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Local Pretreatment Programs

States that have NPDES authority, like Iowa, are required to develop state pretreatment programs for EPA approval.  States can be granted pretreatment authority by demonstrating that their program meets all federal requirements.  Iowa was delegated pretreatment authority by EPA in 1982.

In a state with pretreatment delegation, publicly owned treatment works (POTWs) must develop local pretreatment programs for approval by the state.  Once a local pretreatment program is approved by the state, the state and EPA conduct periodic checks to ensure that the local program is operating properly.  If a POTW does not have an approved local pretreatment program, the national pretreatment standards and requirements are enforced by the state.

POTWs develop local pretreatment programs to implement federal standards and to protect local interests.  To gain approval for a local pretreatment program, a POTW must prepare pretreatment program documents for state review.  These documents must meet the requirements for local pretreatment programs in 40 CFR 403 and must contain the following elements:

  • Building Blocks: Local pretreatment programs require legal authority, an information base on the industrial dischargers, a professional staff, and adequate funding.
  • Effluent Limits: For industrial users of the sewage system, effluent limitations that enforce federal standards and protect local interests must be established.
  • Implementation Activities: POTWs must undertake activities to implement their effluent limits including notification, permit administration, inspection, monitoring, and enforcement.
  • Information Handling and Public Access: Local pretreatment programs must provide the public with the means to comment on program elements and must allow the public to access information about the program. 

For more information on each of the local pretreatment program elements, use the above links or see the discussion below.


Local Pretreatment Program Building Blocks

A local pretreatment program must have the following four major building blocks to succeed. These building blocks are:

Legal Authority - A POTW must have the legal authority to implement a local pretreatment program, based on state law and local ordinances.  State law authorizes municipalities to regulate industrial users of municipal sewage systems, and a municipality can establish a local ordinance for its local program.  The legal authority granted by state and local law must authorize the POTW to:

  • limit the pollution levels in wastewater discharges from industrial users;
  • enforce national pretreatment standards;
  • implement local limits;
  • issue industrial pretreatment permits;
  • inspect and monitor permitted industries; and
  • take enforcement action against violators.

Industrial User Information Base - A POTW must develop a comprehensive database describing its industrial discharges.  Large POTWs with many industries often have computerized databases to record pollutant levels in wastewater samples.  This allows for easy comparison of observed and allowed discharges and the automatic detection of violations.  Industrial user databases can be used by a POTW to determine the source of problems, to calculate local limits, and to plan for expansions.

Staffing - A local pretreatment program requires adequate staffing.  Personnel are required for monitoring and inspections, laboratory analysis, technical assistance, legal assistance, and program administration.  The required personnel depend upon the size of the sewage district, the number of industrial users, and POTW policies.

Funding - Funding for a local pretreatment program may be included in the municipal budget for the POTW or recovered through charges to the industrial facilities.  Charges can be included in a POTW’s basic fees or levied separately.  The fees for a local pretreatment program can be based on the amount of POTW services required by an industrial facility, the wastewater flow from an industrial facility, or the quantity of pollutants discharged.


Local Pretreatment Program Effluent Limits

A POTW must develop effluent limitations for each industrial facility covered by the local pretreatment program.  The effluent limitations may consist of federal standards, local limits, or both.  At a minimum, all industrial facilities must comply with federal prohibited discharge standards.  Industries that are subject to federal categorical standards must also comply with those standards.  The POTW may establish local limits more stringent than, or in addition to, the federal standards for some or all of its industrial users. 

