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ATC Associates Inc " 1117 Lone Palm Avenue, Suite B Modesto, California 95351%TCI 209-579-2221 ASSOCIis ATES INC fax 209-579-2225 for chemical analyses of TPHg and total petroleum hydrocarbons quantified as diesel (TPHd) utilizing EPA Method 8015M, BTEX utilizing EPA Method 8021B, and oxygenate fuel additives including methyl tert-butyl ether (MTBE) utilizing EPA method 8260B GROUNDWATER ELEVATION Water level measurements were collected from wells MWI. through MW7 on July 15, 2005 Depth to water ranged from 52 99 feet below ground surface (bsg) to 53 91 feet bgs Water elevations ranged from a high of—29 78 to a low of—30 00 representing an average increase in water table elevation of 1 57 feet since April 2005 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 15, 2005, was approximately 0 001 foot per foot or approximately 5 feet per mile and the gradient direction was generally to the west-southwest (Figure 3) A summary of groundwater monitoring data is presented in Table 1 ANALYTICAL RESULTS Chemicals of Concern (CDCs) were detected in both groundwater samples collected from MW 1 } and MW2 TPHg was detected in the groundwater sample collected from MW2 at a concentration of 102 µg/L Benzene was detected in the groundwater sample collected from MW2 at a concentration of 0 8 pg/L MTBE was detected in the groundwater samples collected from MWIand MW2 at concentrations of 1 1 pg/L and 3 4 pg/L, respectively Groundwater samples collected from MW3 through MW7 were not collected Groundwater samples collected from wells MW1 and MW2 did not contain concentrations of TPHd Historically, none of the wells have contained TPHd 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 ID number is T0607700242 The depth to water data was submitted electronically to the State Water Resources Control Board (SWRCB) Geotracker database (confirmation number 2917356729) and the laboratory data was also submitted electronically to the SWRCB Geotracker database (confirmation number 3954257965) Documentation of the data submittal is contained in Attachment 3 CONCLUSIONS The concentration of petroleum hydrocarbons in groundwater samples collected from MWl and MW2 are within the historical range as established by previous sampling events Sampling was reduced to monitoring MW1 and MW2 quarterly, while monitoring MW3 through MW7 S 16257712QR-2005 doc 3