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' ARCADIS Phase II Field <br /> Investigation and LNAPL <br /> ' Mobility Evaluation Report <br /> Union Pacific Railroad Company <br /> ' Former Maintenance Facility <br /> Tracy, California <br /> 1. Introduction <br /> ARCADIS U.S., Inc. (ARCADIS) has prepared this Phase 11 Field Investigation and <br /> LNAPL Mobility Evaluation Report on behalf of the Union Pacific Railroad Company <br /> (UPRR) regarding the UPRR Former Maintenance Facility in Tracy, California(the <br /> Site). The Site is located southeast of the corner of Sixth Street and MacArthur Drive in <br /> Tracy, California(Figure 1). <br /> ' In June 2008,ARCADIS conducted a preliminary(Phase 1) investigation,which <br /> consisted of advancing cone penetrometer testing (CPT)/laser-induced fluorescence <br /> (LIF) borings to evaluate the distribution of Light Non-Aqueous-Phase Liquid (LNAPL) <br /> in an area where LNAPL has been observed in shallow groundwater wells(MW-06A, <br /> MW-08A, MW-11A, PZ-01, PZ-02, TW-01, TW-02, and TW-04) near the engine house <br /> (the Source Area). The site closure requirements and purpose of the Phase I <br /> ' investigation are described in the LPH Investigation Work Plan, Former Tracy <br /> Maintenance Facility, Tracy, California, prepared by ARCADIS and dated February 29, <br /> 2008 (ARCADIS 2008). Results of the Phase I investigation confirmed that LNAPL <br /> ' (identified as diesel product)impacts were observed in LIF borings south of the railroad <br /> tracks, northwest of the Engine House, and in the vicinity of the oil-water separator <br /> (Figure 2).Additional investigation was recommended to better delineate LNAPL and <br /> understand potential impacts to groundwater. Further investigation activities were <br /> recommended in the Phase 11 Field Investigation Work Plan, prepared by ARCADIS <br /> and dated January 6, 2009(the Work Plan;ARCADIS 2009a). The Phase 11 field <br /> investigation was conducted from November 2009 through March 2010 in accordance <br /> with the Work Plan. <br /> ' The Phase II field investigation included the following: <br /> • Advancing 31 LIF borings <br /> ' • Advancing 26 CPT/HydroPunchTm(HP) borings and collecting grab groundwater <br /> samples <br /> • Advancing LIF borings and collecting groundwater samples from the Toxic Pits <br /> ' Cleanup Act(TPCA) pond (LIF-33, LIF-34, HP-16, HP-11, and HP-18) <br /> Conducting free-product bail-down tests at MW-16A,TW-01, and TW-04 <br /> ' • Collecting undisturbed soil cores near five LIF locations (LIF-02, LIF-06, LIF-10, <br /> LIF-22, and LIF-25) <br /> ' • Installing five new wells(MW-23A, MW-24A, MW-25A, MW-26A, and MW-27A) <br /> ~ g4nani mo IM11.2pID10)dx <br /> ' 1 <br />