Oceana Marin History
In response to requests by the County of Marin, the District entered into service agreements with the developer of Oceana Marin, a 251-lot subdivision adjacent to Dillon Beach. 1913 Act Assessment Bonds of the County of Marin provided financing for portions of the project. Service commenced in June of 1973 to 12 dwellings. By the end of FY 11/12, a total of 227 dwellings were being served.
The collection system consists of 6- and 8-inch AC and PVC pipe. All wastes flow by gravity to a pre-treatment basin and pump station located near the edge of a bluff overlooking the mouth of Tomales Bay. The station is a buried concrete box about 20 feet long by 10 feet wide by 10 feet deep. The sewage flows into a grit and grease separator, then through a grinder into a holding basin. It is then pumped from the holding basin to the treatment and storage ponds located at the top of the headlands, just east of Oceana Marin, where the wastes are held and treated by aerobic decomposition. Prior to 1990, natural aerobic decomposition occurred. As pond loading increased, it was necessary to boost introduction of air by using floating aerators, which were installed in 1990.
In the fall of 1981, an irrigation disposal system was installed and irrigation disposal of treated effluent from the ponds was initiated. Irrigation was accomplished by a system of subsurface perforated pipes laid in gravel ditches aligned along contour lines and was undertaken only when the field was dry and all effluent could be absorbed into the soil within the irrigation field.
In February 1982, the District was notified that its grant application for Environmental Protection Agency (EPA) and State Department of Water Resources money to fund a study of ways to enlarge the existing facility or relocate same to the sand dune area near Dillon Beach had been approved. Completion of the study was delayed until late 1986 due to lack of federal/state funds. Additional studies on the viability of the dune disposal option were accomplished in 1988 in an engineering study conducted by Questa Engineers under contract to the County of Marin in connection with an Environmental Impact Report being prepared for a development proposal for Parcel K, a parcel that is surrounded by District-served lands in Oceana Marin. So far, development of Parcel K has not progressed and remaining work on the dune disposal option has been delayed.
During FY 88/89, the wastewater disposal system exhibited some surface seepage. A study was commissioned to determine the nature and extent of improvements necessary to accommodate anticipated growth in the Oceana Marin area and to correct the seepage problem. In 1990, a new pressurized sub-surface irrigation system was installed that maximized the disposal capacity and reliability of the irrigation field. Also installed in late 1990 was a computerized control unit that monitors and operates equipment and transmits failure alarms from the Oceana Marin lift station to the District's control center in Novato. In 1992, an accurate flow meter that sends sewage flow data via the computerized control unit was installed at the lift station. In 1992 and 1993, substantial improvements were made in the treatment pond piping, and aerators were installed in the treatment pond to improve disposal water quality. In FY 93/94, the District began design of a dosing system to enhance operation of the pressurized sub-surface irrigation system. The dosing system was constructed in FY 94/95 as a component of the Oceana Marin Build-Out Master Plan required by the California Regional Water Quality Control Board.
During FY 00/01, Pacific Mechanical Corporation was employed to upgrade the Oceana Marin pump station with two rotary lobe pumps equipped with variable frequency drives. The project was designed to resolve long-standing reliability issues at this remote location. The project was completed in June at a cost of $217,000 with money borrowed from the Novato Water District. The borrowed money was fully repaid with interest. The Oceana Marin Improvement District had a cash balance of $192,000 by the close of FY 12/13.
In 2012, 3,150' of 6" and 8" collection pipe was rehabilitated by insterting a resin-impregnated lining into the existing pipe at a cost of $232,000.