An environmental expert who analyzed how toxins are being removed from Richmond’s contaminated Zeneca site gave a mixed review of their effectiveness at a recent meeting, concluding that sea level rise could render some technologies obsolete.
The Tue., July 8 meeting, hosted online by the Richmond Shoreline Alliance, attracted about 30 attendees, including Richmond city council members Soheila Bana and Sue Wilson and members of Richmond’s Recreation and Parks Commission.
The property, along the south Richmond shoreline, has sparked controversy over the city’s plans to allow it to be developed for housing and commercial uses. The project has been stalled by lawsuits.
Soil, soil vapor and groundwater contamination expert Martin Hamann, technical advisor for the Richmond Shoreline Alliance, said it’s important to evaluate the cleanup technologies, saying the site’s toxin levels are high enough to make it unsafe for human occupancy.
The site was home to various industrial companies for more than 100 years, companies that continuously disposed of hazardous chemicals into the land, groundwater and San Francisco Bay.
You can tour zeneca site online
Two major types of contaminants at the site include: Volatile organic compounds (VOCs) and heavy metals. VOCs are contaminants that easily evaporate into the air. Heavy metals, such as lead, arsenic, copper and zinc, stick to particulates around the site. At the moment, levels of VOCs and heavy metals in the site’s groundwater pose a high risk to aquatic life and human health.
The Department of Toxic Substance Control (DTSC) has implemented cleanup techniques to remove the hazardous contaminants. Hamann analyzed the effectiveness of the four strategies.
Soil vapor extraction doesn’t work on heavy metals or groundwater
Soil Vapor Extraction (SVE) is one of the primary ways of eliminating VOCs from contaminated sites. It works like a vacuum cleaner, sucking the volatile chemicals from underground wells into a carbon filter.
However, the technique doesn’t work on heavy metals or groundwater. In addition, Hamann said that SVP is less effective on claylike and shallow soils, both of which are prevalent at the Zeneca site.
In addition, recent reports have noted that the SVP at the Zeneca site has been drastically less productive in the last year, filtering out a total of 2 pounds of VOCs in 2024, compared to the 69 pounds it has removed since its installation in 2022. It also couldn’t be used for five months last year due to high ground water levels. Hamann concluded that SVP is not a viable permanent solution.
“My assessment is that the soil vapor extraction at Zeneca in the areas that they’re doing it has been limited in its effectiveness,” Hamann said on the Zoom call. “And in addition to being limited in its effectiveness, it’s more limited now than it has been in the past.”
Biological active permeable barrier called ‘fairly effective’
The second cleanup tool Hamann analyzed is biological active permeable barriers (BAPBs), which are placed underneath the soil and act as a filter for the ground water. As water passes through, the barrier traps dissolved heavy metals and precipitates them into solids, removing them from the water.
Hamann noted that BAPBs do not filter arsenic as well as other heavy metals. In addition, the barriers must be continuously monitored to ensure they don’t become blocked by contaminants.
BAPBs also have a finite life span. As the barriers continue to precipitate out contaminants, their capacity to hold heavy metals slowly decreases. However, since being installed in 2002, the BAPB at the former Zeneca site is still functional. Hamann explained that this strategy has continued to be fairly effective, and although it’s not foolproof, he is hopeful that BAPBs could prove to be a somewhat longer-term solution for the site.
Ground water injections ‘promising’ as long as they don’t exacerbate heavy metal contamination
Another strategy to combat VOCs is to inject into the ground other chemicals that react with and eliminate the contaminants. This technique commonly uses vegetable oils or microscopic iron.
It can take years for benefits to be seen. The injections have only recently been deployed at the Zeneca site, so it’s unclear whether they will be effective. In addition, there is a chance that the injections could cause stabilized heavy metals in the ground to shift, further contaminating the surrounding soil and groundwater.
Though it’s unclear how effective the injections will be, Hamann said that based on his experience it’s possible they will help.
“It just needs to be monitored to understand whether there’s any sort of adverse, unintended consequence with the heavy metals,” he said.
Capping could provide a long-term protective shield
The final approach to evaluate at the former Zeneca site is capping. Capping is not a cleanup tool but is a barrier placed between the contaminated soil and living things at the surface. Though a barrier does not “treat” an issue, it provides a long-term solution that’s protective of human life.
Richmond resident Michael Gliksohn noted during last Tuesday’s meeting that at previous meetings, the DTSC said a cap had already been installed, and along with monitoring the groundwater and soil contamination levels, it said that was all that was necessary before the proposed housing development would be built.
“So has DTSC done what they thought they needed to do before they could build 4,000 apartments?” Gliksohn asked. “Things seem to be quite different than that.”
Hamann explained that a temporary cap was installed at the site, but it has outlived its planned life. Experts are considering reconstructing more permanent ones.
Capping does have possible shortcomings, including erosion, destruction from earthquakes, tree roots or even rodents that dig holes in the caps.
The caps must be well-constructed and continuously attended to, Hamann said.
Rising sea water levels threaten long-term cleanup effectiveness
Hamann also addressed how rising sea water levels could impact the various cleanup methods.
According to state predictions, sea levels are expected to rise by up to one foot by the year 2030, up to 3.5 feet by 2050, and up to 7.6 feet by the year 2100.
Rising sea water levels lead to rising ground water levels. Therefore, soil vapor extraction will become less useful over time, as there will be less dry soil to extract VOCs from, Hamann said.
The biological barrier technique would likely continue to work, unless barriers become flooded enough that water passes around or over the barriers.
Similarly, with higher ground water levels, the chemical injections will become less effective with a larger mass to treat.
The caps should remain effective as long as they are dry. Once a cap becomes submerged in water, its functions are compromised.
“My bottom line admonition is that the cleanup that we have right now at Zeneca is designed for today’s environment. There is some consideration about sea level rise, but I think they’re not looking far enough into the future,” Hamann said.
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“My bottom line admonition is that the cleanup that we have right now at Zeneca is designed for today’s environment.“
— Martin Hamann, soil and groundwater contamination expert
Meeting attendee Annemarie Charlesworth followed up on Hamann’s conclusions by inquiring about the community’s involvement.
“I understand that the remediation efforts in place are inadequate,” she wrote in the Zoom chat box. “Clearly, this is going to have an increasing impact on human health. What is your opinion or advice about engaging public health, business owners and future residents about this?”
Hamann shared that regulators tend to fear public scrutiny and that public involvement can lead to better outcomes.
“If there was no opposition [by the public] at all on this site, the cleanup would probably be a little bit different than what it is now, simply because there is all this oversight, all these eyes on this project.” Hamann said.
He encouraged attendees to remain civically engaged to ensure the safety of current and future generations.
“It’s you showing up here that is very important, but also staying informed, asking questions, asking questions of the regulators, asking questions of the city council members, asking questions of the developers, those sort of things,” he said. “You need to make sure your voice is heard.”
This was a fascinating read! As a science lover, it is always interesting to hear about how we can use it to affect change, and it seems like that is happening here.