance of a water quality standard would take place.(9) Any person subject to the numeric limits for BOD5 , or CBOD5 shall have the option of establishing, to the continuing satisfaction of the Division, a relationship between BOD5 or CBOD5 and COD (chemical oxygen demand), TOC (total organic carbon), or TOD (total oxygen demand) with respect to such effluent, and the COD, TOC, or TOD values so established shall be substituted for the BOD5 , or CBOD5 , values required under section 62.5(1), above.43 CR 10, May 25, 2020, effective 6/14/2020