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G E O P H Y S I C A L <br /> NOS <br /> I 1C/ L INC, ULTANTS <br /> NORCAL <br /> July 10, 1996 <br /> Mr. Roger Hoffmore <br /> Pacific Environmental Group, Inc. <br /> 11315 Sunrise Gold Circle, Suite M <br /> Rancho Cordova, CA 95742 <br /> Dear Mr. Hoffmore: <br /> This report presents the findings of the geophysical investigation performed by <br /> NORCAL Geophysical Consultants, Inc. on the vacant lot at 2409 E. Main Street in <br /> Stockton, California. The survey was conducted on June 18, 1996 by Geophysicist <br /> Donald J. Kirker. <br /> SITE DESCRIPTION AND PURPOSE <br /> The area of investigation, as specified by Pacific Environmental Group, is an asphalt <br /> covered lot that measures approximately 100 ft by 135 ft, as shown on the Site <br /> Location Map, Plate 1. It is bordered by Main Street to the south, F Street to the <br /> west, Marsh Street to the north, and a parking lot to the east. Light poles, metal <br /> bumper poles, and above ground metal 55 gallon storage drums are located along the <br /> east boundary of the site. Metal poles severed at the ground surface are located in <br /> the northwest and southwest corners of the survey area. A concrete pad, <br /> representing the footprint of a former building, is located in the center of the survey <br /> area. A smaller concrete pad, with a gravel filled metal vault is located northeast of <br /> the larger pad. Further inspection of this vault revealed the fill port to an existing <br /> underground storage tank (UST). <br /> Historical information, provided by Pacific Environmental Group, indicates that this <br /> site was formerly occupied by a Chevron service station. This information also <br /> indicates that several underground storage tanks (UST's) were removed when the <br /> service station was demolished. However, it is not known if all of the UST's were <br /> removed. Therefore, the purpose of this survey is to obtain subsurface information <br /> that will aid in determining the possible location of additional UST's. <br /> METHODOLOGY AND INSTRUMENTATION <br /> We used the vertical magnetic gradient (VMG), ground penetrating radar (GPR), and <br /> electromagnetic line locating (EMLL) methods. The VMG method was used to <br /> determine the presence of buried ferrous metal that may represent an UST. The GPR <br /> and EMLL methods were used to aid in further characterizing the source of the <br /> detected VMG anomalies, as well as to locate possible UST associated utility lines. <br /> 1350 INDUSTRIAL AVENUE SUITE A • PETALUMA. CA 94952 <br /> TELEPHONE (7071 753 1312 • FAX (7071 762-5587 <br />