San Anselmo Creek near Cascade Falls
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Creosote wood in San Anselmo Creek and off-gassing as the upper deck rots
San Anselmo Creek, May 2020. Site where project will build root wads and create new fish habitat.
Replace concrete & invasive species
Bridge is built by Army Corps of Engineers
1956
2013
Project starts: First public workshop held. Construction planned for 2016
Multiple rounds of public input, redesigns, enviromental studies, evaluation of materials, cultural & historical study, etc. Continued delay tactics by a small minority dramatically increase cost of the project
2014–2019
2020
486 page Environmental Report complete
Town votes unanimously on June 3 to accept the Mitigated Negative Impact Environmental Report and move the replacement bridge project forward.
Mitigated Negative Declaration
486 page multi-year environmental impact report which fully complies with California Environmental Quality Act Statute & Guidelines
National Oceanic and Atmospheric Administration findings from 2018-19 studies of the creek by specialized biologists
Click on any of the FAQs to learn more
What about a so-called "alternative" plan for construction?
What about the new bridge’s building materials and its carbon footprint?
Will the new bridge be too big?
Will there need to be major excavation in the roadway after the bridge is built?
Will the bridge replacement project harm Northern Spotted Owls?
No, it’s right-sized. Like the current bridge, it will be one-lane and exactly the same length. It will be noticeably wider than the dangerously-narrow current bridge, but will be no wider than Caltrans’ minimum acceptable width for new bridges. The current bridge’s divider is regularly smashed and damaged by wide vehicles crossing. And the new bridge’s pedestrian/bicycle lane (ADA-acceptable width) will, at last, provide safe crossing for people with mobility issues and for small kids on bikes.
In 2016 the neighbors were polled, via an independent survey. By a wide margin, they opted for a concrete bridge, the building material used for every other Fairfax vehicular bridge. The concrete design is both cheaper ($113,000) than steel to install but also has the advantage of being virtually maintenance-free for 100+ years (unlike steel). It is an attractive design, appropriate for the neighborhood, and our community.
Studies comparing the carbon footprints of concrete vs. steel in construction have produced no consistent advantage for one or the other. In fact, there are many varieties of concrete available; some have a particularly-low carbon footprint, and others even act as a carbon sink. Nearly all new steel is produced using iron oxide and coking coal at extremely high temperatures in a blast furnace. There is currently no technology to make steel at scale without using coal.
Even if the underlying bridge material were steel, it would be covered with concrete, as would the bridge deck. In any case, most of the concrete used by the project will be for new abutments (the bridge’s supports) and a necessary “wing wall” to protect the banks from further erosion. There are no viable alternatives to using concrete for this purpose.
One lone neighbor (with no engineering experience) has been pushing an idea to block off vehicular traffic for 3 weeks while installing a prefabricated steel bridge. He claims the project could be completed that quickly. Unfortunately, that idea is a pipe dream. His plan doesn’t include needed time to carefully remove the carcinogenic creosote-impregnated bridge supports, nor to do the necessary creek work to protect the bank against erosion, slow the water velocity, and protect downstream properties from flooding.
Additionally, multiple construction contractors and the newly-retired engineer in charge of Marin County’s bridge program have all agreed that his ideas are totally not viable from an engineering perspective.
Definitely not, especially given the mitigation (i.e., preventive) steps that will be taken. The primary concern would be interference with the owls’ breeding. Northern spotted owls tend to breed every couple years, typically returning to the same nests to do so. Because they are a threatened species, the government requires the locations of active nests to be confirmed by positive observation by specifically-chosen scientific observers, and all locations to date have been carefully documented.
The nearest spotted owl nest site to the bridge replacement location is .28 miles away.
Purported observations of owls or their calls by random, unauthorized individuals are meaningless and have no legal importance. In fact, they might actually be from another variety of owl, or from a spotted owl foraging in the neighborhood with no consequence to its breeding.
The government agrees that this distance is sufficient to ensure that there will not be visual disturbance of the owls’ breeding. Potential noise disturbance is mitigated by having the construction work take place only after the owls’ breeding season has ended, and by restrictions on the decibels of noise that the construction creates. Of course, this noise level is attenuated by distance, yet another reason that northern spotted owl breeding will not be at risk. More information is available by consulting the U.S. Fish and Wildlife Service issued guidelines entitled Estimating the Effects of Auditory and Visual Disturbance to Northern Spotted Owls and Marbled Murrelets in Northwestern California and their Appendix B, Northern Spotted Owl Sound and Visual Harassment Support Tools (2006).
The U.S. Fish and Wildlife Service, and the federal government overall, concur that--due to the mitigations that the bridge project will employ--northern spotted owl breeding will not be at risk.
No. The existing bridge sits, not centered in the roadway, but instead right up against the northern boundary of the Town’s right-of-way (ROW), and immediate neighbors have raised legal issues regarding exactly where their property lines end. There could be issues of potential litigation were the new bridge to be placed at the exact same location.
Instead, the new bridge will be located in the very middle of the ±40-foot-wide ROW, with equal distance on both sides of the roadway beyond. This siting allows for a much more-efficient construction process. Since the footprints of the existing and new bridge will overlap, the ingenious construction plan will build the new bridge on the south side of the existing bridge (while the existing bridge remains in service), and move it sideways to its permanent location after the existing bridge is removed.
Prior to the removal of the old bridge, the existing utility pipes (sewer, water and natural gas) would be placed on a temporary short routing just north of the existing bridge and supported in place during construction. They would eventually be relocated, housed and hung just under the new bridge deck, very close to where they currently sit. So, despite unscientific assertions to the contrary, little or no street excavation will be required to accommodate the pipes once bridge construction has been completed.
