Wastewater Compliance

Campus operations at the University of Arizona generate a significant discharge of wastewater to the local sewer system.  This discharge consists of domestic sewage from restrooms, and industrial wastewater from campus operations such as building and grounds maintenance, laboratories, art studios, and food preparation.  Industrial discharges to the sewer are regulated by Pima County under the provisions of an Industrial Wastewater Pre-treatment Ordinance.  First established in 1984, Pima County's Ordinance establishes a permit and reporting system for generators like the University.  Permits specify operational requirements for generators and industrial wastewater, and require periodic monitoring and reporting to verify continuing compliance. 

Pima County's wastewater conveyance and treatment systems are regulated under permits required by the Clean Water Act, and the associated National Pollutant Discharge Elimination System (NPDES).  Pima County's publicly owned treatment works (POTW) is required to meet federal requirements prior to discharge to the Santa Cruz riverbed.  The Industrial Permits issues to upstream sources of industrial wastewater, like the University, are structured to minimize discharges of a wide variety of pollutants that might damage the POTW, or compromise compliance with federal requirements for water quality applicable to treated wastewater prior to river discharge. 

The University of Arizona currently maintains three (3) Industrial Wastewater Discharge Permits that are monitored at four (4) sampling locations. Wastewater sampling and laboratory analysis necessary to demonstrate Permit compliance is conducted at least every six months.

Hazardous Waste Disposal

As a component of the University's compliance with Industrial Wastewater Permits, the University prohibits disposal of hazardous waste into the POTW.  The University has communicated this policy to Pima County as a formal declaration, which makes the University subject to fines and penalties for violations.  In the event of violation of Discharge Permit requirements, an attempt will be made to trace the upstream source of illicit discharges to the responsible department or research unit.  Any fines assessed for non-compliance will be the financial responsibility of the identified responsible unit. 

Prohibited Discharges

The information below is extracted directly from the County Ordinance. This is NOT an all-inclusive list. Some wastes prohibited from discharge by Pima County are not "hazardous" but must still be handled by RMS Staff. If you have any questions about sink/drain disposal of any material, contact Herb Wagner at 520-621-1790 for additional information as required.

Industrial wastewater discharges that may be adverse or harmful to the POTW, POTW personnel, POTW equipment, or POTW effluent quality, including, but not limited to:

  • Any gasoline, benzene, naphtha, solvent, fuel oil or any other liquids, solids, or gases which create or tend to create a fire or explosion hazard in the POTW, or to be injurious in any other way to the POTW.
  • Any biodegradable oils, fats and greases, such as lard, tallow or vegetable oil, in concentrations that may cause adverse effects on the POTW.
  • Any waste having a pH lower than 5.0 or greater than 11.0 standard units.
  • Any wastes containing a concentration in excess of the discharge limitations in any PERMIT for the following parameters: Arsenic, Barium, Boron, Cadmium, Chlorine, Chromium, Copper, Cyanide, Lead, Manganese, Mercury, Oil & Grease, Nickel, Phenol (total), Selenium, Silver, Sulfides or Zinc.
  • All aromatic and halogenated hydrocarbons are prohibited from discharge.
  • Single pass cooling or heating water or any POTW hydraulic loading is strictly prohibited.
  • For a more comprehensive list see the Pima County Industrial Wastewater Ordinance.

Allowable Sewer Discharges

  • Chlorine bleach solutions;
  • Ethanol, in amounts of 500 ml or less when flushed with copious quantities of water;
  • Inorganic buffer solutions, not containing heavy metals or other prohibited contaminants;
  • Inorganic acid or basic wastes, not containing heavy metals or other prohibited contaminants and only after neutralizing to a pH between 5.0 and 11.0;
  • Black and white photo developer provided that it is not contaminated with even the smallest amount of photographic fixer, and the pH of the developer is with the range of 5 and 11.