Sewer Disposal Guidelines

**Important**

At present, the constituents of greatest concern for the campus are salts (measured as total dissolved solids or electrical conductivity), copper, aluminum and cyanide. The wastewater treatment plant has historically experienced permit violations for these three pollutants. Accordingly, the campus community is urged to be especially vigilant in following sewer disposal policies for these constituents.

The following sewer discharge limits are in place:

  • Electrical Conductivity: Wastewater shall not cause or contribute to permit violations at the wastewater treatment plant. Any sewer discharges that exceed 900 umhos/cm and any new proposed water softeners (or other water treatment devices that discharge waste brine) must be approved by Michael Fan at (530) 752-7553.
  • Aluminum: Wastewater shall not contain greater than 87 parts per billion.
  • Copper: No added copper allowed.
  • Cyanide: Wastewater shall not contain greater than 20 parts per billion.

If your waste exceeds any of these limits, please contact Environmental Health and Safety (EH&S), for proper disposal at (530) 752-1493.

Overview Of The UC Davis Wastewater Collection And Treatment System

With more than 21,000 students and 9,500 faculty/staff members on the campus, UC Davis generates approximately 1.6 million gallons of wastewater each day. The University operates its state-of-the art tertiary treatment plant in the south campus to treat this wastewater. A sanitary sewer collection system across the campus carries wastewater from office buildings, housing laboratories, food service facilities, and other support facilities to the wastewater treatment plant.

Much of the wastewater generated on the campus is normal domestic sewage (from those who live on campus or from campus restrooms). However, wastewater from laboratory drains and other non-domestic wastewater sources also drains into the sanitary sewer. While campus policy does not allow for disposal of hazardous chemicals to the sewers, the University recognizes the potential for discharge of inappropriate materials into the sanitary sewer. Accordingly, the University has implemented programs to help prevent inappropriate sewer disposal and monitor for the effectiveness of these programs.

The University operates its wastewater treatment plant under a permit issued by the State Regional Water Quality Control Board (RWQCB). The permit specifies how much treated wastewater can be discharged into the creek, where and when monitoring samples are to be collected, and what analyses are to be run. Samples are collected many times each week to monitor the treated wastewater before it is discharged in Putah Creek. Samples are also collected directly from Putah Creek, both upstream and downstream of the treatment plant outfall, to monitor for negative impacts to water quality.

The University's permit contains strict discharge limitations designed to protect water quality. UC Davis provides monitoring results to the RWQCB on a monthly basis to evaluate compliance with these limits. The RWQCB reviews this data, periodically inspects the plant, and has the authority to cite the campus for violating the conditions of the permit. The University's wastewater treatment plant has a good record of compliance with all discharge requirement limits, though new extremely low limits for some constituents have been set. To ensure continued compliance with permit conditions and prevent problems from occurring at the wastewater treatment plant, the University has recently developed a comprehensive sewer disposal policy with specific sewer discharge limits for over 100 constituents of concern. The sewer disposal policy and discharge limits are known in the parlance of wastewater engineering as "Local Limits." Please refer to the Sewer Disposal "Flow" Chart (pdf), for more information.