ARCHIVED REPORTS PHASE II FIELD INVESTIGATION AND LNAPL MOBILITY EVALUATION REPORT

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ARCADIS Phase II Field Investigation and LNAPL Mobility Evaluation Report Union Pacific Railroad Company Former Maintenance Facility Tracy, California residual saturation that could be expected in the subsurface. This test ' additionally provides several LNAPL mobility modeling input parameters including irreducible water saturation, initial LNAPL saturation, and porosity. The subsample used for this test is collected from the portion of the core that has the highest LNAPL saturation per visual inspection of the core photographs. Air/Water Capillarity Package(AWC)—ASTM D6836 and API RP40: This method generates a Soil Water Characteristic Curve by measuring the amount of water extracted from a water-saturated sample under increasing amounts of negative pressure. The results of this test provide the necessary data to calculate the capillarity curve van Genuchten fitting parameters. The subsample used for this ' test is collected from a portion of the core with similar soil structure to the FPM test, and is preferentially not highly impacted with LNAPL. t Pore Fluid Saturation Package (PFS)—API RP40: This method gives additional data on the total water and LNAPL saturation of the core,which provides information on the variability of the LNAPL saturation throughout the core and ' helps to verify that the FPM test was run on the portion of the soil that had the highest LNAPL impact. These subsamples are collected from portions of the core with similar soil structure to the FPM sample and high LNAPL saturation. ' Relative Permeability(WLRP)—API RP40: This test provides unsteady-state LNAPL and water production history, endpoint saturations, and relative permeability curve. ' Grain Size Analysis (GSA)—ASTM D422/4464: This test provides a standard grain size distribution of the LNAPL-impacted soil. It is intended to better understand the ' geology of the Site and to determine how results of the above-mentioned tests will translate to other portions of the Site. This subsample is collected from soil adjacent to one of the other tests, specifically AWC for this Site. ' 3.5 LNAPL Bail-Down Testing ARCADIS conducted LNAPL bail-down tests at wells TW-01, MW-06A, and TW-04 on November 4 and 5, 2009. LNAPL bail-down tests involve inducing a gradient for LNAPL flow and monitoring the LNAPL recovery response. LNAPL bail-down tests t were performed by rapidly removing a known "standing"volume of LNAPL from a conventional monitoring well that is screened across the water table. In an attempt to remove LNAPL from the filter pack, LNAPL in the well was removed and then allowed ' to recover for several minutes.Additional LNAPL that migrated into the wells was also removed. Therefore, the removal of LNAPL was not instantaneous. ' 10