** More data needed, acoustics expert says.
By David Boyce
Almanac Staff Writer
A resident of New York City or Los Angeles or New Orleans might do a double or even a triple take at the level of night noise being investigated in Portola Valley, but interruptions to the sounds of silence at night are not taken lightly in this town.
Using a microphone he said was 1,000 times more sensitive than the human ear — and at the town’s expense — acoustics expert Timothy Brown visited the homes of four residents late at night in January.
He searched high and low for the source of a subtle hum, and the next day he did the same at a few places in town that have noisy equipment that runs 24 hours a day.
He monitored the boilers at The Sequoias retirement community at 501 Portola Road. He probed the air near two pumping stations, one operated by the West Bay Sanitary District and located behind the Village Square shopping center, and the other operated by California Water Service Co. on Portola Road near the border with Woodside.
Then he went back to his San Francisco office at Charles M. Salter Associates and analyzed his tape recordings for matches between equipment noise and home noise.
“Nothing really lined up,” he said in a reference to the homes of Annaloy Nickum on Brookside Drive and Steve Dunne on Canyon Drive, both of whom urged the Town Council to look into the problem. “It would take more study to isolate (the sounds) better,” said Mr. Brown. “We can rule things out, but we can’t really say what it is yet.”
The noises appear to be structural vibrations that have the frequencies of electrical devices such as motors, he said.
Meanwhile, two more residents who live in the same area as Ms. Nickum and Mr. Dunne report hearing a low hum at night.
Peter and Charlotte Thunen, who live near the Cal Water pump, did better: Mr. Brown matched the noise they hear with the pump. The water company is addressing the noise, said Planning Manager Leslie Lambert, who is handling the issue for the town.
For Al and Jo Shreck of Golden Oak Drive, Mr. Brown said they could probably find the noise source in their own house, said Ms. Lambert.
What’s next?
If there are next steps, it will be up to residents to sort them out. The acoustics analysis has used up the $2,000 the council set aside to look into the matter and Ms. Lambert recommended against more spending at the February 8 council meeting.
“It does not appear that any town function or any regulated (entity) such as The Sequoias is the cause of the problem,” she said.
The council unanimously agreed with her recommendation, with Councilman Ted Driscoll absent.
Before the council’s decision, Ms. Nickum said she now hears new droning sounds on nighttime walks. “Now that I’m sensitized, it’s very easy to pick up these noises,” she said.
“I’m sorry that we don’t have a solution for you,” said Mayor Steve Toben while noting that he is now more sensitive to the issue of noise pollution.
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