Water and Pollution Control Department

Application for Wastewater Treatment

The first step in the permitting process is to determine if the contributor should be designated as a non-domestic contributor.

A non-domestic contributor is defined as a contributor of wastewater containing gaseous, liquid, or solid material, other than typical domestic wastes, to the municipal sanitary sewer system.  Many commercial or industrial facilities discharge only domestic waste and do not require a pretreatment permit.  Other contributors discharge such small volumes of non-domestic waste that their discharge has an insignificant potential to adversely impact the WPC Facility or the sanitary sewer system.  Such facilities are also exempt from pretreatment permitting requirements.  The Application for Wastewater Treatment and Industrial Waste Information Questionnaire provide the information city staff use to make the determination of which facilities require a pretreatment permit.

If a facility is required to obtain a pretreatment permit, it will be placed in one of three classes as follows:

Class 1:  Significant Industrial User (SIU)

• discharges an average of 25,000 gallons per day or more of process wastewater to the Publicly Owned Treatment Works (POTW), excluding sanitary, non-contact cooling, and boiler blowdown wastewater; or
• contributes a process waste stream which makes up five percent or more of the average dry-weather hydraulic or organic capacity of the POTW; or
• is designated as such by the City on the basis that the contributor has a reasonable potential to adversely affect the POTW’s operation or for violating any pretreatment standard or requirement.

Class 2:  Categorical Industrial User (CIU)

Class 3:  Minor Non-Domestic User

Pretreatment Permit

Pretreatment permits will include quality and quantity limitations, monitoring and reporting requirements, and a compliance schedule when appropriate.  Contributors may be required to pre-treat or eliminate the discharge of wastewater which does not comply with the limitations.  Dilution in order to meet the permitted limits is prohibited.

Contract for Wastewater Treatment

New Sources

New Categorical Standards

Local Pretreatment Limits

Upon promulgation of a Federal Categorical Pretreatment Standard for a particular industrial category, the federal standard, if more stringent than the local discharge limitations, will supersede the limitations previously in the pretreatment permit for all facilities included in the federal category.

Since most of the pretreatment facilities in Ames do not fall under a federal categorical standard, the City of Ames has been required to develop local discharge limits to control the pollutant discharges from the non-domestic wastewater dischargers to the Ames sanitary sewer system.  Local limits are calculated by staff, approved by the IDNR, adopted by the City Council, and incorporated into the individual permits. City staff use an Excel spreadsheet to take into account all of the information required in the development of local discharge limits.  Information used to calculate local limits includes, but is not limited to, the following:

• WPC NPDES permit limits
• Skunk River water quality standards
• Federal 40CFR Part 503 land-applied biosolids limits
• Treatment process inhibition limits
• Treatment process removal efficiencies
• WPC Facility influent and effluent flows
• WPC Facility biosolids mass produced
• Treatment plant influent/effluent/biosolids data
• POTW worker safety limits
• Background domestic contributions
• Growth/safety factors

Prior to City Council adoption of new or revised local discharge limits, the City will notify all permitted contributors of the proposed discharge limits and provide an opportunity for comment.  Upon adoption of new or revised limits, the City will provide the contributor a reasonable period of time in which to comply with the new limits.  The City will establish and enforce deadlines for meeting pretreatment limits.

Monitoring and Reporting

In addition to the facility self-monitoring, the City is required by federal regulations to independently sample and analyze each waste discharge to verify compliance with the pretreatment limitations.  If city analytical results do not verify well with non-domestic facility results, monitoring frequency will increase as the City investigates sampling and monitoring differences between the facility’s laboratory and the city’s laboratory.  All samples must be collected and analyzed according to federal analytical methods detailed in 40CFR Part 136.  Samples not sampled and analyzed according to 40CFR Part 136 are unacceptable as analytical data for the pretreatment program.

The minimum frequency of self-monitoring, reporting, and verification monitoring is listed in the following table.  More frequent monitoring and reporting may be required because of the volume and/or nature of the wastewater being discharged.  Monitoring and reporting frequencies will be determined on a case-by-case basis for each non-domestic facility.  When federal pretreatment regulations exist, the more frequent of the monitoring and reporting requirements established by the regulations or the City’s monitoring and reporting requirements will be followed.

Minimum Monitoring and Reporting Requirements
Ames, Iowa

Periodic monitoring reports must be completed with data obtained through appropriate sampling and analysis performed during the period covered by the report and must cover topics such as status of compliance with the permit provisions, plant upset duration, special discharges, changes is discharge quality or quantity, etc.  All pretreatment samples must be collected and analyzed according to procedures listed in 40 CFR Part 136.

If sampling performed by the contributor indicates a violation, the contributor is required to notify the City within 24 hours of becoming aware of the violation.  The contributor must also repeat the sampling within 10 days of becoming aware of the violation and submit the sample results to the City within 30 days of becoming aware of the violation.  In addition, the contributor must notify the City immediately of any discharge, including any spills or slug loadings, as defined in 40CFR part 403.5(b) (such as discharges resulting from a spill, equipment failure, human error, or negligence, etc.), that may contribute to an interference or other deleterious situation in the POTW (including the sanitary sewer system).  In addition, a written notification must be submitted to the City within five calendar days of the incident.  The notification must include steps the contributor intends to take to prevent future occurrences of the deleterious discharge.

All pretreatment sampling and analysis must be performed in accordance with 40CFR Part 136.  Alternative analytical methods may be approved on a case-by-case basis for Minor Non-Domestic contributors.  Grab samples must be collected for pH, cyanide, total phenols, oil and grease, sulfide, and volatile organics.  For all other parameters, flow-proportional composite sampling techniques must be used whenever possible.  Time-proportional composite sampling techniques may be approved for use on a case-by-case basis.

The City and the contributor shall be required to retain for a minimum of three years any records of monitoring activities and results and shall make such records available for inspection and copying by the EPA and IDNR (and the City in the case of the contributor). This period of retention shall be extended during the course of any unresolved litigation regarding the contributor or the City or when requested by the EPA, IDNR, or the City.

Sampling records shall include at a minimum (in chain-of-custody format) the following:

• The date, exact place, method, and time of sampling and the names of the person or persons taking the samples
• The dates analyses were performed
• Who performed the analyses
• The analytical techniques/methods use
• The results of such analyses