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v <br /> WEISS ASSOCIATES <br /> Gordon Boggs / 10 .lune 1988 / Page 2 <br /> 2} What is the lateral movement of hydrocarbons away from the, excavation? <br /> 3) Were native soil samples collected from the sides of the tank excavation pit at <br /> the soil/water interface? fl !SUVE0 <br /> o dawn radient monitoring well, V4) There i5 n g 14 19$8 <br /> 5) What are the feasible alternative remediation options for the site?ENVIR0r, �TAL H>ALTH <br /> 6) How will leaving the slab in place affect future site remediatio <br /> ff-RM1T/SERVICES <br /> Each of these concerns is addressed individually below, and an outline of our preferred <br /> remedial option is presented as Attachment B. <br /> 1) COMPARISON OF HYDROCARBON CONCENTRATIONS IN SOIL BENEATH <br /> THE SLAB TO CONCENTRATIONS IN SOIL FROM PERIMETER BORINGS AND <br /> THE EXCAVATION SIDE-WALLS <br /> As detailed in our reports dated 10 June 1987 and 15 October 1987, hydrocarbons <br /> were detected in only one out of 17 samples collected from 11 soil borings drilled around <br /> of 20.7 <br /> ring <br /> the perimeter of the tank excavation. A sample lc�Ced crom a excavationl' analyzed tbyuEPA <br /> I drilling of boring B-2, near the southwestern corner <br /> Method 8015, gas chromatography with flame ionization detection (GC/FID), contained <br /> 1,200 parts per million total fuel hydrocarbons (TFHC) (Figure 1). <br /> Seven native soil samples, collected from the side-walls of the excavation adjacent to <br /> the slab on 22 January and 15 March 1988, have been also been <br /> analyzed <br /> by E221{JatMethod <br /> 8015 for TFHC (Figure 1). Analytic results for the five samples <br /> presented with analytic reports and chain-of-custody forms in our report dated 10 <br /> February, show between 65 and 3,700 ppm TFHC in samples from the southwestern corner <br /> of the excavation and less than 10 ppm in samples from the eastern wall. Analytic results <br /> and sampling procedures for the remaining two samples collected on March 15, which will <br /> be presented in our excavatio:, closure report following the next phase <br /> f site <br /> remediation, show 420 ppm TFHC in the southwest corner and less than 10 ppm T <br /> the northeast corner. <br />