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Helping communities and businesses access compliance, technical and financial assistance for their environmental needs.

Ohio communities with wastewater treatment plants that have design capacities ranging from 1,000 gallons per day up to five million gallons a day (MGD) can access free on-site assistance to help address problems at their wastewater treatment plants. DEFA’s publicly owned treatment works (POTW) Compliance Assistance Unit (CAU) experts work alongside local wastewater treatment staff to help identify factors impacting the plant’s ability to operate in compliance with its discharge permits. For more than 25 years, DEFA CAU staff have traveled the state, helping POTWs identify and create cost-effective, affordable solutions to bring them back into compliance. Some of the services provided include:

  • conducting plant performance evaluations to identify causes of compliance issues such as problems with plant design, plant operation, and administration;
  • troubleshooting complex plant problems;
  • creating innovative and cost-effective solutions for improving plant performance;
  • offering onsite training of personnel in process control procedures such as nutrient analysis (ammonia, nitrate, orthophosphate), solids inventory and sludge wasting, and clarifier optimization, including return activated sludge (RAS) rates;
  • helping improve sludge handling and disposal procedures;
  • teaching operators inexpensive, easy and effective methods of process control;
  • investigating concerns over industrial dischargers that may be impacting the system;
  • determining current plant loadings and capacities;
  • performing microscopic evaluations to identify filamentous bacteria and how to select against them;
  • helping facilitate inflow and infiltration evaluations of sewer systems;
  • reviewing/evaluating new treatment technologies; and
  • providing training presentations at wastewater trade seminars and workshops.

CAU assistance has helped communities save money, lower operating costs, and return to compliance. DEFA is committed to helping small communities avoid expensive enforcement proceedings and achieve compliance with technical know-how and hands-on experience.

How does the compliance assistance unit (CAU) work?

Example 1: The CAU was contacted by a treatment plant manufacturer about a new wastewater treatment plant that was not meeting its discharge permit. The community was threatening to call in a performance bond due to the noncompliance. The system was supposed to spray irrigate treated wastewater on a dedicated field, but was not meeting the total inorganic nitrogen limit of 10 mg/L required by its permit. The CAU began its troubleshooting process by performing wet chemistry analysis and installing data logging instruments to measure critical chemical parameters. Through this analysis, the performance limiting factors were identified. A process control scheme was created to give the operator a decision-making strategy based on the new process control data collection procedures. The CAU continued to work with the operator until he was comfortable with the new procedures and the wastewater treatment plant was consistently meeting permit limits. Through the cooperation of the operator, the owner, the consulting engineer, and the CAU, litigation and enforcement were avoided, and the wastewater treatment system has maintained long-term compliance.

Example 2: A community constructed a new treatment system to meet a new total phosphorus limit in their NPDES permit. The problem was they only met their phosphorus permit limit nine times in 53 months of testing, despite adding alum to bind with the dissolved phosphorus. The CAU was invited to see if they could help the community. Within a month, the wastewater treatment system was in compliance. The community stopped the chemical feed and cycled mixers on and off. This not only saved them chemical costs but also electrical costs and produced cleaner water that has met their total phosphorus limit most months in the following three years, with only an occasional violation. The CAU trained the operator in appropriate process control methods to keep the wastewater treatment system in compliance to keep the system in compliance.

If you need assistance or have questions regarding what CAU might be able to do for you, please contact Ryan Laake, CAU supervisor at Or contact the CAU staff: Jon van Dommelen at, Andy Gall at, and Nick Hammer at Also, read our Wastewater Treatment and Compliance Assistance Brochure.

If you're struggling to keep your wastewater treatment plant in compliance, rest assured that it isn’t rocket science. Let our experts teach you cheap, easy, and effective process control tools to diagnose treatment problems and then monitor the system to keep it in compliance. Join us April 15, 2021 from 9-10 a.m. EST for our free webinar Out of Compliance with Your NPDES Permit? Get On-Site Help From the Compliance Assistance Unit. Presenters: Jon van Dommelen, Nick Hammer, Jon Bernstein, DEFA.