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GEOMATRIX REPORT OF OFF-SITE SOIL AND GROUNDWATER INVESTIGATION U.S. Can/Welty Road Vernalis, California 1.0 INTRODUCTION This report presents results of field activities performed by Geomatrix Consultants, Inc. (Geomatrix), on behalf of Chevron Environmental Management Company(ChevronTexaco) at the U.S. Can/Welty Road Property(the site) at 25375 Welty Road southwest of the intersec- tions of Highway 33 and Welty Road in Vernalis, California(Figure 1). The field investigation activities described in this report were conducted in August 2003. The scope of the investiga- tion included advancing three off-site soil borings to collect soil and grab groundwater samples and to collect groundwater samples from two on-site monitoring wells. Work was performed in accordance with Geomatrix's February 11, 2003 Off-site Soil and Groundwater Investigation Work Plan (Work Plan) and July 2003 Amendment to the Off-site Soil and Groundwater Inves- tigation Work Plan (Amendment). The Work Plan and Amendment were submitted and subse- quently approved by the Regional Water Quality Control Board- Central Valley Region (RWQCB). The purpose of this investigation was to obtain data to assess the lateral off-site extent of petroleum hydrocarbon-affected soil and to evaluate groundwater quality on-site and down- gradient of the site. This report contains a brief summary of previous work conducted(Section 2.0), a description of the objectives of this investigation (Section 3.0) and sampling activities performed(Section 4.0) in August 2003, the results obtained from this investigation (Section 5.0), and conclusions regarding site conditions based on data collected to date (Section 6.0). The work described herein was performed in accordance with the ChevronTexaco's revised Consistent Technical Approach (CTA)that is typically applied at ChevronTexaco historical pipeline sites (Geomatrix 1997 and 2002b). 2.0 BACKGROUND This section presents a discussion of the site use and previous environmental investigations conducted at the site. I:\Doc_Safe\6000s\6447.001\OffSite Rpt\US Can SoilGW Rpt 2003.doc 1