ARC 9204C

ARC 9204C

Rulemaking related to effluent and pretreatment standards

The U.S. Environmental Protection Agency (EPA) delegated NPDES permitting authority to Iowa in 1978 for all facilities outside tribal lands, as granted under Clean Water Act section 402(b). Iowa’s NPDES rules must implement all of the provisions in 40 CFR §123.25, and these rules must be as stringent as the federal provisions.

This chapter was reviewed and edited consistent with Executive Order 10. The changes remove outdated requirements; shorten, simplify and clarify regulations and terminology; remove redundancy; and reference regulations that appear elsewhere in state or federal law. Chapter 62’s rule-referenced document, the Iowa Wasteload Allocation Procedure (www.iowadnr.gov/environmental-protection/water-quality/wasteload-allocations), has been updated to reflect the November 11, 2020, version already cited in Chapter 61.

Notice of Intended Action for this rulemaking was published in the Iowa Administrative Bulletin on January 8, 2025, as ARC 8626C. A public hearing was held on the following date(s):

●January 28, 2025

●January 29, 2025

Twenty-nine people attended the first public hearing, and 19 people attended the second public hearing. No public comments pertinent to this rulemaking were provided at the hearings.Two comment letters were received during the public comment period.

This rulemaking is substantially identical to the Notice. Two minor changes from the Notice have been made to Chapter 62 in response to the comments. Duplicative and confusing sentences were removed from the general secondary treatment requirements, and a citation to the Code of Federal Regulations was added in regards to less concentrated influent wastewater for combined sewers.

ITEM 1.Rescind 567—Chapter 62 and adopt the following new chapter in lieu thereof:

CHAPTER 62

EFFLUENT AND PRETREATMENT STANDARDS:
OTHER EFFLUENT LIMITATIONS OR PROHIBITIONS

567—62.1(455B) Prohibited discharges.

62.1(1) The discharge of any pollutant from a point source into a navigable water is prohibited unless authorized by an NPDES permit or by a permit issued pursuant to Section 404 of the CWA and certified pursuant to 567—subrule 61.2(6).

62.1(2) The prohibitions in 40 CFR §122.4 are adopted by reference.

62.1(3) The following discharges are prohibited:

a.The discharge of wastewater into a POTW or a semipublic sewage disposal system (DS) in volumes or quantities in excess of those to which a significant industrial user is committed in either a treatment agreement described in 567—subrule 60.3(3) or a local control mechanism (in the case of a POTW with an approved pretreatment program); and

b.Discharge of the pollutants listed in 40 CFR §403.5(b) to a POTW, a semipublic sewage DS, or a PSDS.

62.1(4) Waste in such volumes or quantities as to exceed the design capacity of the treatment works, cause interference or pass through, or reduce the effluent quality below that specified in the operation permit of the treatment works is considered to be a waste that interferes with the operation or performance of a POTW or a semipublic sewage DS and are prohibited.

567—62.2(455B) Secondary treatment information: effluent standards for POTWs and semipublic sewage DSs.

62.2(1) General. This subrule describes the minimum level of effluent quality attainable by secondary treatment in terms of CBOD₅; suspended solids (SS), the pollutant parameter total suspended solids; and pH. The pollutant measurement CBOD₅ is used in lieu of the pollutant measurement BOD₅, as noted in 40 CFR §133.102(a)(4). All requirements for each pollutant measurement shall be achieved by POTWs and semipublic sewage DSs except as provided for in 62.2(2) and 62.2(3).

a.CBOD₅, as noted in 40 CFR §133.102(a)(4). The 30-day average percent removal shall not be less than 85 percent, and the percent removal shall be calculated by adding five units to the effluent CBOD₅ monitoring data and comparing that value to the influent BOD₅ monitoring data. Site-specific information on the relationship between BOD₅ and CBOD₅ shall be used in lieu of the five-unit relationship if such information is available.

b.SS, as noted in 40 CFR §133.102(b).

c.pH, as noted in 40 CFR §133.102(c).

62.2(2) Special considerations.

a.Combined sewers and percent removal. 40 CFR §133.103(a) is adopted by reference.

b.Industrial wastes and POTWs; standard secondary adjustment. 40 CFR §133.103(b) is adopted by reference.

c.Waste stabilization lagoons. Secondary treatment standards for waste stabilization lagoons are the same as those found in 62.2(1) concerning secondary treatment with the exception of the SS standards, which are as follows:

(1)The 30-day average shall not exceed 80 mg/l.

(2)The 7-day average shall not exceed 120 mg/l.

d.Less concentrated influent wastewater for separate and combined sewers; lower percent removal or mass loading limit. 40 CFR §133.103(d) and (e) are adopted by reference.

e.Upgraded facilities designed to operate in a split flow mode.

(1)The department may substitute either a lower percent removal requirement or a mass loading limit for the percent removal requirements in 62.2(1), provided that the treatment works is designed to split part of the primary treated wastewater flow around the secondary treatment unit(s). The design to accommodate split flow must be approved by the department and consistent with applicable design standards for wastewater treatment facilities. Paragraph 62.2(2)“d” applies to facilities considered under this subrule. This subrule shall not be considered for facilities eligible for treatment equivalent to secondary treatment under 62.2(3).

