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Chevron Products Company 3
<br />Former Chevron Station 9-5775, 301 W Kettleman Lane, Lodi, CA July 24,2000
<br />• concentrations of TPHg, benzene, MtBE, ETBE, and TAME ranging up to 11,000 ug/l, 6,800
<br />ug/l, 62,000 ug/l, 2,400 ug/l, and 780 ug/l, respectively Historical groundwater analytical data
<br />is included in Attachment C
<br />In October of 1999, G -R continuously monitored the groundwater elevations at the site over a
<br />three-day period (G -R, Offsite Source Survey, dated November 2, 1999) The results of the
<br />study indicated that groundwater elevations fluctuate in daily cycles corresponding to the
<br />operation of nearby City of Lodi Municipal Well #12, located approximately 350 feet southwest
<br />of the site
<br />Between December and February of 1999, five additional monitoring wells (MW -5 through
<br />MW -9), four soil vapor extraction wells (VE -1 through VE -4), one groundwater extraction well
<br />(EX -1), and two soil borings (SB -2 and SB -3) were installed by V&W Drilling (G -R,
<br />Monitoring Well Installation Report, dated March 30, 2000) Soil samples collected from the
<br />borings were reported to contain detectable concentrations of TPHg, benzene, and MtBE
<br />ranging up to 1,740 mg/kg, 446 mg/kg, and 100 mg/kg, respectively The highest
<br />concentrations were reported in samples from borings EX -1 and VE -1 located in the area of the
<br />former USTs Groundwater samples collected from the monitoring and extraction wells were
<br />reported to contain detectable concentrations of TPHg, benzene, MtBE, ETBE, and TAME
<br />ranging up to 51,000 ug/l, 39,000 ug/1, 720,000 ug/l, 18,000 ug/l, and 6,000 ug/l, respectively
<br />Quarterly Monitoring Data
<br />• Quarterly groundwater monitoring and sampling of monitoring wells MW -I through MW -9
<br />began in January of 2000 TPHg has been reported in monitoring wells MW -1, MW -3, MW -4,
<br />MW -5, and MW -6 at concentrations ranging from 150 to 51,000 ug/l In the most recent
<br />quarterly sampling event (second quarter 2000), TPHg was detected in monitoring wells MW -1,
<br />MW -3, MW -5, MW -6, and EX -1 at concentrations of 862 ug/1, 1,390 ug/l, 1,140 ug/l, 162 ug/l,
<br />and X50,000 ug/l, respectively
<br />0
<br />Historically, benzene has been reported in monitoring wells MW -1, MW -3, MW -4, MW -5,
<br />MW -6, and EX -1 at concentrations ranging from 0 72 to 39,000 ug/1 During the most recent
<br />quarterly sampling event, benzene was reported in monitoring wells MW -1, MW -3, MW -4,
<br />MW -5, MW -6, and EX -1 at concentrations of 4 61 ug/l, 651 ug/l, 5 92 ug/1, 385 ug/l, 66 1 ug/1
<br />and 19,000 ug/1, respectively
<br />MtBE has been detected in monitoring wells MW -1, MW -3, MW -4, MW -5, MW -6, MW -8,
<br />MW -9, and EX -1 at concentrations ranging from 2 75 to 720,000 ug/l During the most recent
<br />quarterly sampling event, MtBE was detected in monitoring wells MW -1, MW -3, MW -4, MW
<br />5, MW -6, MW -9, and EX -1 at concentrations of 57,800 ug/1, 8 28 ug/l, 211 ug/l, 474 ug/l, 378
<br />ug/l, 53 4 ug/l, and 350,000 ug/l, respectively
<br />Historical monitoring data from these wells indicate that groundwater at this site has been
<br />measured between 54 to 59 feet bgs Groundwater flow has generally been reported to the
<br />077 41991 04319-5775PAR doc
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