Wastewater Treatment Facility Upgrade

The Graton Sanitation Zone was formerly operated by Sonoma County Water Agency.  In 2003 the Graton Community Services District was approved by LAFCO and the wastewater collection and treatment facility was transferred to the management of a locally elected Board of Directors and General Manager.  Lescure Engineers, Inc. was retained as district engineer having previously served as consultant to the local agency formation effort.

Current facilities include two primary treatment ponds, a settling pond, two treated wastewater storage ponds, a chlorine disinfection chamber, an office building, a 22 acre irrigation field, a discharge point into Atascadero Creek and an underground pipeline linking the Graton treatment plant with the Forestville Sanitation District.  Secondary wastewater is currently being used to irrigate 1-year-old redwood trees planted on the Graton irrigation property. Graton Community Services District also has contracts with offsite parties to accept secondary wastewater for crop irrigation.

Graton Community Services District has established a goal of achieving zero discharge through increased irrigation. In the revised study, the 22-acre irrigation site will be retained for irrigation rather than converted to a storage pond.  The efficiency of this site for irrigation will be enhanced by additional plantings and by diverting runon from the north end of the property through the construction of a drainage swale or a french drain. Additional offsite user contracts are being sought.

In 2006 a pilot testing program was performed to determine the efficacy of alternative treatment methods including employment of “fuzzy filters” with suspended air flotation (SAF) technology.  Employment of energy conservation measures was also investigated.  The study resulted in acceptance of the new technology by the State Water Resources Control Board.

The project also includes measures to control infiltration and rainfall inflow at the plant, including raising the perimeter berms and diverting rainfall runon from the ponds through road resurfacing and leveling and installation of stormwater drainage systems. Implementation of water conservation techniques, such as low flow shower heads and toilets, and other methods that will reduce the inflow to the treatment plant are planned. 

Lescure Engineers produced construction documentation for flood-proofing and treatment system upgrades, including drawings, specifications and bid documents.  Under the supervision of Peter J. Lescure, PE, the project has been advertised, bid and now stands with an executed construction contract.  Notice to Proceed will be issued when funding is approved by FEMA/CA Office of Emergency Services, the California Energy Commission and the State Water Resources Control Board Clean Water State Revolving Fund.  Lescure Engineers will provide all Construction Management services utilizing its own staff with special inspections provided by subconsultants.