5 Colo. Code Regs. § 1002-85.5

Current through Register Vol. 47, No. 11, June 10, 2024

Section 5 CCR 1002-85.5 - SPECIFIC LIMITATIONS FOR DISCHARGERS OF NUTRIENTS

The effluent limitations and stormwater management practices in this section shall be implemented in the Colorado Discharge Permit System (CDPS) and National Pollutant Discharge Elimination System (NPDES) permits authorizing the discharge to surface water beginning no sooner than July 1, 2013. Monitoring requirements are included in Section 85.6 . All facilities should refer to section 85.6 regardless of the determination of applicable permit limits.

(1) Numeric Limitations for Domestic Wastewater Treatment Works (DWWTW)

(a) Existing Treatment Facilities:

(i) Exclusions

The numeric limits in subsections (iii)(a) and (b) below will not be included in CDPS and NPDES permits and will only be included in preliminary effluent limitations for Site Location and Design Approvals upon request and with a delayed effective date for the following categories of dischargers:

(A) Any DWWTW with a design capacity of less than or equal to 1.0 million gallons per day.

(B) Any DWWTW owned by a disadvantaged community.

(ii) Delayed Implementation of Effluent Limits

The numeric limits in subsections (iii)(a) and (b) below or division approved alternative or modified effluent limits consistent with 85.5(3)(b)(iv) or 85.5(3)(d) will be included in preliminary effluent limitations with a delayed effective date for Site Location and Design Approvals and will not be included in effluent limitations in CDPS permits prior to December 31, 2027 for the following categories of dischargers:

(A) Any currently permitted DWWTW subject to Watershed Protection Control Regulations 71-74 (5 CCR 1002-71, 5 CCR 1002-72, 5 CCR 1002-73, and 5 CCR 1002-74).

(B) Any existing permitted DWWTW with a design capacity of less than or equal to 2.0 million gallons per day.

(C) Any existing permitted facility discharging into low priority 8-digit hydrologic units code watersheds [Purgatoire - 11020010, Upper Arkansas-John Martin Reservoir - 11020009, Upper San Juan -14080101, Upper Arkansas-Lake Meredith - 11020005, Upper White -14050005, San Luis - 13010003, Chico - 11020004, Kiowa - 10190010, Middle South Platte-Sterling - 10190012, San Miguel - 14030003, Alamosa-Trinchera -13010002, McElmo - 14080202, Lower Gunnison -14020005, Arkansas Headwaters - 11020001, Upper Yampa -14050001, Upper Gunnison - 14020002, and Uncompahgre - 14020006].

(iii) All Others

For all Domestic Wastewater Treatment Works not identified in subsections (a)(i) or (ii) above and discharging prior to May 31, 2012 or for which a complete request for preliminary effluent limits has been submitted to the division prior to May 31, 2012, the following numeric limits shall apply:

PARAMETER	PARAMETER LIMITATIONS	PARAMETER LIMITATIONS
.	Annual Median ¹	95th Percentile ²
(a) Total Phosphorus	1.0 mg/L	2.5 mg/L
(b) Total Inorganic Nitrogen as N ³	15 mg/L	20 mg/L

1 Rolling Annual Median: The median of all samples taken in the most recent 12 calendar months.

2 The 95th percentile of all samples taken in the most recent 12 calendar months.

3 Determined as the sum of nitrate as N, nitrite as N, and ammonia as N.

(b) New Treatment Facility:

PARAMETER	PARAMETER LIMITATIONS	PARAMETER LIMITATIONS
.	Annual Median ¹	95th Percentile ²
(a) Total Phosphorus	0.7 mg/L	1.75 mg/L
(b) Total Inorganic Nitrogen as N ³	7 mg/L	14 mg/L

1 Rolling Annual Median: The median of all samples taken in the most recent 12 calendar months.

2 The 95th percentile of all samples taken in the most recent 12 calendar months.

3 Determined as the sum of nitrate as N, nitrite as N, and ammonia as N.

(1.5) Voluntary Incentive Program for Early Nutrient Reduction for Domestic and Non-Domestic Wastewater Treatment Works

(a) The commission has created a voluntary incentive program for facilities that voluntarily reduce phosphorus and/or nitrogen nutrient concentrations below concentrations allowed by Regulation #85 effluent limits.

