Pacific Gas and Electric Co. told regional water quality officials in Southern California that the utility will begin early this month installing a larger pump to draw chromium 6-tainted groundwater out of the desert floor around the Colorado River at the California-Arizona border, preventing it from reaching the river waters, which are a major source of drinking water in the southern end of California.

As the tainted water has reportedly migrated within 125 to 150 feet of the river, PG&E’s utility told the water officials that the utility is prepared to construct an underground barrier to further protect the river water, according to a report in Thursday’s Los Angeles Times. The use of chemical agents in the tainted groundwater to break down the toxic elements is also being considered.

The regional water district serving much of Southern California is worried that the underground plume of some 108 million gallons of tainted water with concentrations of chromium 6 at the 12,000 parts/billion level might reach a Colorado River aqueduct and an intake point used by water suppliers in both California and Arizona. No traces to date have been found in the river, the LA Times reported.

Chromium 6 is the toxic chemical that made famous “Erin Brockovich,” the woman and the motion picture, four years ago, relating to some of PG&E’s utility natural gas transmission operation in the Mojave Desert, about 130 miles northeast of Los Angeles.

PG&E’s gas utility officials and others last month expressed confidence that their ongoing efforts will be successful in preventing any contaminated water supplies from getting into the Colorado River near Topock, AZ, where a major PG&E natural gas transmission pipeline picks up interstate supplies from the Southwest.

The center of the concerns is the long-ago disposal of quantities of water containing chromium 6 that the utility used from 1951 through 1969 as a means of preventing corrosion and mold in water cooling towers at its isolated gas pipeline receiving station along the Colorado River. The underground plume of tainted water that had been dumped untreated in percolation beds for 18 years is now threatening the river.

While noting last month that no traces of chromium 6 have been found in the river water, the California toxic substance control department director was quoted as saying the state views the situation “very seriously,” and that is why it is pushing PG&E’s utility to do more pumping to accelerate removing the contaminated water.

Beginning in mid-March, PG&E’s removal program took 20,000 gallons of groundwater daily from three extraction wells at Topock, trucking the contaminated water away to a toxic waste disposal site. The state officials said they are confident this pumping will move the chromium 6-tainted groundwater away from the river supplies.

The situation arising at the Arizona border natural gas pipeline juncture is similar to the compressor station PG&E maintains in the Southern California high desert town of Hinkley, near Barstow, CA, that was first uncovered as a potential problem in 1987. It was the focus of the Erin Brockovich movie and a $333 million settlement with local residents in that town. In both Topock and Hinkley, chromium 6-tainted water used in cooling towers was dumped in unlined evaporation ponds where it percolated down into the groundwater.

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