Environmental Comparison of The Tunnel and The Proposed Bypass

The photo at the right shows the bypass route going through McNee Ranch State Park and the shorter tunnel route which leaves the scenic coastal mountains untouched. Pacifica and the northern San Francisco penninsula are in the background. Larger versions are also available: 512x544 JPEG [163 K] and 400x425 GIF [65 K]

[Photo: Pacific Aerial Images
Art: Chuck Kozak]

Environmental Impact Statement

The Tunnel Alternative

Given the minimal environmental impact of a tunnel, this alternative could be approved with a simple supplement to the current environmental document.

For reference on time for this process, in 1986 Caltrans completed a supplemental EIR moving the bypass from the Preferred Alignment to the Martini Creek Alignment in 6 months, despite major impacts to agricultural and riparian lands.

The Proposed Bypass

An update to the 1986 EIS is required by the Federal Highway Administration (FHWA), the project's funding source. The EIS is ten years old and requires major revisions: feasibility of the tunnel alternative (study underway); review of new information on the stability and earthquake safety of the freeway's enormous cuts and fills; new endangered species listings; and impacts to the newly-formed Monterey Bay Marine Sanctuary.

Impact to Parkland

The Tunnel Alternative
No impact to the McNee Ranch portion of Montara State Beach The tunnel alignment is entirely outside the park boundaries Montara Mountain and McNee Ranch would be preserved intact for future generations.
The Proposed Bypass
There is enormous visual impact and destruction of recreational resources. The fenced freeway bisects the park, cutting off public access. An excellent system of trails and bikeways would be destroyed. Two campgrounds planned for the park would be abandoned because of the noise from traffic.

Impact to Natural Habitat

The Tunnel Alternative
Minimal impact. Wetland mitigation required at north tunnel portal approach for an seasonal pond on Shamrock Ranch, habitat for the California Red-Legged Frog.
The Proposed Bypass
San Pedro Creek supports the most viable steelhead population in the county, a species recently determined by the National Marine Fisheries Service to be an endangered species.
Clay siltation from road cuts and fills would severely damage steelhead habitat, as well as the habitat of other threatened and endangered species, including the California Red-Legged Frog, Hickman's Cinquefoil, and the San Bruno Elfin Butterfly.

Flood Control

The Tunnel Alternative
No impact. The project is consistent with San Pedro Creek Flood Control and Marsh Restoration Project being planned by the Army Corps and the City of Pacifica, currently at the Draft EIS stage.
The Proposed Bypass
The enormous road cuts and fills of the freeway bypass and increased water runoff during storms endangers nearby Pacifica residents.
Major flooding in the area occurred in 1962, 1972, 1982, and 1986. The 1986 event, estimated to be a 35-year flood, damaged 183 homes and 10 businesses at a cost estimated at $4 million. The freeway would increase storm runoff by 18% in the flood-prone watershed.

Permit Process (U.S. Army Corps of Engineers)

The Tunnel Alternative
Given the minimal environmental impacts, the tunnel would not require an Individual Permit from the US Army Corps of Engineers to comply with the provisions of Section 404(b)(1) guidelines for the Clean Water Act (CWA).
The Proposed Bypass
Given the impacts to wetlands and endangered species, the freeway bypass would require an Individual Permit from the Corps. Under Section 404(b)(1) of the CWA the Corps must deny a permit to the bypass if there is a "practicable alternative" which minimizes adverse environmental impacts. The tunnel is that alternative.

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