PG&E: Toxic tank in Santa Rosa best left alone

A huge underground tank full of toxic black sludge in downtown Santa Rosa should be left where it lies because it is too difficult to safely remove and poses little threat to neighboring Santa Rosa Creek, according to the Pacific Gas & Electric Co.

The utility has also concluded that the contamination on the site of its former manufactured gas plant is immobile enough that it does not need to install a costly barrier designed to prevent waste material from migrating toward the creek, arguing it would be too disruptive and unnecessary.

The hands-off approach outlined for the Santa Rosa City Council last week represents a departure from the aggressive cleanup efforts that PG&E has undertaken on the property in recent years, which have resulted in the removal of tons of similar material.

But PG&E’s environmental consultants say the new strategy is justified because years of water-quality monitoring data shows that neither groundwater in the area nor the creek are at risk of contamination.

“The stuff is immobile. It hasn’t gone anywhere over the past 100 years and we have over 25 years of data,” Max Reyhani, principal engineer with Terra Pacific Group, told the council. “I think that’s a pretty good indication of the stability of site conditions.”

PG&E’s latest plan still needs the approval of the North Coast Water Quality Control Board, which has been overseeing cleanup of the property for nearly 30 years. The City Council, which has no direct authority over the cleanup of the site, has requested regular status reports on the downtown project.

Water board staff expressed confidence that continuing to monitor groundwater in the area made more sense than requiring the removal of the tank and material at this point.

“With the monitoring, I am extremely confident that we’re not going to have an issue that actually manages to migrate to the creek (over the next decade),” said Craig Hunt, supervisor of the water board’s cleanup division.

But not everyone is so sanguine about the situation.

Allen Hatheway, author of a 2012 textbook on the subject of cleaning up former gas plant sites, called the claims that the tank can’t be removed “nonsense.”

In an interview, the retired Missouri University of Science and Technology professor of geological engineering and author of the 1,400-page book, “Remediation of Former Manufactured Gas Plants and Other Coal-Tar Sites,” said the claim that it is safer to leave such potent contaminants in the ground is “a standard utility industry argument” used to avoid costly cleanup efforts.

While there are challenges to performing such work in downtown environments, remediation companies are more than capable of completing such work, Hatheway said.

“It can be done and it’ll be a lot more straightforward than the City Council has been led to believe,” said Hatheway, who said he reviewed council materials and watched a tape of the meeting. He is not involved in the cleanup effort and has not studied PG&E’s plans in detail.

“Is it appropriate to just walk away and leave that?” he asked.

Remnants of past

The industrial history of the 1.5-acre site on the northern bank of Santa Rosa Creek at First and B streets stretches back to 1876 when the Santa Rosa Gas Light Co. began producing and distributing gas to light city streets and heat cooking stoves. Unlike the natural gas used today, gas in the 1800s and early 1900s was manufactured locally from coal or heavy oil. The process left behind wastes that were frequently disposed of on or near the property.

Coal tar contains polynuclear aromatic hydrocarbons, a family of chemicals that includes known cancer-causing agents. The steel tank in question is 50 feet long, 6 feet wide and filled with coal tar that is the consistency of taffy and has a high concentration of naphthalene, Reyhani said.

PG&E purchased the plant in 1908, closed it in 1924 and used it for several decades as a distribution facility. Then in 1987, it sold the site to a private development partnership, 137 Santa Rosa Group, which agreed to clean it up before constructing an office building on the property.

Regulators warned the developers, including Hal Musco, the owner of a petroleum services company, of the need to fully clean the property up. Local fire officials granted a permit allowing the tank, which was located near a high-pressure gas main, to be left in the ground, but only after being emptied and filled with an inert material.

That never happened, and a parking lot was built over the site in 1989. Decades of legal wrangling between the water board, developers and PG&E followed. The water board got serious in 2004, after the construction of the Prince Memorial Greenway uncovered contamination along the northern bank of the creek at the site. The board issued fines and, in 2006, PG&E took the lead in the cleanup.

Millions spent on cleanup

The utility has spent tens of millions to date on the project, including the removal of two other underground tanks and a multiyear effort to cook 600,000 pounds of coal tar out of a 46-foot-wide, 22-foot-deep redwood pit. The technology was used because digging the material out would have released noxious fumes into the neighborhood. Half of the parking lot at the building - which houses Westamerica Bank and TLCD Architecture, among other tenants - was walled off for more than a year as probes heated the coal tar and captured the vapors. The remaining material in the redwood tank was then sealed off with concrete in 2013.

PG&E has since turned its attention to the remaining underground storage tank. Reyhani said they’ve explored a number of different ways to remove the coal tar, but can’t find a solution that is better than just leaving it be for now.

The tank, which sits just a few feet below the surface and 10 to 15 feet above the water table, is too big and heavy to pull out while full. They’ve explored heating or dissolving the coal tar to liquefy it and pump it out. They’ve looked at freezing it or encapsulating it in place. They’ve also considered installing a huge tent over the parking lot to capture the fumes during removal.

“None of these technologies were able to overcome the number of technical, logistical and chemical challenges associated with this material,” Reyhani said.

Instead, PG&E will wait for an opportune time in the future, such as when the property is redeveloped, and will remove the tank at that point, Reyhani said. The utility would also consider removing it if new technology made the job more feasible, he said.

Hunt, the water regulator, said it could be “decades” before the tank was removed. The downtown location, near occupied office buildings, is the main reason removal isn’t currently feasible, he said.

“If this were just an open field, we’d go and have it done,” Hunt said.

That comment made Councilman Gary Wysocky wonder if financial considerations were playing a role in the project direction.

“Now I’m thinking you’re not disturbing that because you don’t want to disturb 10 parking spaces,” Wysocky said.

Hunt said that wasn’t the case. He said regulators “would still make them do it” if the effort covered “half the parking lot.”

Reyhani called the open field analogy “very hypothetical.” He said leaving the tank in place and monitoring it makes sense because of the logistical challenges and the “physical and chemical properties of this material,” which he said has a strong odor of mothballs.

The installation of a containment wall, which PG&E has been exploring since 2010, would be equally challenging and is no longer being considered, Reyhani said. To protect sensitive species in the creek, work could only be done for four months in the summer. The creek would have to be dammed, the greenway would be closed, and heavy machinery would then work in the creek bed to install the barrier. The process would then need to be repeated for two to three years, Reyhani said.

Soil contamination

The Santa Rosa Fire Department, which has an oversight role because of its regulation of hazardous materials and spills, hired its own consultant to review PG&E’s proposal. Mark Smolley, with Palo Alto-based Cambridge CM, said the plan made sense. Asked by Vice Mayor Chris Coursey to rank his confidence that contamination from the site wouldn’t reach the creek or groundwater in 10 years, Smolley said “8 or 9” on a scale of 1 to 10.

Hunt agreed that the soils on the property and a neighboring one are contaminated, but he stressed that there is no evidence the contamination is mobile or water sources are impacted.

PG&E spokeswoman Brittany McKannay said Friday that the company has worked closely with regulators and numerous experts to formulate the remediation plan for the site.

“Based on their collective feedback and scrutiny we support this work as the best path forward for both the community and environmental impacts,” she said.

You can reach Staff Writer Kevin McCallum at 521-5207 or kevin.mccallum@pressdemocrat.com. On Twitter @srcitybeat.