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t1 Mr Mike Infurna Page 2 • 3 shoves the locations of the monitoring wells at both sites "B Zone" or "C Zone" gradient maps are not presented An evaluation of the potentiometric surface elevations relative to well screen depths indicates that vertical gradient components are quite variable and depth-sensitive It appears that a division of the aquifer into these zones does not allow for an adequate interpretation of the horizontal gradients Groundwater Sampling On September 8, 2003, site wells MW1, MW4 and U-Haul MW7 were purged and sampled Well MW2 was dry Well MW3 was not accessible for sampling Approximately four well casing volumes were purged from well MW1 before the well went dry Approximately three well casing volumes were purged from well U-Haul MW7 Well MW4 went dry after approximately 100 milliliters (mL) of water were purged Groundwater in well MW4 never recovered During the purging of wells MW1 and U-Haul MW7, temperature, pH and electrical conductivity parameters were measured Groundwater samples from wells MW 1 and U-Haul MW7 were collected after physical parameter stabilization and groundwater recoveries of 19% and 100%, respectively Purgewater retrieved from well MW4 was submitted for lab analysis Samples were stored in an ice chest refrigerated to a temperature of approximately 4°C Purgewater from wells MW1 and U-Haul MW7 was contained in appropriately labeled DOT-approved 55-gallon drums Purge logs are included in Attachment A Samples were delivered under chain of custody protocol to Argon Laboratories (FLAP #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 detected in wells MW1, MW4 and well U-Haul MW7 at concentrations of 200,000 parts per billion (ppb), 7,000 ppb and 4,000 ppb, respectively Benzene ranged from 59 ppb in MW4 to 13,000 ppb in well MW1 Analytical results are summarized in Table 2 Attachment B contains laboratory reports and chain of custody documentation Gasoline oxygenate additives and EDB were not detected in wells MW1, MW4 and U-Haul MW7 above laboratory method detection limits (MDLs) 1,2-DCA was detected at a concentration of 380 ppb in well MW1, 49 ppb in well MW4 and 160 ppb in well U-Haul MW7 Analytical results are summarized in Table 3 Attachment B contains laboratory reports and chain of custody documentation SUN MARY Water levels were measured in all accessible monitoring wells The potentiometric surface at the site fell more than ten feet since the previous monitoring event in May 2003 NGZA_FSIVOL 11DATAIGROUNDZEIHARRYSIReports\QMR1200313QM2003 doe