MORGAN HILL
– The Santa Clara Valley Water District may spend up to
$1,050,000 to buy, install and operate a treatment system that
would remove perchlorate from water taken from one of Morgan Hill’s
contaminated municipal wells.
MORGAN HILL – The Santa Clara Valley Water District may spend up to $1,050,000 to buy, install and operate a treatment system that would remove perchlorate from water taken from one of Morgan Hill’s contaminated municipal wells.
Meanwhile, city officials announced last week that two wells shuttered for perchlorate contamination have retested nondetect, although they will likely remain off-line for stabilization.
If water district directors approve the Calgon treatment plant proposal today, the system should be up and running by July 1, Mayor Dennis Kennedy said Monday. City officials had requested the district provide treatment to remove the chemical at one of its existing wells by July.
“That is excellent news,” Kennedy said. “The proposal came from our city staff and we’re very pleased that the water district is moving forward in this direction.”
The plant will likely be installed at the Tennant Avenue well across the street from the Olin site at Railroad Avenue, Kennedy said. That well was closed in spring of 2002 when its water tested far above the 4 parts per billion level where the state mandates “action” by reporting that fact to water users.
The city responded by taking the well off-line. Since that time, three other city wells tested positive – though at low levels – and were taken off-line.
Tewes announced last week that the Nordstrom and East Dunne wells have retested nondetect, which is below the state action level. The Condit well tested at 5 ppb. However, all wells remain off-line until the levels have stabilized, Tewes said. Wells will be next be tested for perchlorate on May 28.
Roughly $1 million of the water district funds would cover capital outlay for the treatment plant, with the remainder covering operating funds for change-out of the units.
“The only cost the city will incur will be the cost of power (electricity) for pumping, which we normally would take care of anyway,” Kennedy said.
Still out in the cold are owners of more than 1,000 private wells between south Morgan Hill and north Gilroy.
“The theory is that while it (the proposed treatment system) doesn’t solve San Martin’s problems, it does help,” said Mike DiMarco, spokesman for the water district. “It’s not the ‘be all, end all’ – but if water is being pumped out by a huge well like that, if perchlorate is one-third of that water, it will help.
“And it’s something that we can do right now.”
DiMarco said he doesn’t know yet if there is a similar plan in the works for San Martin municipal systems. Nothing has been proposed for private wells in San Martin or Morgan Hill.
“Pumping at the Tennant Avenue site will decrease the spread of the plume south and draw the contamination back towards the site,” DiMarco said. “This may, in fact, help the San Martin residents as well.”
There is debate over how the perchorate problem is affected by percolation ponds for groundwater recharge the water district maintains in Morgan Hill on San Pedro and East Main avenues.
One theory maintains that, as the water filters down into the aquifer, it dilutes the contaminated water.
However, another point of view is that the more water that enters the aquifer, the faster the perchlorate plume is pushed south toward San Martin.
DiMarco does not agree with that contention.
“The percolation ponds are not the villain here,” he said. “If you are not putting water back in the underground basin, you lose your water source and land will start sinking. There is a fairly involved system of underground pipelines and it would be affected too.”
The perchlorate came from a highway safety flare manufacturing plant the Olin Corp. ran at Tennant and Railroad avenues from 1955 to 1996. The chemical was rinsed into a percolation pond on the site, leached down into the underground aquifer and has been found in municipal and private wells as far south as Leavesley Road in Gilroy.
While Olin has claimed responsibility and is, with the water district, providing bottled drinking water for residents who have contaminated wells, the company is required by the state Regional Water Quality Control Board to begin to operate its plan for clean up of the soil and water by the end of the year.
The water district staff report said the city’s urgency about the treatment plant is challenging to finding a “permitted, installed and operating system.” The state Department of Health Services has approved only two perchlorate removal systems, Calgon’s Ion-Exchange System and Envirogen’s Fluidized Bed Reactor System.
The water district staff’s analysis concluded that only the Calgon system would satisfy the July deadline.
According to the report, the Calgon system is a “self-contained, skid-mounted ion-exchange unit that can be installed at one of the city’s existing well sites.” It is smaller, cheaper and quicker to install than the Envirogen method.
The Calgon system, the Water District report claims, is also a “non-regenerative system that has no waste discharge.”
Calgon will replace the spent units – they last from several days to several months – and will remove them off-site, the report said, keeping the process consistent with California Environmental Quality Act.
The ion exchange method draws water into cells containing adsorbent material. Ion exchange resins are common but silica gels, activated carbon and molecular sieves are also used, according to the Calgon Carbon Corp. The perchlorate ions attach themselves to resin units and add chloride molecules; the altered chemical configuration renders the perchlorate harmless.
However, in the past, along with treated water, the process produced a brine solution which must be disposed of. This was dumped, in the ocean or elsewhere or burned. Dumping will become illegal in California by 2006. Ion exchange is frequently used to treat water in Southern California which has a serious perchlorate problem because of the numerous defense facilities.
Calgon Carbon will provide start-up services and will work with the water district and city staff. The report said that the water district has staff who are state-licensed, and can operate the plant, as does city staff, but that additional personnel may be required. The report said that the district would prefer to operate the plant itself.
Olin has already started with the remediation efforts plan for the soil, he said, and this will be the first step toward remediation on the groundwater itself.
Perchlorate interferes with the uptake of iodide to the thyroid and, in sensitive systems, can cause problems. Infants and pregnant women are especially susceptible because of the developing brains of fetuses and newborns.
