Source: http://www.laramieboomerang.com, June 29, 2014
By: Chilton Tippin
The Wyoming Department of Environmental Quality is investigating potential contaminants in soils, groundwater and soil vapors beneath downtown Laramie.
The investigation encompasses roughly 61 acres, including portions of Grand Avenue, Third, Fifth and Garfield streets, as well as other areas.
The DEQ intends to determine “the extent and nature” of tetrachloroethene, or PCE, in and around the downtown area, said Cindi Martinez, DEQ Voluntary Remediation Program project manager.
PCE is a chlorinated solvent, commonly used in dry cleaning fluids, textiles and other industrial applications, according to Environmental Protection Agency data.
A 1998 environmental assessment of a downtown site found concentrations of PCE in groundwater exceeding the federal maximum contaminant level, according to a report by Trihydro Corporation, the firm contracted by DEQ for the recent investigation.
PCE can be carcinogenic to humans and cause depression of the central nervous system, said Edward Clennan, University of Wyoming organic chemist.
EPA information states, “Some people who drink water containing (PCE) in excess of the maximum contamination level over many years could have problems with their liver and may have an increased risk of getting cancer.”
Martinez said she “wouldn’t imagine” PCE exists at concerning levels in the area under investigation, but said it’s too early in the studies to tell.
“I don’t have any data to support that at this time,” she said. “Quite honestly, if you were to review other information, PCEs in groundwater are extremely common in any type of urban area.”
The DEQ opened the “Laramie Third Street PCE Plume Orphan Site” because the 1998 environmental assessment found the chemical in the groundwater and soils of a vacant parcel of land at 851 N. Third St.
The site is located about midway between Harney and Canby streets.
The site is termed an “orphan” by DEQ because “there is no viable party that is responsible for causing or contributing to the contamination present at the site.”
Although the contaminants were found more than 15 years ago, the DEQ didn’t contract the current investigation because the site wasn’t high on the agency’s priority list, Martinez said.
The DEQ orphan site priority list takes into account several risk factors, such as nature of the contaminant, local environmental conditions and potential exposures to humans and ecological receptors.
“According to priority, we address the ones that are the most important as funding is available,” Martinez said.
In the 1998 assessment, three soil borings were drilled and groundwater was sampled from each boring for volatile organic compounds. PCE was detected in all three groundwater samples, with concentrations ranging from 3.1 to 10.3 parts per billion, according to the Trihydro report.
The maximum contamination level for PCE is 5 parts per billion, according to EPA data.
“This is the lowest level to which water systems can reasonably be required to remove this contaminant should it occur in drinking water,” according to EPA data.
Martinez said the latest investigations have yet to reveal a source.
“I can’t speculate on that,” she said. “It’s impossible to tell. This is very early. I can’t speculate on how or why. I have no data to support any kind of theory at this point.”
The current field investigation phase began June 9 and ended Thursday.
Crews drilled about 35 wells in the investigation area, going beneath the surface to install temporary borings and collect soil and groundwater samples. They also took soil vapor samples and installed permanent monitoring wells, according to a DEQ flyer on the investigation.
Now that samples are gathered, they’ll be sent to a lab for analysis, Martinez said. Samples could be returned within the month, she said.
“It depends on the holding times of the samples and the medium of the samples, so it varies,” she said. “But I suspect that I should have most, if not all, of the lab results, at least in raw form, from the labs within a month.”
Based on findings, the DEQ plans to determine whether more investigation is needed to evaluate if soil vapor is potentially affecting indoor air quality, according to the DEQ flyer.
Additionally, the DEQ will determine whether cleanup or mitigation efforts are necessary.
It’s too early to estimate what the samples might reveal, Martinez said.
“It’s pretty premature to be speculating on what we’ll find,” she said. “But, because they (PCEs) were found, and we are at a juncture where we can expand the investigation, we did that.
“But, there is no guarantee that there is anything substantial.”