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PHONE 285-2400 <br /> CABLE ADDRESS: TIMOIL <br /> SEATTLE TE (FAX) 206-283-8036 <br /> TACOMA ry LJC A TL <br /> PORTLAND rr 12 To 1 lil, HEALT11 <br /> r1 <br /> STOCKTON i �,. _.� f <br /> RENO 2 oN T I M E _i 1 UK�IC� �/ O • <br /> RICHMOND <br /> LOS ANGELES 9 9 <br /> e <br /> 5 5 TS 4 <br /> T 2737 WEST COMMOMAI SEATTLE,WA 98199-1233 <br /> PRODUCTS M P.O. BOX 24447 SEATTLE,WA 98124-0447 <br /> TIME TESTED E <br /> October 21, 1996 <br /> Mr. Harlan Knoll <br /> San Joaquin County Public Health Services <br /> Environmental Health Division <br /> P.O. Box 2009 <br /> Stockton, California 95201 <br /> f <br /> RE: Submittal of Environmental Investigation and Quarterly Summary Report for i <br /> Jackpot Food Mart, 14000 E. Highway 88, Lockeford, California (Property No. 04-049) <br /> Dear Mr. Knoll, <br /> G <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 soils and to determine whether or not groundwater <br /> had been impacted. Based on the results of the investigation, Time Oil implemented quarterly <br /> groundwater monitoring. <br /> i <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. Accordingly, please find enclosed Science & <br /> Engineering Analysis Corporation's (SECOR's) "Environmental Investigation and Quarterly Summary <br /> Report" dated October 9, 1996, This report documents the results of the additional investigative r <br /> activities, and presents analytical results and field observations collected during Third Quarter 1996 <br /> groundwater sampling activities. I <br /> For your convenience a surnmary of previous site activities is attached. <br /> Additional Site Investigation <br /> On July 15 through 18 and July 31, 1996, six groundwater monitoring wells were installed onsite and <br /> offsite to assist in defining the extent of hydrocarbon impacts. As in previous site activities, soils <br /> encountered during drilling consisted of fine silty sands to approximately 15 feet below ground surface <br /> (bgs); this strata was underlain by fine to coarse sands to approximately 30 feet bgs. Clayey silt and silty 4: <br /> clay were generally encountered at 30 feet to 35 feet while fine to coarse sands and gravelly sands were <br /> encountered to 70 feet bgs. Silty Clay with sandy and gravelly stringers was encountered from 70 feet <br /> bgs to the extent of each boring. Groundwater was first encountered at depths of approximately 75 feet <br /> to 80 feet bgs. <br /> is <br /> Each of the wells was installed as follows: <br /> s; <br /> f <br /> Casing Total Screened <br /> Well No. Diameter (in.) Depth (ft.) Interval (ft.) Purpose <br /> r:. <br /> MW-5 2 100 35 HC delineation to the NW of former tanks(sidegradient) <br /> MW-6 2 100 35 HC delineation to the NE of former tanks(upgradient) <br /> MW-7 2 100 35 HC delineation to the NE of former tanks(uptsidegradient) <br /> MW-8 2 100 35 HC delineation to the E of former lanks(sidegradient) <br /> MW-9 2 100 35 HC delineation to the SE of former tanks(sidegradient) <br /> MW-1 0 2 97.5 35 HC delineation to the SW or former tanks(downgradienl) <br /> r: <br /> The casing diameter, well depth, and screened interval of each well was selected by a representative of ; <br /> SECOR based on the proposed well use and the estimated depth to groundwater at each drilling location. <br /> t <br />