Back in the good old days, solvents such as perchlorate fuels from industrial processes, aerospace, government suppliers and dry cleaners were dumped into the local San Gabriel Valley soils at the beginning of the Sputnik era. It's contaminated one of the largest groundwater basins in the region, holding over 3.5 trillion gallons of water. This water is not being replenished adequately any more due to subsequent paving over of vast areas with asphalt and concrete, which creates not only water supply and water quality issues, but contributes to ground subsidence and dying trees and vegetation as water table levels recede due to over-pumping. The EPA identified this area in 1979, and has completed the necessary data review from groundwater samples at the local wells along Main Street in Alhambra (black dots in picture above). This is from a file found at the EPA Region 9 website for Area 3.A report from the Pasadena Star-News on April 15, 2010 reported on the EPA outreach that took place this past week in the San Gabriel area:
Progress is being made on the federal effort to clean contaminants in the San Gabriel Valley's last Superfund site.
EPA officials are meeting with Alhambra, Rosemead and San Gabriel residents to explain the extent of groundwater contamination under their cities.
"Now we have the data, so we can begin to consider ways to clean it up," EPA area project manager Lisa Hanusiak told residents at the Alhambra Library on Wednesday.
The area in question, which includes the cities of Alhambra, San Gabriel and parts of Rosemead, Temple City, San Marino and South Pasadena, was declared a Superfund site in 1984. But it was not until a few months ago that EPA scientists completed their full investigation on the extent of contamination there.
That investigation revealed extremely high levels of tetrachloroethylene (PCE) and trichloroethylene (TCE) - up to 300 times the level allowed for drinking water. Those chemicals - used in degreasers, industrial solvents and dry cleaning solutions - are carcinogens.
The chemicals leached into the groundwater after decades of dumping by businesses.
The EPA is attempting to determine the companies responsible for the contamination in order to get them to pay for part of the cleanup.
The EPA will spend the next year preparing several plans for removal of the contamination. Officials will select a remedy by next year, Hanusiak said.
There is a watchdog group that's emerged, The San Gabriel Valley Oversight Group. It's a nonprofit, public benefit corporation. It was founded in 2006 by a group of five individuals who live in the San Gabriel Valley, California. They have very interesting information on their site, including a real informative power point slide show. The chart below is at the end of the slide show, and shows how the water levels in the wells have been consistently declining over the last 17 years.
It's important to not only clean out these plumes of contamination, but to also develop remedies for unpaving as much area as possible along with recharging strategies for when it does actually rain. We're definitely running into critical groundwater issues now, and it will also mean water recycling to conserve what we have at this point, since climate change has chased away the clouds and rain.How things have changed since before I was born.
Update 6/4/17: Contaminated ground water in San Gabriel Valley gets $250 million boost, extending cleanup until 2027
Update 7/18/17: WQA report on Area 3 decontamination progress
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