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Wastewater Practices: Organic Chemical Discharge


The Washington Suburban Sanitary Commission (WSSC) regulates the use and operation of the sewerage system for the University of Maryland campus. The discharge of organic chemicals the sanitary sewer is stringently regulated since such materials can cause fires and explosions in the system, interfere with operations at the treatment facility, and/or pass through the treatment facility.

Laboratories may be significant users of toxic organics (e.g., solvents), which cannot be treated by conventional wastewater treatment systems. The discharge of many of these chemicals is regulated by WSSC as well as by hazardous waste regulations. Sink disposal of these toxic organics (also known as TTOs) must be prevented and must be disposed of as hazardous waste.

This fact sheet identifies only the key toxic organic chemicals whose disposal is specifically regulated by WSSC. The fact sheet does not list all chemicals that are subject to WSSC disposal regulations; nor are all hazardous wastes included. Contact the Department of Environmental Safety, Sustainability and Risk (ESSR) for assistance in determining hazardous waste disposal requirements.


Hazardous waste includes solids, liquids and gases that possess a hazardous characteristic (e.g., toxic, corrosive, ignitable or reactive), or substances that are specifically listed as hazardous waste by Environmental Protection Agency (EPA) or Maryland Department of Environment (MDE) on the basis of their usage or chemical constituents. MDE regulations include specific methodology for the identification of hazardous waste.

Total Toxic Organics (TTO) The WSSC discharge limit for TTO is 2.13 milligram per liter which is the sum of all TTO's with values greater than 10 micrograms per liter.

Applicable University Policy

University of Maryland Environmental, Safety and Health Management Policy

Applicable Regulation

  • The Plumbing and Gas Fitting Regulations
  • 40 CFR Part 403- General Pretreatment Regulations for Existing and New Sources of Pollution.

Summary of Requirements

WSSC specifically regulates the disposal of toxic organic chemicals (TTOs) to the sewer system. TTO discharge for the campus is limited to a concentration limit of 2.13 milligram per liter (one part per million), effectively constituting a discharge prohibition on these listed substances. For this reason, TTOs should be disposed of as hazardous waste. Contact Environmental Affairs for assistance with disposal practices.


It is recommended that laboratory and operations personnel be trained in the above discharge requirements.


The University of Maryland is currently not subject to sampling and analysis of wastewater effluents. However, non-complying discharges must be reported to WSSC. Notifications are the responsibility of ESSR and a compliance demonstration is generally required.


Reports must be maintained for a period of three years. Records are maintained by Environmental Affairs.

University Resources

Department of Environmental Safety, Sustainability and Risk (301) 405-3960
ESSR Fax No.    (301) 314-9294
ESSR Website:

Written 5/98
Reviewed 3/04

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