Venting for the removal of hydrocarbon vapors from gasoline contaminated soil

Abstract

The utilization of a venting strategy to remove gasoline vapors from contaminated soil strata was investigated in this exper‐ment. A contained gasoline “leak”; was created in a large outdoor facility which simulated soil strata and a static water table. An air flow was established, and vapor samples taken before, during, and after venting were checked for hydrocarbon content. The effluent air was regularly sampled for carbon dioxide and total hydrocarbons. Carbon dioxide data were used to estimate the amount of microbiological activity, and total hydrocarbon data were used to calculate the total amount of gasoline removed by venting. Hydrocarbon condensates from the effluent air were collected periodically and the compositions of these condensates were compared to the compositions of the starting gasoline and the residual that remained in the soil.

During 11 days of continuous venting, 57% of the original 75 gallons of gasoline was removed by venting. Carbon dioxide production indicates that microbes may have consumed as much as 2%. The balance is consistent with the amount remaining in the soil as determined by core sampling. As anticipated, venting appears to be most effective in removing low molecular weight components, especially the paraffins and olefins.

Key words:

• gasoline leaks
• venting
• biodegradation
• hydrocarbon vapors
• soil contamination