Industrial Pretreatment


The main objective of this EPA / ADEQ mandated program is to protect each of the following: the wastewater collection system, the wastewater treatment facilities and staff, surface waters and the groundwater, which receives recharge from the City of Prescott (COP) facilities. These goals will be achieved by permitting, monitoring, and sampling discharge from Industrial and Commercial users, in conjunction with educating industrial, commercial and residential users about substances that are harmful to the wastewater system and its processes. The Arizona Department of Environmental Quality (ADEQ) issued an official approval for the City of Prescott Pretreatment Program on October 1, 2013. We welcome your feedback via email to submit questions or comments about the Program.

The City of Prescott requests your help! We are conducting an on-going survey to help us understand the types of waste that are discharged into City sewers. This survey is a necessary component of the Pretreatment Program. The City requests that all businesses complete the Sewer Use Questionnaire. We suggest that you print out the .pdf document (below) that best fits your business type. Questionnaires may be emailed or completed online using the following link:  Take Online Sewer Use Survey. For the online survey, you must complete every question and click on “submit” at the end in order for the survey to be recorded. If you exit the survey or lose your internet connection, you will need to restart the survey and complete all questions from the beginning.

Survey User Questionnaires

Except for reporting required by the State and Federal regulatory agencies and specific information identified by public record disclosure laws, the City will not disclose any information that is provided in the Sewer Use Questionnaire to third parties.  Public support and participation will ensure that the City implements a pretreatment program that is representative of all businesses within the City’s service area. Thank you for taking the time to complete the sewer usage questionnaire. We greatly appreciate your participation. Please contact Water Protection at 928-777-1630 if you have any questions on the Sewer Use Questionnaire.


The General Pretreatment Regulations, Code of Federal Regulations 40 CFR Part 403, require the City of Prescott (City) to control wastewater discharges from significant industrial users (SIUs) through permits or similar means to ensure compliance with pretreatment standards and requirements. The regulations also specify that individual control mechanisms, in the form of Industrial Wastewater Discharge Permits (IWDP), be issued to SIUs and be enforceable by the City.
The City’s legal authority to issue an IWDP is described in City Code, Title II, Chapter 2-1, Section 2-1-65-2.  Each SIU is responsible for obtaining an IWDP from the City’s Public Works Director prior to discharging wastewater to the Publicly Owned Treatment Works (POTWs).


The Fats, Oils Grease (FOG) Prevention Program is derived from the City Code and is designed to integrate the use of Best Management Practices (BMP’s), grease interceptors, and regular maintenance of the interceptors to prevent FOG from entering the public sewer system.

BMPs for Fats, Oils Grease Prevention
FOG causes many problems in the sewer system and the FOG Prevention Program (FPP) helps outline strategies to reduce FOG problems. This prevents sewer overflows, prevents escalating sewer rates, assists in regulatory compliance, and protects the City from civil lawsuits and regulatory fines. The FPP protects the environment, improves the quality of life in Prescott, and guards the City’s liability.

Additional Information


  • Utilities
  • Ryan Osborn
  • Water Protection Specialist
  • Wastewater Collections

    1505 Sundog Ranch Rd

  • 928-777-1684
  • Utilities
  • Scott Calvert
  • Water Protection Specialist
  • Wastewater Collections

    1505 Sundog Ranch Rd

  • (928) 777-1615


  • Common maintenance schedules range from monthly to semi-annually. Your maintenance schedule will depend on the volume of cooking done at your facility and on how diligent your staff is in implementing BMPs. You should observe the condition and the cleaning of your grease interceptor each time it is maintained. If the final chamber of the interceptor has FOG floating on the surface then FOG can be passing through the interceptor into the sewer system. This indicates that more frequent maintenance is necessary.

  • All new commercial food service facilities are required to install a grease interceptor prior to opening. Existing facilities may be required to retrofit their sewer system with a grease interceptor. The City Building Department may also require the installation of grease traps.

  • FOG is a problem for both the property owner and the sewer system. Grease is singled out for special attention because of its poor solubility in water and its tendency to separate from the water and adhere to other surfaces.
    Fats, oils and grease in sewage coat the inside surfaces of the pipe and cause maintenance problems. The consequences include reduced sewer capacity and pipe blockages which resulting in sanitary sewer overflows. This happens in both private and public sewer drains and the extra maintenance and repairs can be extremely costly. When problems occur in the public system, the cost is paid for by the residents, through higher sewer rates.

    Oil and grease also hamper effective treatment at the wastewater treatment plant. Grease as a warm liquid may not appear harmful. But, as the liquid cools, the grease or fat congeals and causes mats to form on the surface of settling tanks, digesters, and the interior of pipes and other surfaces which may cause a shutdown of wastewater treatment processes.

    Commercial food service facilities are required to have grease interceptors installed in their private sewer system. The interceptor helps to remove FOG prior to discharging into the public sewer system.
    Best Management Practices (BMPs) are another strategy to prevent FOG discharge. BMPs simply spell out tactics used to minimize the amount of FOG that goes into sewer drains.

  • BMP stands for Best Management Practice. BMPs are useful for reducing the amount of FOG that goes down the drain, thereby reducing cleaning frequencies on grease traps and interceptors. Reduced FOG also lowers the risk of clogged pipes and sanitary sewer overflows. An example of a BMP is wiping excess grease out of pots and pans with a paper towel before washing them.

  • Grease interceptor inspections will be completed to ensure that the system is functioning properly. The depth of the sediment and grease layers will be checked. The inspector may require that the interceptor be clean if the combined grease and sediment layers are beyond the capacity of the interceptor. The inspector may also ask to see the maintenance and cleaning records for the trap or interceptor.

  • An interceptor is an outdoor, underground vault, typically with a capacity of 500 gallons or more, designed for the purpose of removing fats, oils, and grease and preventing them from entering the sanitary sewer system. The vaults have a two or three compartment system. The wastewater flows between each compartment and is given enough time to cool, allowing any remaining grease to congeal and rise to the surface. Other food particles are able to settle to the bottom of the vault. Grease interceptors must be maintained on a regular basis to prevent FOG from passing through the interceptor and into the public sewer system.

  • A grease trap is a small reservoir built into the wastewater piping a short distance from the grease producing area (typically the kitchen area). It is designed for the purpose of removing fats, oils, and grease and preventing them from entering the sanitary sewer system. Baffles in the grease trap reservoir hold the wastewater long enough for the grease to congeal and rise to the surface. Other food particles settle to the bottom of the reservoir and form sludge. The grease and sludge can then be removed and disposed of properly.

  • FOG is short for fats, oils and grease. FOG is found in lots of foods such as meats, sauces, salad dressings, foods cooked in deep fryers, cookies, pastries, cheese, butter and many more. FOG is present in many places in kitchens and food services facilities especially on dirty dishes.

  • During new construction or remodel of a commercial food service facility the Building Department will require that a grease interceptor is installed. Requirements for the size of a grease trap will be determined by the Building Department, in accordance with the International Plumbing Code. Businesses in existing spaces may be required to install a grease trap or grease interceptor by the sewer utility in order to comply with their Fog Prevention Program.


Prescott Christmas Parade Route and Event Street Closures for December 4, 2021

Posted on December 3, 2021

Enhanced security measures will be in place The City of Prescott will be implementing enhanced security protocols and street closures for the Christmas Parade and Courthouse lighting. Some streets will remain closed longer than usual, to promote enhanced security for… Read more »

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