Protecting the Environment
The San Francisco Bay is home to one of the most diverse communities of flora and fauna in the world, one that must coexist with the millions of people that live and work in the Bay Area. To protect these natural treasures, we have implemented a comprehensive program to safeguard the Bay’s fragile environment during construction activities.
California has always led the nation – and often the world – when it comes to protecting the environment. We are taking numerous steps to make sure the Seismic Retrofit Projects do not affect the environment around the bridge, from wildlife and plants to the Bay waters and shoreline they call home.
The environmental protection team has extensively surveyed, mapped and delineated the wetlands, eelgrass beds and sand flats near the Bay Bridge, primarily around the OTD and the east side of YBI. These areas have been designated with fencing, buoys and signage as Environmentally Sensitive Areas in which construction and access are restricted. In addition to these habitat areas, the team works to protect marine mammals, birds and fish that live in and around the Bay. To protect marine mammals, such as harbor seals, sea lions, harbor porpoises and gray whales, the team monitors to ensure they are not in the area prior to the start of any pile driving of the bridge’s more than 2,000 temporary and permanent piles. In addition, the team monitors their behavior during pile driving and other marine activities to ensure they are not disturbed.
The Bay Bridge and other Toll Bridge projects are global leaders in developing ways to reduce underwater noise caused by construction activity. One innovation is the marine pile driver energy attenuator, or “bubble curtain”, a dense shower of underwater bubbles (enveloping a bridge piling, for example) that helps protect fish and other marine life by dampening sound pressure waves during pile driving.
The teams’ regular hydro acoustic (underwater sound) monitoring, fish studies, and monitoring of bird predation as an indicator of fish mortality and injury have greatly contributed to the understanding of the effects of sound pressure waves on fish and the development of best practices to protect fish from elevated sound levels. In support of overall fish protection efforts in the area, the project also has helped fund more than 15 fish (e.g., salmon, steelhead trout) research and habitat restoration projects in the San Francisco Bay.
Since birds have been roosting on the original Bay Bridge for years, the team designed special platforms (a.k.a., “Cormorant Condos”) under the Skyway to provide nesting habitat in the same area. The project will provide opportunities for the creation and/or enhancement of shorebird roosting habitat in the East Bay. Furthermore, the team regularly monitors birds in the area, such as the American peregrine falcon, California least tern, California brown pelican, double-crested cormorant and western gull, to ensure they are not disturbed by construction activities. In December 2011, the environmental team stepped up when it witnessed territorial peregrine falcons attacking a young red-shouldered hawk on the Skyway of the new East Span. Team members picked up the bruised but otherwise healthy bird on the bridge and took it to the Lindsay Wildlife Museum, where the hawk made a quick recovery. A team member picked up the hawk and released it back into the wild in the Marin Headlands, with the help of the Golden Gate Raptor Observatory.
Eelgrass is extremely important to the Bay’s ecosystem in that it filters silt from the water and provides habitat for fish, birds and marine invertebrates. Beds of eelgrass are located near the project site, on the east side of YBI as well as near the OTD.