Cleanup work at Camp Bonneville will resume in earnest this month after Clark County hired a new contractor.
Weston Solutions Inc., an international company headquartered in Pennsylvania that has an office in Seattle, was awarded a $7.6 million contract in May.
Greg Johnson, a munitions safety advisor for Clark County Public Works, said Tuesday that workers from Weston will start cleaning up the central valley floor by the end of the month.
The U.S. Army, which used the 3,840-acre site in east county as an artillery range and training area from 1909 to 1995, continues to pay for the cleanup.
Last year, the Army agreed to pay $20 million in the next 10 years.
A study released last month by the Environmental Protection Agency provided the county with more data about the extent of the contamination, Johnson said, including the detection of perchlorate in the portions of Lacamas Creek and the north fork of the creek that run through Camp Bonneville.
EPA did the site analysis in response to a request from the Rosemere Neigh
borhood Association and Columbia Riverkeeper.
Perchlorate can be found in rocket fuel, fireworks, flares and explosives, as well as in bleach and some fertilizers. According to the EPA, perchlorate can interfere with the functioning of the thyroid gland and disrupt the production of hormones needed for normal growth.
Monica Tonel, EPA site assessment manager in Seattle, said perchlorate was measured in the creek at .13 parts per billion.
No perchlorate was detected in a sediment sample taken just beyond Camp Bonneville boundaries, Tonel said.
Ben Forson, site manager for the state Department of Ecology, which has been overseeing the cleanup of Camp Bonneville, said the perchlorate detected in Lacamas Creek was far below advisory levels. The EPA issues a drinking water advisory when perchlorate reaches 15 parts per billion, more than 100 times higher than the level detected in Lacamas Creek. He said Ecology's cleanup level is 11 parts per billion.
The perchlorate comes from the rockets and other explosives detonated over the years in an area known as "Landfill 4," and Forson said the plume that has contaminated groundwater at levels high enough to be dangerous has been monitored for years.
"The plume is stable," he said Tuesday.
The perchlorate detected in the creek could be from polluted runoff, Forson said.
The low level detected in Lacamas Creek would likely be detected across Camp Bonneville, he said.
The explosives in Landfill 4 were cleaned out in 2004. They included illegal fireworks seized by local law enforcement, but most of the mess was the Army's.
Forson said crews dug down as far as 29 feet, but stopped when the excavator started to sink in the soft clay soil.
The extensive cleanup of Camp Bonneville has included cost overruns and funding disputes.
In 2010, the county and Ecology terminated its contract with Mike Gage of the Bonneville Conservation Restoration and Renewal Team. Gage's crews found and removed hundreds of unexploded munitions, but also discovered that the Army had greatly underestimated how much work had to be done.
Seven of nine firing ranges have been cleaned up, but lead has been more pervasive than predicted.
One range has lead four feet underground.
The Army took issue with Gage for what it considered lavish entertainment and travel expenses.
The county owns the property, and has long planned to turn a portion of the cleaned-up site into a regional park.