State Tests Results Find No Chlorinated Solvents Above Health Risk Levels in Wake Forest Neighborhood

RALEIGH – State officials reported Friday that a second round of soil vapor testing in Wake Forest’s Stony Hill Road area detected no chlorinated solvents above health risk levels.

The N.C. Division of Waste Management said the tests detected no trichloroethylene, or TCE, and found one incidence of tetrachloroethylene, or PCE, that was below health risk levels. The state agency conducted the soil vapor testing Nov. 15-16 in the northern Wake County community.

TCE and PCE are chlorinated solvents. When they are present in groundwater, related soil vapor can travel through spaces in soil beneath structures. If levels of the chlorinated solvents are high enough, the vapor can enter the home and affect the health of people living in the homes.

The state agency contacted the residents in the affected area Friday with the test results.

Eighteen crawl spaces and four sub-slabs were tested. The division found no detections of TCE in any of the samples, and found one low-level detection of PCE. However, the one low-level detection for PCE – found in a sub-slab area of one home – is considered to be below the health risk criteria of the N.C. Department of Environment and Natural Resources and the Environmental Protection Agency.

Sub-slab testing, which consists of sampling through a small port drilled through concrete slab floors, is conducted when a residence does not have a crawl space. EPA officials reviewed and concurred with DENR’s screening process.

This is the second round of soil vapor testing conducted in the area. The first round of soil vapor testing was conducted the week of Oct. 15. During the first round of testing, one home had results above levels of concern for below-ground soil vapor, but that home’s crawl space was clean. Another home’s levels were only slightly above the level of concern for below-ground soil vapor. A vacant residential lot, tested because the neighboring home could not be accessed, showed elevated below-ground soil vapor contaminant levels. Also, one home showed an elevated level of isopropyl alcohol, or rubbing alcohol. The second round of testing showed that all of these homes are safe.

State officials selected the homes for the second round of soil vapor testing based on several factors. Some homes were selected for testing because they adjoined property where below-ground soil vapor levels were shown to be elevated in the first sampling event. One home was chosen because it could not be accessed during the first round of testing. Other homes were tested a second time based on the results of the first round of tests.

The state Division of Waste Management plans next week to conduct follow-up groundwater testing of more than 100 potable wells within three quarters of a mile of probable contamination sources in the Stony Hill Road area. For most homes, next week’s tests will repeat testing conducted by the EPA earlier in order to verify the EPA’s sampling results.

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