REMEDIATION OF PETROLEUM-CONTAINING SOIL AND GROUNDWATER AT A FORMER RAIL YARD LOCOMOTIVE FUELING AREA

摘要

A multi-faceted remedial program was implemented at a former locomotive fueling area (FLFA) at a rail yard in upstate New York to address diesel -affected soil and groundwater. Main line tracks running through the FLFA prohibited removal of affected soil and, consequently, an in situ remedy was developed. The remedy combines air sparging to provide oxygen to intrinsic diesel-degrading microorganisms and to volatilize petroleum compounds, and soil vapor extraction to actively remove volatilized diesel compounds fr om the subsurface. System components include vapor extraction and air sparging wells within the FLFA and low-flow biosparging wells between the FLFA and down gradient properties. The biosparging wells create an oxygen barrier to migrating diesel compound s. Based on vapor extraction flow rates and the concentration of volatile organic compounds (VOCs) in extracted air, an estimated 1,000 pounds of petroleum mass have been removed by the vapor extraction system to date. Mass removal and biological activit y is strongly correlated with seasonal fluctuations in subsurface temperature, which varies by more than eight degrees Celsius in the treatment zone over the course of a year. Analyses of microbial biomass in the treatment area indicate that diesel -degrading organisms increased by four orders of magnitude in unsaturated soil and by three orders of magnitude in saturated soil within five months of system start up. Regulated VOC and semi -volatile organic compound (SVOC) concentrations in soil decreased in s ubsurface soil to below detection limits in most locations in approximately 24 months. Concentrations of petroleum compounds in groundwater have been reduced to less than regulatory standards over the majority of the site and have declined 84 percent on average. This integrated in situ approach to the treatment of diesel -impacted soil and groundwater has greatly reduced cleanup costs and cleanup time for the site.