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• Page 2 %we V September 19, 2000 Proposed Scope of Work The previous borings revealed petroleum hydrocarbons depleted in volatile content in both groundwater and the water well. The source of the groundwater contaminants appears to be from the former tank pits, given their proximity to the tank pits on the east side of the building. Additional exploratory borings are proposed to delineate the extent of this degraded contaminant plume (see Figure 1). The water well contaminants were quantified as very low concentrations of a degraded diesel, which did not match the laboratory diesel standard. The well log shows that this well has a sanitary seal, which crosses clay strata. It does not seem likely that light non-aqueous phase contaminants would sink or be pulled into this water well from pumping. However, it is possible that the water well may have a self-oiling pump, the oil reservoir of which may have a leak, causing this problem. The water well will be resampled to check the results of the first sampling. One exploratory boring is proposed adjacent to the well to ascertain whether contaminants are in near proximity to the well. This boring will attempt a vertical sample profile of soil and groundwater in the upper strata above the clay strata into which the well is sealed. Wright will also perform a regulatory file search of possible nearby sources of contaminants, which could be contributing sources. Proposed Work Tasks Regulatory File Search Wright will perform a regulatory file search of the State and local regulatory databases, and of the PHS- EHD files to a one-mile radius. The purpose of this search is to identify possible nearby sources of petroleum contaminants. which may have migrated onto the site. Exploratory Drilling and Soil Sampling Five borings were positioned to ascertain distribution of the contaminants in site soil and groundwater. Drilling permits will be secured from PHS-EHD, and all utilities will be cleared prior to doing the fieldwork. The borings will be advanced to depths of about 20 to 25 feet with the exception of the boring next to the water well, which will be advanced to about 45 feet if possible. Moderate to severe flowing conditions were encountered in previous boreholes, which required drilling methods to be alternated between push and auger ddiling depending upon the severity of the flowing condition. Some soil samples may not be recoverable in instances of severe flowing since the sampler may not be advanced to the desired depth. The boreholes will be drilled with truck mounted hollow stem auger and/or direct push drilling equipment. All drilling equipment and sampling tools will be cleaned prior to arriving, between driving samples and before leaving the site. The augers or drill rods will be advanced to the desired sampling depth interval, and a drive split spoon sampler will be driven ahead of the drill bit. The sampler will be retrieved and disassembled, and any soil filled brass or acetate liners retained for chemical analysis, will be sealed with Teflon®paper or foil and plastic end caps. Each sample will be labeled, logged onto chain of custody forms and placed in a chilled ice chest on crushed ice. Drill cuttings we rammed and left on site. The boreholes will be logged using the United Soil Classification system under the supervision of a registered geologist. Additional lithologic information may be collected to describe the subsurface geology. Soil samples will be field screened for presence of contaminants by checking for presence of odor and staining, and a photo ionization meter will be used for soil field vapor measurement use.