November 29, 2010 10:11 AM
KAREN JONAS, Staff Writer
HINKLEY • The Lahontan Regional Water Quality Control Board will be deciding soon if an expansion to the treatment of the chromium 6 water plume in Hinkley will be put into place, but residents probably won’t see the results in their lifetimes.
Pacific Gas and Electric is proposing to expand its current operation of injecting the chromium 6 tainted water with ethanol to convert it to the less dangerous chromium 3. In a feasibility study done by the water board, the ethanol treatment would probably take about 150 years to restore chromium 6 levels to the naturally occurring levels of 3.1 parts per billion.
The study also shows that the removal of the chromium 6 tainted groundwater will take more than 100 years, even with the most effective treatment.
PG&E is currently injecting ethanol into the plume in order to convert the chromium 6 into chromium 3 which is much less toxic. The company pumps contaminated water out and sprays it onto alfalfa plants so that it will not be spread through the air. PG&E also injects clean water as part of the pro – gram to cleanse the groundwater.
The expanded program will include increased pumping and will occur over a larger area, said Lauri Kemper, assistant executive officer for the Lahontan water board.
Kemper said the program was chosen out of five different alternatives because PG&E had tested a variety of treatments over the years, and the ethanol treatment worked best with higher concentrations of chromium 6.
The plume of contaminated water has been slowly growing and is now about 2 miles long and nearly 1 mile wide.
PG&E has been ordered by the water board to clean up the chromium 6, but the plume continues to grow.
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