Demonstration of a Long-Term Sampling Approach for Volatile Organic Compounds in Indoor Air

A long-term low flow capillary canister sampling system was demonstrated and validated at Naval Weapons Station (NWS) Yorktown bycharacterizing VOCs from vapor intrusion (VI) using the innovative low flow sampling system and comparing the results to those from both long term diffusion tube sampling (2 weeks) and consecutive multiple day 24-hour canister sampling. The innovative low flow rate capillaryflow controller provides flow rates ranging from 0.1 to 0.5 mL/min, allowing collection of samples over a 1-3 week sampling period. Twolocations in each of two large buildings impacted by VI were sampled for six consecutive quarters. Results, focused on TCE which was thehighest concentration VOC sampled, demonstrate that the low flow capillary canister system samples collected concentrations over two-week sampling periods that were comparable to average values collected daily over two weeks using the traditional canister sampling approach. TCE concentrations measured using diffusion samplers were significantly different. Seasonal impacts on VOCs concentrations were noted, but did not negatively affect capillary canister performance. Sampling using the capillary canister system required no additional expertise relative to the traditional approach. The capillary canister sampling system controllers are lower cost than traditional flow controllers, and the extended sampling period the approach provides allows for estimation of long-term average exposure, thus allowing for a more robust mitigation decision, which can translate into significant long-term cost savings.