ARCHIVED REPORTS PHASE II FIELD INVESTIGATION AND LNAPL MOBILITY EVALUATION REPORT

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tARCADIS Phase II Field Investigation and LNAPL ' Mobility Evaluation Report Union Pacific Railroad Company ' Former Maintenance Facility Tracy, California 3.4 Undisturbed Soil Core Collection ' ARCADIS supervised Gregg collect five undisturbed soil cores using a hollow stem auger rig from December 21 through December 24, 2009. Soil cores were collected ' according to the ARCADIS Standard Operating Procedure for Light Non Aqueous Phase Liquid Soil Core Collection(ARCADIS 2009b). Soil cores collected at LIF-02 (near TW-01), LIF-06 (near TW-02), LIF-10(near MW-08A), LIF-22, and LIF-25 (near MW-06A; Figure 7)were sent to PTS Laboratories (PTS)for ultraviolet(UV)and natural light photography. ' Laboratory analysis of the undisturbed soil cores is an iterative process. PTS first takes natural and UV light photographs of the core. The natural light photographs detail the soil structure. Polyaromatic compounds in petroleum products fluoresce within the visible light spectrum when exposed to UV light. Then, the UV photographs were used to assess LNAPL distribution in the soil cores.ARCADIS reviewed the core photographs generated by the laboratory and selected core segments for testing based on the soil structure observations and visual degree of LNAPL impact. Brighter blue fluorescence indicates higher LNAPL saturation zones. The UV photography showed the cores as being slightly impacted with LNAPL. Core photographs are presented in ' Appendix C. Petrophysical tests were designated for specific intervals from each of the soil cores to characterize aquifer-matrix parameters and fluid saturations after soil core photographs ' were reviewed and lithologic soil descriptions and LIF results were correlated. Subsamples for each test were designated for the portion of the core with the most LNAPL impact by targeting areas showing the highest UV fluorescence. ' The assigned subsample locations and laboratory reports are included in Appendix C. Tests performed on the soil cores are described below, with an explanation of the pertinent modeling inputs generated from the tests. • Residual Saturation by Water Drive (RSWD)—Proprietary method by PTS and ' American Petroleum Institute(API) RP40: This method passes water through the subsample to displace free LNAPL. This test provides porosity, initial LNAPL saturation, and residual LNAPL saturation under saturated conditions, which is expected to be greater than residual saturation under unsaturated conditions. • Free-Product Mobility(FPM)—American Society for Testing and Materials(ASTM) D425M and API RP40: This method utilizes centrifugal force to displace free ' LNAPL in a subsample of the soil core with air, which provides the minimum M'Pan wyJnVIMo PWY(11� 2010) 9