SITE INFORMATION AND CORRESPONDENCE

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Advanced GeoEnvironmental, Inc January 3, 2012 Page 2 The use of these methods is also dictated by the proximity of above ground features to the survey area. Typically, the VMG cannot be used in close proximity to above ground metal objects, such as buildings and wrought-iron fences. Magnetic interference from these objects will often mask the detection of a nearby buried UST. The MD and EMLL are not as sensitive as the VMG and can typically be used closer to these above ground metal objects. GPR is not effected by above ground metal objects, and is typically used to survey areas in close proximity to these features. Based on the objective of this survey and the specific site conditions, we used the metal detection (MD), electromagnetic line locating (EMLL), and ground penetrating radar (GPR) methods. The MD/EMLL method was used to survey for shallow subsurface metal objects that may represent a UST and possible UST associated utilities. It was scanned over the established grid along south-north and/or west-east trending traverses spaced approximately 5 ft apart. When a buried object was detected, the MD was then scanned along additional traverses. The GPR method was used to image variations in the electrical properties of the shallow subsurface. These variations can provide information on the location and dimensions of buried objects and fill boundaries and/or former excavations. We scanned the site with GPR along south-north trending traverses spaced 2.5-ft apart. The GPR records were processed on site and examined for reflection patterns characteristic of a UST. Descriptions of the MD and GPR methods are provided in Appendix A. 3.0 RESULTS The results of the MD, EMLL, and GPR surveys are presented on the Geophysical Survey Map, Plate 1. This map shows the limits of the geophysical investigation, the locations of above ground features, and the locations of any detected subsurface features and utilities. Since a utility search was not the primary objective of this survey, there may be additional utilities that are not shown. The EMLL and MD surveys detected an electric, storm drain, and two undifferentiated utility lines. All are located in the north half of the survey area, as shown on Plate 1. The electric line passes through the northwest corner to a light pole, and the storm drain line trends east from a catch basin. One of the undifferentiated utilities parallels the electric line. The other trends into the survey area from the north, where it ends abruptly near a soil boring drilled by Advanced Geo Environmental. It is uncertain if the undifferentiated utilities represent lines associated with the present building to the north or abandoned lines associated with former facilities. The MD did not define any below ground metal objects within the designated survey limits that could represent a possible UST. However, it should be noted that electromagnetic interference from the wrought-iron fence precluded the use of the MD within approximately 5-ft of this structure. The GPR records obtained throughout the survey area exhibit continuous reflection patterns that we interpret as representing shallow fill horizons associated with the pavement and near surface soils. These records also show deeper continuous reflections as well as isolated hyperbolic