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The Pine Mountain Tanks Project is a two-phase effort, which will span multiple years, and adds a pair of 2-million-gallon concrete water storage tanks near Concrete Pipe and Sky Oaks roads, bolstering water supply resiliency for firefighters, as well as for the town of Ross and other area residents.
Construction Update (April 23, 2024)Construction currently paused for seasonal environmental factors The Pine Mountain Tanks project, a multi-year effort to replace the aging Pine Mountain Tunnel’s use as a water storage facility with two, 2-million-gallon concrete tanks, has reached its scheduled, Year 1 pause for weather and environmental factors. Since construction began in the summer of 2023, crews have worked to excavate the site and install a retaining wall in preparation for the eventual installation of the pre-stressed concrete tanks. The construction site, located on the Mt. Tam Watershed, remains winterized, and construction is on hold through July 31. Concrete Pipe Road is open to the public during all normal business hours. |
Contact Information
- Marin Water Construction Management team: 415-945-1560
- Maggiora & Ghilotti, Inc., (project contractor): 415-459-8640
Maintaining Infrastructure is Top Priority
The Pine Mountain Tunnel was constructed in 1919 to convey water from Alpine Reservoir to Fairfax and San Rafael and was converted to a water storage facility in 1971 and remains in that use today. The storage replacement project will enhance water system resiliency and replaces aging infrastructure on the District’s watershed. A pair of 2-million gallon pre-stressed concrete storage tanks will replace the existing Pine Mountain Tunnel with a modernized design that provides seismic stability, water quality improvements, and low maintenance. This project also increases water system capacity in Ross Valley by approximately 30%. This is a major, multi-year construction project that is expected to be ongoing through January 2029.
| Project | Pine Mountain Tunnel Tanks Replacement |
| Program | A1A11 Replacements - Storage Tanks |
| Project Number | D21043 |
| Contact | Alex Anaya | AAnaya@marinwater.org |
Project Description
This project will cease use and replace the Pine Mountain Tunnel with two 2-million gallon pre-stressed concrete tanks located on Concrete Pipe Road at culvert marker CP-5.
Benefits
The benefit of this project is to cease use of Pine Mountain Tunnel for storage, improving water quality, and increase the reliability of storage within Ross Valley, providing emergency storage on the watershed to aid in firefighting capabilities and allow for the future replacement of Ross Reservoir.
Schedule and Status
Planning: Winter 2020/21 - Spring 2021
Design: Spring 2021 - Summer 2025
Construction: Summer 2024 - Spring 2029
*Construction window from August 1 - January 31 to protect Northern Spotted Owl
Expenditure Schedule
Actuals ThroughFY 22 (Rounded) | FY 23Estimate | FY 24Estimate | FY 25Estimate | FY 26Estimate | FY 27Estimate | FY 28Estimate | FY 29Estimate | Total |
$1,128,000 | $490,000 | $1,000,000* | $3,500,000 | $4,000,000 | $5,000,000 | $5,000,000 | $2,750,000 | $22,868,000 |
*Pending funding
Funding Sources
Capital Maintenance Fund | State Appropriation | Other Funding Sources* | Total |
$10,118,000 | $1,000,000 | $11,750,000 | $22,868,000 |
*Other funding sources to be determined