Arsenic levels in soil complicate Fountaingrove cleanup

Construction workers begin work on rebuilding Jim Roatch's home along Hadley Hill, in the Fountaingrove area of Santa Rosa on Wednesday, February 28, 2018. Roatch had to have 85 tons of dirt removed from his property before building could commence, because arsenic was found in soil samples. (Christopher Chung/ The Press Democrat)


Before Jim Roatch could rebuild his Fountaingrove home, the semi-retired contractor needed to prove his hillside property was clean.

That meant hiring a contractor to remove the ash and debris left behind after the Tubbs fire leveled his $1.2 million Hadley Hill Drive home, making sure the soil was returned to its prefire condition.

But after the lot was cleared and scraped, several soil samples still showed arsenic levels above what the city and county considered acceptable for his location, which at the time was 7.2 parts per million.

Arsenic is a naturally occurring metalloid that can cause cancer in humans if ingested in high concentrations, such as by drinking contaminated well water.

The threshold set by the county struck Roatch as an absurdly conservative standard to meet, especially for a naturally occurring element in dirt that will be contained under a plastic barrier at a home connected to the city’s water supply.

“It just seems to me that they went way overboard,” Roatch said this week.

Anxious to get his home rebuilt and his life back, however, Roatch in December bit the bullet and had 11 more inches of dirt removed from the site and hauled to a landfill, costing him tens of thousands of dollars and weeks of delay.

The extra effort paid off. When the soil was retested, the new samples came back well below the 7.2 ppm level. He got his building permit Feb. 22.

The very next day, the Sonoma County Health Department and the Army Corps of Engineers decided to relax the cleanup standard for arsenic, raising the acceptable levels in soil to 22 parts per million for a large section of Fountaingrove, where 1,400 homes were incinerated in October.

“That’s ridiculous,” Roatch said of the timing of the change. “If it wasn’t that important, why did I have to go through all that?”

The new level, established after an analysis of 383 soil samples, is now what department officials agree is closer to the average natural background level for arsenic in the area.

Under the new standard, Roatch would have easily passed his December soil test, the highest reading of which was 14 parts per million. In that scenario, he could have been under construction weeks ago.

The revised standard will make it easier for people to rebuild, said Erik Lundquist, planning manager at Hogan Land Services of Santa Rosa, which Roatch hired to help him navigate his project.

“Hindsight being 20-20, it sure would have been nice to have that come out a little earlier,” Lundquist said. “He wasted time, and time is money.”

The Herculean effort underway to clean up debris from the nearly 5,300 homes and businesses destroyed in Sonoma County has been made more complicated by confusion over just how “clean” the cleared lots must be before rebuilding can proceed.

Roatch is not the only one dealing with delays over soil test results.

David Welch’s site on Shelter Glen Way was cleared in late December by a crew hired by the Army Corps. The workers were responsive and did a great job removing the debris, he said. They told him test results would take a few days to get back and a couple weeks to process.

Two months later, the retired Agilent Technologies employee is anxious to start building but exasperated by the runaround he says he has been getting from the Army Corps and the county.

All he has gotten from multiple calls to the various hotlines set up for fire victims are vague third-hand information about “negotiations” going on between the Corps and the county over the soil levels.

“I’ve gotten that answer three times now,” Welch said. “We’re ready to go, but we’re sitting on our hands.”

Understanding and establishing appropriate and safe toxicological levels in soils is tricky business. This is particularly so for arsenic because of the variability in concentration levels, the difference between natural and man-made sources (such as treated wood), widely divergent cleanup standards and conflicting information about the hazards from different types of exposure.

The background level for Sonoma County set by the U.S. Geologic Survey is 5.9 parts per million. The standard set by the U.S. Environmental Protection Agency for soil is 0.39 parts per million and 10 parts per billion for drinking water.

There is generally far more concern about arsenic in drinking water than in soil because arsenic’s primary risk to human health is through ingestion, explained Christine Sosko, the county’s director of environmental health.

The county and Army Corps of Engineers have been talking for weeks about revising the standard for arsenic after test results at cleared lots returned with levels higher than the 7.2 ppm standard initially set by the county and Corps in November.

At that time, the federal and local agencies worked together to establish cleanup guidelines that set acceptable levels for 17 substances considered potentially hazardous to human health, mostly metals such as lead, mercury and thallium.

Because many of those substances naturally exist in the environment at different levels depending on geology and other factors, different standards were set for 10 different geographic areas in the burn zones in the county.

Mostly the standards were the same for all areas. For example, the cleanup goal for copper was and remains 3,000 ppm in all locations. Similarly, all areas have the same threshold for barium (5,200 ppm), chromium (36,000 ppm) and selenium (380 ppm).

But allowable arsenic levels were different for every geologic zone, ranging from a low of 6.2 ppm in Kenwood to a high of 22 ppm in parts of Santa Rosa.

In many cases, different volcanic geologic formations sit side by side, with significantly different cleanup levels for parcels across the street from one another.

Traveling northeast through the Tubbs fire burn area takes one through four different zones in 4 miles.

The cleanup goal for Coffey Park was set at 22 ppm, but 7.2 ppm for neighboring Fountaingrove. The value then increases to 22 ppm for the Rincon Valley floor, but drops to 7.2 ppm for the hillside estates along Foothill Drive.

This makes some sense because the ancient volcanic soils in the rocky Fountaingrove area, known as tertiary volcanics, are different than those in the more recent but related sedimentary soils in the surrounding valleys, referred to as quaternary Pleistocene volcanic.

The Army Corps realized during the cleanup that some of the parcels where results remained stubbornly above the 7.2 ppm level appeared to be on the border between the two geologic areas. They concluded it would be more appropriate to have a consistent — and easier to meet — goal of 22 ppm in the two areas.

The Corps changed the goal for the cleanup sites it was managing, and it recommended the county and the city change them for the private cleanup projects they were overseeing as well.

If the county didn’t make the change, it ran the risk of having contractors digging deeper and deeper in search of “cleaner” soil that might not exist, Sosko said. That wouldn’t be in anyone’s best interests, she said.

“What we’re all doing is trying to make a determination that these properties are being returned to a prefire existing condition,” Sosko said.

How many parcels this issue affects is not clear. Maps suggest there are hundreds of sites in the geologic areas where the arsenic standards were relaxed, but a precise tally was not available.

Army Corps officials said 20 sites out of 384 failed their arsenic tests under the stricter limit, and 33 sites would now be held to the more relaxed standard.

County and city officials didn’t know how many homesites involved in their private cleanup programs fall under the new standard, but they estimate that only about 5 percent of sites they’re managing are affected.

As for the fairness of changing the standards midstream, officials don’t see an issue.

Any homeowner who thought the background arsenic levels of their properties were higher than the standards they were being held to always had the opportunity to have a licensed geologist make that case to the county.

You can reach Staff Writer Kevin McCallum at 707-521-5207 or On Twitter @srcitybeat.