For years, Pleasant Valley residents have been hearing booming sounds. The booms seem to happen during the summer, on weekdays and come in double bursts. According to documentation by residents, the booms occur between 11 a.m. and 3 p.m. and sound as if they are coming from the east. The source of the sounds has caused many theories, but it looks as if they may remain a mystery.
Recent letters to the editor propose the source of the sounds as being training exercises at Fallon Naval Air Station in Nevada, some 150 miles east of Placerville, or blowing up old army equipment at Sierra Army Depot in Herlong some 175 miles northeast of Placerville. Another theory is roadwork on Highway 88. Still another theory targets the quarries closest to Pleasant Valley — one on Quarry Road off Cedar Ravine or another one on Snow’s Road.
David Oppenheimer of the U.S. Geological Survey office in Menlo Park says explosions are difficult to pick up seismically. The USGS has two seismic stations in El Dorado County and monitors all seismic activity in the United States.
When contacted by the Mountain Democrat, Oppenheimer said, “To really pinpont a seismic activity, we need five seismic stations. We track the activity and locate it on our Website. Since there is little seismicity in your area, we don’t operate many stations.”
The sparse station coverage and the lower magnitude of explosions make it difficult to locate explosions, but Oppenheimer said if he is given an accurate time for the booms and the location of the hearer, he can visually inspect the seismic waveforms to see if there was an explosion and try to pinpoint a location.
“There are some places where we have routinely located explosions in the past,” said Oppenheimer. One of those locations is the quarry on Lotus Road west of Placerville and another is the Sierra Quarry on Quarry Road in Placerville. both operated by Loring Brunius.
“Not us. We only blasted once last year, said Brunius of his Placerville operation, “and not at all this year. I haven’t been able to do any blasting at all in Lotus.”
Brunius, 86, has owned Sierra Quarry, a limestone quarry, since 1975, but the quarry has been in operation since 1852.
“No one around here is blasting,” said Brunius, “including the quarry in Georgetown. There are too many regulations.”
Brunius has heard the booming noises, but said he has no theory about what might be causing them.
Snows Road Quarry operator Rob Findleton has only had the quarry since January.
“It was closed until then and we still aren’t officially open, but we haven’t been doing any blasting.”
In fact, Findleton has heard the booms himself while at the quarry.
“Three or four people have stopped by to ask about the booms and we’ve heard them in the background while we’re talking. It’s not us.”
Swansboro resident Lou Bacigaloup said he called the Sierra Army Depot about the booms and was told that they stopped using the open detonation process in 2002 and that they have no ammunition stores. Bacigaloup thinks the booms might be from atmospheric pressure in the Tahoe Basin.
Cindy Matthew, forecaster for the National Weather Service office in Sacramento, checked with several sources before declaring that there is no atmospheric condition that would cause such regular booms in the area. She suggested that planes from Travis Air Force Base, flying east over El Dorado County might be a possibility.
The Mountain Democrat contacted both Travis Air Force Base and Beale Air Force Base.
“Our planes are heavy aircraft that don’t go fast enough to cause the booms,” said a public affairs representative at Travis.” They usually head north, toward Lake Berryessa and not toward the east.”
“From my experience the sound you are describing would not come from a Beale aircraft. We use the Air Force U-2 Dragon Lady intelligence, surveillance and reconnaissance aircraft, MC-2W Liberty intelligence, surveillance and reconnaissance aircraft, RQ-4 Global Hawk intelligence, surveillance and reconnaissance aircraft, and the T-38 Talon training jet; none of which break the sound barrier. We do not fly any fighter aircraft from Beale,” e-mailed Shawn P. Nickel, senior airman, USAF, public relations representative from Beale.
Propane cannon, used by some growers to deter birds is another suggested possibility, but most of the growers who use propane cannons are in Apple Hill, more than five miles distant from Pleasant Valley and it is not thought the sound could carry that distance.
Contact Wendy Schultz at 530 344-5069 or firstname.lastname@example.org. Follow @wschultzMtDemo on Twitter.