SLO city to hold groundwater contamination meeting 

Industrial pollution in San Luis Obispo groundwater will be the subject of multiple upcoming public meetings.

The city of SLO is hosting a meeting on Nov. 16 to discuss a PCE plume found below the city in the San Luis Valley Groundwater Basin.

A toxic chemical, PCE is a product of dry cleaning and industrial activities that are no longer active, according to the city.

SLO recently leveraged a $2.2 million state grant to undergo testing and analysis of PCE in its groundwater, which led to the detection a plume that roughly follows the path of the San Luis Creek, between Los Osos Valley Road and the downtown area, according to a map.

click to enlarge

• Map Courtesy Of The City Of SLO
• PLUME The city of San Luis Obispo is leveraging state grant funds to study and remediate a plume of PCE contamination in the San Luis Valley Groundwater Basin.

PCE contamination in SLO has been on the minds of local and state officials for a while, according to city Water Resources Manager Nick Teague, but the grants are helping SLO begin to fully measure and tackle the problem.

The city stopped using groundwater in its water supply in 2015—a decision made partly due to concerns over water quality and drought and partly due to newly available water from Lake Nacimiento, Teague said.

The goal is to eventually restore local groundwater to a point where it can be added back to the drinking water mix.

"We don't utilize groundwater right now, but we'd like to," Teague said.

The Nov. 16 meeting—which will be held in the Ludwick Community Center from 5:30 to 8 p.m.—is meant to update the public about the PCE studies and what lies ahead.

According to a press release on the meeting, the city has been "taking steps to study the location, width, depth, pace and movement of theplumewith the goal of providing high-quality drinking water to the community."

For residents worried about PCE contamination before 2015, Teague noted that the city's formerly active wells were located outside of the plume. He also said the recent tests are showing that PCE levels are declining. Some of the tests detected PCE at levels slightly higher than the state drinking water standards, but not "10 or 100 times" them.

"One of the interesting findings from this is concentrations were much lower than what people expected to see," Teague said. "That tells us the PCE source has basically been eliminated and we're seeing some degradation or dilution of PCE."

Just outside of city limits, another toxic groundwater investigation continues near Buckley Road and the SLO County Airport. A long-running inquiry into a TCE plume that's contaminated more than a dozen area wells took a recent turn.

Groundwater tests submitted by Oilfield Environmental and Compliance to the Central Coast Regional Water Quality Control Board showed that there's likely a new source of TCE—three years after regulators allegedly found the culprit.

In 2019, the Central Coast water board pinned the TCE pollution on a local machine shop, Noll Inc. But contradicting evidence revealed in 2021 caused the agency to start an investigation of the machine shop's neighbor, a former industrial lab.

Those new test results at 795 Buckley Road, dated June 3, show TCE levels as high as 930 micrograms per liter (μg/L)—nearly 200 times the federal drinking water standard and higher than the levels found at Noll Inc. The site also tested positive for elevated levels of benzene, another toxic chemical, according to the report.

Greg Bishop, a senior engineering geologist for the regional water board, told New Times in an email that the agency is considering its next steps for "issuing regulatory directives" at 795 Buckley.

He also said the board is planning to hold a public meeting in the near future to allow Buckley Road area residents a chance to ask questions about the investigation and other groundwater pollution issues.

"An announcement on the date of the public meeting is forthcoming," Bishop said. Δ