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'1-10` F 285 P
<br /> CABLE A,39E=SS C
<br /> SEATTLE T (FAA 236 283 8C35
<br /> TACOMA E"
<br /> PORTLAND
<br /> STOCKTONRENO
<br /> S1 I' i Ta
<br /> LOS ANG DES 4 ,� "E TIME ® L CO . _
<br /> n s 5 2737 WEST COMMODORE WAY SEATTLE WA 98199 1233
<br /> QODUCTS P O BOX 24447 SEATTLE WA 98124-0447
<br /> TESTED ^"
<br /> E
<br /> July 29, 1998
<br /> Mr Harlin Knoll
<br /> San Joaquin County Public Health Services
<br /> Environmental Health Division
<br /> PC Box 2009
<br /> Stockton, California 95201
<br /> RE Submittal of Second Quarter 1998 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 (PHS/EHD),
<br /> an additional environmental investigation was implemented at the subject site in December 1994 to evaluate
<br /> the extent of hydrocarbon-impacted soils and to determine whether or not groundwater had been impacted
<br /> A total of four groundwater monitoring wells were installed during this investigation In July 1996, six
<br /> additional groundwater monitoring wells were installed on and off of the subject site to assist in defining the
<br /> >� extent of groundwater impacts Based on the results of the investigations, Time Oil has implemented
<br /> groundwater monitoring +
<br /> i
<br /> Please find enclosed Science & Engineering Analysis Corporation's(SECOR's) "Quarterly Monitoring Report,
<br /> April - June 1998" dated July 27, 1998 This document presents analytical results and field observations
<br /> collected during Second Quarter 1998 groundwater sampling activities
<br /> For your convenience a summary of previous site activities is attached
<br /> Second Quarter 1998 Groundwater Sampling Results-_April 1998
<br /> On April 28, 1998, samples were collected from each of the groundwater monitoring 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 was encountered in the wells at depths of 66 50 feet to 81 31
<br /> feet below ground surface Free product was not encountered in any of the wells The locations of the wells
<br /> are identified on Figure 2 of the attached report
<br /> Since the January 1998 sampling event, groundwater elevation increased in each well by 0 65 feet to 147
<br /> feet, resulting in an overall increase in groundwater elevation of 1 07 feet across the site Groundwater flow
<br /> direction also changed from southeast to southwest Changes in groundwater depth and flow direction are
<br /> most likely a result of seasonal vanation Table 1 in the attached report summarizes all groundwater
<br /> elevation data collected to date
<br /> Analyses identified elevated concentrations of hydrocarbons in the samples collected from MW-1 (60,400
<br /> ppb gasoline, 2,200 ppb benzene, 12,500 ppb toluene, 2,200 ppb ethylbenzene, 10,300 ppb xylenes), MW-2
<br /> (2,370 ppb gasoline, 37 5 ppb benzene, 25 5 ppb toluene, and 578 ppb xylenes), MW-3 (3,110 ppb gasoline,
<br /> 411 ppb benzene, 99 8 ppb toluene, 103 ppb ethylbenzene, and 446 ppb xylenes), and MW-5 (4,460 ppb
<br /> gasoline, 388 ppb benzene, 494 ppb toluene, 92 8 ppb ethylbenzene, and 716 ppb xylenes) Lower
<br /> concentrations of hydrocarbons were found in the samples collected from MW-4 (340 ppb gasoline, 8 2 ppb
<br /> benzene, 17 ppb ethylbenzene, and 12 ppb xylenes), MW-6 (762 ppb gasoline, 79 8 ppb benzene, 7 0 ppb
<br />
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