Industrial Pretreatment

Assuring the discharge of industrial waste does not detrimentally affect the operation and safety of publicly owned treatment works.

The purpose of the Industrial Pretreatment Program is to assure that the discharge of industrial waste does not detrimentally affect the operation and safety of publicly owned treatment works (POTWs). A POTW is a municipally owned wastewater treatment facility and all associated wastewater collection infrastructure. Industrial waste is any discarded substance (solid, liquid or gas) created by industries, manufacturing trades or businesses, or the development of natural resources. If industrial waste is not properly pretreated and controlled it can endanger municipal worker health and safety, damage infrastructure, disrupt the operation of municipally owned wastewater treatment facilities, and negatively impact the environment.

Pretreatment of industrial wastewater can be as simple as allowing solids to settle in order to remove materials heavier than water that could clog sewer pipes, or adjusting the pH of the waste to prevent an acidic or caustic discharge that could corrode pipes and pumps. Pretreatment can also involve complex chemical processes to remove heavy metals, reverse osmosis and micro-filtration processes to remove chemical compounds, and biological processes to reduce excessive loadings that could overload the POTW.

All POTWs in New Hampshire are required to implement the Pretreatment of Industrial Wastewater Rules. Additionally, federal regulations set the minimum pretreatment standards for certain high-risk POTWs and those with a design flow greater than 5 million gallons per day. These federal regulations also require that these POTWs establish an Industrial Pretreatment Program. There are 13 POTWs in New Hampshire that directly implement the Federal Industrial Pretreatment Program: Claremont, Concord, Derry, Dover, Franklin, Jaffrey, Keene, Manchester, Merrimack, Milford, Nashua, Rochester and Somersworth.

NHDES works with municipalities, industries, consulting engineers and other stakeholders to accomplish the goal of industrial pretreatment by:

  • Conducting an annual audit of one of the 13 federally delegated POTWs to ensure compliance with federal and state pretreatment regulations.
  • Conducting annual compliance inspections of two of the 13 federally delegated POTWs and of six of the other NH POTWs to ensure compliance with federal and state pretreatment regulations.
  • Conducting 15 inspections of industrial users each year throughout the state to ensure compliance with federal, state, and local regulations.
  • Processing Industrial Wastewater Indirect Discharge Requests to ensure new and proposed modifications to industrial wastewater discharges will comply with regulations and be properly treated by the POTW.
  • Reviewing and approving municipal sewer use ordinances for compliance with regulations and inter-municipal agreements dealing with wastewater treatment.
  • Investigating illicit industrial discharges and connections, and pursuing enforcement action when necessary.

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Resources

Industrial Wastewater Indirect Discharge Request

An industrial user must submit the completed application and the state required fee to the municipality which owns the publicly owned treatment works (POTW) proposed to receive the discharge.  The municipality must approve and certify the application prior to submittal to the Wastewater Engineering Bureau for approval. The POTW includes the wastewater treatment facility and/or publicly owned sewers.  The municipality may require its own separate permit application and fee.

Request an IDR

Dental Amalgam

Dental amalgam is comprised of nearly 50% mercury, which is considered a hazardous waste (D009 characteristic waste). Environmentally, mercury is a concern because of the many ways it can contaminate soil, water, surface water and air because of improper disposal. When mercury waste is disposed of down the drain, there is potential for contamination of water and/or sludge at the wastewater treatment plant or the septic system. 

Dental practices that discharge amalgam waste in their wastewater are required by New Hampshire Administrative Rules to have an amalgam separator that is certified by the manufacturer as meeting International Organization for Standardization (ISO) 11143:2008(E) standards and is designed and constructed for the expected volume and flow rate of discharge from the dental practice it serves. New and transferred dental practices that generate amalgam wastewater in New Hampshire are required to fill out a Dental Amalgam Separator Self-Certification Form and return it to the NHDES address or email address listed on the form. Existing dental practices are required to submit annual certification that their amalgam separator is maintained in accordance with the separator manufacturer's recommendations. EPA also provides Dental Effluent Guidelines.

Sewer Use Ordinance

All municipalities in New Hampshire with a POTW, or who have an inter-municipal agreement to discharge to a POTW, have a sewer use ordinance (SUO). This establishes the legal authority for a municipality to control and regulate the discharge of wastewater to its POTW. SUOs are required to comply with pretreatment standards and municipalities must obtain NHDES approval of any adoption or revision.

NPDES permits contain a state permit condition that requires municipal permittees submit a copy of their current SUO to NHDES at a frequency of no less than every five years. The 13 POTWs that are federally delegated for pretreatment must also obtain USEPA approval of the SUO. In addition, recipients of financial assistance are required to develop and maintain a SUO per Env-Wq 507.13.

Inter-Municipal Agreement

An inter-municipal agreement (IMA) establishes the legal framework for two or more municipalities to conduct shared operations. When an IMA deals with the control and regulation of the treatment of wastewater, the NHDES is charged by statute to review and approve the IMA before it can be enforced by the municipalities. Municipalities should contact NHDES early in the process to ensure the IMA includes the appropriate language/requirements.