Industrial Pretreatment Program

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Industrial User Permit Information Dental Amalgam Program Household Mercury Surcharge Information Additional Information

The Industrial Pretreatment Program permits, inspects, and surveys customers who discharge industrial wastewater. Pretreatment is the treatment of industrial wastewater before sending it to the wastewater treatment plant. Wastewater treatment plants are also known as a POTW, or publicly-owned treatment works.

The design of a wastewater treatment plant is to handle typical household wastes; not that from certain types of industries or businesses. This program issues permits to customers who produce large volumes of wastewater. Permits are also issued based on the potential of their wastewater to impair the POTW. It requires certain industrial users to pretreat their wastewater before discharging it to the sewer. Pretreatment enables wastewater customers to reduce, remove or alter a pollutant before sending it to the POTW.

Program objectives are:

  • Prevent interference with POTW operations;
  • Prevent contamination of the POTW’s biosolids;
  • Prevent pass-through to the POTW’s receiving stream;
  • Prevent exposure of POTW workers to chemical hazards.

The Pretreatment Program is an EPA federally-mandated program. It falls under the administration of the State of North Carolina PERCS Unit. It lists the City of Raleigh as the Control Authority.

Industrial User Permit Information

Contact the Industrial Pretreatment Program before discharging industrial waste to the sewer system. Staff will discuss your operation and send you a permit application if approval is necessary. Please see the links below for the Industrial User Permit application and a short Industrial Waste Survey form.

Industrial User Permit Application

Industrial Waste Survey

Dental Amalgam Program

On July 14, 2017, the U.S. EPA published the Dental Effluent Guidelines (40 CFR 441). This regulation reduces the discharge of mercury and other metals from dental offices to POTWs. Dental amalgam contains mercury in a concentrated form that is easy to collect and recycle.

All dental facilities subject to this regulation must install an amalgam separator that meets the ISO 11143 criteria. They are also required to put in place

  • two Best Management Practices (BMPs),
  • submit a One-Time Compliance Report to the Industrial Pretreatment Program,
  • conduct ongoing operation and maintenance of the amalgam separator and
  • maintain associated documentation and records.

Any new practice opening must comply immediately with all requirements upon opening the practice.

Existing sources must achieve compliance and submit a One-Time Compliance Report by October 12, 2020.

Dental Discharger Fact Sheet

One-Time Compliance Report

Household Mercury

Mercury is bioaccumulative, which means it builds up in the food chain.  The highest concentrations are found in predatory fish and shellfish in a form of mercury called methylmercury.  Methylmercury is the most toxic form of mercury and people exposed to high levels may experience adverse health effects.  Exposure at high levels can harm the brain, heart, kidneys, lungs and immune system, and can potentially produce learning disabilities if prenatal or childhood exposure occurs.  

Common sources of mercury in the household include:

  • Thermometers
  • Electrical Switches
  • Barometers
  • Thermostats
  • Dental fillings
  • Light Bulbs
  • LCD screens
  • Batteries

If you are concerned about your potential exposure to mercury, contact your physician.  More information is available from the NC Department of Environmental Quality and the EPA.

Surcharge Information

All industrial users of the POTW are subject to industrial waste surcharges on discharges which exceed the following levels:

  • BOD greater than 300 mg/l
  • TSS greater than 250 mg/l
  • Total Nitrogen greater than 30 mg/l
  • Total Phosphorus greater than 5 mg/l

They are also subject to permit application fees, permit modification fees, and annual administrative fees. Review of the rates occurs on an annual basis and are subject to change. For updated surcharge information, please contact the Industrial Pretreatment Coordinator.


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Water Treatment