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I � S E C 0 R . Mr Harlin Knoll October 28, 2005 Page 2 Number of Detections Minimum Maximum Constituents above the MDL of the 4 Concentration in pg/L(Well ID) Concentration in pgIL(Weil ID) Total Samples TPHd 1 <50 2508(MW-4) TPHg 1 <50 5,700(MW-4) Benzene 0 <0 5 <0 5 MtBE 2 <0 5 100(MW-3) Definitions MDL=Method detection limit pg/L= Micrograms per liter Notes a =Laboratory report indicates the observed sample pattern is not typical of#2 fuel/diesel It elutes in the DRO range earlier than#2 fuel Groundwater monitoring well MW-1 Is located next to the former waste oil tank At one . time, groundwater samples collected from MW-1 did have detectable concentrations of oil and grease However, oil and grease have not been detected in groundwater samples collected from this well In over a year No detections of TPHg have been reported In MW-1 since groundwater sampling began In May 1996 The most recent detection of TPHd In well MW-1 occurred during quarterly monitoring In October 2004, at a concentration of 77 micrograms per liter (pg/L) The last TPHd detections prior to that monitoring event occurred In November of 1997 and 1998 MtBE has never been detected In MW-1 at or above Its method detection limit (MDL) In almost 10 years of quarterly groundwater sampling Groundwater monitoring well MW-2 is located downgradlent, and to the north, of well MW-1 and the former underground storage tank (UST) pit Random, low level detections of TPHd have been reported In well MW-2 over the past 10 years of quarterly groundwater monitoring, at a maximum concentration of 150 NgIL TPHg, benzene, toluene, ethylbenzene, and xylenes (BTEX) have never been detected In this well Sporadic detections of MtBE have occurred In this well over the past 10 years, but MtBE has never been detected In this well at or above Its primary maximum contaminant level (MCL) of 13 NgIL Additionally, MtBE has not been detected in this well at or above Its MDL in over 2 years of groundwater monitoring and sampling Groundwater monitoring well MW-3 is located downgradlent, and to the east, of MW-1 and the former UST pit BTEX has not been detected at or above Its MDL in groundwater samples collected from monitoring well MW-3 since January 2002 Benzene was detected iIn MW-3 at a concentration of 46 jug/L during the May 2000 sampling event Benzene has k S N 1Files\Protects\Chevron\Retail\#9-82641Penodic Monitoring\2005\3Q2005 QMR doc s