A subcontractor for the Oregon Department of Environmental Quality (DEQ) began another round of testing last week to identify wells in north Lebanon neighborhoods that may be contaminated with industrial chemicals.

The use of the chemicals trichloroethylene (TCE) and tetrachloroethylene (PCE) by several former dry cleaning businesses are responsible for much of the groundwater contamination.

In 1990, PCE was found in groundwater at Lebanon's Century Park. Since then the DEQ has sampled about 120 wells for volatile organic compounds (VOC). About 50 wells have been identified as having VOC levels above safe drinking water standards, according to a DEQ fact sheet.

The contamination extends beneath an area of about 0.6 square miles. The area being studied by DEQ is bounded by Harrison Street to the north, "D" Street to the south, Hiatt Street to the east and 10th Street to the west.

In 2007, testing identified four additional Lebanon wells with concentration levels as high as 39 parts per billion (ppb) for PCE and 14 ppb for TCE. The U.S. Environmental Protection Agency (EPA) sets the maximum contaminant level of PCE and TCE in drinking water at 5 parts per billion (ppb). Both chemicals are considered possible cancer agents.

Although most homes are now on city water, DEQ has identified about 300 active wells. Homeowner participation in the testing program is voluntary and free of cost.

"I would be surprised if we didn't find more contaminated wells," said Don Hanson, DEQ project manager.

As an interim step, the DEQ is providing bottled water to homes with unacceptable concentrations of contaminants.

"We want to identify everybody, and then move on to a more permanent solution," Hanson said.

The most likely fix is for DEQ to pay for those residents with affected wells to be hooked up to city water. DEQ has already paid to connect one house to Lebanon's water system, which draws its water from the Santiam Canal, and is not affected by groundwater contamination.

Another option is to extract the water out of the ground, filter it, transport it to higher elevation and then inject it back into the water table and repeat the process until contamination is at acceptable levels, said Chris Martin, an environmental engineer with Hart Crowser, the Portland based firm contracted by DEQ to test Lebanon wells.

The sources of contamination identified by the DEQ are:

€ Johannsen Cleaners (now Richard's Cleaners) at 910 Park St.

€ Kwik Clean at 535 Park St.

€ NuWay Cleaners at 581 S. Main St and 525 S. Main St.

€ Poly Clean, 70 E. Oak St

€ Union Cleaners, 581 and 525 S. Main St.

Most of the businesses have been closed for three decades and more. Only the former Johannsen Cleaners is still in operation, as Richard's Cleaners.

Contamination occurred primarily before 1980, when rules on dumping cleaning solvents were less strict and it was common to dispose of wastewater onto the ground or into sewer systems. DEQ conducted cleanup at the locations of the cleaners about a decade ago.

The most recent testing shows concentration levels at the dry cleaning sites range from 181 ppb billion for PCE (ppb) and 454 ppb for TCE.

Hanson said there are probably other businesses that contributed to Lebanon's groundwater contamination as TCE and PCE are widely used industrial solvents. In fact, several other chemical compounds including metheylene chloride and diesel have been detected in local groundwater.

Lebanon's watertable is about 10 feet below the surface, making it more susceptible to contamination than at other geographic locations such as Eastern Oregon, where the aquifer can be as deep as 200 feet.

"Any time you have a shallow a water table and solvents it's a bad combination," Hanson said, adding that solvents can travel up to a mile from the contamination source.