Posted by: Jan | May 7, 2018

Construction Noise Impacts


In this blog, I’ll report on the findings from the Water Board Hearings about the noise impacts from the tunnel construction on the small communities in the North.

The towns of Hood and Clarksburg are in the middle of the massive tunnel project. That is where the pumping station will be located.

An expert sound witness hired by Save the California Delta Alliance to testify in the Water Board Permit Hearings about the WaterFix (Delta Tunnel) permits, reviewed the WaterFix Noise Chapter and found that, in his opinion, the calculations for sound used by the DWR are incorrect. Walter Salter testified that, ‘Construction noise levels are likely underestimated in some areas, by as much as 10 dB to 15 dB or more…” He found that, “Construction noise (pile driving, blasting, and trucking activities) is expected to significantly interfere with the activities at certain recreational facilities or businesses available for community enjoyment, such as the Clarksburg Marina and the Hood Supply Company (restaurant).”

During his testimony, Salter testified that it is likely that school children in Hood and Clarksburg would not be able to hear what their teachers are saying during the six months of construction for years and years!

Is the noise level really going to be bad? Slater stated that, “4 pile drivers could be in concurrent use at each ‘feature’ or facility/intake with up to 90,000 pile strikes per day at each facility. Over a 12 to 15-hour work day, that would result in over 100 pile strikes per minute, and perhaps several per second.”

Yes! That sounds very, very bad to me. That isn’t something communities should be subjected to.

How close are these communities to the pumping stations being built? Here is how the construction sites dwarf the small legacy town of Hood:
scda_70 TownOfHood.png

And on the other side of the river, the Clarkson School is close enough that kids won’t be able to hear their teachers:
scda_71 Clarksburg.png

Even for Discovery Bay, the construction is further away, but it will be annoying and disruptive. And up and down the Delta waterways, boating in the Delta will no longer be peaceful and scenic.

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Responses

  1. Reblogged this on California Water Research and commented:
    Noise impacts of the WaterFix project construction are underestimated in the CEQA environmental documents.

    • Thanks, Deirdre!

  2. Hi Jan,

    I don’t know what decibel level they are estimating for the pile driving but distance from the noise source and particular frequencies can wreak havoc on the human ear. One thing readers need to take into account is the fact that the scale for noise is exponential. Sound power is measured indirectly as it cannot be measured without a conversion so we measure sound pressure and convert it to sound power. Anyway, I always remember my college professor telling me that a 3dB reduction in noise is a 50% reduction so the estimates for the pile drivers being off by 10 or 15 dB is HUGE! Here is a good reference for some common noise:

    http://www.industrialnoisecontrol.com/comparative-noise-examples.htm

    In a past life I did a lot of acoustic work in the outdoor power products design and development, so those number you posted really caught my attention.

    -Dave

    • You are right, Dave! The noise expert witness called the error “gross” and explained he meant huge. Thank you for the link an additional information!!!

  3. Amazing how hypocritical the CDfW staff are. They held our project up for months because we wanted to drive 40 piles in the San Joaquin river because they said it would disturb and damage the fish hearing. I guess they must be providing hearing aids to the Delta fish when driving thousands of piles for the tunnels monstrosity.


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