Bridge construction and bridge closures are part of everyday life in the earthquake prone Bay Area. Thousands of commuters balance concerns over bridge safety with the frustrations associated with delays to rebuild and retrofit vital connectors like the Bay Bridge. Residents of the Orinda Estates neighborhood face a similar challenge with the Manzanita Bridge. Located on Manzanita Drive, the bridge traverses San Pablo Creek and serves as the neighborhood's main link to Camino Pablo and the rest of the city.
City Engineer Janice Carey provided City Council members with an update on the Manzanita Bridge Replacement Project at their November 3rd meeting. A statewide program to conduct a seismic analysis of publicly-owned bridges, like the Manzanita Bridge, and to take actions to retrofit the structures as needed was initiated by the California State Legislature over two decades ago in response to the Loma Prieta earthquake. Efforts to replace the 72 year-old Manzanita Bridge have been in the works for over 13 years and possibly much longer.
The most recent stumbling blocks to moving the bridge replacement project forward were sightings in the area of the red-legged frog and the Alameda Whipsnake. The surveys and reports required by the U.S. Fish and Wild Life Service related to these threatened species stalled the project for over a year. To mitigate the impact of the project on the habitats of the frog and snake, the City will purchase conservation credits, specifically three acres of land from a qualified conservation bank at a cost of $60,000. Currently, the City has requested reimbursement through CalTrans for the purchase of these credits.
"I have been watching the bridge deteriorate, and I have some concerns about the structural integrity of the bridge," stated Gretchen Latimer, an 11-year resident of the Orinda Estates neighborhood, in her comments to the City Council. She added that the recent heavy rains brought water cascading down Manzanita Drive and over the bridge.
Carey explained that each year a CalTrans structural engineer inspects all bridges in Orinda to ensure the safety and integrity of the structures. CalTrans evaluated the Manzanita Bridge over the summer and no problem or imminent danger was reported. In response, Council Member Amy Worth asked City staff to request CalTrans to set up a more regular monitoring schedule of the existing bridge.
At this point Carey estimates that the projected two-year construction process will start in 2011. The window for working on the bridge is tight-construction that directly involves the creek must be done between June 15th and October 15th per the permit requirements of the U.S. Department of Fish and Game.
As currently designed, the City will build a temporary bridge downstream to the north of the existing bridge for residents to use while the old bridge is demolished and replaced by a new, seismically upgraded bridge. Ms. Latimer queried City staff about the impact on timing to complete the new bridge if the temporary bridge step were bypassed. Carey stated that the bridge construction process could be potentially expedited by a year, but without a temporary bridge, residents would have to take a fairly windy detour out of the neighborhood via Camino Don Miguel. Ms. Latimer later indicated that the neighbors would need more information in order to determine if this were a viable option.
City Engineer Janice Carey provided City Council members with an update on the Manzanita Bridge Replacement Project at their November 3rd meeting. A statewide program to conduct a seismic analysis of publicly-owned bridges, like the Manzanita Bridge, and to take actions to retrofit the structures as needed was initiated by the California State Legislature over two decades ago in response to the Loma Prieta earthquake. Efforts to replace the 72 year-old Manzanita Bridge have been in the works for over 13 years and possibly much longer.
Lamorinda Weekly, Moraga CA