We are pleased to announce that Noise Monitoring Services has been selected to perform underwater noise monitoring for the Edinger Bridge replacement project in Huntington Beach, California. Since late July, we have been working with MBC Applied Environmental Sciences of Costa Mesa to monitor underwater sound near the construction site. This monitoring is required during pile driving for the protection of sea turtles, marine mammals and fish living in the sensitive marine habitat around the bridge.
The project involves the rebuilding of the road bridge on Edinger Avenue, which spans a channel running into the harbor. High underwater noise levels can occur during pile driving when these structures are built. Previous studies have shown that pile driving can create sound levels in the water that are high enough to injure or kill fish, and harm turtles and mammals. This project requires compliance with Caltrans underwater noise limits for the protection of fish of 206 dB Lpeak and 183 dB SEL per impact. Various methods are being utilized to reduce the noise, including use of ‘bubble curtains’ (which create a wall of bubbles around the pile) and reduction of the hammer impact force.
Sea turtles, an endangered species, are known to live in the area. The turtles are not native to the area but are attracted to the warm water of the nearby San Gabriel River, which is heated by the outlet of a power plant. While no turtles have entered our area of the bay yet, we were visited by a young gray whale (picture below). The one-year-old, 15-foot-long whale is thought to have been separated from its group on its migratory route to its feeding grounds off the coast of Alaska. After construction was halted, the whale eventually made its way out of the bay and into the open ocean.
The hydroacoustic noise monitoring systems we are using on this project consist of measurement-quality hydrophones connected to precision sound level meters. These continuously log sound level data as well as record audio files to enable waveform analysis of individual pile impacts. Click here for more information on our underwater noise measurement services.