Data Collection for an Ambient Air Exposure Assessment at a Former Manufactured Gas Plant. Melissa L. Kunkel and Ian D. MacFarlane, EA Engineering, Science, and Technology, Incorporated, 15 Loveton Circle, Sparks, Maryland 21152; Robert Newman, EA Hunt Valley, 11019 McCormick Road, Hunt Valley, Maryland 21031; Robert G. Tardiff, EA Washington, D. C Metro Plaza One, 8401 Colesville Road, Suite 500, Box 21, Silver Spring, Maryland 20910
A former manufactured gas plant (MGP) is the subject of an investigation to assess the nature and extent of potential contamination at the site, and evaluate potential human health risks to onsite receptors. Byproducts from former MGP operations (i.e., tar, ash/slag and fill) have been identified in surface and subsurface soils at the site, and have the potential to emit volatile organic constituents (VOC), polycyclic aromatic hydrocarbons (PAH), and respirable particulate metals to ambient air. A monitoring program was established to evaluate potential concentrations of constituents being emitted from the site and to provide data for input to the human health risk assessment. The initial phase of monitoring consisted of evaluating VOC concentrations at upwind and downwind locations along the site perimeter. Samples submitted for VOC analyses were collected and analyzed according to EPA Method T014. The second phase of the assessment consisted of evaluating PAH and metal concentrations at upwind and downwind perimeter locations, as well as in an area of excavation. Samples submitted for PAH analyses were collected using Polyurethane Foam (PUF) Organic Toxics Samplers. Samples submitted for metals analysis were collected using PM,, Critical Flow High-Volume Samplers. Results show no evidence that worker exposure standards were exceeded for constituents of concern. Average concentrations of VOC of concern detected at the site perimeter were similar to concentrations detected at background sampling locations in the vicinity of the site. Particulate matter PAH and inhalable particulate matter metals were not detected above the method quantitation limit at the site perimeter. Naphthalene was detected above the sample quantitation limit, but below the OSHA TWA, in the area of excavation.