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Results of Geophysical Investigation <br /> Ranch Market <br /> 23569 S. Santa Fe Road <br /> Riverbank, California <br /> 1 <br />' Introduction 4n May 3, 2004, Spectrum Geophysics conducted a geophysical <br /> investigation on a portion of the Ranch Market, located at 23569 <br /> S Santa Fe Road in Riverbank, California The purpose of the <br /> investigation was to identify possible underground storage tanks <br /> (USTs) <br />' The area of investigation, as designated by Matt Hanko of <br /> Geocon, measured approximately 210 by 130 feet This site was <br /> mostly asphalt-covered with a smaller soil-covered area located <br />' on the northwest portion and a grass-covered area in the <br /> southwest portion <br /> Methods The equipment used in this investigation consisted of a Geometncs <br /> 858 Cesium Vapor Magnetometer, a GSSI SIR-3 ground <br /> penetrating radar (GPR) with a 400 MHz antenna, Fisher m-scope <br /> metal detector, and utility locators <br /> Total Field Maimetics <br />' A Geometries 858 Cesium Vapor Magnetometer was used in an <br /> effort to identify significant magnetic anomalies that might be <br />' associated with high concentrations of buried ferromagnetic <br /> material The operating principle is the self-oscillating split-beam <br /> Cesium Vapor (non-radioactive Cs 133) This optically pumped <br />' magnetometer uses the properties of the electron to make its <br /> measurements Polarized light at a particular wavelength is <br /> radiated through a gas cell containing the working gas of the <br /> magnetometer This polarized light "bumps" the electrons to a <br /> higher energy state A coil applies a small RF field to this gas cell <br />' This applied AC current flowing through a coil then "bumps" some <br /> electrons down to a lower energy state Light absorbed when these <br /> electrons are "re-pumped" results in light flickering at the Larmor <br /> tfrequency This frequency is then measured with a light sensor <br /> Readings of the Earth's total magnetic field were taken at 0 3 <br />' seconds along north-south lines spaced 5 feet apart The magnetics <br /> data were processed in the field and used to generate total field <br /> magnetics contour maps to assist in identifying possible USTs <br /> Spectrum Geophysics 3 <br />