Tests: TCE In Soil, Not In School
Hanover — The latest round of testing for Trichloroethylene, or TCE, at Richmond Middle School has shown no evidence of the potentially carcinogenic chemical indoors, but tests did find the compound deep in the soil on the school grounds, confirming for the first time that the vapor has migrated across Route 10 from a military research laboratory.
The news this week that there are no detectable traces of TCE inside the middle school was welcomed by school administrators, who are preparing for the first day of classes next Wednesday.
“We’re thrilled for this round of testing, and it’s great for the opening of school, but testing will continue,” Superintendent Frank Bass said.
Although the initial TCE spill at the Army’s Cold Regions Research and Engineering Lab that contaminated the area occurred decades ago, this is the first time that officials have tested soil gases for TCE east of Route 10. The chemical was found in the soil at depths of 10, 25, 50 and 75 feet.
However, Darrell Moore, who is the project manager of TCE cleanup for the U.S. Army Corps of Engineers, has assured school officials that the TCE underground on the school property poses no health risk.
“I would safely bring my newborn baby into the school and not be concerned,” Moore said Thursday. “Soil vapor, what we’re looking at at depth, there’s no risk because there’s nobody being exposed. You want to address it, but the risk of somebody being hurt, there’s no chance.”
Trichloroethylene was once used as a liquid solvent, and there were large spills at lab in the 1970s. In recent years, the Army has learned that TCE vapor was in the soil underneath the lab and was seeping into the building through cracks in the floor and contaminating the indoor air, known as vapor intrusion.
In March, the Army announced plans to test the middle school, nearby Dartmouth College-owned housing and a couple businesses for the presence of TCE vapor.
The testing was spurred after Army officials tested the perimeter of the lab’s property in 2012 and found high levels of TCE at the northeast corner of the property’s perimeter. Because officials found such elevated levels on the property’s boundary, they had reason to suspect that there were levels of contaminated soil gas at abutting properties.
Those earlier tests found trace amounts of TCE in nearby buildings, including in April, when trace amounts were detected in the air within the middle school. However, the readings were below the state Department of Environmental Services’ threshold level for commercial buildings.
Moore said he was not surprised this month’s tests found TCE in the soil underneath the middle school property.
“It would have been a surprise if we would have found nothing over there,” Moore said.
A letter was sent to parents on Thursday informing them of the recent tests.
“Tests on a number of soil samples taken at (various) depths confirmed that TCE vapor has, at some point in the past, migrated beyond the border of the CRREL campus and into soil layers under some portions of the school property,” the letter said.
The letter goes on to state that the concentrations of contamination vary based on the location and the depth, and it points out that the closest boring site to the building with detectable levels of TCE vapor is more than 100 feet away.
According to a draft report by a consultant working for the Army Corps of Engineers, there were seven soil boring tests that took place to the west of the school building in the parking lot along Route 10. Three other tests were done in the playing fields to the south of the school building.
According to the draft report, which still needs to be reviewed by federal officials, at a depth of 10 feet, the detected levels ranged from “nondetectant” to 99 micrograms per cubic meter. At a depth of 75 feet, the levels were as high as 53,000 micrograms per cubic meter.
By comparison, across Route 10, at the northeast corner of the Army’s property, readings in 2012 at a depth of 75 feet were as high as 2.3 million and 3 million micrograms per cubic meter.
The highest levels on the school property occurred in the parking lot and along the western corner that abuts Route 10.
Moore stressed that while the contaminated soil vapor once migrated to the school property, it is no longer moving. He referred to it as a “static plume.”
Boring samples have also been conducted at the Dartmouth Printing Co. property, which abuts the middle school to the north, and at the Dartmouth-owned Rivercrest property, which is to the north of the Army lab.
Moore said more borings will need to be done at the Rivercrest property to define “the plume.” There are no occupied homes or businesses at Rivercrest.
Although there are no detectable traces of TCE within the school, Moore and school officials would still like to remove the chemical from the ground.
The Army Corps of Engineers has plans at the end of the year to test a pilot extraction program that utilizes a vacuum. The process would be tested on the lab property, and if it works, the process could be utilized on the middle school’s property, Moore said.
“We know that it poses no danger at the present time,” Bass said about the contaminated soil gas. “But we have an obligation now that we’ve found it to try to dissipate it the best we can.”
If the vacuum extraction is ineffective, there are other technologies that the Army Corps of Engineers could try. While the ultimate goal is to completely remove the contamination, Moore said, that might not be possible.
“The reality is I don’t think you can actually remove it all,” Moore said. “Over time, you can reduce it to levels that are not a concern.”
The soil gas is trapped under ground because of a layer of silt and sand that acts somewhat like a cap at the Army lab property.
If the TCE vapor does reach the surface where there is no building, then it dissipates into the ambient air, Moore said.
Although this month’s test did not detect TCE in the school building, the Army Corps of Engineers plans to test the indoor air every three months.
Next month, a second round of indoor air testing is scheduled for the nearby businesses and Dartmouth owned housing to the south of Army lab. Indoor air testing at Dartmouth Printing Co. will also take place in September.
Moore will address the Dresden School Board at its meeting on Monday at 7 p.m. at the Hanover High School library, and community members with questions or concerns are welcome to attend and ask questions.
Bert Davis, the director of CRREL and a parent of an incoming Richmond seventh-grader, has been dealing with TCE issues for years, and said while it can be concerning, he feels comfortable sending his children to the middle school.
“All that can be done that is scientifically credible is being done,” Davis said. “Millions of dollars are going into how to deal with this.”
Sarah Brubeck can be reached at firstname.lastname@example.org or 603-727-3223.