5 Colo. Code Regs. § 1002-72.4
Current through Register Vol. 47, No. 20, October 25, 2024
Section 5 CCR 1002-72.4 - POINT SOURCE EFFLUENT LIMITATIONS1. The Division shall not issue industrial process wastewater and wastewater facility discharge permits (pursuant to Regulation #61) or notices of authorizations for use of reclaimed water (pursuant to Regulation #84) to any point source discharges, including new point sources, that allow effluent limitations (permitted phosphorus concentration) exceeding 0.05 mg/l total phosphorus. The 0.05 mg/l total phosphorus limitation set forth in this section 72.4 shall not apply where discharges consist of construction dewatering, so long as no phosphorus or nitrogen is added to the groundwater being discharged. Monitoring of total phosphorus must be conducted monthly and in accordance with CDPS permitting practices, which could potentially require more frequent monitoring such as when necessary to ensure sufficient data which are representative of the monitored activity pursuant to Regulation #61.8(4)(d). Construction dewatering shall be subject to the following practice-based effluent limits, unless infeasible: (a) Route dewatering water through a sediment control (e.g., sediment trap or basin, pumped water filter bag) designed to prevent discharges with visual turbidity; (b) Use well-vegetated (e.g., grassy or wooded), upland areas of the site to infiltrate or evapotranspirate all or a portion of dewatering water; (c) Maintain pre-existing vegetation or equivalent control measures for areas within 50 horizontal feet of receiving waters; (d) To prevent dewatering-related erosion and related sediment discharges: use stable, erosion-resistant surfaces (e.g., lined or piped structures, well-vegetated grassy areas, clean filter stone, geotextile underlayment) to discharge from dewatering controls; do not place dewatering controls, such as pumped water filter bags, on steep slopes; and control discharges to minimize channel and streambank erosion and scour in the immediate vicinity of discharge points; and (e) If any of the practice-based effluent limits described in 72.4.1(a) through (d) are infeasible, the permittee shall document in a plan that is part of the records maintained for the discharge permit (e.g., Remediation Activities Management Plan or Discharge Log) why each practice-based effluent limit is infeasible and shall submit a report to the Division within 30 days of commencement of discharge documenting the same. 2. The Division shall not issue discharge permits (pursuant to Regulation #61) for discharges from drinking water treatment facilities that allow effluent limitations exceeding 0.20 mg/l total phosphorus concentration as a 30-day average except that, at the request of a permittee, the Division is authorized to allow up to a 90-day averaging period for this limit in the discharge permit. Nothing in this regulation should be construed to supersede the Colorado Primary Drinking Water Regulations.3. Nutrient monitoring for industrial process wastewater sources and wastewater facilities shall be in accordance with the requirements of subsection 72.8.1.4. Subject to section 72.4.1, no industrial process wastewater source or wastewater facility within the Cherry Creek watershed shall discharge an effluent with a total phosphorus concentration greater than 0.05 mg/l total phosphorus as a 30-day average except that, at the request of a permittee, the Division is authorized to allow up to a 90-day averaging period for this limit in the discharge permit or in the notice of authorization issued pursuant to Commission Regulation #84. No land application with a return flow factor established in accordance with section 72.4.5(a) or (b) shall discharge a 30-day flow-weighted average phosphorus concentration greater than 0.05 mg/l divided by the return flow factor except that, at the request of a permittee, the Division is authorized to allow up to a 90-day averaging period for this limit in the discharge permit or in the notice of authorization issued pursuant to Commission Regulation #84. Where land application is relying on lysimeters to determine the amount of water returned to ground water in accordance with section 72.4.5(c), the effluent concentration prior to being applied to the land shall not exceed 1.0 mg/l total phosphorus as a thirty-day flow weighted average except that, at the request of a permittee, the Division is authorized to allow up to a 90-day averaging period in the discharge permit or in the notice of authorization issued pursuant to Commission Regulation #84.5. For purposes of this regulation, return flow factors for land application sites shall be determined as follows: (a) For land application sites with decreed augmentation plans, the return flow factor shall be determined from the applicable augmentation plan.(b) For land application sites with available studies of return flow factors, but no approved augmentation plan, the return flow factor may be determined upon Division approval from the study results.(c) Where no approved augmentation plan or available study exists, or where the Division has not approved the use of an available study, lysimeters shall be installed in accordance with a plan approved by the Division and readings from such lysimeters will be used to determine the monthly volume discharged at each land application site.6. Whenever a discharger requests a compliance schedule in connection with a permit issuance or permit renewal, the discharger shall (on the same date) notify the Authority of that request, solicit Authority comments, and submit evidence of that notice to the Division. The Division shall not take final action on any compliance schedule until Authority comments are received or 45 days after the date that notice was provided to the Authority, whichever occurs first. This provision shall not apply in the case of minor modifications to permits as defined by Regulation #61, section 61.8(8)(e).7. For all land application sites, the phosphorus concentration shall be determined by: (a) Phosphorus concentrations for each direct discharge and land disposal site using a return flow factor will be calculated by the following formula: Applied Phosphorus Concentration (mg/l) = (Sum of the concentrations of all samples (mg/l as P) for the outfall or land application site for the month / the number of samples collected and analyzed for that month) / the return flow factor
(b) Phosphorus concentrations for each land treatment site using lysimeters will be calculated by the following formula: Applied Phosphorus Concentration (mg/l) = Sum of concentrations of all samples (mg/l as P) for each lysimeter in the land application site for the month / the number of lysimeters
45 CR 11, June 10, 2022, effective 6/30/202247 CR 06, March 25, 2024, effective 4/30/2024