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f Harding Lawson Assoolmtes <br /> r � <br /> JAIRODUCTION <br /> �7 <br /> This report presents the results of additional soil and water sampling <br /> performed by Harding Lawson Associates (FLA) at the 7-Eleven facility at <br /> ' 455 best Grant Line Road, Tracy, California. The facility has three under- <br /> ground gasoline storage tanks, one of which leaked unleaded gasoline and has <br /> - i now been emptied. HLA previously installed four ground-water monitoring <br /> 0 wells to evaluate the lateral extent of gasoline constituents in the soil <br /> �# and ground water and to determine the direction of ground-water flow. The <br /> results of that investigation were presented in a report dated February lO, <br /> r <br /> Y� l 3987. 8erause none of the four monitoring wells was directly downgradient <br /> I <br /> of the leaking tank, we recommended that an additional monitoring well be <br /> installed tc determine if gasoline products were migrating off site. s- <br /> our scope of services for this additional work was as follows: <br /> 1. Obtain a well permit from th--' 5an Joaquin Local Health District <br /> (SJLHD) <br /> -boring at the northeast corner of the <br /> 2, grill and sample a 7-Eleven <br /> property to a depth of 20 feet; t;-iis location is downgradient of the <br /> tank leak. <br /> s 3. Screen all samples in the field with a portable vapor meter to <br /> evaluate the presence of certain organic vapors. . <br /> _ 4. Install a monitoring well (MWS-5), consisting of a'2-inch-diameter, <br /> flush.threaded, Schedule 40 PVC casing and well screen, in actor-_ <br /> I dance with procedures of the 5JLHD. r: <br /> Determine the elevationof the top of the wel5. <br /> '1 casing. <br /> 5� <br />