Petroleum Hydrocarbons and Organic Chemicals in Ground Water: Prevention, Detection, and Remediation® Conference

Monday, November 3, 2008 : 2:20 p.m.

Mass to Concentration Tie-in for Passive Soil Gas Surveys: Improved Technique for Source Area, Spatial Variability, and Vapor Intrusion Assessment

Joseph Odencrantz, Ph.D., PE1, Paul C. Johnson, Ph.D.2 and Harry O`Neill1, (1)Beacon Environmental Services Inc., (2)Arizona State University

The mass to concentration tie-in [MtoC Tie-In] correlates passive soil gas (PSG) data in mass to active soil gas data in concentration determined by EPA Method TO-17. Passive soil gas surveys consist of rapid deployment of hydrophobic sorbents (dozens to several hundred locations typically installed in one day) to a depth of six-inches to three-feet in a grid pattern with exposure in the field from three days to two weeks to target a wide variety of organic compounds.  A power function is used on a compound-to-compound basis to correlate spatially varying mass (nanograms) from selected locations within a passive soil gas survey to concentration (ug/m3) at those same locations. The correlation from selected PSG locations is applied to the remainder of the PSG grid. The MtoC Tie-In provides added value to a PSG survey, with the PSG data then used to estimate risk throughout the limits of the investigation for quantitative assessment.

 The results from a site in Northern California show the MtoC Tie-In correlations for both Benzene and Total Petroleum Hydrocarbons (TPH). The correlations are applied on a compound-to-compound basis to the remaining locations in the PSG-grid to provide an estimate of concentration that can be used for comparison to risk/screening levels or fate and transport diagnostic tools (partitioning equations, solubility laws, etc.). An example of how the correlations are applied is presented in tabular form. The results from a chlorinated solvent shows the MtoC Tie-In correlation from a site in Maryland for Tetrachloroethylene (PCE). In this instance, there was a near-perfect relationship between the PSG mass and the active soil gas concentration (R-squared value of 1). The concentration estimated throughout a PSG-grid enables a vast new realm of interpretive power at sites.

Joseph Odencrantz, Ph.D., PE, Beacon Environmental Services Inc. Joe Odencrantz is the Technical Director and Western Region Manager for Beacon Environmental. Dr. Odencrantz is a licensed civil engineer in several states and an internationally recognized expert in fate and transport processes, forensics, and investigation methods. He obtained his master of science and doctoral degrees in civil and environmental engineering from the University of Illinois at Urbana-Champaign and has published extensively on organics in environmental systems, natural attenuation, cleanup levels, risk, policy and treatment systems.

Paul C. Johnson, Ph.D., Arizona State University Paul C. Johnson is an Executive Dean of the Ira A. Fulton School of Engineering at Arizona State Univeristy. He has worked in the environmental area since 1987, having numerous patents and publications. He is Editor in Chief for the NGWA's journal, Ground Water Monitoring and Remediation.

Harry O`Neill, Beacon Environmental Services Inc. Harry O’Neill is the President of Beacon Environmental Services and has managed soil gas investigations for more than 15 years working on DOD, DOE, and commercial projects. Mr. O’Neill has been on the forefront of the acceptance of passive soil gas sampling technologies at the national and international level and has overseen the implementation of over one-thousand soil gas surveys.


Petroleum Hydrocarbons and Organic Chemicals in Ground Water: Prevention, Detection, and Remediation® Conference