Pine Mountain Tunnel Tanks Replacement Project (Lake or Streambed Alteration Agreement No. EPIMS-MAN-28080-R3)
4 Documents in Project
Summary
SCH Number
2021090343
Lead Agency
Marin Municipal Water District
Document Title
Pine Mountain Tunnel Tanks Replacement Project (Lake or Streambed Alteration Agreement No. EPIMS-MAN-28080-R3)
Document Type
NOD - Notice of Determination
Received
Posted
12/30/2022
Document Description
The project is limited to the removal and rerouting of a segment of one intermittent tributary and a segment of one ephemeral tributary to San Anselmo Creek, and installation of an energy dissipation structure at another intermittent tributary at the project site. This work is part of a larger project, with additional activities not covered under the Agreement, to construct two water storage tanks, each with a capacity for 2-million gallons, which will be partially buried into the hillside. A culvert upstream of the ephemeral tributary and a culvert and headwall downstream of where the two tributaries join will be removed. The flow from the intermittent tributary will be rerouted into a concrete channel and the flow from the ephemeral tributary will be rerouted via an 18-inch diameter pipe, with flows from both tributaries being released to where to the existing culvert and energy dissipation structure that outfalls further
downstream of where the two tributaries currently join. The existing culvert and dissipation structure will be refurbished or replaced, which will include placement of rock riprap (17.78 cubic yards). A security fence, along with emergency lighting, will be erected around the site. Each storage tank will also have emergency overflow piping connections that will reroute overflowing water through an 18-inch diameter pipe to a new 11-foot by 9-foot dissipation structure that will be located upslope of another intermittent tributary at the project site. Rock riprap (8.89 cubic yards) will be placed below the dissipation structure for erosion control. The project will result in permanent impacts to approximately 0.183 acres and 386 linear feet of stream and riparian habitat, and the removal of 23 trees. The project will not result in any temporary impacts to stream and riparian habitat.
Contact Information
Name
Alicia Bird
Agency Name
CDFW
Job Title
Environmental Scientist
Contact Types
Responsible Agency
Phone
Location
Cities
Unincorporated area
Counties
Marin
Regions
Northern California, San Francisco Bay Area
Other Location Info
The Project is located at three unnamed tributaries to San Anselmo Creek just
downslope of Sky Oaks Road between Sky Oaks Road and Concrete Pipe Road near the intersection with Bolinas Road, in the County of Marin, State of California; Latitude 37.971742°N, Longitude 122.604497°W; Assessor’s Parcel Number 197-120-23.
Notice of Determination
Approving Agency
CDFW
Approving Agency Role
Responsible Agency
Approved On
County Clerk
Marin
Final Environmental Document Available at
2825 Cordelia Road, Suite 100, Fairfield, CA 94534
Determinations
(1) The project will have a significant impact on the environment
No
(2a) An Environmental Impact Report was prepared for this project pursuant to the provisions of CEQA
No
(2b) A Mitigated or a Negative Declaration was prepared for this project pursuant to the provisions of CEQA
Yes
(2c) An other document type was prepared for this project pursuant to the provisions of CEQA
No
(3) Mitigated measures were made a condition of the approval of the project
Yes
(4) A mitigation reporting or monitoring plan was adopted for this project
Yes
(5) A Statement of Overriding Considerations was adopted for this project
No
(6) Findings were made pursuant to the provisions of CEQA
No