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CONCEPT OF OPERATION AND IMPLEMENTATION <br /> The tracer leak detection method relies upon the addition of a highly volatile liquid <br /> chemical to the product in the tank. If a leak occurs in the underground storage system, product <br /> is released into the surrounding soil. The tracer escapes from the product by vaporization and <br /> disperses into the soil by molecular diffusion. Various means are used to sample the soil vapors <br /> in the immediate vicinity of the underground storage tanks and associated piping. Each probe <br /> has an effective detection radius of approximately 10 feet. This means that a given probe should <br /> detect a leak anywhere within the area described by the 10 foot radius around the probe. The <br /> tracer must be placed in the tank at least two weeks prior to the probe sampling for this method <br /> to be effective. This process of leak detection by placing a liquid or gas tracer in a liquid <br /> product followed by detection of the tracer underground in the vapor phase is protected under <br /> TRACER patents. <br /> Pipelines are located using radio frequency induction and/or connection equipment. <br /> The throughput factor is used to determine the amount of tracer chemical used to inoculate <br /> a given tank. The throughput factor is a multiplier and is based on the number of tank refills <br /> expected within the first three days after inoculation. Tracer is added to the tank in an amount <br /> that will insure adequate tracer concentration after receiving all product deliveries scheduled for <br /> the first three days after inoculation. <br /> LEAK DETECTION CRITERIA <br /> The classification of leakage is based on the presence or absence of tracer. <br /> PASS FAIL <br /> Criteria: Criteria: <br /> NO tracer detected tracer detected <br /> If requested, total volatile hydrocarbon (TVHC) concentrations are measured to give <br /> additional information about site conditions. The TVHC data provide information about the <br /> severity of the leakage, and the degree of any possible environmental damage that may have <br /> occurred. The TVHC data is not used as a criterion factor to determine the status of a particular <br /> tank(s) or piping and is provided as supplemental information only. <br /> - 2 - <br />