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YJ <br /> envir•os® <br /> Soil samples collected from eight soil borings contained non detectable levels of TPPH <br /> with the exception of four soil samples The concentration of TPPH in these four soil <br /> samples ranged from 1 4 to 970 ppm <br /> BTEX was ND in all of the soil samples collected from the borings, with the exception of <br /> 0 010 ppm of benzene, toluene, and xylenes detected in Boring B-3 at a depth of 26 5 fbg <br /> Petroleum hydrocarbons detected in Borings B-3 and B-5 have been delineated by samples <br /> collected at greater depths from each boring The sample collected at the bottom of Boring <br /> B-7 contained only 14 ppm TPPH and was ND for BTEX Furthermore, TCLP analyses <br /> of samples from Borings B-5 and B-7 were ND for BTEX compounds <br /> The concentrations of BTEX in soil have decreased to nearly non-detectable levels in all <br /> locations sampled during this investigation It appears that operation of the soil vapor <br /> extraction system and natural attenuation processes have reduced concentrations of <br /> petroleum hydrocarbons previously detected in the soil beneath the site <br /> In addition to the soil chemical analytical data generated in this report, soil chemical <br /> analytical data from previous investigations documents ND or low levels of BTEX in soils <br /> beneath the subject property Based on the results of the soil boring investigation and <br /> previous data, further operation of the soil vapor extraction system is not warranted <br /> Therefore, we request that approval be granted to shut down the soil vapor extraction <br /> system and allow natural attenuation processes to biodegrade residual hydrocarbons <br /> If you have any questions regarding the contents of this document, please call <br /> Sincerely, <br /> Enviros, Inc <br /> Joe W Neely <br /> Projec GeologistOQ�pFESSlpyAf <br /> Diane M Lundqui , P E NO C46725 <br /> Senior Engineer ` <br /> C46725 sl crvf� <br /> orf OF CA1.+F <br /> 369 4 <br />