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Mr Jeffrey Wong Page 2 A potentiometric surface map generated using the September 24, 2001 monitoring data is shown on Figure 2 Groundwater monitoring data are summarized in Table 1 Monitoring data sheets are included in Attachment A Prior to sampling, wells MW 1 through MW4 were purged of a minimum of three well casing volumes During the purging process physical parameters (temperature, pH and electrical conductivity) were measured in each respective well, and well MW 1 went dry once Groundwater samples were collected after physical parameter stabilization, and at least 80% water level recovery of initial depth to water measurements Subsequently the samples were placed in an ice chest cooled to a temperature of approximately 4°C Purgewater was contained in appropriately labeled DOT-approved 55-gallon drums, and is currently being stored onsite pending proper disposal options Purge logs are included in Attachment A Groundwater samples were delivered under chain of custody protocol to Argon Laboratories (FLAP #2359) Analysis consisted of gasoline oxygenate additives, 1,2-DCA and EDB using EPA method 8260, BTEX using EPA method 8020, and TPHg using modified EPA method 8015 Wellhead Surveying On September 24, the wellhead elevation of monitoring well MW7 associated with the U-Haul Facility at 2701 N Wilson Way was surveyed relative to the wellhead elevations of the Harry's Auto Mart monitoring wells Water levels were measured at the U-Haul Facility on September 24 by Blaes Environmental personnel Ground Zero and Blaes subsequently exchanged water level data Groundwater elevation data for well MW7 are included in Table 1 The location of well MW7 is shown on Figure 2 On September 24, the potentiometric surface in MW7 was approximately 0 05- 0 09 feet higher than the potentiometric surface in the Harry's Auto monitoring wells This difference is attributed to the deeper screened interval in well MW7 Differences in potentiometric surface elevation related to well completion depths have also been documented at the U-Haul site As requested by PHS/EHD, Ground Zero has obtained permission from U-Haul to monitor and sample well MW7 in the future GROUNDWATER ANALYTICAL RESULTS TPHg and benzene were detected in the samples from each site monitoring well TPHg concentrations ranged from 260 parts per billion (ppb) to 180,000 ppb, and benzene concentrations ranged from 0 8 ppb to 14,000 ppb in wells MW3 and MWI, respectively 1,2- DCA was detected in all wells except MW3 at concentrations ranging from 220 ppb in well MW4 to 960 ppb in well MW 1 Gasoline oxygenate additives and EDB were not detected in the samples from any monitoring well Analytical results are summarized in Table 2 Attachment B contains laboratory reports and chain of custody documentation H-rYslrepaRs\gmr13ym2001 doc