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f Mr Nuel Henderson Page 2 of 4 t� During this event no consistent vertical gradient direction was apparent An interpretive potentiometric surface map generated using the May 30, 2006 groundwater elevation data for the shallow groundwater monitoring wells is shown on Figure 2 A potentiometric surface map generated using groundwater elevation data from the deeper groundwater monitoring wells is shown on Figure 3 In both cases groundwater generally flowed towards the east and northeast Groundwater monitoring data are summarized in Table I Monitoring data sheets and well construction details are included in Attachment A Also included in Attachment A are tabulated results of depth to water measurements at the ARCO station On June 8, 2006, a Lubcke Environmental Services technician collected groundwater samples from monitoring wells MW 1, MW7, MW8, MW 11, MW 13B, MW 15A, MW 15B, MW 15C, MW 17C and VW 1 A minimum of three well casing volumes was purged from each well prior to sampling During the purging process, physical parameters (pH, electrical conductivity, and temperature) were monitored Subsequent to parameter stabilization, and 95% recovery of initial depth to groundwater measurements, groundwater samples were collected and placed in an iced cooler for transport to Argon Laboratories (ELAP #2359) under chain of custody protocol Analysis consisted of gasoline oxygenates, EDB and 1,2-DCA by EPA Method 8260B, TPHg by EPA Method 8015M and BTEX by EPA Method 8021B Purge water was transferred into labeled 55-gallon drums approved by the Department of Transportation (DOT) The waste is stored onsite within a secured arca Purge logs are included in Attachment A GROUNDWATER ANALYTECAL RESULTS Groundwater Monitoring Wells TPHg and benzene were not detected in wells MW7, MW 11, MW 15A, MW 15C and MW 17C TPHg was detected in well MW 1 at a concentration of 240 parts per billion (ppb) No BTEX compounds were detected in MW 1 TPHg and benzene were detected in well MW 8 at concentrations of 5,000 ppb and 490 ppb, respectively TPHg and benzene were detected in well MW 13B at concentrations of 120,000 ppb and 12,000 ppb, respectively TPHg and benzene were detected in well MW15B at concentrations of 340 ppb and 1 3 ppb, respectively Dissolved TPHg and BTEX levels were within historical ranges, and appear to be stable to decreasing TPHg and BTEX concentration data are summarized in Table 2 Attachment B contains laboratory reports and chain of custody documentation G 1GR0UNDZE\R0MQMRti200612gm2006 dor