The latest rounds of environmental tests at Needham and Webb elementary schools showed lower levels of chemicals in the ground beneath the schools.
The compounds that are being monitored, PCE and TCE, can cause harmful health effects in high enough concentrations.
Indianapolis-based EnviroForensics conducted the tests earlier this month, marking the third round of testing in two months. Tests before spring break showed levels of TCE higher than the acceptable level set by the Indiana Department of Environmental Management, and school officials closed the two schools for a day.
At that time, levels of PCE were also higher than normal, but didn’t exceed the level set by the department. Tests mitigated concerns about airborne particles, as all three rounds of testing this spring have shown levels of the compounds significantly lower than the department’s screening levels.
But this is the first round of results this year in which all areas showed concentrations of TCE below 70 micrograms per cubic meter, which is what has been deemed acceptable by the state department. March 9 tests showed some sub-slab areas at Webb Elementary School with TCE levels of 225, 242 and 849 micrograms per cubic meter. This month’s tests showed no areas with more than 50 micrograms per cubic meter, and most with less than 10.7 micrograms.
Although levels are decreasing, the school board recently approved contracts for the design and construction of a depressurization system to further lower levels of the compounds and ensure those compounds don’t make it into the air inside the schools, operations director Jeff Sewell said.
“One of the recommendations we entertained was the concept of installing vapor mitigation systems in both of those buildings to provide long-term assurance that vapors that have been found underneath the slab underneath the schools could not make it into the indoor air space,” Sewell said.
That system will include pipes that run down through the floor and up through the roof. A fan will pull air from beneath the floor so that any vapors from underneath the floor can’t infiltrate the air in the schools, he said.
Construction will start as school ends, and will likely take two to four weeks. It will be completed before the fall semester.
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What was tested;air and ground underneath Needham and Webb elementary schools.
Why;previous tests showed levels of harmful compounds TCE and PCE at higher than normal levels for underground samples.
Acceptable limits set by Indiana Department of Environmental Management for underground testing;70 micrograms per cubic meter of TCE and 1,400 micrograms per cubic meter of PCE.
Acceptable limits set by department for air testing;2.1 micrograms per cubic meter of TCE and 42 micrograms per cubic meter for PCE.
Webb Elementary;range of less than 10.7 micrograms to 49.4 micrograms for underground TCE and range of less than 31.9 micrograms to 51.5 micrograms for underground PCE. All less than 0.27 micrograms for air TCE. All less than 0.34 micrograms for air PCE.
Needham Elementary;all less than 10.7 micrograms of underground TCE and range of less than 31.9 micrograms to 60.4 micrograms of underground PCE. All less than 0.27 micrograms for air TCE and all less than 0.34 micrograms for air PCE.
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