Soil contamination

Latest dioxin test results for Oroville levels released

John Lane gathers samples during recent research in Arbuckle.

John Lane gathers samples during recent research in Arbuckle.

Photo By Chico environmental science and planning

The latest results of soil tests for dioxins of the area around the Pacific Oroville Power Inc. (POPI) cogeneration plant have been released, and while the numbers are significant, it’s still not clear what, if any, action will result.

Dioxins, which are created mostly through industrial processes, have been linked to human reproductive and developmental problems, damaged immune systems and cancer. The contaminants in the Oroville area are believed to have come from a couple of sources over the past 50 years—two fires at the now-closed Koppers wood-treatment plant in the Highway 70 Industrial Park and, more recently, from emissions and ash accumulation from the POPI cogeneration plant, which closed last year.

The numbers are significant in that they play a role in an out-of-court settlement currently being negotiated between a number of California counties—including Butte—and the owner of the POPI plant, New Jersey-based Covanta, which operated similar plants in Northern California. The Butte County District Attorney’s Office is leading the settlement negotiations for the counties.

“There is not a lot we can do right at this point,” said District Attorney Mike Ramsey. “We are still chugging along with [Covanta] looking for an out-of-court settlement. That should happen by the end of the month.”

According to a report by Chico Environmental Science and Planning, eight soil samples were gathered on Feb. 27 and March 20 of this year—four from just outside the perimeter of the POPI plant and four others between 1 and 2 miles away, based upon prevailing wind patterns.

The highest level—83.8 parts per trillion (levels of 40 ppt and higher are considered unhealthful by the World Health Organization)—was found about a mile south of the plant near Lincoln Boulevard and Ophir Road. Other offsite samples turned up 17.2 ppt north of the site at 20th Street and Nelson Avenue, 27.7 ppt along Ophir Road about 2 miles south of the POPI site, and 46 ppt near Oroville Dam Boulevard and Highway 70.

John Lane, the owner and principal soils scientist for Chico Environmental, writes in the report’s conclusion that because samples show elevated levels of dioxins and furans (contaminants associated with dioxins) both at the POPI plant and throughout the Oroville area, more sampling is needed.

“With such limited data, it cannot be determined if observed soil dioxin levels are a result of cogeneration activities at the POPI facility,” Lane wrote.

POPI, which initially burned scraps of wood from forestry operations to create electricity, began using “urban waste” as the timber industry slowed down. That waste included demolished buildings trucked to the North State from the Bay Area.

Tests showed that resulting ash contained dioxins, including a huge pile of ash that sat for three years off Hicks Lane in north Chico before it was recently hauled away to a landfill in Wheatland. Ash from the plant has also been used as a soil amendment in an orchard off Shippee Road in Durham and in corn fields in the Glenn County community of Artois.

Offsite tests near the Durham orchard also ranged from dioxin levels of 17.4 ppt to 29.4 ppt. Those tests were taken on neighboring land that receives runoff from the orchard. A test on adjacent land that does not receive runoff showed a level of 0.96 ppt.