A. Rezendes, Alpha Analytical, 8 Walkup Drive, Westboro, MA 01581, Tel: 508-439-5181, Email:  arezendes@alphalab.com
M. Marando, GEI Consultants, Inc., 400 Unicorn Park Drive, Woburn, MA 01801,Tel: 781-721-4000, Email: mmarando@geiconsultants.com
P. King, GEI Consultants, Inc., 400 Unicorn Park Drive, Woburn, MA 01801,Tel: 781-721-4000, Email: pking@geiconstultants.com

Naphthalene is becoming an increasing concern in regards to vapor intrusion investigations. A number of states ( Massachusetts , New York , New Hampshire ) have the compound listed as a target analyte in vapor intrusion guidance documents, and that TO-15 is the preffered methodology for detecting this compound, although naphthalene is not considered a “VOC” as defined in this method. This paper presents the results of a side-by-side comparison of field and conventional laboratory analysis techniques for measuring naphthalene from a flux chamber.  The zNose® Model 4200 Ultra-Fast Gas Chromatograph has been used for several years to monitor airborne naphthalene concentrations in real-time during remedial activities.  Results from the zNose® are compared with results for samples collected with evacuated fused-silica lined canisters that were analyzed by using US EPA TO-15, and samples collected on an PUF/XAD resin cartridge and analyzed by US EPA TO-13.

A Vapor Intrusion Study Using Multiple Lines of Evidence

Christine J. Weaver, Weston Solutions Incorporated, 205 Campus Drive, Edison, NJ 08837, Tel: 732-417-5836, Fax: 732-417-5801
Paul J. Bovitz, Weston Solutions Incorporated, 205 Campus Drive, Edison, NJ 08837, Tel: 732-417-5815, Fax: 732-417-5801
James T. Moore, US Army Corps of Engineers - New York District, 190 State Route 18, Suite 202, East Brunswick, NJ 08816, Tel: 732-435-0079, Fax: 732-249-0734
James A. Kelly, US Army Corps of Engineers - New England District, 696 Virginia Road, Concord, MA, 01742-2751, Tel: 978-318-8227, Fax: 978-318-8614

Over the past 4 years we have evaluated 58 buildings located over six groundwater plumes at the Former Raritan Arsenal in Edison , NJ to determine if VOC-contaminated groundwater is affecting indoor air quality.  Initially USACE developed its own methodology for evaluating risks under CERCLA, including site-specific risk-based non-residential criteria, in the absence of state regulatory guidance.  The vapor intrusion pathway was subsequently assessed in accordance with the New Jersey Department of Environmental Protection (NJDEP) vapor intrusion guidance (VIG) beginning in 2004. Initial screening criteria (e.g. presence of buildings within 100 feet of the delineated groundwater plume boundary) were used to determine what buildings required investigation. Subsequent investigations included sampling subslab soil gas, soil, indoor air and ambient air concentrations of VOCs.  A weight of evidence approach was used to determine whether further action was required, based on:

• Exceedances of residential VIG benchmarks in subslab soil gas and subsequently, indoor air; 
• Evaluation of individual constituents as potential DOD-related contaminants;
• Comparison of indoor air concentrations with background ambient air concentrations;
• Comparison of concentrations of VOCs in groundwater, subslab soil gas and indoor air; 
• Replicability of sampling results and consistency of ratios of VOC concentrations in groundwater, subslab soil gas and indoor air;

The NJDEP has concurred that over 40 buildings require no further action.  Twenty buildings require ongoing monitoring and investigations, of which 10 have had remedial systems installed to address vapor intrusion.  Where systems have been installed, USACE has followed its own risk-based criteria, consistent with CERCLA. 

Vapor Intrusion Investigations Utilizing Passive Soil Gas Sampling.

James Whetzel, W. L. Gore and Associates, Inc., 100 Chesapeake Blvd., Elkton, MD,  21921, Tel: 410-506-4779, Fax: 410-506-4780, Email: jwhetzel@wlgore.com
Harry Anderson, W. L. Gore and Associates, Inc., 100 Chesapeake Blvd., Elkton, MD,  21921, Tel: 410-506-4852, Fax: 410-506-4780, Email: handerson@wlgore.com
Jay Hodny, Ph.D., W. L. Gore and Associates, Inc., 100 Chesapeake Blvd., Elkton, MD,  21921, Tel: 410-506-4774, Fax: 410-506-4780, Email: jhodny@wlgore.com

Investigating the vapor intrusion (VI) pathway is a critical part of the overall investigation of a site where the potential exists for human exposure to chemicals of concern.  Determining whether or not an exposure pathway exists can be a complex and expensive endeavor. Recent state and advisory group guidance documents provide good overviews of the investigative process and of the techniques available; one of these techniques is passive soil gas sampling. Passive soil gas (PSG) sampling is a versatile tool that can be used to screen sites for the presence of potential chemicals of concern, to map subsurface soil gas plumes, and to focus subsequent sampling by more complex and costly methods.  Advantages of PSG include simple and quick installation and retrieval, the ability to collect soil gas in low permeability high-moisture soils, time integrated sampling, and the ability to detect a broad range of chemicals at low concentrations.  Although PSG data is often reported in units of relative mass levels, recent laboratory and field studies have been performed to examine the technique as a tool to estimate soil gas concentrations.  Providing soil gas concentrations improves the ability of the technique to focus subsequent sampling and to screen sites for potential vapor intrusion risk. This presentation will include a description of a PSG sampling tool, the GORE™ Module, will describe the calculations used to determine concentrations, will include a summary of laboratory study results, and will present examples of field studies and investigations that incorporate estimated concentration values. The presentation will also discuss how PSG sampling data are being used as a part of VI investigations.   

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