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Work Plan to Delineate Soil Contamination in the Ag Chem Area ARCADIS Former Occidental Chemical Corporation Lathrop, California 1. Introduction On behalf of Glenn Springs Holdings, Inc., (GSH),ARCADIS U.S. (ARCADIS) has prepared this Work Plan to Delineate Soil Contamination in the Agricultural Chemical (Ag Chem)Area (Work Plan)for the former Occidental Chemical Corporation(OCC) manufacturing facility(Site).The Site is located at 16777 Howland Road in Lathrop, San Joaquin County, California (Figures 1 and 2). GSH is undertaking investigation and remediation activities in the Ag Chem Area under Executed Voluntary Cleanup Agreement(VCA) HSA-VCA 10/11-097, dated June 17, 2011, under the oversight of the California Department of Toxic Substances Control(DTSC, 2011)(Figure 2).The Ag Chem Area is located in the northwest portion of the Site, as defined in Exhibit G of the VCA. Exhibit C of the VCA lists several different tasks to be completed. Task 1: Submittal of Existing Data and Scoping Meeting was completed at a March 7, 2012 meeting with Tom Olson of DTSC, GSH and ARCADIS. This Work Plan summarizes investigation that is needed to complete Tasks 2 through 4(Risk Evaluation and Cleanup Level Determination, Feasibility Study, and Remedy Selection Document). The Ag Chem Area is currently paved and is used by the current owner(J.R. Simplot [Simplot))for storage. Site access is controlled by fencing and a security guard shack. Historical operations within the Ag Chem Area began in 1957 under Best Chemicals, which was acquired by OCC in 1963. The Ag Chem Area was used for blending and packaging concentrated pesticides into formulated dilute products for agricultural and home and garden use(The Source Group,2001). Full-scale dibromochloropropane (DBCP) manufacturing was conducted in the Ag Chem Area from 1963 to 1971 and from 1974 to 1976(The Source Group, 2001).Ag Chem Area facilities included warehouse buildings, an office building,two aboveground storage tanks (ASTs) located in a tank farm, an underground storage tank(UST) located in a rail car loading area, sumps/pumps and aboveground and belowground piping (Geomatrix, 1996). OCC conducted these operations under an Interim Status Document(ISD) issued by the California Department of Health Services(DHS) (currently the DTSC)to regulate the storage of hazardous wastes(DHS, 1981). In 1983, OCC sold the property to Simplot and the ISD was rescinded upon Simplot's request. However, in 1993, DTSC issued Simplot a Report of Violation indicating that the Ag Chem Area had not been closed in accordance with current requirements. Subsequently, Simplot and DTSC entered into a Consent Agreement to complete closure of Ag Chem Area facilities (Geomatrix, 1996). Subsequent investigations and interim remedial actions were conducted in the Ag Chem Area, as summarized in Section 2. These activities did not fully delineate soil with contaminant concentrations above published screening levels. Therefore, as described in Section 3,ARCADIS proposes to conduct supplemental field sampling to fully delineate the area. The methodology for assessing field data in the context of risk I alhrop work pan supplemental nw,sl ag chem 05012012 dote