East Shore Wastewater Improvement Project
Client: Marin County Environmental Health Services Division
Questa was retained in January 2005 to develop a community wastewater solution for the 95 residences in the East Shore region of Tomales Bay centered about the town of Marshall. The community is served by individual septic systems, most of which are located on the shoreline and are in need of upgrade, replacement, or repair. These systems have been identified as a contributing source of public health and water quality problems in Tomales Bay, a 303(d) listed water body, impaired for pathogens. The Pathogens TMDL for Tomales Bay was adopted in 2005; the East Shore Wastewater Improvement Project was one of the County’s first implementation efforts. The County has received approximately $1.2 million to improve wastewater systems in the area through a multi-phase upgrade plan for the area.
Questa’s role was to identify and develop an affordable project, meeting the community needs as well as requirements of funding and regulatory agencies (SWRCB and EPA). This entailed a comprehensive review of prior work and new issues, a comparative analysis of the feasibility, costs, and environmental impacts of potentially viable alternatives, identification and design of a recommended project, and development of a revenue plan for financing. The project included extensive public outreach with the local community and the environmental organizations in the West Marin County area, including more than a dozen public meetings over a three-year period.
To develop geotechnical conclusions and design recommendations, Questa conducted a design-level engineering geologic and geotechnical investigation for the collection system and leachfield treatment areas, including reconnaissance geologic mapping, subsurface investigation, and laboratory testing. A stability analysis was also performed for the leachfield site.
The selected project included the development of a STEP collection system and community leachfield for an initial phase, including 35 properties, a future expansion to include an additional 20 properties, and a combination of individual upgrades and small cluster systems for the remaining properties. An onsite wastewater management zone was formed to oversee facility operation and maintenance. A full EIR was completed and certified in April 2007. Questa completed the project design in May 2007. Bids were received in June 2007, within the engineer’s budget estimate. Assessment district balloting was completed in June 2007 (94% approval vote) to secure a low-interest loan through the California Infrastructure Bank. Following receipt of Caltrans and Coastal Commission permits, project construction began in the fall of 2007 and was completed and put into full operation in July 2008. Questa provided construction management, development of ordinances, and operational start-up assistance to complete its services for this initial phase of the East Shore project. Questa has also conducted feasibility studies for the Phase 2 area.