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f (YVATC A S S O C I A T E S I N C GROUNDWATER ELEVATION Water level measurements were collected from wells MW1 through MW7 on July 8, 2004 Depth to water ranged from 54 87 feet below ground surface (bgs) to 55 71 feet bgs Water elevations ranged from a high of—3165 to a low of—31 79 representing an average decrease in water table elevation of 0 76 feet since April 7, 2004 The water level data were used to develop a groundwater elevation contour map (Figure 3) Review of the groundwater elevation contour map indicates that the hydraulic gradient beneath the site on July 8, 2004, was approximately 0 0014 foot per foot or approximately 7 feet per mile and the gradient direction was generally to the south (Figure 3) A summary of groundwater monitoring data is presented in Table 1 ANALYTICAL RESULTS Chemicals of Concern (COC's) were only detected in the groundwater samples collected from MWl and MW2 TPHg was detected in the groundwater sample collected from MW1 and MW2 at concentrations of 78 µg/L and 76 pg/L, respectively Benzene was detected in the groundwater sample collected from MW2 at a concentration of 12 pg/L MTBE was detected in the groundwater samples collected from MW 1 and MW2 at concentrations of 4 7�Lg/L and 11 gg/L, respectively iGroundwater samples collected from wells MW3, MW4, MW5, MW6, and MW7 did not contain concentrations of TPHg, TPHd, TPHk, BTEX constituents, or fuel oxygenates at or above the laboratory reporting limits Groundwater samples collected from wells MW 1 through MW7 did not contain concentrations of TPHd or TPHk, and have not since March 27, 2001 Analytical results for groundwater samples are contained in Table 2 Laboratory data sheets and chain-of-custody documentation are contained in Attachment 2 GEOTRACKER DATA UPLOAD The site facility global 1D number is T0607700242 The depth to water data was submitted electronically to the State Water Resources Control Board (SWRCB) Geotracker database (confirmation number 6931309342) and the laboratory data was also submitted electronically to the SWRCB Geotracker database (confirmation number 6807491600) Documentation of the data submittal is contained in Attachment 3 CONCLUSIONS The concentration of petroleum hydrocarbons in groundwater samples collected from MW1 and MW2 are within the historical range as established by previous sampling events and have — generally decreased over time Concentrations of petroleum hydrocarbons remained below laboratory reporting limits in samples collected from MW3, MW4, MW5, MW6, and MW7 TPHk has not been detected in samples collected from wells MW1, MW2, and MW3 since at . least 2000 TPHd has not been detected in samples collected from wells MW1 through MW4 since at least March 2001 TPHk has never been detected in samples collected from wells MW4 S%257713QR-2004 doc 3