Editor’s note: This story has been corrected to reflect that only certain areas are closed at Hollywood Beach.
PORT ANGELES — Engineers at the city of Port Angeles still don’t know why recesses are forming in the sand off Hollywood Beach, closing certain areas of the beach to bathers.
But they’re looking into one possible cause — rotting wood.
“It’s still a mystery,” said Craig Fuller, city engineer.
Currently, engineers are investigating the possibility that wood debris deep under the sand is causing the depressions, Fuller said.
“There is a lot of sawdust. It is decaying, and the gases can loosen the sand,” he said.
City engineers examined the beach July 10 and 13 during extremely low tides and found three large recesses that some call “sinkholes” in the sand.
The largest measured 10 feet by 12 feet and 3 feet deep.
They prompted the city to post signs closing the beach to the public.
A work crew uncovered an aluminum pipe that was initially suspected as being a cause for the recesses but found that it was simply a discarded piece of pipe and not connected to any drainage system.
While searching for the source, crews took samples of the water from the holes and from the nearby seawater to see if a freshwater source was emerging on the beach and carrying the sand away.
There is no change in salinity of the water in the indentions, which eliminates a fresh water source — either a natural spring or a drainage pipe — as being the culprit, Fuller said.
Bob Campbell, facility coordinator for the Feiro Marine Life Center, located on City Pier adjacent to Hollywood Beach, reported the holes to the city July 7.
Campbell frequently wades into the harbor’s waters to seine for small sea animals that live in the flats to show to students at the center.
The first hole was found by Feiro employees about a month ago, and when more recesses began appearing, he called the city.
The recesses are located in tidal flats between 20 and 120 feet from the usual tide line, and are exposed during the lowest minus-tides.
City crews will examine the area again during the next set of low minus-tides, to see if the holes are still there — and if so, try to identify a cause, Fuller said.
The next set of extreme minus-tides will occur Aug. 7 though Aug. 11, according to National Oceanic and Atmospheric Administration charts.
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Reporter Arwyn Rice can be reached at 360-452-2345, ext. 5070, or at arwyn.rice@peninsuladailynews.com.
