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y it Mr Mike Infurna Page 2 . groundwater in C Zone well MW1D was 58 09 feet btoc Since previously measured on August 30, 2004 water levels rose an average of 2 92 feet in the A Zone wells, 5 44 feet in the B Zone wells, and 5 45 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 December 20, 2004, the potentiometric surface of the A Zone wells ranged from 38 60 feet to 38 69 feet below mean sea level (MSL) The potentiometric surface of the B Zone wells ranged from 38 57 feet to 38 66 feet below MSL The potentiometric surface in C Zone well MW1D was 38 63 feet below MSL 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 Flow is toward the east and northeast at a gradient of approximately 0 001 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 east at a gradient of approximately 0 001 ft/ft while flow in the B Zone is toward the east-southeast at approximately 0 0003 ft/ft Groundwater Sampling • On December 20 and 21, 2004, 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 labeled 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 8260B, BTEX using EPA Method 8021B, and TPHg using modified EPA Method 8015B GROUNDWATER ANALYTICAL RESULTS TPHg was not detected in the samples from wells MW5, MW7 and MW1D BTEX compounds were not detected in samples from wells MW5 and MW7 TPHg was detected in the samples collected from the remaining site wells at concentrations ranging from 250 parts per billion (ppb) in MW6 to 89,000 ppb in MW 1 Benzene levels in these wells ranged from C 0 5 ppb in MW3 to 11,000 ppb in well MW1 Analytical results are summarized in Table 2 Attachment B contains laboratory reports and chain of custody documentation Gasoline oxygenates and additives were not detected in wells MW3 and MW7 1,2-DCA was G 1GROUNDZEIHARRYSNReports\QMR1200414QM2004a doc