The work will be conducted at the Bon Tempe treatment plant located at the end of the Sky Oaks Road in Fairfax CA, and at the San Geronimo Water Treatment Plant located at 330 San Geronimo Valley Drive, Woodacre, CA.
This project will provide structural upgrades to the Marin Municipal Water District’s two potable water treatment plants. The control buildings and filters will be seismically strengthened and brought up to a condition where they can expect to be operable within 24 hours after a design magnitude earthquake. As part of the upgrade the filters will be fitted with air scour system to allow less volume of water to be used during a backwash thus preserving the potable water supply.
Drinking Water Supply
Water Quality Improvement
Habitat Protection and Restoration
This is a Drinking Water Supply project. Marin Municipal Water District (MMWD) was established in 1912 and provides drinking water to a population of about 190,000 in Marin County. The MMWD treatment plants currently being used to produce drinking water were constructed in 1958 and 1961 respectively and while some seismic retrofitting has been done, the treatment plants do not meet the desired level of service requirements for critical water supply infrastructure. This project will ensure that the control buildings and filters will withstand a design magnitude earthquake and be functioning within 24 hours of that earthquake.
Part 2 - Detail
In 2015, an assessment entitled Water Treatment Plant Master Plan was conducted in order to evaluate the district’s potable water treatment plants from the perspective of seismic stability, and therefore the district’s potential capacity to provide drinking water to the service area in Marin following a major earthquake. The assessment found that the structures were inadequate to withstand a design magnitude earthquake, and identified specific work needed in order to ensure the district’s ability to treat water following a major seismic event. $48.7 M in upgrade work was identified for the treatment plants. This project includes a subset of the recommended work, as described below.
This project will upgrade seismic and structural components of the control buildings, chemical rooms, and filters at both treatment plants. The work will include repairs to existing structures at know failure points such as increasing the distance to the edge of concrete for bolts that are anchoring key structural elements. Installation of concrete and steel beams and walls in the filters, removal of old underdrains to facilitate the work, replacement with new underdrains, installation of air scour for improved media cleaning and installation of new filter media.
The reliability of MMWD’s water treatment plants will affect the North Bay sub region. MMWD currently receives 25% of its water supply from the Sonoma County Water Agency. In the event that the MMWD treatment plants are not function after an earthquake the SCWA will be the only source of water for MMWD’s approximately 190,000 customers.
This project will not provide separate, specific benefits to a DAC, as the project will benefit the entire MMWD service area rather than just a subset of the population.
The scope of this project, and the grant request amount, are scalable.
This project addresses the Regional Priority Need for regional water reliability and long-term sustainability. The project will strengthen the district’s water treatment infrastructure and allow production of drinking water following a major seismic event, increasing water supply reliability and long-term sustainability.
The reliability of MMWD’s water treatment plants will affect the NorthBay sub region. MMWD currently receives 25% of its water supply from the Sonoma County Water Agency. In the event that the MMWD treatment plants are not functioning after an earthquake the SCWA will be the only source of water for MMWD’s approximately 190,000 customers.
This will avoid increased strain on the SCWA to provide water to all of the NorthBay Region during what is likely to be a time of wide ranging emergency. The project will also increase Marin Municipal Water District’s capacity to offer mutual aid in the event the North Marin Water District’s treatment plant is unable to operate.
This project will include conducting post-construction monitoring for a period of years, in accordance with IRWM grant requirements. Additionally, district Engineering staff continuously evaluate treatment plant conditions and quantity and quality of the water produced. The goal of this project is to provide potable water within 24 hours of a major seismic event; this will measured by ensuring the design meets current structural codes.
This will avoid increased strain on the SCWA to provide water to all of the North Bay Region during what is likely to be a time of wide ranging emergency.
This project will address the “Regional Water Reliability/Long-term Sustainability” priority, as implementing this project will strengthen MMWD’s ability to provide potable water under a post-earthquake emergency scenario. The seismic upgrades to be accomplished under this project are critical for long-term reliability and sustainability of producing and distributing potable water in Marin.
As described above, this project addresses the Regional Priority Need for regional water reliability and long-term sustainability. The project will strengthen the district’s water treatment infrastructure and allow production of drinking water following a major seismic event, increasing water supply reliability and long-term sustainability.
Water supply reliability will be greatly improved. During periods of emergency MMWD will be able to provide clean safe drinking water to resident of Marin County.
Provide potable water within 24 hours of design magnitude earthquake.
No formal cost benefit analysis has been performed for this project. However, the project costs were estimated as part of the Water Treatment Plant Master Plan. Structural upgrades to the building and filers at both treatment plants are anticipated to cost $8.3M. This capital investment will ensure the reliability of the treatment plants and the plants will be operational and produce water after a major earthquake.
Increases Water Supply Reliability
Advances/ Expands Conjunctive Management of Multiple Water Supply Sources
Increases Water Use and/or Reuse Efficiency
Provides Additional Water Supply
Promotes Water Quality Protection
Reduces Water Demand
Advances/Expands Water Recycling
Promotes Urban Runoff Reuse
Addresses Sea Level Rise
Addresses other Anticipated Climate Change Impact (e.g. through water management system modifications)
Improves Flood Control (e.g. through wetlands restoration, management, protection)