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David Relos August 30, 2011 Page 3 of 6 limited penetration of the radar signal. For purposes of this proposal, Wightman Petrie has assumed a depth limitation for the GPR of approximately 8 feet below land surface. Areas of the former UST system will be scanned by GPR and delineated using varying interval grid patterns. Multiple scans in a north -south and east -west direction will be performed utilizing the GPR, looking for anomalies. Any identified anomalies (i.e., disturbed subsurface soils) will be marked on the surface using paint, as appropriate for utility locators and for soil boring locations by Wightman Petrie. Soil Sampling via Geoprobe Methodology Using Geoprobe methodologies (small track mounted hydraulically driven sampling probe) soil samples will be collected from a total of four (4) locations. Boring locations will be determined based upon the results of historical document review and field data gathered from the completion of the Ground Penetrating Radar. In general, Wightman Petrie would propose to install one (1) soil boring within the centralized area of the former tankpit, one (1) soil boring upgradient of the former tankpit, and two (2) soil borings downgradient of the former tankpit. For each of the Geoprobe boring locations, discrete soil samples will be collected at 5 -foot intervals throughout the soil profile until saturated soil conditions are encountered (assumed to be approximately 10 feet below land surface). Each soil sample interval will be screened for the presence of volatile organics by placing a portion of the soil sample into a plastic bag, allowing time for equilibration, and insertion of a photo ionization detector (PID) probe to observe a reading of "total VOCs" in parts per million (ppm). All data associated with the field screening of VOCs will be recorded for future reference (Soil Boring Logs). In addition, a portion of each discrete sampling interval will also be collected for submittal to a laboratory. Wightman Petrie proposes to submit two (2) soil samples from each of the four (4) boring locations based on the PID field screening results and /or other indications of the presence of potential contamination (visual or olfactory). In the event that field screening with a PID, visual or olfactory observations do not indicate the presence of contamination; the two (2) depth intervals immediately above the soil /groundwater interface will be submitted for laboratory analysis. Each of the soil samples selected for laboratory analysis will be analyzed for the presence of Benzene, Ethylbenzene, Toluene, Xylene (BTEX) constituents, Methyl -tert-butyl Ether (MTBE), N- Heaxane and Naphthalene via EPA Method 8260, Total Petroleum Hydrocarbons — Extended Range Organics (TPH -ERO) via EPA Method 8015M, and carcinogenic Polynuclear Aromatic Hydrocarbons (cPAHs), in accordance with IDEM guidance for kerosene and other similar heating oils. Wightman Petrie will utilize IDEM guidance Terra -Core Methods to collect soil samples from each discrete sampling interval for the analysis of BTEX constituents. All soil samples will be labeled, packed on ice and forwarded to the laboratory under chain -of- custody procedures. Temporary Geoprobe Well Installation for Groundwater Sampling Wightman Petrie proposes to convert each of the four (4) Geoprobe soil borings to temporary wells with insertion of a Geoprobe groundwater sampling device, which allows for the extension of a stainless steel slotted screen for collection of a groundwater sample from the point at which the saturated or water - bearing zone is encountered. For this proposal, Wightman Petrie has assumed that the water - bearing zone will be encountered within 20 -feet of land surface. Once installed, each temporary well would be purged until such time as the water discharge becomes relatively free of solids or until at least three (3) gallons of water has been removed. Wightman Petrie proposes that groundwater from each of the temporary wells be analyzed for Volatile Organic Compounds via EPA Method 8260, and carcinogenic PAHs via EPA Method 8270 SIM. Each groundwater sample will be appropriately labeled, packed on ice, and forwarded to the laboratory (priority