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BACKGROUND 1NFO1vr1ATION To aid in preparing this Workplan, we have performed two preliminary site visits and reviewed the following documents provided by you: 1. Draft Phase I Hazardous Materials Study, Tracy Multimodal Station, Cit)) of Tracy, California,prepared by Espana Geotechnical Consulting, dated March 8, 1996. 2. Preliminary Geotechnical Report for the Tracy Multimodal Station, City of Tracy, California,prepared by Espana Geotechnical Consulting, dated March 11, 1996. 3. Limited Phase 11 Environmental Site Assessment, Proposed Tracy Multimodal Station, Tracy, California, prepared by Kleinfelder,dated May 8, 1998. 4. Phase I Environmental Site Assessment, Proposed Multimodal Station, Tracy, California, prepared by The Twining Laboratories, Inc., dated February 27,2002. The referenced Espana 1996 Draft Phase I ESA was completed without right-of-entry permission and requested Southern Pacific Railroad (SP) facility maps. The parcels located adjacent and south of the study parcel were reportedly utilized by SP for railroad maintenance facilities until the mid-1940s. Ownership of the vacant Site was later transferred to UP. The majority of the structures-were removed by the late 1980s. Due to lack of an access agreement, borings for the referenced Espana geotechnical study were performed within the adjacent city streets. Espana recommended the performance of soil and groundwater sampling to confirm or refute the potential presence of railroad- related contamination. The referenced Kleinfelder 1998 Phase lI.ESA included the performance of nine soil borings (B1 through B9) within the vacant triangular parcel (portion of APN No. 235-150-16) previously investigated by Espana. The borings were advanced to a maximum depth of 36.5 feet below ground surface (bgs). The soil conditions encountered in the borings generally consisted of silty clay to 13 feet bgs underlain by silty and clayey sands and clayey silts. Groundwater was encountered at depths between 9 and 12 feet bgs. Soil samples were collected at five-foot intervals starting at five feet bgs. Groundwater samples were obtained from borings B 1 through B6. The 5- and 10-foot-deep soil samples and the six groundwater samples were analyzed for the contaminants of concern (COCs) including volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), petroleum hydrocarbons, and heavy metals. Toluene was detected in one soil sample obtained from boring B6 at a concentration of 0.11 milligrams per kilogram (mg/kg).. Unidentified petroleum hydrocarbons (UPH) were detected in the 15-foot soil sample obtained from boring B7 at a concentration of 87 mg/kg. Heavy metals were reported at assumed naturally occurring background levels. Identified groundwater contaminants include benzene at 2.4 micrograms per liter (ug/1) in B6, the SVOC phenanthrene at 110 ug/l in B6, and UPH at 340 and 190,000 ug/l in B1 and B6, respectively. Other CDCs in soil were not detected. Kleinfelder recommended that the report be submitted to San Joaquin County for review and comment. Twining completed the referenced Phase I ESA of the Site in February 2002. With the exception of some paved surfaces, and concrete slabs and foundation remnants, the Site was described as generally vacant and undeveloped. Twining identified the following recognized environmental conditions associated with the former onsite railroad operations: Creosote and heavy metal impacts associated with railroad ties and ballast. Petroleum hydrocarbon and solvent impacts associated with the former Oil Shed on Multimodal North. Project No.S8675-06-01 -2- October 16,2003