Municipal Wastewater Treatment Plants

General Treatment Process:

SEDIMENTATION/CENTRIFUGATION NEWSLETTER - February 2002, No. 266 Central Contra Costa Award Centers on Treatment of Industrial Waste Central Contra Costa County Sanitary District has an aggressive, effective outreach program that targets industrial users, commercial users and the public. The 45-mgd (170,000-m3/d) plant treats an average daily flow of 51.7 mgd (196,000 m3/d), making effective pretreatment very important. The district's household hazardous waste collection procedures, integrated pest management program, green business program, and grease control program involve businesses and communities in a cooperative effort to reduce pollutants at the source.

Sewage Collection and Maintenance Central San's sewer collection infrastructure consists of 1,400 miles of underground pipeline. The pipes range in size from 6 inches to 102 inches in diameter. maintaining this system is an ongoing process involving approximately 40 employees. These employees operate from a centrally located facility in Walnut Creek where crews can reach a pipeline emergency within 30 minutes. Pumping Stations Much of the wastewater flows through the pipes by force of gravity. But there are some areas where hills prevent natural flow and pumping facilities are required to "lift" the water over these inclines. Central San operates 20 pumping stations throughout our service area 24 hours a day. Treatment Plant Our state-of-the-art secondary treatment facility can handle up to 45 million gallons per day (mgd) of dry weather flow and 240 mgd of wet weather flow. In an effort to find new and improved ways of treating wastewater, Central San recently replaced its chlorine disinfection system with ultraviolet disinfection, making us the largest wastewater plant in the nation using this process. Also we now produce our own electricity through a cogeneration system that saves about $1 million per year in electric utility costs.