To identify the need for and the nature of local limits, a POTW must determine if any public health or environmental problems will exist even with full enforcement of the federal pretreatment standards.  This determination addresses the following issues:

  • Interference - Will the pollutant load remaining after the federal standards are implemented interfere with the sewage treatment system?  Analyze POTW's susceptibility to various problems and its history of breakdowns.
  • Biosolids Contamination - Will any the industrial pollutants contaminate the POTW's biosolids?  Determine the concentration of contaminants from industrial waste in the POTW's biosolids and analyze the environmental residuals associated with each biosolids disposal method.
  • NPDES Permit Violations - Will the pass-through of any pollutants cause an NPDES permit violation?  Determine if any of the pollutants from industrial waste will pass through the POTW in quantities significant enough to cause a permit violation.
  • Surface Water Impacts - Will any of the pollutants that pass through the treatment plant adversely affect the receiving waterbody?  Examine the conditions of the receiving waterbody and determine if pollutant pass-through could have a substantial impact on the waterbody.
  • Worker Safety - Will any of the pollutants create a safety hazard for POTW employees?  Review the design and operation of the wastewater collection and treatment system and the chemical composition of the POTW's inflow to determine if any of the industrial pollutants individually, or in combination, will create a worker hazard.
If the answer to any of the above questions is "yes," a POTW must establish local limits.  Local limits are established as follows:
  • determine the maximum concentration of each pollutant in the incoming industrial wastewater that will not cause the problems listed above, then
  • calculate the maximum pollutant loading from each industry that can be allowed without exceeding the maximum concentration of pollutants arriving at the treatment plant. 

The calculations must consider the level of pollutants already present, the chemical decomposition of pollutants, and the need to accommodate future industrial growth.


Local Pretreatment Program Implementation Activities

To implement the effluent limits established in their local pretreatment programs, POTWs must undertake the following activities:

Notification - Industrial facilities in cities with local pretreatment programs must be notified of the applicable effluent limits. The limits can be based on categorical pretreatment standards, prohibited discharge standards, or local limits.  The effluent limits are incorporated in a pretreatment permit issued by the POTW to the industrial facility.

Permit Administration - POTWs must ensure that industries comply with the effluent limits in their pretreatment permits.  To ensure compliance, a POTW will identify sampling locations at an industrial facility and will specify effluent limits for each location.  In addition, industries must be required by the POTW to submit monitoring reports at least twice per year.

Inspections & Monitoring Visits - POTWs must inspect and informally visit permitted industrial facilities.  The inspection and visit frequency depends on the industries' potential impact on the sewage system and on the environment.  The volume of wastewater discharges, toxicity of the discharge, and/or variability of monitoring results are used to determine the timing and length of inspections and visits.  The POTW must conduct both regular and unannounced visits to collect wastewater samples.  Inspections and visits may also occur in response to a pretreatment permit violation, a public complaint, the suspected presence of hazardous materials, or a violation of the POTW's NPDES permit.

Enforcement - If an industrial facility violates its pretreatment permit, the POTW will take enforcement action after verifying the violation with sampling.  Once a violation is confirmed, the violating facility will be required to comply within a specified period and their discharge will be monitored to ensure compliance deadlines are met.  If the deadlines are not met, civil and/or criminal proceedings, including fines and injunctions, may be initialed by the POTW.


Local Pretreatment Program Information Handling and Public Access

A local pretreatment program is a public service to protect the public health and environmental quality of a community.  Public support for a local pretreatment program depends on public's ability to 1) participate in the program and 2) access information regarding the program.  The POTW staff is responsible for working with industries and the community to define the objectives and benefits of the local program.  The POTW can hold meetings with the public, industry, and environmental groups during program implementation.  When local limits are developed or revised, all interested parties must be notified and invited to comment.

In general, all the information that a POTW collects on industrial dischargers is available to the public and to government agencies.  However, if an industry can demonstrate that the release of information would divulge trade secrets, records can be restricted.  In these cases, POTW records that might disclose industrial trade secrets are labeled confidential and are not made available to the public.  Nevertheless, effluent data is always available to the public without restriction.

Non-confidential records regarding a local pretreatment program must be maintained by a POTW at an accessible and convenient location.  In addition, POTWs must inform the public whenever a significant violation occurs, and must annually publish the names of industries that significantly violated the pretreatment standards during the previous year.


For questions regarding pretreatment, please contact Eric Wiklund at 515/725-0313 or Eric.Wiklund@dnr.iowa.gov.

Contact information for the local pretreatment coordinators in Iowa can be found at: Iowa Pretreatment Coordinators.


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