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PHONE 285 2400
<br /> ` CABLE ADDRESS TIMOIL
<br /> SEATTLE TE (FAX) 206 283 8036
<br /> TACOMA N
<br /> PORTLAND
<br /> STOCKTON T
<br /> r ROSAN ANGELES 9 'i t i ' NE TIME OIL C O .
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<br /> 6 , 2737 WEST COMMODORE WAY SEATTLE WA 98199 1233
<br /> PRODUCTS
<br /> T P O BOX 24447 SEATTLE,WA 98124 0447
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<br /> IME TESTED _E
<br /> April 19, 2001
<br /> Mr Harlin Knoll
<br /> San Joaquin County Public Health Services
<br /> Environmental Health Division
<br /> P O Box 2009
<br /> Stockton, California 95201
<br /> RE Submittal of"Quarterly Monitoring Report, January—March 2001"for
<br /> Jackpot Food Mart, 14000 E Highway 88, Lockeford, California (Property No 04-049)
<br /> Dear Mr Knoll,
<br /> At the request of the San Joaquin County Public Health Services Environmental Health Division (PHSIEHD),
<br /> an environmental investigation was implemented at the subject site in December 1994 to evaluate the extent
<br /> of hydrocarbon-impacted soils and to determine whether or not groundwater had been impacted A total of
<br /> four monitoring wells were installed during this investigation In July 1996, six additional monitoring wells were
<br /> installed on and off of the subject site to assist in defining the extent of groundwater impacts and quarterly
<br /> monitoring was implemented In August and September 1999, SECOR installed a vapor extraction/air
<br /> sparging system at the subject site to remediate hydrocarbon-impacted sods and groundwater System
<br /> operation began December 13, 1999
<br /> Please find enclosed SECOR's "Quarterly Monitoring Report, January -- March 2001" dated Apnl 16, 2001
<br /> This document presents analytical results and field observations collected during First Quarter 2001
<br /> groundwater sampling, and discusses the efficiency of the remediation system currently in operation
<br /> First Quarter 2001 Groundwater-Sampling Results
<br /> On January 11,2001, samples were collected from each of the groundwater monitonng wells (MW-1 through
<br /> MW-10) at the subject site by a representative of SECOR Prior to purging, the depth to water in each well
<br /> was measured to evaluate elevation, flow direction, and gradient As noted in the attached report,
<br /> groundwater with a southwesterly flow direction and a gradient of 0 04 ft/ft was encountered in the wells at
<br /> depths of 67 76 feet to 76 83 feet below ground surface Free product was not encountered in any of the
<br /> wells The locations of the wells are identified on Figure 2 of the attached report
<br /> Since the November 2000 sampling event, groundwater elevation decreased in each of the wells by 0 27 feet
<br /> to 4 29 feet, resulting in an overall average decrease in groundwater elevation of 129 feet across the site
<br /> Changes in groundwater elevation are most likely a result of seasonal vanation and operation of the
<br /> remediation system Groundwater gradient and flow direction remained consistent with previously collected
<br /> data Table 1 in the attached report summarizes groundwater elevation data collected to date
<br /> Analyses identified elevated concentrations of hydrocarbons in the samples collected from MW-1 (85,100
<br /> ppb TPH-g, 129 ppb benzene, 3,860 ppb toluene, 2,510 ppb ethyibenzene, and 17, 000 ppb xylenes), MW-3
<br /> • (4 9 ppb benzene, 0 6 ppb toluene, 0 6 ppb ethylbenzene, and 2 3 ppb xylenes), MW-4 (155 ppb TPH-g, 15 4
<br /> ppb benzene, 10 9 ppb toluene, 5 9 ppb ethylbenzene, and 28 9 ppb xylenes) and MW-5 (394 ppb TPH-g,
<br /> 20 8 ppb benzene, 10 3 ppb toluene, 40 6 ppb ethylbenzene, and 76 4 ppb xylenes) TPH-g and BTEX were
<br /> not identified in the samples collected from MW-2, MW-6, MW-7, MW-8, MW-9, or MW-10 Low
<br /> concentrations of MTBE were identified in the groundwater samples collected from MW-3 (0 8 ppb), MW-4
<br /> 0 6 ppb), MW-5 (1 6 ppb) and MW-9 (0 5 ppb) MTBE was not identified in the samples collected from MW
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