Sewage flows from houses and businesses through sewer pipes to the sanitary district, where it is filtered and cleaned. Once the water has been removed, it is cleaned and released back into the Bay. What's left is called sludge. Sludge is then disinfected and converted to a biosolid. The District currently produces about 20,000 cubic yards of biosolids each year.
Most treatment plants in the United States pay landfills to dispose of their biosolids. Since 1978, the District has been using its biosolids as a soil amendment on a District-owned farm. The farm--known as Tubbs Island--is located north of the San Francisco Bay adjacent to inter-tidal marshlands and a large nature preserve. Tubbs Island provides habitat for the endangered Salt Marsh Harvest Mouse and other indigenous wildlife. Farmlands in this area are reclaimed baylands used mainly for wheat and oat hay, providing feed for chickens and cattle.  

  Biosolids produced at the District are hauled by special truck to Tubbs Island and used as fertilizer to help crops. This practice is beneficial in two ways: the project results in substantially lower costs for the District, and the addition of biosolids has promoted better farming conditions on Tubbs Island.

The EPA recognized this innovative use of biosolids in 1990. The District was awarded the National First Place Award as the most outstanding project involving land application of biosolids in the United States.

© 2005 Vallejo Sanitation and Flood Control District