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MEMORANDUM <br /> CaUEPA °:dLr �_ <br /> ' �'� ll � 21 Governor <br /> State Water TO: Regional Water Quality Control Board UST Program <br /> Resources <br /> Control Board Managers and Local Oversight Program Managers <br /> 2014 T Street, <br /> Suite 130 <br /> Saaatne sa,CA <br /> 95814 <br /> Mail Code G-8 <br /> (916)227.4319 FROM: an Patton,AanageFAX(916)227-4349 <br /> Underground Storage Tank Section <br /> DIVISION OF CLEAN WATER PROGRAMS <br /> DATE: PW 2 2 1996 <br /> SUBJECT: NEW GUIDANCE ON GROUNDWATER MONITORING OF <br /> METHYL-TERT BUTYL ETHER (MTBE) FROM ACTIVE LUFT <br /> CASES <br /> As discussed in our July 30, 1996, memorandum we have asked for your assistance in <br /> accessing the occurrence of MTBE in groundwater at LUFT sites statewide. <br /> Specifically, we have requested that you add MTBE to the list of gasoline components <br /> which are being monitored in groundwater at your active LUFT sites. <br /> Because there have been many discussions as to the choice of analytical methods for <br /> detection of MTBE, we asked the Lawrence Livermore National Laboratory to evaluate <br /> the efficacy of existing analytical methods used for monitoring of BTEX gasoline <br /> components for the detection of MTBE. A copy of their report is attached. Based on <br /> their findings and recommendations, we offer the following guidance: <br /> • It is recommended that EPA method 8020A (or 8021B) be used to detect BTEX and <br /> MTBE compounds in LUFT groundwater samples. <br /> • Due to a low occurrence of false positives, it is recommended that at least one <br /> groundwater sample per site which was positive for MTBE by EPA method 8020A <br /> (or 8021B) be analyzed by EPA method 8240B (or 8260A) to verify the correct <br /> identification of MTBE (i.e. split samples from a minimum of one well from each <br /> site). We recommend that confirmation analysis be performed for the sample <br /> containing the highest MTBE concentration from the site based on method 8020A <br /> (or 8021B) values. For these samples the 8240B (or 8260A) value should be <br /> reported. <br /> Recycied?aaer Our mtss.on is ra aresene and enhance rhe,quality ofCa!lforntat ivawresources.and <br /> ensure them Procter adocanon and effc:en,use for rhe benefit afaresenr and future generanons. <br />