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i I , Mr Ron Rowe Page 2 of 6 elevation Water levels rose an average of 1 74 feet since last monitored on February 10, 1999 Groundwater flow was generally easterly with a gradient ranging from approximately 0 001 to 0 005 feet per foot A groundwater gradient map generated using the May 4, 1999 monitoring data is shown on Figure 2 Recent groundwater monitoring data are summarized in Table I Monitoring logs and well construction information are included in Attachment A On May 4 through 6, 1999 Ground Zero collected groundwater samples from groundwater monitoring wells MWl through MW13 At least three well casing volumes were purged from each groundwater monitoring well prior to sampling Physical parameters (pH, conductivity, ' temperature) were monitored during purging and allowed to stabilize prior to sampling Samples were collected after groundwater recharged to 100% of the original level Purged water was contained in 55-gallon drums approved by the Department of Transportation and stored onsite in ' a locked enclosure Purge logs are presented in Attachment A Samples were placed on ice and transported under chain of custody to Argon Laboratories (FLAP ' #2359) Samples were analyzed for TPHg using modified EPA method 8015 and BTEX using EPA method 8020 Additional sample matrix collected from monitoring wells MW1, MW3, MW4, MW7, MW 11, MW 12, and MW 13 was analyzed for oxygenates using modified EPA 8260 Analytical results for TPHg, BTEX and MTBE are summarized in Table 2, oxygenate results are summarized in Table 3 Attachment B contains laboratory reports and chain of custody documentation ' Groundwater Analytical Results ' Water levels in wells MW I through MW 12 were above the top of the screened intervals Some have been for a year or more Petroleum hydrocarbons were detected in groundwater samples collected from all monitoring wells, except MW6, MW7, MW9, MW10, NMI I, and MW12 ' Concentrations of petroleum hydrocarbons remained below laboratory detection limits in well MW9 for the second consecutive quarter, in well MW6 for the third consecutive quarter and in ' well MW 10 for the fourth consecutive quarter Hydrocarbon concentrations in well MW7 returned to non-detectable levels following two quarters of detections Concentrations of TPHg and BTEX in the samples collected from wells MWS, MW8, and MW 13 were within the middle ' to low historical range Concentrations of TPHg and BTEX in samples collected from wells MW1 and MW2 continue to decrease Significant concentrations of hydrocarbons indicative of fresh gasoline continue to be detected in water samples collected from wells MW3 and MW4 located along the southern property boundary TPHg and BTEX concentrations are summarized in Table 2 Samples from wells MW 1, MW3, MW4, MW7, and MW 11 through MW 13 were also analyzed for oxygenates Oxygenates were not detected in the samples from wells MW 1, MW7, MW 12, rwk*v\2gm1999