(b) To participate in the voluntary incentive program, a permittee is required to submit a nutrient reduction plan and annual nutrient monitoring reports to the division.

(c) The voluntary incentive program is a performance based program. The program provides incentives for early reductions in nutrient concentrations below the concentrations allowed by the Regulation 85 effluent limits. The incentive that a permittee receives after 2027 is a discharge permit compliance schedule to provide additional time to meet nitrogen and/or phosphorus water quality-based effluent limits, limits derived from waste load allocations, or alternative effluent limits pursuant to Section 31.7 . The additional time provided under the compliance schedule would be beyond that which would be otherwise be granted to a permittee not participating in the incentive program and would be based on additional effort made by the participating permittee to achieve early reduction of nutrients concentrations. The duration of the additional time in the discharge permit compliance schedule will be based on voluntary nutrient concentration reductions, as recorded in annual nutrient monitoring reports and submitted to the division. Participating facilities will begin accruing additional time for their discharge permit compliance schedules beginning on January 1, 2018 and ending on December 31, 2027

(d) The division will include an extended permit compliance schedule in the first renewal permit after the commission adopts numeric nutrient values in Regulation #31 and Regulations #32 through #38 to any permittee who, through participation in the voluntary incentive program, demonstrates success in reducing phosphorus and/or nitrogen nutrient concentrations below the concentrations allowed by Regulation #85.

(e)Nothing in this subsection (1.5) precludes the division from exercising its authority under section 25-8-307, C.R.S. to address public health emergencies or Regulation #61, section 61.8 to address a division determination that the permitted activity endangers human health or the classified uses of state waters and can only be regulated to acceptable levels by permit modifications or termination. The division may exercise such authority with respect to participants in the voluntary incentive program, as well as other sources of nutrients, as may be appropriate.

(2) Numeric Limitations for Non-Domestic Wastewater Treatment Works

(a) The following effluent limits apply to non-domestic existing treatment facilities:

(i) Delayed Implementation of Effluent Limits

The numeric limits in section 85.5 will not be included in effluent limitations in CDPS permits prior to December 31, 2027 for any existing permitted facility discharging into low priority 8-digit hydrologic units code watersheds [Purgatoire -11020010, Upper Arkansas-John Martin Reservoir - 11020009, Upper San Juan - 14080101, Upper Arkansas-Lake Meredith - 11020005, Upper White -14050005, San Luis - 13010003, Chico - 11020004, Kiowa - 10190010, Middle South Platte-Sterling - 10190012, San Miguel - 14030003, Alamosa-Trinchera -13010002, McElmo - 14080202, Lower Gunnison - 14020005, Arkansas Headwaters - 11020001, Upper Yampa - 14050001, Upper Gunnison -14020002, and Uncompahgre - 14020006] except for dischargers that are discharging effluent concentrations of TN or TP that are greater than 53 mg/L and 6 mg/L, respectively.

(ii) All Others

The following effluent limits apply to non-domestic existing treatment facilities not covered by the delay provided in section 85.5(2)(a)(i):

(A) Non-domestic dischargers with a Standard Industrial Classification code in the Major Group 20 (SIC 20).

PARAMETER	PARAMETER LIMITATIONS	PARAMETER LIMITATIONS
.	Annual Median ¹	95^th Percentile ²
(a) Total Phosphorus	10 mg/L	25 mg/L
(b) Total Inorganic Nitrogen as N ³	20 mg/L	27 mg/L

1 Rolling Annual Median: The median of all samples taken in the most recent 12 calendar months.

2 The 95th percentile of all samples taken in the most recent 12 calendar months.

3 Determined as the sum of nitrate as N, nitrite as N, and ammonia as N.

(B) Any other non-domestic dischargers for which the division has determined, based on credible information that the facility is expected, without treatment for nutrients, to discharge total inorganic nitrogen or total phosphorus concentrations to surface waters in excess of the following effluent limits.

