New, Deeper Well Also Yields Contaminants

Times Staff Writer

Water from a new and much deeper well dug by the San Gabriel Valley Water Co. in hopes of finding a purer supply for its 5,300 customers here is just as contaminated as the water drawn from older wells, tests show.

Drilling of the new well began after the water company, at the direction of the state Department of Health Services, notified its Hacienda Heights customers in September that they were receiving water that was unfit to drink because of the presence of dichloroethylene (DCE) and that they should buy bottled water. A week later, state health officials withdrew that recommendation and notified residents that they could safely drink the well water for “a limited period of time” while the company dug a deeper well.

But now that the new well has been dug, to a depth of 700 feet, tests show that its water is just as contaminated with DCE as wells that draw water from 300 feet. Water from the new well is not being distributed to customers.


State health officials said last week that Hacienda Heights customers can continue to drink the well water delivered to their homes and that they are reevaluating the possible health hazard. Harvey Collins, chief of the environmental health division, said new research indicates that DCE does not cause cancer and presents a lower health risk than originally thought.

Deeper Well Impossible

Gary Yamamoto, senior sanitary engineer with the state health department, said that the San Gabriel Valley Water Co. originally planned to drill its new well to a depth of 1,000 feet. But soil conditions forced the drilling company to stop at 700 feet, and that was too shallow to bypass the contamination.

Yamamoto said the company and health department will prepare a letter to send to customers this week explaining the DCE problem and informing them that the plan to obtain purer water by drilling a deeper well has failed.

Michael Whitehead, water company executive vice president, said the company will prepare a plan to solve the DCE problem, probably by installing an aeration treatment system.

Water from the new well registered 1.6 parts per billion of DCE according to a test by the water company, and 1.7 according to a state test.

The amount of DCE contamination is small but well above the 0.2 ppb that the state sets as its action level, the point at which the state advises water producers to reduce the concentration.


EPA Raises Level

Collins said the state is reevaluating its action level for DCE because the federal Environmental Protection Agency has proposed a drinking water standard for DCE of 7 ppb, based on research that indicates that the compound is not a carcinogen. Collins said the state will look at the federal research to reevaluate the state action level.

If the state raises the action level to 7, San Gabriel Valley Water Co. will meet that standard without taking any action. Company officials said the water being delivered to Hacienda Heights contains an average of less than 1 part of DCE per billion.

But if the state does not change the standard, the water company will be required to install a treatment system to remove DCE. And state and water company officials said it could take a year to obtain permits and install an aeration system, which would remove DCE and other volatile organics and emit them into the air. Such a system, similar to those in use in Arcadia and Baldwin Park, would require approval from the South Coast Air Quality Management District.

DCE is related to a family of volatile organic compounds that have been found at high levels in about 60 of the 400 wells in the main San Gabriel basin, the principal water supply for most of the San Gabriel Valley. The compounds, including trichloroethylene (TCE) and tetrachloroethylene (PCE), are mostly solvents used as degreasers and cleaning agents. Some of the compounds have caused cancer in laboratory animals, though the evidence that they cause cancer in humans is based only on theory.

Investigation of Source

How the chemicals got into the area’s ground water is being investigated by the EPA, the regional Water Quality Control Board and other agencies.

Hank Yacoub, supervising engineer for the water quality board, said that it is possible that the DCE leaked into the ground water from one or more of the many industrial companies near the San Gabriel Valley Water Co.’s contaminated wells. He said 41 companies within half a mile of the wells will be sent questionnaires next week inquiring into their handling of chemicals. Yacoub said the companies were selected because they have applied for underground tank permits or are believed to store chemicals.


The wells serving Hacienda Heights are in the City of Industry, about two miles from the Puente Hills landfill. Yacoub said separate monitoring is being done at the landfill to determine if it could be a source of contamination.

Depth ‘Is Disturbing’

Yacoub said the fact that ground water is contaminated so far below ground “is disturbing” and indicates that cleaning up the contamination poses a severe problem. Yacoub said contamination is so extensive in the San Gabriel Valley that an increasing use of treatment systems seems inevitable.

Stephen B. Johnson, supervising civil engineer with Stetson Engineers Inc., which has done extensive survey work on ground water contamination in the San Gabriel Valley, said it was expected that such contaminants as DCE, being heavier than water, would work their way far below the surface eventually.

But, he said, it is a surprise to find them there now. Johnson said the general location of plumes of contaminated water is known, but the depth of the contamination is not well established.

San Gabriel Valley Water Co. has about 42,000 customers in the San Gabriel Valley but the only ones affected by the DCE problem are the 5,300 households and businesses in the western half of Hacienda Heights south of the Pomona Freeway.