(2)Any applicant requesting a permit limit adjustment pursuant to this subrule must include as part of the request an analysis of the infiltration and inflow (I/I) sources in the system and a plan for the elimination of all inflow sources such as roof drains, manholes, and storm sewer interconnections. Infiltration sources that can be economically eliminated or minimized shall be corrected.

f.Dilution. Nothing in this subrule or any other department rule shall be construed to encourage dilution of sewage as a means of complying with secondary treatment effluent standards. Reasonable efforts to prevent and abate infiltration of groundwater into sewers, and prevention or removal of any significant source of inflow, are required of all persons responsible for facilities subject to these standards.

62.2(3) Treatment equivalent to secondary treatment. 40 CFR §133.105 is adopted by reference. Treatment works shall be eligible for consideration of effluent limitations described for treatment equivalent to secondary treatment in accordance with 40 CFR §133.101(g). The pollutant measurement CBOD₅ will be used in lieu of the pollutant measurement BOD₅, as noted in 40 CFR §133.105(e).

567—62.3(455B) Federal standards and effluent limitations.

62.3(1) Federal effluent and pretreatment standards. The following are adopted by reference: 40 CFR Part 125, Subparts H, I, and J, and 40 CFR Parts 401 through 471.

62.3(2) Federal toxic pollutant effluent standards. 40 CFR Part 129 is adopted by reference.

62.3(3) Effluent limitations and pretreatment requirements for sources for which there are no federal effluent or pretreatment standards. For discharges of pollutants from sources that are not subject to the federal effluent standards adopted by reference in 62.3(1), the department shall establish effluent limitations, pretreatment requirements, or both, that represent the best professional judgment for pollutant reduction, consistent with the CWA and Iowa Code chapter 455B.

62.3(4) Effluent limitations less stringent than the effluent limitation guidelines. 40 CFR Part 125 Subpart D is adopted by reference.

567—62.4(455B) Effluent limitations or pretreatment requirements more stringent than the effluent or pretreatment standards.

62.4(1) Effluent limitations necessary to meet water quality standards (WQSs). No effluent, alone or in combination with the effluent of other sources, shall cause a violation of any applicable WQS. When it is found that a discharge that would comply with applicable effluent standards or effluent limitations in this chapter would cause a violation of WQSs, the discharge will be required to meet the water quality-based effluent limits (WQBELs) necessary to achieve the applicable WQSs as established in 567—Chapter 61. WQBELs shall be derived from a wasteload allocation (WLA) calculated for the discharge, as described in the Iowa Wasteload Allocation Procedure (WLAP) (Nov. 11, 2020), or a WLA calculated for a TMDL, whichever is more stringent, except that the daily sample maximum criteria for E. coli set forth in 567—Chapter 61 shall not be used as an end-of-pipe permit limitation.

62.4(2) Pretreatment requirements more stringent than categorical standards. The department or POTW may impose pretreatment requirements more stringent than the applicable categorical standards in 62.3(1) when more stringent requirements are necessary to prevent violations of WQSs, pass through, acute worker health or safety problems, or interference (including inhibiting or disrupting sludge use and disposal practices).

62.4(3) Effluent limitations for pollutants not covered by effluent or categorical standards. When a pollutant is not otherwise regulated under rules 567—62.2(455B) and 567—62.3(455B), effluent limits or pretreatment requirements may be imposed on a case-by-case basis.

a.Effluent limits shall be based on the effect of the pollutant in water and the feasibility and reasonableness of treating the pollutant.

b.Pretreatment requirements shall be based on the effect of the pollutant in water, the effect on the receiving treatment works (including pass through, inhibition, worker safety, and sludge disposal), and the feasibility and reasonableness of treating the pollutant.

567—62.5(455B) Effluent reuse.

62.5(1) Manner of reuse. Treated final effluent may be reused in a manner noted in this rule or as specified in an NPDES permit.

62.5(2) Reuse for golf course irrigation. Treated final effluent may be reused for golf course irrigation if one of the conditions described in 62.5(2)“a” and all of the conditions in 62.5(2)“b” are met.

a.The treated final effluent must meet one of the following conditions:

(1)A minimum total residual chlorine (TRC) level of 0.5 mg/l must be maintained at a minimum of 15 minutes’ contact time of chlorine to wastewater prior to the irrigation of the golf course with treatment plant effluent; or

(2)Disinfected effluent shall be held in a retention pond with a detention time of at least 20 days prior to reuse as irrigation on a golf course. For this purpose, effluent may be disinfected using any common treatment technology, and either an existing pond or a pond constructed specifically for effluent retention may be used.

b.A golf course utilizing treated final effluent shall take all of the following actions:

(1)Clearly state on all scorecards that treated final effluent is used for golf course irrigation and oral contact with golf balls and tees should be avoided;

(2)Post signs that warn against consumption of water at all water hazards;

(3)Color code, label, or tag all piping and sprinklers associated with the distribution or transmission of the treated final effluent to clearly warn against the consumptive use of the contents; and

(4)Restrict public access to any area of the golf course where spraying is being conducted.

These rules are intended to implement Iowa Code chapter 455B, subchapter III, part 1.

[Filed 4/18/25, effective 6/18/25]

[Published 5/14/25]

EDITOR’S NOTE: For replacement pages for IAC, see IAC Supplement 5/14/25.