PARAMETER	PARAMETER LIMITATIONS	PARAMETER LIMITATIONS
.	Annual Median ¹	95^th Percentile ²
(a) Total Phosphorus	1.0 mg/L	2.5 mg/L
(b) Total Inorganic Nitrogen as N ³	15 mg/L	20 mg/L

1 Rolling Annual Median: The median of all samples taken in the most recent 12 calendar months.

2 The 95th percentile of all samples taken in the most recent 12 calendar months.

3 Determined as the sum of nitrate as N, nitrite as N, and ammonia as N.

(b) The following effluent limits apply to non-domestic new treatment facilities:

(i) Non-domestic dischargers within SIC 20.

PARAMETER	PARAMETER LIMITATIONS	PARAMETER LIMITATIONS
.	Annual Median ¹	95^th Percentile ²
(a) Total Phosphorus	5 mg/L	13 mg/L
(b) Total Inorganic Nitrogen as N ³	10 mg/L	20 mg/L

1 Rolling Annual Median: The median of all samples taken in the most recent 12 calendar months.

2 The 95th percentile of all samples taken in the most recent 12 calendar months.

3 Determined as the sum of nitrate as N, nitrite as N, and ammonia as N.

(ii) Any other non-domestic dischargers for which the division has determined,

based on credible information that the facility is expected, without treatment for nutrients, to discharge total inorganic nitrogen or total phosphorus concentrations to surface waters in excess of the following effluent limitations.

PARAMETER	PARAMETER LIMITATIONS	PARAMETER LIMITATIONS
.	Annual Median ¹	95^th Percentile ²
(a) Total Phosphorus	0.7 mg/L	1.75 mg/L
(b) Total Inorganic Nitrogen as N ³	7 mg/L	14 mg/L

1 Rolling Annual Median: The median of all samples taken in the most recent 12 calendar months.

2 The 95th percentile of all samples taken in the most recent 12 calendar months.

3 Determined as the sum of nitrate as N, nitrite as N, and ammonia as N.

(3) Additional Provisions Applicable to Domestic and Non-Domestic Wastewater Treatment Works

(a) Compliance Schedules

A permit shall not be issued which allows a violation of the provisions of this control regulation unless it contains a schedule of compliance requiring specific steps needed to modify or install treatment facilities, operations or other measures and deadlines for completion of those steps. Factors that the division shall consider in developing the deadlines to be included in a compliance schedule, based on information that may be provided by the permittee or is otherwise known, shall include:

(i) Availability of resources needed to modify or install treatment facilities, adjust operations or other measures, including any in-house resources, the availability of consultants and contractors in the area with the appropriate expertise, and the availability of financing for any identified facility construction or other capital project, including the Water Pollution Control Revolving Fund;

(ii) Current conditions at the site, including existing treatment processes, the physical characteristics of the property, and the layout of the facility on the property;

(iii) Sufficient time for operational startup, new plant optimization, and operator training;

(iv) Factors identified by the permittee that might significantly affect the time necessary to complete one or more of the steps necessary to attain compliance;

(v) Sufficient time for the permittee to execute and implement a trade pursuant to section 85.5(3)(d);

(vi) Sufficient time in the event the permittee undertakes a pilot project to develop and/or test new treatment technology for reduction of total inorganic nitrogen or total phosphorus; and

(vii) Other site specific factors affecting the cost and timing of construction activities.

