5310 Hawthorne Rd.
La Plata, MD 20646
Monday - Friday
7:00 a.m. - 5:00 p.m.
What is Pretreatment?
Charles County's Pretreatment Program is designed to control pollutants from commercial and industrial users which may cause damage to the wastewater collection system (sewers), treatment plant equipment or pass through or interfere with wastewater treatment processes.
Some industrial users are classified by EPA as Categorical Industrial Users (CIU). EPA establishes the effluent standards for these industries and sets monitoring parameters. Industrial or commercial users who contribute 25,000 gallons or more to the collection system, or who make up more than 5% of the plant loading, are referred to as Significant Industrial Users (SIU). These users are regulated by the County and are required to monitor their discharge to the sewer on a regular basis to make sure they do not exceed their discharge limitations.
The County establishes pretreatment regulations for restaurants and food handlers which involve removing grease from their wastewater to prevent the grease from entering the sewer system. Automotive establishments are required to have grit, oil and flammable liquids removal systems. Photo processors utilizing silver-coated films or papers, including x-ray films, are required to have a silver recovery system to remove silver from their waste stream prior to discharging to the sewer.
Another regulated discharge is grit, a product of stone cutting and polishing. Plaster castings from orthopedic offices are another potential source of grit. A trap is required on sinks in plaster casting rooms. Grit acts like sand paper in the system and can seriously damage pipes and equipment.
There are annual fees associated with the Wastewater Discharge Permit. An invoice will be sent to permit holders annually from the Accounting office.
Wastewater Discharge Permit (WDP) Documents
- Wastewater Discharge Permit Application (short form) for Food Handlers, Automotive establishments and Photoprocessors (silver film users)
- Standard Detail for a 2,000 gallon grease interceptor for food handlers
- Wastewater Discharge Permit Application (long form) for Categorical Industrial Users and Significant Industrial Users
- Report form for Food Handlers (grease removal)
- Report form for Automotive Establishments
- Report form for Silver film processors (including dental and medical offices employing silver halide film x-rays.)
Before your business can discharge wastes to the County's sewer collection system, your Pretreatment device (grease interceptor; oil/flammable liquids interceptor; silver recovery unit, etc.) must be inspected and approved by the County. To schedule an inspection, please contact the Pretreatment Specialist at 301-609-5632. We try to respond to all requests for inspections within 48 hours; however, circumstances, such as weekends, holidays or other previously scheduled inspections may result in longer response times.
Response to requests for inspections for Categorical Industrial Users (CIU) and Significant Industrial Users (SIU) may take significantly longer and must be scheduled on a case-by-case basis.
Septic and Waste Hauler Program
Haulers wishing to discharge hauled wastes to the Mattawoman WRF must fill out a Waste Hauler application. You must also provide a certificate of insurance from your insurance company and you must have all vehicles which will haul wastes inspected by the Charles County Department of Health.
The following classes of wastes are acceptable to haul to the Mattawoman WRF:
- Landfill leachate
- Activated Sludge/Biosolids (must first obtain a sludge utilization permit)
- Septic tank waste
- Holding tank waste
- Portable toilet waste
- Grease interceptor waste
Industrial wastes and wastes containing any automotive oil, grease or antifreeze cannot be hauled to the Mattawoman WRF. This includes wastes from parking lot storm drains. For more details, please contact the Pretreatment Specialist at 301-609-5632.
Each hauler must provide the Pretreatment Specialist with a monthly log sheet of all waste hauled to the Mattawoman WRF. A Waste Hauler Source Tracking Log may be downloaded. This form must be submitted to the Pretreatment Specialist by the 10th of the following month.