Industrial Discharges


Development and implementation of the District’s Industrial Pretreatment Program is required by USEPA’s National Pretreatment Program (established under the Clean Water Act). The District’s Industrial Pretreatment Program is subject to regulation and oversight by the USEPA and the San Francisco Bay Regional Water Quality Control Board.

The Industrial Pretreatment Program is designed to protect the safety of our workers and the community, protect the District's wastewater collection system and treatment facilities, and ultimately the water quality in the San Francisco Bay by limiting the discharge of toxic or potentially harmful substances into the sewer system. Pollutants with certain physical or chemical characteristics in significant quantities or concentrations can block or damage the collection system, interfere with treatment processes, pass through the wastewater treatment plant to the Bay, or contaminate biosolids generated at the plant thereby limiting disposal options. 

The Environmental Compliance Team at Union Sanitary District runs the Industrial Pretreatment Program by regulating industrial wastewater discharges to the sanitary sewer in the Tri-City area. Facilities with significant industrial wastewater are inspected and evaluated for an Industrial Wastewater Discharge Permit.  Permits are issued to facilities that are required to control the levels of pollutants discharged.  Sampling of the wastewater by the Environmental Compliance Team ensures that the wastewater meets compliance levels.

Industrial Permitting 

Are you new in town, or considering locating in the Tri-City area? Please contact us! All local industries are required to comply with our Sewer Use Ordinances, and many will need to obtain an Industrial Wastewater Discharge Permit from the District prior to discharging to the sanitary sewer system. The industrial wastewater discharge permitting process, sewer service and capacity fees, and Federal and local requirements are summarized in the Industrial User Guide.

Protecting the Safety of Our Workers and the Community

Our dedicated employees at Union Sanitary District maintain underground pipes, pumps, and collection systems in the Tri-City area in order to convey the wastewater to the treatment facility.  Because our employees may be exposed to wastewater in their working environment, it is prohibited to discharge wastewater that would cause harm to our employees due to possible exposure. Exposure can be from direct skin contact with the wastewater or by breathing vapors or eluted gases from the surface of wastewater.  Therefore, industrial wastewater may need to be pre-treated before entering Union Sanitary District’s sanitary sewer conveyance system.  Pretreatment could be adjusting the pH, removing the solids, or removing chemical constituents before discharging to the sanitary sewer. 

Protecting Our Treatment Facility

The District’s wastewater treatment facility uses physical, mechanical, and biological means to process wastewater.  The microbes at the treatment facility are unable to breakdown some of the constituents stemming from industrial wastewater.  Constituents such as heavy metals, solvents, and oil are “incompatible” with the microbial treatment.  These constituents are toxic if they are fed into the treatment systems that depend on microbes to breakdown the wastewater.  Incompatible wastes “interfere” with the normal operation of the treatment system.  Therefore, some industrial wastewater needs to be pre-treated before entering Union Sanitary District’s wastewater treatment facility.

Regulating Industrial Wastewater

In efforts to control incompatible waste streams from entering the conveyance system, interfering with the normal operations of the treatment facility, and preventing these incompatible pollutants from harming employees or killing-off the microbes in the wastewater treatment systems, the Industrial Pretreatment Program was established.  Incompatible pollutants which interfere with the treatment system, could pass through without treatment and create a toxic environment in San Francisco Bay and the Hayward Marsh, which are the receiving waters for the treated water leaving Union Sanitary District.  Any incompatible pollutants, not passing through to the Bay or Marsh could end up in the solid waste, biosolids, which could make the biosolids too toxic to be used as a soil amendment and may have to be processed as hazardous waste. But, before incompatible waste steams even get to the treatment plant, they are conveyed through underground pipes that need to be protected from corrosion and explosion.  The pH of the wastewater from an industrial process could be acidic or caustic to the point that it will destroy the wastewater conveyance pipes and eventually cause dangerous “sink holes” in the surface road.  Also, if any flammable or combustible solvents are discharged they could elute gases that may cause a fire or an explosion, immediately destroying miles of conveyance pipe and possibly harming the public and damaging the property at the street surface.  Industrial Wastewater Discharge Permits regulate the types of wastewater allowed which may have to be pre-treated to prescribed levels in order to make the wastewater compatible with the conveyance system and USD’s treatment facility, thereby reducing hazardous exposure to personnel, the public, and receiving waters.

The Goals of the Pretreatment Program

  • Protecting the life, health, and safety of operating and maintenance personnel;
  • Protecting the treatment plants from interference with process operations and pass through of harmful pollutants;
  • Ensuring the health, safety, and welfare of the public;
  • Providing the opportunity for beneficial reuse of biosolids;
  • Providing the opportunity for water reclamation.

Future Trends

As wastewater treatment systems improve for both industrial discharges and USD’s treatment facility, we can plan on reusing the treated water by reclaiming it for irrigation or as a recharge to the underground water storage used by private and public well-water sources.  Presently, USD reuses a small portion of the treated wastewater within the treatment plant itself.  However, there is no water reclamation system in place for the general public of the Tri-City area at this time.



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5072 Benson Road

Union City, CA 94587-2508

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