(b) Exceptions

The numerical effluent limitations set forth in sections 85.5 , 85.5 , and 85.5(2) shall not apply under the following circumstances:

(i) Where a discharger demonstrates to the satisfaction of the division that its discharge is unlikely to cause or contribute to ambient nutrient concentrations in its receiving waters that exceed the relevant numeric levels for total phosphorus and total nitrogen set forth in section 31.17 of Regulation #31;

(ii) Where noncontact cooling water discharges contain nutrients (phosphorus or nitrogen) and nutrients in the discharge originate from the receiving water as intake water or through use of chemicals shown to be necessary for proper operation of the cooling tower;

(iii) Where discharges consist solely of ground water that is pumped for the purpose of dewatering a construction site or for building sumps so long as no phosphorus or nitrogen is added to the ground water being discharged; or

(iv) If effluent concentrations higher than the applicable numerical limitations under this Control Regulation are adequate to achieve the total phosphorus and total nitrogen instream values set forth in section 31.17 of Regulation #31, then those alternative concentrations will apply as effluent limitations under Regulation #85 rather than the numerical limitations set forth in sections 85.5(1) and 85.5(2) hereof.

(c) Variances

(i) Variances from the numerical effluent limits set forth in sections 85.5 , 85.5 and 85.5 of this control regulation may be granted by the division where it is demonstrated by the permittee to the division's satisfaction that the nutrient reduction benefits of meeting the section 85.5 effluent limitations do not bear a reasonable relationship to the economic, environmental, or energy impacts resulting from meeting those effluent limitations. Meeting the effluent limitations in section 85.5 shall be presumed not to bear a reasonable relationship to the associated economic, environmental, or energy impacts where:

(A) Greater than 50% of the median annual TN or TP incremental load within the 8-digit Hydrologic Unit Code (HUC) watershed results from permitted process wastewater point source discharges, if

* for public sector entities, the Municipal Screener value is 2 or greater.

* for private sector entities, the required increase in treatment will cause more than 10 percent change in the entity's level profitability, or similar effect on liquidity, solvency, and leverage.

(B) 20-50% of the median annual TN or TP incremental load of the 8-digit HUC watershed results from permitted process wastewater point source discharges if:

* for public sector entities, the Municipal Screener value is 1.5 or greater.

* for private sector entities, the required increase in treatment will cause 5 to 10 percent change in the entity's level of profitability, or a similar effect on liquidity, solvency, and leverage.

(C) < 20% of the median annual TN or TP incremental load of the 8-digit HUC watershed results from permitted process wastewater point source discharges if:

* for public sector entities, the Municipal Screener value is 1 or greater.

* for private sector entities, the required increase in treatment will cause less than 5 percent change in the entity's profitability, or a similar effect on liquidity, solvency, and leverage.

(ii) A request for a variance shall be accompanied by proposed alternate effluent limits that represent the highest degree of nutrient removal that is consistent with the reasonable relationship test.

(iii) Variances shall be granted, denied, or revised as appropriate at the time of permit issuance or renewal.

(d) Nutrient Trading

(i) Point Source to Point Source Nutrient Trading. The numerical effluent limitations set forth in sections 85.5 , 85.5 and 85.5 may be modified for individual discharge permits pursuant to a trade of nitrogen or phosphorus between point sources where the division has determined that the trade will result in equal or better instream water quality for that parameter at all locations and at all times.

Point source to point source nutrient trades shall be based on a 1:1 ratio.

(ii) Nonpoint Source to Point Source Nutrient Trading. The numerical effluent limitations set forth in sections 85.5 , 85.5 and 85.5 may be modified for individual discharge permits pursuant to a trade of nitrogen or phosphorus credits from a nonpoint source to a point source on a stream segment or watershed basis where the division has determined that the trade achieves a net water quality or environmental benefit and does not cause adverse localized impacts.

Nonpoint source to point source trades shall be based on a minimum 2:1 ratio, but may be revised based on site-specific data that demonstrates a lower ratio achieves the criteria specified in the paragraph above.

(4) MS4 Permit Requirements for Nutrient Source Reductions

The following requirements, at a minimum, shall be incorporated into a CDPS Permit for discharges from a Municipal Separate Storm Sewer System (MS4) required to obtain a CDPS Permit pursuant to Regulation #61.

