SR 06:147 - Laserfiche WebLink

Treatment Plant The Dublin San Ramon Services District provides wastewater treatment services to the City of Pleasanton under a number of wastewater treatment and disposal contracts between the two agencies. The District owned and operated wastewater treatment plant is located immediately southeast of the 1-680 / Stoneridge Drive interchange (see Figure VI-I, above). It provides both primary-, secondary-, and some tertiary-treated wastewater (which is utilized for irrigation purposes). At the wastewater treatment plant, wastewater first passes through screens which remove large objects such as rags, sticks, and cans. It then passes through a grit chamber where sand, grit, and small stones settle prior to removal. The wastewater then moves to sedimentation tanks where most of the remaining solids settle to the bottom as raw sludge. Treatment then entails removing sludge and setting it aside for further treatment. This first phase of sewage treatment is called the "primary treatment" stage (see Figure VI-2). Secondary treatment takes the effluent from the sedimentation tanks and transfers it to an aeration tank where it is mixed with air and bacteria-infested sludge to further break down the organic matter. After several hours, bacteria activates the sludge, which can be used again, in the aeration tank where it is mixed with new sewage and air. After settling and chlorination, the treatment plant discharges the resulting water into the Livermore-Amador Valley Water Management Agency (LA VWMA) pipeline.' This pipeline transports the wastewater to the East Bay Discharge Authority facility. This facility de-chlorinates and then discharges the wastewater into the outfall system to San Francisco Bay.' The treatment plant does not discharge all water into the pipeline, but uses a portion - after it undergoes additional tertiary treatment - for irrigation in non-residential landscape areas, and parks. The existing sewage treatment facility recently completed an expansion project to bring the average dry-weather wastewater-flow design capacity from 11.5 million gallons per day (mgd) of wastewater capacity to 17 mgd.3 The City of Pleasant on is currently entitled to half ofthis amount, or 8.5 mgd of the sewage treatment plant's capacity. The city's average annual wastewater flow is approximately 6.0 mgd. The current 8.5 mgd wastewater treatment capacity is sufficient to serve Pleasanton's planned build-out growth as anticipated in this General Plan. The maximum treatment plant ultimate design capacity is currently planned for 20.7 mgd average dry-weather flow in confonnance with the Livermore-Amador Valley Water Management Agency Joint Powers Agency 1997 influent limits. Flows at the treatment plant are not expected to reach 17.0 mgd until around 2012. The Dublin-San Ramon Services District has not begun expansion planning for the increase from 17.0 mgd to the maximum 20.7 mgd. This future expansion will allow PIeasanton dry-weather flows to reach, but not to exceed, 10.3 mgd. The sewer district designed the existing sewage treatment plant to meet this expansion at its current site. I Dublin San Ramon Services District Website: http"//wwwosrsn c.om/c.onstnlrtion ~nrnj~ds spc.t1on/l:wwm::l html. 11/2 t/05. 2 Livermore-Amador Valley Water Management Agency website: http"//1::1v""m::i cnm!F::.cil1tif's/T Jlvwm::l Syst.em.php, I t/2t/05. 3 Brown and Caldwell, Dublin San Ramon Services District Wastewater Treatment Plant Master Plan, January 1984. VI-4