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SOIL AND GROUNDWATER INVESTIGATION REPORT AND SECOND QUARTER 2005 MONITORING AND SAMPLING AT US CAN—WELTY ROAD 35275 WELTY ROAD VERNALIS, CALIFORNIA 1. INTRODUCTION This report presents the results of the soil and groundwater subsurface investigation, and second quarter 2005 groundwater monitoring and sampling performed by Science Applications International Corporation (SAIC)at the US Can—Welty Road site(subject site). SAIC performed this investigation on behalf of Chevron Environmental Management Company(CEMC)and under the direction of the California Regional Water Quality Control Board—Central Valley Region(RWQCB)in order to evaluate the lateral and vertical extent of petroleum-affected soil and groundwater previously identified adjacent to the subject site. The site is located at 35275 Welty Road,in Vernalis, San Joaquin County, California (Figure 1), and is a right-of-way(ROW) site associated with the former Standard Oil of California (Standard)Wait-Mendota-Richmond Pipeline and Tidewater Associated Oil Company(TAOC)Pipeline (referred herein as Old Valley Pipeline [OVP]). Based on previous environmental investigations at the subject site, CEMC requested that,prior to SAIC's soil and groundwater investigation, a work plan be created to delineate the lateral extent of residual petroleum hydrocarbons beneath the site. SAIC prepared a work plan(SAIC,2004)that proposed to characterize the soil northeast of soil boring GMX-12 and groundwater down gradient of the subject site. Following review of the SAIC work plan,the RWQCB approved it in a letter dated March 22,2004. A copy of that letter is included in Appendix A. The scope of work performed by SAIC was conducted in accordance with the Technical Approach to Site Evaluation and Decision Making;Historical Pipeline Portfolio, Central Valley Region,February 2005 (CTA; Geomatrix Consultants, Inc.,2005), and in accordance with the approved work plan. 2. SITE DESCRIPTION AND HISTORY Currently, a paper insulation manufacturer, Insulair Inc.,occupies the site. The subject site was formerly occupied by a container manufacturer and a can manufacturer. The site is located in a rural and light- industrial area bordered by Welty Road on the east,Highway 33 on the north, and agricultural fields on the south and west. The subject site location is presented on Figure 1. The subject site is located within the Central Valley Physiographic Province of California. The site has a relatively flat topography that slopes gently downward to the northeast and is situated at an elevation of approximately 103 to 105 feet above mean sea level(MSL). From the early 1900s to the 1960s Standard Oil(predecessor to Chevron)operated the former Old Valley Pipeline(OVP),which transported heated heavy petroleum(crude oil and Bunker C fuel oil) from Bakersfield to Richmond, California. The OVP was located along the northeastern side of the subject site and parallel to the existing Union Pacific Rail Road(UPRR)tracks and Highway 33. The former Tidewater Associated Oil Company(TAOC)pipeline was also present between the site and Highway 33. The TAOC pipeline was used to transport heated heavy petroleum(crude oil and Bunker C fuel oil) from the Central Valley to the San Francisco Bay Area and operated from the early 1900s until its decommission in the 1970s. (Hereinafter,the two former pipelines, OVP and TAOC, shall be collectively referred to as OVP.) 1 From Science to Solutions-