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Prix it Services, Inc Technical Solutions,for the Industrial Would, ENHANCED LEAK DETECTION NEW CONSTRUCTION WORK PLAN Introduction Section 25190.1.0)(1)of Assembly Bill 2481 (AB 248 1)explains that"enhanced leak detection"can be used as one of three options of leak detection that must be demonstrated before a tank system can be placed into operation after installation. LG 162-1 states that enhanced leak detection is the only approved option of the three at this time 1. Enhanced Leak Detection (ELDS) is defined as a test method that ascertains the physical integrity of an underground tank system by introduction, and external detection, of a substance that is not a component of the fuel formulation that is stored in the tank system." It further requires that the"test method shall be third- party certified,in accordance with section 2643(f),for the capability of detecting both vapor and liquid phase releases from the underground storage tank system. The enhanced leak detection test method shall be capable of detecting a leak rate of at least 0.005 gph or less, with a probability of detection of at least 95% and a probability of false alarm no greater than 5%." The Tracer Tight® leak detection methodology meets such requirements. Concept Tracer Tight' is a unique method of testing underground storage tank systems for tightness. A unique chemical called a tracer is added to the product stored in the tank. The tracer is an inert chemical that evaporates readily from the fuel. After tracer is added to the system, it is distributed between the vapor and liquid inside the tank. Use of the system carries the tracer throughout the piping. If any small leak exists in the system,the tracer is allowed to escape from the system, either as a vapor or as a dissolved component of the liquid. Once outside the system, the dissolved tracer evaporates from the liquid and the tracer vapors begin to migrate away from the location of the leak in all directions. After an appropriate waiting period,the tracer vapors are detectable at least ten feet or more away from the leak in all directions. Samples of air collected from the soil within the radius of detection of the tracer reveal the leak as a presence of the tracer chemical. Because the tracer chemical is not normally found in the environment or in fuel products, the Tracer Tight' method is able to discriminate between previous contamination and current leakage. 1 As of July 25,2003. 0 Copyright 2003 Praxair Services,Inc.