GILROY
– There are no signs that a plume of potassium perchlorate
contamination spreading southward from an old industrial site in
Morgan Hill has reached Gilroy’s municipal water system, city
officials said Tuesday.
GILROY – There are no signs that a plume of potassium perchlorate contamination spreading southward from an old industrial site in Morgan Hill has reached Gilroy’s municipal water system, city officials said Tuesday.
Officials said testing of Gilroy’s eight municipal wells last November showed no signs of the chemical, which has been detected in one municipal well in Morgan Hill and more recently in other private wells in the Morgan Hill and San Martin areas,
“All of our wells have come up non-detect for any perchlorate …” said Dan Aldridge, operations services supervisor for the city’s water system on Tuesday.
Last week the Santa Clara Valley Water District announced a state investigation had found a plume of the chemical – originating from a now-closed industrial site – has traveled much farther through the underground aquifer than originally thought. They said hundreds of private wells southeast of the old Olin Corp. site around Tennant and Railroad avenues were in danger of being contaminated and would be tested. At least 450 wells are under scrutiny and the district has received hundreds more requests for tests.
Potassium perchlorate is a byproduct of fusee production, which Olin conducted on the site from 1955 to 1996, officials said. It is a naturally occurring salt and is used in flares, matches, solid rocket propellants and fireworks.
The chemical is known to cause tumors and thyroid problems. But so far, the amounts found in local wells are far below the danger levels and are not considered a major threat to public health, water district officials said.
At this point, the wells in question are located in an area bounded by Tennant Avenue to the north, Masten Avenue to the south, Monterey Road to the west and Center Avenue to the east, officials said.
Tuesday, Aldridge said the plume is two and 3/4 miles away from the city’s Well 5, which sits in the area of Leavesley Road and Murray Avenue and is the one officials would be most concerned about if the plume reached it.
Aldridge said water district officials told him it took 40 years for the plume to travel 4.5 miles. Averaged out at a spread of 1.8 feet per day, it would take 22 years for the contamination to reach Well 5, Aldridge said, which taps a deep-water aquifer and ranges between 390 to 840 feet in depth.
“It’s a slow-moving plume, and the farther out it gets from the site, the more diluted it becomes,” he said. “Hopefully they’ll get them all fixed and all the problems (solved) before it gets this far.”
Officials plan to test city wells again in February and July, Aldridge said.
“We’re following up on this,” he said.
The city’s eight wells are tied into a centralized distribution and tank system and are rotated weekly, he said. lndividual wells may not run at all for certain periods of time but be pumping heavily at other times, he said.
“We do a vast array of state-mandated tests every year, so we’re monitoring not only perchlorate but a whole list of (chemicals) …” Aldridge said. “We spend tens of thousands of dollars every year to make sure our water’s safe and to monitor it. If anything comes up, we’ll address it immediately.”
