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' Cw6g£ea!recti is 14C. Page 4 Groundwater Monitoring Report Project No.425.2 March 21, 2005 Stagnant water in the well casing was purged using a Honda@ centrifugal pump or a ' Waterra@ pump with dedicated tubing as recorded in the field logs (Appendix C). The rate of well purging was monitored. The wells were purged of at least three casing volumes or until the groundwater parameters (temperature, conductivity, and pH) had stabilized (Appendix C) indicating that water representative of actual aquifer conditions was entering the well. Groundwater parameter stabilization was characterized by three successive readings within 10%. ' Before a sample was collected, the well's water level was allowed to recharge to at least 80% of its initial level. MW-7, MW-8, and MW-106 exhibited poor recharge. Heavy sheen was ' noted in MW-2. All the water removed from the monitoring wells and not used as a sample was placed in a properly labeled 55 gallon DOT (Department of Transportation 17-H) approved container and temporarily stored on-site. ' A 1-foot stainless steel bailer and stainless steel wire line or a Waterra@ pump with dedicated tubing was used to collect each sample. Extreme care was exercised while collecting samples ' to prevent agitation of the water contained in the bailer. Water samples were transferred from the bailer into 40-n-1 VOA vials preserved with hydrochloric acid using a bottom- emptying device that minimizes sample aeration during transfer of the sample. All samples were checked for headspace bubbles, labeled, inserted into foam holders and placed into a cooled ice chest for transport to the laboratory. The sampling technician .wore disposable ' gloves while collecting all samples. A chain of custody document, listing all samples collected and their intended analyses, ' accompanied the samples from field to the laboratory, thereby providing a means to track the movement and insure the integrity of the samples. ' 1.3 Laboratory Analyses The groundwater samples collected on January 21, 2005 were delivered to Excelchem ' Environmental Labs (California Certification # 2119), of Roseville, California, for analysis. The samples were analyzed using the following methods: • BTEX —EPA method 8260B ' • TPH-Gasoline— EPA method 8260B 0 MTBE— EPA method 8260B ' Sherwood Laboratory, Hilmar, CA has been used for the Quarterly Monitoring sample analysis in the past. GTI choose Excelchem Environmental Labs for year 2005 quarterly ' monitoring sample analysis by the bidding process to various labs. Excelchem will do the required analysis by EPA method 8260B starting from first quarter 2005. Additionally, 1