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<br /> PHONE 285 2400
<br /> SEATTLE , CABLE ADDRESS TIMOIL
<br /> TACOMA E (FAX) 206 283 8036
<br /> PORTLAND "
<br /> STOCKTON i l2 I TRENO
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<br /> RICHMOND 2 of liyll9€� O o r
<br /> ` LDS ANGELES 9H ,�� ; µ (/�J[} L
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<br /> 7 6 S T5 2737 WEST COMMODORE WAY SEATTLE, WA 98199-12$3
<br /> PRODUCTS PO BOX 24447 SEATTLE, WA 98124-0447
<br /> TIME TESTED "^
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<br /> May 19, 1997
<br /> Mr Harlan Knoll
<br /> San Joaquin County Public Health Services
<br /> Environmental Health Division
<br /> P O Box 2009
<br /> Stockton, Califomia 95201
<br /> RE Submittal of First Quarter 1997 Groundwater Monitoring Report 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
<br /> (PHS/EHD), an additional environmental investigation was implemented at the subject site in December
<br /> 1994 to evaluate the extent of hydrocarbon-impacted sods and to determine whether or not groundwater
<br /> had been impacted A total of four groundwater monitonng wells were installed dunng this investigation
<br /> In July 1996, six additional groundwater monitoring wells were installed on and off of the subject site to
<br /> assist in defining the extent of groundwater impacts Based on the results of the investigations, Time Oil
<br /> has implemented groundwater monitonng
<br /> 1 Please find enclosed Science & Engineenng Analysis Corporation's (SECOR's) "Quarterly Monitoring
<br /> Report, March 1997" dated May 6, 1997 This document presents analytical results and field
<br /> observations collected dunng First Quarter 1997 groundwater sampling activities
<br /> For your convenience a summary of previous site activities is attached
<br /> First Quarter 1997 Groundwater Sampling esults- March 1997
<br /> On February 26, 1997, samples were collected from each of the groundwater monitonng wells (MW-1
<br /> through MW-10) at the subject sde by a representative of SECOR Pnor to purging, the depth to water in
<br /> each well was measured to evaluate elevation, flow direction, and gradient As noted in the attached
<br /> report, groundwater with a soutimestedy flow at a rate of 0 08 ft/ft was encountered in the wells at
<br /> depths of 67 65 feet to 78 92 feet below gmund 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 December 1996 sampling event, groundwater elevation increased in MW-1, MW-2, MW-3,
<br /> MW-4, MW-6, MW-7, MW-8, and MW-9 by 0 88 feet to 1 52 feet, and groundwater elevation decreased
<br /> in wells MW-5 and MW-10 by 1 87 feet to 10 30 feet, respectively These changes resulted in an overall
<br /> average increase in groundwater elevation of 0 75 feet across the site (excluding measurements from
<br /> MW-10) Since the previous sampling event, groundwater gradient increased slightly from 0 02 ft/ft to
<br /> 0 08 ft/ft Changes in groundwater gradient and elevation and are most likely a result of seasonal
<br /> variation Groundwater flow direction remained unchanged from the previous quarter Table 1 in the
<br /> attached report summanzes all groundwater elevation data collected to date
<br /> Analyses identified elevated concentrations of hydrocarbons in the samples collected from MW-1 (2,740
<br /> ppb gasoline, 280 ppb benzene, 320 ppb toluene, 68 5 ppb ethylbenzene, and 458 ppb xylenes), MW-3
<br /> (2,090 ppb gasoline, 136 ppb benzene, 37 4 ppb toluene, 70 ppb ethylbenzene, and 54 3 ppb xylenes),
<br /> MW-6 (1,510 ppb gasoline, 93 ppb benzene, 137 ppb toluene, 23 4 ppb ethylbenzene, and 297 ppb
<br /> xylenes), and MW-9 (1,570 ppb gasoline, 119 ppb benzene, 67 4 ppb toluene, 47 ppb ethylbenzene, and
<br /> 248 ppb xylenes) Lower concentrations of hydrocarbons were found in the samples collected from MW-
<br /> 2 (190 ppb gasoline, 4 1 ppb benzene, 14 ppb toluene, 0 9 ppb ethylbenzene, and 6 9 ppb xylenes),
<br /> MW-4 (390 ppb gasoline, 4 6 ppb benzene, 1 0 ppb toluene, 0 9 ppb ethylbenzene, and 1 4 ppb xylenes),
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