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Mr Mike Infurna Page 2 groundwater in C Zone well MW11) was 50 26 feet btoc Since previously measured on March 14, 2005, water levels rose an average of 2 79 feet in the A Zone wells, 2 75 feet in the B Zone wells, and 2 65 feet in the C Zone well Water level data are summarized in Table 1 Monitoring well locations are shown on Figure 2 Field data sheets are included in Attachment A Groundwater elevation was determined in each well by subtracting the depth to groundwater measurement from the respective surveyed wellhead elevation On June 13, 2005, the potentiometric surface of the A Zone wells ranged from 30 68 feet to 30 71 feet below mean sea level (MSL) The potentiometric surface of the B Zone wells ranged from 30 66 feet to 30 86 feet below MSL The potentiometric surface in C Zone well MW1D was 30 80 feet below MSL I Due to the complexity of the well depth/potentiometric surface relationship, groundwater gradient was interpreted in several ways Figure 3 interprets the gradient using data from the A and B Zone wells together Indicated flow is predominantly toward the west and northwest at a gradient that ranges from approximately 0 0004 ft/ft to 0 0015 ft/ft Potentiometric surface maps utilizing data from the A and B Zones separately are depicted on Figures 4 and 5, respectively Flow in the A Zone is interpreted to be toward the northeast and southeast at gradients of approximately 0 0005- 0 0013 ft/ft while flow in the B Zone is toward the west at approximately 0 0006 ft/ft Groundwater Sampling On June 13 and 14, 2005, the site wells were purged and sampled During purging, temperature, • pH and electrical conductivity parameters were measured Purging continued until these parameters had stabilized A minimum of three well casing volumes was purged from each well Purge water was contained in appropriately Iabeled DOT-approved 55-gallon drums Purge logs are included in Attachment A Groundwater samples were collected after adequate groundwater recovery Samples were collected in sealed, preserved VOAs and stored in an ice chest refrigerated to a temperature of approximately 4° C Samples were delivered under chain of custody protocol to Argon Laboratories (ELAP #2359) Sample analysis consisted of gasoline oxygenate additives, 1,2-DCA and EDB using EPA Method 826013, BTEX using EPA Method 802113, and TPHg using modified EPA Method 8015B GROUNDWATER ANALYTICAL RESULTS TPHg and BTEX compounds were not detected in the samples from wells MW5, MW7 and MW1D TPHg was detected in the samples collected from the remaining site wells at concentrations ranging from 84 parts per billion (ppb) in MW6 to 98,000 ppb in MW 1 Benzene levels in these wells ranged from 1 7 ppb in MW3 to 14,000 ppb in well MW 1 Analytical results are summarized in Table 2 Attachment B contains laboratory reports and chain of custody documentation EDB was not detected in any well The gasoline additive 1,2-DCA was not detected in wells MW3 and MW7 1,2-DCA was present in each of the other wells at concentrations ranging from GIGROUNDZEIHARRYSNReportslQMR1200512QM2005a doe