[Home] [Master Table of Contents]
Area of Concern 63
Soil Gas Survey Results, January - February 2001
Introduction
A soil gas survey was performed at AOC 63 located in the southeastern portion of CSSA. This report contains a summary of the analytical results from the AOC 63 survey. A detailed description of the methodology is included behind the Soil Gas Surveys tab in Volume 3-1.1. This work was performed in conjunction with soil gas surveys performed at SWMU B-3, SWMU B-4, AOC 55, AOC 57, AOC 65 and the WWTP from January 2, 2001 through February 23, 2001.
The distribution and concentrations for the compounds detected are addressed below. Minor amounts of benzene, toluene, and xylene were detected in soil gas samples throughout the soil gas survey. The detection of these compounds is attributed to artifact contamination from the gas generator used to power the vacuum pump and/or the combustion engine of the geoprobe truck. The frequency of detectable BTEX compounds decreased substantially after the gas generator was moved to the front of the geoprobe rig, and the rig was shut down during sample collection. The BTEX concentrations detected during the soil gas survey are presented in the data tables, but are not discussed in the soil gas findings. The complete laboratory results are presented in Appendix A. Sample locations are presented in the AOC 63 Sample Location Map, Figure AOC63-1.
Determination of Sampling Locations
AOC 63 consists of three metallic barrels that are partially filled with gravel and buried halfway in the ground. This AOC was selected for soil gas testing to determine whether subsurface VOC contamination is associated with these drums. The disposal history and past contents of the drums are unknown. Two points were selected between the drums approximately 25 feet apart, and within 5 feet of the nearest drum. The grid layout for AOC 63 is presented on Figure AOC63-1.
Soil Gas Survey Results for AOC 63
Two soil gas samples were collected at AOC 63 at locations presented on Figure AOC63-1. This site was chosen as an area of concern because of the presence of three 55‑gallon drums partially buried in the ground. Two samples were taken between these drums at a sampling depth of four feet. Laboratory results are provided in Attachment A. No figure is included in this report depicting a contaminant plume in this grid layout because no target VOC compounds were detected from the sampled grid points. The data suggest that these drums are not a source of VOC contamination.
Summary of Findings and Recommendations
From the soil gas survey results, it appears that no significant VOC contamination has been released to, or is present in, the soil and groundwater underlying AOC 63. No additional investigation activities are proposed at AOC 63 with regard to VOC contamination.