(a) Public education and outreach on stormwater impacts associated with nutrients. The MS4 permittee must develop, document, and implement a public education program to reduce water quality impacts associated with nitrogen and phosphorus in stormwater runoff and illicit discharges and distribute educational materials or equivalent outreach to targeted sources (e.g., residential, industrial, agricultural, or commercial) that are contributing to, or have the potential to contribute, nutrients to the waters receiving the discharge authorized under the MS4 permit.

CDPS Permits shall authorize MS4 permittees to meet the requirements of this section through contribution to a collaborative program to evaluate, identify, target and provide outreach that addresses sources state-wide or within the specific region or watershed that includes the receiving waters impacted by the MS4 permittee's discharge(s).

(b) Pollution Prevention/Good Housekeeping for Municipal Operations associated with nutrients. The permittee must develop and implement a municipal operations program that has the ultimate goal of preventing or reducing nitrogen and phosphorus in stormwater runoff associated with the MS4 permittee's operations.

Written procedures for an operation and maintenance program to prevent or reduce nitrogen and phosphorus in stormwater runoff associated with the MS4 permittee's operations shall be developed. The program must specifically list the municipal operations (i.e., activities and facilities) that are impacted by this operation and maintenance program.

CDPS Permits shall authorize MS4 permittees to meet the requirements of this section through contribution to a collaborative program to evaluate, identify, and target sources state-wide or within the specific region or watershed that includes the receiving waters impacted by the MS4 permittees discharge(s).

(5) Nonpoint Source Discharges

(a) Best Management Practice Implementation

(i) Governmental entities, individuals, corporations, partnerships, associations, agencies, and other entities with responsibility for activities or facilities that cause or could reasonably be expected to cause nonpoint source nutrient pollution of waters are encouraged to adopt and implement/install BMPs to the maximum extent practicable to reduce nutrient loads from such sources.

(ii) Agricultural operations that apply supplemental nutrients as part of crop production activities are encouraged to develop and implement nutrient management plans to the maximum extent practicable to reduce nutrient loads from such sources. Nutrient planning should be based on current soil, manure, and plant tissue test results developed in accordance with guidance or industry practice, such as that developed or recognized by Colorado State University.

(iii) The choice of which type of voluntary nonpoint source control measures shall be made by the entities identified in paragraphs (i) and (ii) above.

(iv) The division shall collaborate with owners/operators of agricultural operations in pursuing incentive, grant, and cooperative programs to control nonpoint source pollution related to agricultural and silvicultural practices.

(b) Public Information and Education

(i) Thedivision and entities identified in Section 85.5 are encouraged to develop and implement a public information and education program. This program will focus on the prevention of pollution from sources that could be mobilized from present and future activities as well as measures that could abate known nonpoint source pollution. Areas for abatement include, but are not limited to, general agricultural and silvicultural practices, landscaping activities, and other nonpoint sources of nutrients.

(ii) The program will be consistent with the voluntary, incentive-based approach and focus on the general public, and agricultural and local government sectors.

(c) Additional Nonpoint Source Actions

(i) During the triennial review of this control regulation, the division shall report to the commission on the progress implementing the activities addressed under this section.

(ii) If voluntary nonpoint source BMPs are not effective in managing nutrients by May 31, 2022, the commission may consider the adoption of prohibitions or precautionary measures to further limit nutrient concentrations.

(iii) Pursuant to section 25-8-205(5), C.R.S., after May 31, 2022 the commission may consider adopting, in consultation with the commissioner of agriculture, control regulations specific to agricultural and silvicultural practices if the commission determines that sufficient progress has not been demonstrated in agricultural nonpoint source nutrient management.

5 CCR 1002-85.5

40 CR 23, December 10, 2017, effective 12/30/2017

46 CR 10, May 25, 2023, effective 6/14/2023