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D sly <br /> Wm. J. Hunter & Associates 2220 Loma Vista Dr. <br /> Registered Geologists ��� g�� Sacramento, CA 95825 <br />�-� Petroleum& Mineral Appraisers (916) 972-7941 <br /> ENVIRONMENTAL HEALTH FAX (916) 972-1683 <br /> HEALTH <br /> PERMIT/SERVICES <br /> WORKPLAN FOR SOIL & GROUNDWATER INVESTIGATION <br /> VALLEY SHOWCASE <br /> 913 W. Fremont Street; Site Code 1114 <br /> Stockton, CA <br /> Prepared for <br /> San Joaquin County PHS <br /> Environmental Health Division <br /> by <br /> Wm. J. Hunter & Associates <br /> June, 1995 <br /> PURPOSE OF WORK: <br /> In February, 1988, a 500 gallon UST which had contained gasoline <br /> was removed from the property. A soil sample taken from beneath <br /> the tank site at 13 ' bgl revealed the presence of toluene, <br /> xylene, & petroleum as TVPH. The removed spoil was returned to <br /> the site and no further work was done at that time. <br /> In February & March, 1994, three (3) groundwater monitoring wells <br /> were placed on the property to evaluate the extent of that con- <br /> tamination. The results of that work revealed that both soil & <br /> groundwater had been impacted by the UST, and further investiga- <br /> tive work would be required. <br /> On December 19 & 20, 1994, the site of the removed UST was <br /> re-excavated in order to remove as much impacted soil as posible. <br /> Due to site restrictions, it was not possible to remove all of <br /> the contamination, and the hole was filled with pea gravel and <br /> covered with concrete. Refer to WJH report titled "Interim <br /> Report Covering Results of Soil Excavation" dated March, 1995 for <br /> details of that work. <br /> Quarterly monitoring and sampling of the three (3) groundwater <br /> monitoring wells placed on the site show that the gradient is to <br /> the north, and the downgradient well, MW-2, has been recording <br /> significant levels of BTEX & TPH-G since its placement in 1994 . <br /> Neither MW-1 nor MW-3 have recorded petroleum compounds since <br /> monitoring began, showing that the groundwater plume has been <br /> defined to the east, west, & south. It has not been defined in <br /> the downgradient direction to the north. Soil contamination has <br /> not yet been fully defined in any direction. <br /> Groundwater was measured at about 8 . 5 ' below grade during the <br /> March 28, 1995 sampling, a rise of over 6 ' in 3 months . Because <br /> of this shallow depth, it is felt that a series of shallow, small <br /> diameter soil borings or push-type equipment is the most cost <br /> 1 <br />