(1) Document Number: RPP-RPT-36893. Rev. 0 EXECUTIVE SUMMARYThis report documents the results of preliminary surface geophysical exploration activities performed between September and October 2007 at the waste management areas surrounding the TX and TY tank farms. The TX-TY tank farms are located in the 200 West Area of the U.S. Department of Energy's Hanford Site in Washington State. The objective of the preliminary investigation was to acquire background characterization information using magnetic gradiometry (Mag) and electromagnetic induction (EM) methods to understand the spatial distribution of buried metallic objects that could potentially interfere with the results of a subsequently completed high resolution resistivity survey.Data coverage included a total of approximately 82 acres over five main focus areas: the eastern cribs (216-T-26 through 216-T-28), northern cribs (216-T-36-13 and T216-T-13), south tile field (216-T-19), western trenches (216-T-21 through 216-T-25), and the area directly west ofthe TX farm.Results of the background characterization indicate that there are several areas located around the tank farms that have large metallic subsurface debris or metallic infrastructure that will likely influence the resistivity results.Figure ES-1 shows the results of the magnetic vertical gradient response patterns, in nanoTeslas (nT). The vertical magnetic gradient reveals some shallow ferrous materials most noticeably between the eastern TX farm fence and the eastern survey boundary. Several other linear features appear within the survey area and are exhibited by the red and blue color contours. Areas that have no buried metallic objects are represented by yellow hues. Interpreted responses were correlated to available infrastructure maps and then grouped into three classes based on how they might influence resistivity data: below ground (pipes and utilities), above ground (overhead electric lines, surface transfer lines, structures), and roads (with different material properties and increased moisture).Figure ES-2 shows the electrical conductivity survey results using the 10 kHz frequency. The color scale was developed so that background conditions are represented by orange and yellow colors and high conductivity features are shown in red tones. The figure shows several high conductivity regions that could be indicative of subsurface metals, including stainless-steel pipes. The features correlate with the results of the magnetic survey, which provides the ability to segregate ferrous metals that will appear on the Mag and EM data, and non-ferrous metals that will only be visible only on the EM results. Unlike the Mag survey, overhead electric lines are visible in the electromagnetic survey, most noticeably west of the TX-TY farms. ES-1RPP-RPT-36893, Rev. 0