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( Z, k�A-. <br /> ' t <br /> ,. MEMORANDUM <br /> L /EPA <br /> Pae Vrdwn <br /> State Water 2z Govemor <br /> Resources TO: Regional Water Quality Control Board UST Program <br /> Contrai Board Managers and Local Oversight Program Managers <br /> 2014 T SUveL <br /> Suite 130 <br /> Sacramento,CA <br /> 93814 <br /> NWR Code G-8 <br /> (916)227-4319 FROM: <br /> FAX(916)227-4349 Parto a nage <br /> Underground Storage Tank Section <br /> DIVISION OF CLEAN WATER PROGRAMS <br /> DATE: AUG 2 2 1996 <br /> SUBJECT: NEW GUIDANCE ON GROUNDWATER MONITORING OF <br /> CfETHYL,-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 Ieast one <br /> groundwater sample per site which was positive for MTBE by EPA method 8020A <br /> (or 8021B) be analyzed by EPA method 824bB (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 rhe 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 /> r}� Rerycled Pacer Dur mur'on is:a preserve and ennenes:he guaGry ofC:iifarma't water ruourrex and <br /> ~t r!tsure thea draper al ocation and e�cent use for the eereist of pre:ent and fiuture genera-ars. <br /> E� <br />