Dive Brief:

• One would expect that a highway crossing of a major river might spark environmental concerns, but it is a little surprising that the $3.9 billion construction of a new Tappan Zee Bridge over the Hudson River north of New York City now has a provision about the sound of pile-driving – underwater.
• The joint venture that the New York State Thruway Authority contracted to build the bridge is using a "bubble curtain" of sound-baffling compressed air around the piles being driven and, if all goes well, will not kill fish from two endangered species of sturgeon that use the river.
• Sharp sounds could kill the fish, biologists say, and part of the permit for the project requires putting acoustic transmitters and ID tags into 120 fish, putting 40 underwater receivers in place and tracking the health of the fish.

Dive Insight:

The worst-case scenario for the Thruway Authority would be finding that the underwater noise is killing fish, in which case the project could be brought to a halt. It already has to cease pile-driving between August and October, the period when the Hudson has the most sturgeon. Not one to give humans short shrift, the project already installed heavier windows in some nearby building to muffle the noise.