COUNTY OF SAN MATEO
Department of Public Works
October 15, 2008
BOARD MEETING DATE:
October 28, 2008
Honorable Board of Supervisors
James C. Porter, Director of Public Works
Emergency Bank Stabilization along Gazos Creek Road
Adopt a resolution declaring the Gazos Creek Road large redwood treefall and bank failure an emergency and authorizing the Director of Public Works to approve and oversee emergency bank stabilization work at the site (F-151 [32D]).
Commitment: Ensure basic health and safety for all.
Goal 7: Maintain and enhance the public safety of all residents and visitors.
Adoption of this resolution enables work that is required to effectively preserve the integrity of a county-maintained roadway that provides primary access for residents and visitors to the area.
Gazos Creek Road is adjacent to Gazos Creek, which runs through a steep, narrow canyon. Due to the natural hydrology and geology of the area, landslides, treefalls, and in-stream logjams are fairly common and often result in roadway slip-outs and large in-channel accumulations of woody debris, which threaten the integrity of the roadway and can pose a risk to public safety.
On March 11, 2008, the Department of Public Works’ (DPW) staff was alerted of a large redwood treefall along Gazos Creek Road. The treefall originated on the roadside bank of the channel and spans the entire channel. The treefall is comprised of the following redwood trees: one 3 to 4-foot diameter tree, two 2 to 3-foot diameter trees, and several small trees. The treefall resulted in a large void (approx. 40’ x 20’ x 15’) behind the rootwads and along the road shoulder, destabilizing the bank and significantly reducing the creek’s capacity (Attachment A - Photos).
County staff immediately contacted the regulatory agencies to begin the permitting process to stabilize the slope. However, permits for the work have not been issued yet. The roadway and disturbed bank are extremely vulnerable to failure during high creek flow events during the upcoming winter. Emergency repair prior to the rainy season is imperative to prevent possible roadway failure, ensure access along the roadway for the residents that live upstream of the treefall, and prevent sediment delivery to Gazos Creek.
Due to the presence of sensitive aquatic species such as federally threatened Steelhead and California red-legged frog and federally endangered Coho salmon, the County began the permitting process in Spring 2008 with the intent to complete the work in October 2008 prior to the rainy season. DPW staff conducted numerous field visits with staff from the Department of Fish and Game (DFG), National Marine Fisheries Service, and the US Army Corps of Engineers (USACE) to develop a work plan to complete the work. In addition to the bank stabilization work, the work plan included in-channel management of the large redwood trees and debris. Due to the lengthy permitting process, permits have not yet been issued for this work.
Gazos Creek Road is the primary access route to several private residences and privately owned parcels and also provides secondary access to State Park lands (Attachment A - Map). The only other access route is via the unpaved upper portion of Gazos Creek Road (generally closed during the winter) through Big Basin State Park to Route 236 in Santa Cruz County. In the event of road failure, emergency access would be limited and difficult, and residents would not be able to readily access their property and possessions until the roadway could be restored. Failure of the roadway would deliver a large amount of sediment and asphalt into critical habitat for Steelhead and Coho salmon during the spawning and migration season and could also lead to the collapse of an adjacent stand of large redwood trees.
With high flows anticipated during the upcoming winter season, an emergency situation now exists. The emergency bank stabilization work will be performed by Road Division staff. Best management practices and conservation measures will be implemented to ensure environmental impacts are minimized and a qualified biologist will supervise all work. No work will take place within the active channel. Emergency projects are exempt from the requirements of CEQA and the Local Coastal Program. After-the-fact notifications are required and will be filed with the State Water Resources Control Board, DFG, and USACE.
County Counsel has reviewed the relevant regulations pertaining to emergencies and concluded that the proposed project complies with regulatory requirements (see Attachment B). A resolution has been approved as to form by County Counsel.
A cost estimate for the bank stabilization work has not been finalized, but it is anticipated not to exceed $25,000.
This work will be financed by the Road Fund.
There is no impact to the General Fund.
Attachment A -
Photos and Site Map
Attachment B -
County Counsel Review of Emergency Regulations