Chlorobenzene Plume Based on Initial Investigations and Modeling<\/p><\/div>\n

With the landfill facility set for a 100-acre expansion, their next task is to relocate the extraction well and treatment system. Before the remedial system can be moved, they needed to characterize the intended site, which is located downgradient of the proposed landfill – the location of a known chlorobenzene plume. The DNAPL (dense non-aqueous phase liquid) plume is located in fractured igneous bedrock (Scituate granite gneiss).<\/p>\n

During the initial development of the landfill facility, thorough subsurface investigation and modeling was performed to map groundwater flow and contaminant transport. Based on the models and historical data, GZA conducted five deep bedrock explorations to further characterize the hydrogeologic properties of the subsurface, and determine contaminant distribution at the proposed new pump and treat site.<\/p>\n

Extensive in situ testing programs were conducted in the five boreholes, which were drilled to about 110 feet into bedrock. Their program included discrete zone sampling, bedrock permeability testing (packer testing), and borehole geophysics.<\/p>\n

The results of the borehole testing, allowed GZA to identify the discrete bedrock zones to be monitored, which aimed to further delineate the extent of the plume. For this task, GZA chose to install permanent multilevel groundwater monitoring systems.<\/p>\n

A multilevel groundwater system allows the monitoring of a number of discrete groundwater zones in one borehole. Sealed ports are placed at various depths to obtain a 3D profile of the subsurface by collecting samples and water levels from each zone.<\/em><\/p>\n