ANALYZING AND VISUALIZING CO-MINGLED VOC PLUMES AND THE POTENTIAL IMPACT ON DOWNGRADIENT RECEPTORS USING GIS

This poster describes the use of GIS to integrate, analyze and visualize data collected from an expedited field investigation in the spring and summer of 2003 in a mixed commercial and residential area of Central New Jersey. The remedial investigation fully delineated a 4,000-foot long co-mingled volatile organic compound (VOC) plume and evaluated the potential for the chlorinated VOCs detected in groundwater to affect indoor air quality in the structures located downgradient of the site.

Chlorinated solvent impacts were identified in overburden (unconsolidated glacial deposits) and fractured bedrock groundwater. The primary sources were areas of historic waste disposal at inactive industrial facilities. The delineation of the full extent of the plume required collecting direct-push groundwater samples during five mobilizations over a three month period. A key success factor was the continual refinement of the site conceptual model by incorporating new data and reinterpreting site conditions to direct the expansion of the sampling program. GIS was used to map the data as it was received, update the model and plan further sampling locations. The use of ArcGIS software was also crucial in visualizing multiple co-mingled plumes in order to clearly show contributions from off-site sources. To streamline data organization and presentation, a geodatabase was built for the project.

A detailed groundwater receptor evaluation was conducted in 2003, which included identification of well locations and water use for all properties within one mile, characterization of potential sensitive receptors in the site vicinity and determination if the properties within the delineated chlorinated VOC plume have basements that may be pathways for potential vapor impacts. GIS was used to analyze and visualize the findings of this expanded receptor evaluation. The findings show that a majority of the buildings within the delineated chlorinated VOC plume have basements. GIS is currently being used in this ongoing project to assess the risk due to potential vapor intrusion downgradient of the site.

Use of GIS has been a key in this project in order to visualize and evaluate the data and present the findings to clients, regulators and other stakeholders.