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page 2, 4075 Main St. <br /> The Proposal, as submitted, is not approved because it is incomplete. The one element <br /> of the Proposal that addresses issues raised by PHS/EHD is the installation of a <br /> groundwater extraction well. The installation of a groundwater extraction well will be <br /> required. However, prior to the installation of a groundwater treatment system, a <br /> pumping test must be conducted to determine whether or not extraction and treatment is <br /> a feasible groundwater remediation alternative, either interim or permanent, for this site. <br /> A new work plan is due to be submitted to PHS/EHD by April 23, 2001. The work plan <br /> must include the following elements. <br /> 1. A plan to continue the investigation of the vertical and lateral extent of the <br /> contaminant plume in soil. <br /> The contamination must be vertically defined on the property, as well as vertically <br /> and laterally defined to the east and south, offsite of the property. <br /> 2. A plan to continue the investigation of the vertical and lateral extent of the <br /> contaminant plume in groundwater. <br /> Significant quantities of petroleum hydrocarbon contamination are present in all <br /> current monitoring wells at this site. Depth discrete groundwater samples from <br /> levels below 75 feet below surface grade (bsg)will be required to complete the <br /> investigation of the vertical extent of the plume. Appropriately screened <br /> monitoring wells will be required to track dissolved contaminant concentrations at <br /> different depths of the aquifer. The lateral extent of the dissolved plume is <br /> undefined in all directions and must proceed off site. Prior to installation of <br /> additional monitoring wells, PHS/EHD recommends that a detailed three <br /> dimensional analysis of the subsurface lithology and dissolved plume dimensions <br /> be compiled utilizing techniques such as continuous core sampling with <br /> simulprobe or cone penetrometor testing. <br /> 3. Installation of an extraction well and at least one soil vapor extraction well to <br /> enable the completion of a pumping test and a soil vapor extraction test. <br /> Details for conducting these tests must be included. These tests are necessary <br /> to properly evaluate the most effective remedial alternatives for this site. An air <br /> sparge test may be necessary as well. <br /> 4. Completion of the sensitive receptor/well survey. <br /> As noted in the December 5, 2000 correspondence, the initial survey that was <br /> submitted in October 2000 was incomplete. Please refer to that correspondence <br /> for specific details lacking from the submitted survey, and address each of them. <br /> 5. Analysis of soil and water samples. <br /> Analysis of soil and groundwater samples must include: total petroleum <br /> hydrocarbons (TPH) as diesel and TPH as gasoline by EPA Method 8015m; <br /> benzene, toluene, ethylbenzene and xylene by EPA Method 8020; and 1,2- <br /> dichloroethane, ethylene dibromide, and fuel oxygenate additives including <br /> ethanol and methanol by EPA Method 8260. <br />