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r <br /> ' 4?e0lo tcaITec/uurslac • Page 5 <br /> � g <br /> Additional Investigation Work Plan <br /> Cardoza(Main St) <br /> Project No 662 2 <br /> October 8,2001 <br /> 1 • A bailer blank for each well will be collected prior to sampling by filling the <br /> decontaminated stainless steel bailer with water (provided by the laboratory) and then <br /> filling a VOA vial (provided by the laboratory) using the same procedures for actual <br /> ' sample collection <br /> Bailer blanks for each sample, along with a field blank (prepared from water provided by <br /> ' the laboratory poured into a VOA vial on site) will accompany the samples to the laboratory <br /> and serve as checks against cross contamination <br /> ' A chain of custody document, listing all samples collected, accompanies the samples from <br /> field to laboratory, thereby providing a means to track their movement and insure their <br /> integrity <br /> ' AlI water purged from each monitoring well and not used as a sample, will be placed in a 55 <br /> gallon DOT approved container, properly labeled and stored on site until its proper <br /> disposition can be arranged <br /> ' 32 Groundwater Laboratory Analyses <br /> Groundwater samples from each well will be submitted to California Laboratory Services <br /> (State Certified Laboratory #1233) for analysis for <br /> • Benzene, toluene, ethylbenzene and xylene (BTEX) by EPA method 602/5030 <br /> • Gasoline range petroleum hydrocarbons (TPH-G) by EPA method 5030/8015(m) <br /> • Gasoline oxygenates (MTBE, DIPE, ETBE, TAME & TBA) by EPA method 8260 <br /> • 1,2-DCA and EBD by EPA method 8260 (one event only) <br /> ' • Methanol & Ethanol by GC-FID (one event only) <br /> The detection limits for these compounds are listed below A Chain of Custody will be <br /> ' completed for all samples collected and tracked to ensure sample integrity <br /> Detection Limits 131 EX xy s, TPH-0 Methanol <br /> - EDB Ethanol <br /> ater µg <br /> ' 4.0 RISK EVALUATION <br /> ' 4.1 Contaminant Distribution and Mass Estimation <br /> Through interpretation and extrapolation of the data generated through the history of the <br /> ' project, the distribution of the contamination, both laterally and vertically, will be <br /> determined The contaminant distribution information will then be used in estimation of the <br /> contaminant mass <br /> Mass estimate calculations will be performed to determine the mass of gasoline present at <br /> this site To accomplish this task the soil analytical data obtained from previous <br />