|
,r PNC^ F 295 2�Z„
<br /> CASLL AMIESS T, OI
<br /> TSEATTLE
<br /> ACOMA ,E '1=AAA ?03 283 8036
<br /> PORTLAND "
<br /> ,STOCKTON I I i? I To
<br /> RENO I aE TIME ® I ® .
<br /> RICHMOND
<br /> LOS ANGELES 4 a
<br /> 7 e s .5 2737 WEST COMMODORE WAY SEATTLE WA 98199 1233
<br /> PRODUCTS P O BOX 24447 SEATTLE WA 98124-0447
<br /> TIME TESTED '""
<br /> May 4, 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 First 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 /> Please find enclosed Science & Engineering Analysis Corporation's (SECOR's)"Quarterly Monitoring Report,
<br /> January - March 1998" dated April 15, 1998 This document presents analytical results and field
<br /> observations collected during First Quarter 1998 groundwater sampling activities
<br /> For your convenience a summary of previous site activities is attached
<br /> First Quarter 1998 Groundwater Sampling Resufts-January 1998
<br /> On January 27, 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 southeasterly flow direction at a hydraulic gradient of 0 02 ft/ft was encountered in the
<br /> wells at depths of 67 88 feet to 82 18 feet below ground surface Free product was not encountered in any of
<br /> the wells The locations of the wells are identified on Figure 2 of the attached report
<br /> Since the October 1997 sampling event, groundwater elevation increased in MW-2 and MW-5 by 0 96 feet
<br /> and 5 26 feet, respectively, while groundwater elevation decreased in MW-1, MW-3, MW-4, and MW-5
<br /> through MW-10 by 0 27 feet to 1 54 feet Changes in groundwater depth, flow direction, and gradient are
<br /> most likely a result of seasonal variation 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 (6,570 ppb
<br /> . gasoline, 304 ppb benzene, 1,410 ppb toluene, 1,020 ppb ethylbenzene), MW-2 (875 ppb gasoline, 23 9 ppb
<br /> benzene, 38 3 ppb toluene, 5 3 ppb ethylbenzene, and 241 ppb xylenes), and MW-3 (935 ppb gasoline, 235
<br /> ppb benzene, 0 7 ppb toluene, 35 1 ppb ethylbenzene, and 24 5 ppb xylenes) Lower concentrations of
<br /> hydrocarbons were found in the samples collected from MW-4 (342 ppb gasoline, 44 3 ppb benzene, 8 6 ppb
<br /> ethylbenzene, and 1 8 ppb xylenes), MW-5 (102 ppb gasoline, 6 2 ppb benzene, 0 8 ppb ethylbenzene, and
<br /> 3 6 ppb xylenes), MW-6 (166 ppb gasoline, 18 8 ppb benzene, 2 0 ppb ethylbenzene, and 19 2 ppb xylenes),
<br />
|