Can This Go Down the Drain?
UC Davis Local Limits Program Update - March 2012
Forty Five Thousand People Generate a Lot of Wastewater
With over 30,000 students and 15,000 faculty/staff members on the campus, UC Davis generates over 2 million gallons of wastewater each day. The campus wastewater is treated at the University Wastewater Treatment Plant off Old Davis Road and then discharged either to the North Fork or the South Fork of Putah Creek.
Much of the wastewater generated on the campus is domestic sewage from restrooms and dormitories. However, wastewater from laboratory drains and other non-domestic wastewater sources also go to the wastewater treatment plant. Discharge of inappropriate materials into the sanitary sewer can damage sewer pipes, jeopardize the health of maintenance workers, and cause adverse environmental impacts. Accordingly, the University has developed the Local Limits program to help prevent inappropriate sewer disposal.
The Local Limits Program
Essentially, the program is designed to provide specific guidance to answer the question, "Can this go down the drain?" The goal of the Local Limits program is to educate users and prevent problematic constituents from being discharged into the sewer before they create problems. As part of the program, the University has developed a comprehensive sewer disposal policy with specific sewer discharge limits for over 100 constituents of concern.
Compliance with the New Discharge Permit is Top Priority
The Regional Water Quality Control Board mandates maximum discharge limits for several constituents in the campus wastewater treatment plant permit. Currently, 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 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 Mike Fan at (530) 752-7553.
- Copper: No added copper allowed.
- Aluminum: Wastewater shall not contain greater than 87 parts per billion.
- Cyanide: Wastewater shall not contain greater than 20 parts per billion.
Other limits that are also closely monitored include:
- Lead – 21 µg/l
- Iron – 3.0 mg/l
- Methylene chloride--100 µg/l
- Silver – 1.2 µg/l
- Hexachloroethane--2.6 µg/l
- Bis(2-ethylhexyl)phthalate – NO ADDED Discharge
- Tributyltin – NO ADDED Discharge
- Mercury – NO ADDED Discharge
If your waste contains any of these constituents at concentrations above the local limits, please contact EH&S to arrange for collection and proper disposal of the waste.
UC Davis has a Local Limits Web Page
The entire sewer disposal policy, with numeric discharge limits, is available online. If you do not see a limit for a chemical you are interested in, please contact Mike Fan at (530) 752-7553 or firstname.lastname@example.org to make sure drain disposal is acceptable prior to pouring your solution down the drain.
Sink Labels Now Available
Bright yellow & red sink labels to educate the campus about sewer disposal are now available. If you have sinks that have not been labeled contact EH&S at (530) 752-1493 or email@example.com.