Sunnyvale

The Donald M. Somers Water Pollution Control Plant is an advanced wastewater treatment facility serving homes, businesses and industries in the city of Sunnyvale.

Wastewater draining from indoor sources in Sunnyvale flows through sewer pipes that direct the wastewater to the Water Pollution Control Plant for treatment before being discharged to the San Francisco Bay. If left untreated before discharge, residential, commercial and industrial wastewater would upset the delicate ecosystem of southern San Francisco Bay.

In addition to wastewater treatment services include regulatory inspections and storm water management to business and industry in Sunnyvale, information on water pollution prevention and water conservation for residents, and environmental education services to schools and youth.

Funded by user fees, the mission of the Water Pollution Control Plant is to conduct a cost-effective wastewater management program that is environmentally sound and regulated to protect public health, safety, property, and the quality of the Bay.

Originally constructed in 1956, the plant utilizes primary, secondary and tertiary treatment processes to treat the wastewater. Information about the history of the plant, its construction and wastewater treatment is detailed below.

For more detail about what we do here, click on the links provided below:

Environmental Education

Plant Tours

Pollution Prevention

Regional Coordination

Regulatory Requirements

Services

Links to Other Agencies

History

Sunnyvale incorporated in 1912, with a population of about 1,500. Most of the land was filled with fruit orchards and farms, and it was appropriate to dispose of wastewater by simply running a pipe to the water of the San Francisco Bay, where the tide carried it out to sea.

During the 1940s, Sunnyvale become an important industrial and residential community. In that decade, the population grew to 10,000. Because of the population boom, studies were undertaken to verify the need for a citywide sewage treatment system. The resulting sewage treatment plant, constructed in 1956, was a primary, or one-step plant that could process 7.5 million gallons of wastewater a day. However, it soon became overloaded due to an increased number of residents, canneries, and other industries locating in Sunnyvale.

By 1960, the population had grown to over 50,000 residents plus many more non-residents working in the new industries sprouting up. The increase in wastewater treatment from this growth created the need to expand the plant.

Construction to increase the treatment capacity to 15 million gallons per day was completed in 1962. However, even with this plant expansion, it became apparent that special consideration to treatment processes would have to be made because of the high cannery flows. Cannery waste, which depletes great quantities of the oxygen available in the water as the waste decays, was identified as being a serious problem for the shallow and fragile South Bay environment. It became necessary to provide additional treatment.

Examining processes which would best solve the problem led the City engineers and design consultants to suggest converting a salt evaporating pond at the south end of the Bay to an oxidation pond. A 115-acre pond was purchased from the Leslie Salt Company for this purpose. This controlled ponding process copied a natural method of wastewater treatment, and added another vital step in upgrading the treatment of Sunnyvale's wastewater.

Over the years, a second evaporation pond of 325 acres was purchased. The ponding system continues to be an invaluable part of the treatment process but it is unusual, since most cities lack the space and funding to incorporate ponds into their wastewater treatment plant's process.

New developments in chemistry and environmental studies during the technology explosion of the 70's led to further understanding about the processes needed to protect our waters from pollutants. New concepts were incorporated into wastewater treatment, and resulted in the continued expansion of the Sunnyvale Water Pollution Control Plant. When a third process, called tertiary treatment, was added to the Plant in 1978, total capacity increased to 22.5 million gallons of treated wastewater each day. The final upgrade to increase the Plant to its present capacity of 29.5 MGD was completed in 1984.

The City's wastewater management program emphasizes three areas: 1) industrial pretreatment to lower the pollutant load prior to entering the municipal system, 2) using recycled wastewater for industrial and landscape needs to help to alleviate the fresh water shortages in this area, and send less fresh water into the predominantly saltwater Bay and 3) improving the quality of the treated discharge (effluent).

New processes and chemicals are given careful consideration for use at the plant to maintain and improve the quality of the effluent. Studies have resulted in the use of chemicals called polymers which are much less hazardous to the environment than the chemicals previously used. Further studies in all areas of plant operation will continue to keep us abreast of the best technology available to cost-effectively meet our community needs, while meeting all environmental requirements.

The Sunnyvale Water Pollution Control Plant was named "Plant of the Year" by the California Water Environment Association in 1989. Originally designed more than fifty years ago, it still encompasses the best in wastewater technology based on sound environmental principles.