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' Beginning in October 1996, ground water samples collected from the wells • at Site #1 have been analyzed for various water quality parameters (Table ' 3-2) and heterotrophic plate counts (for microbes) to evaluate the effectiveness of the natural attenuation process The increase in heterotrophic count in the samples collected from MW-4 and MW-5 when ' compared to baseline results indicates that the presence of the ORC socks is enhancing microbial activity As presented in Table 3-2, the general water quality parameter measurements confirm that the subsurface 1 conditions have changed from anaerobic to aerobic conditions, as evidenced by comparison of past-ORC to baseline (October 1996) conditions Furthermore, as discussed in Attachment A, pre-ORC ' measurements of certain constituents can be used to calculate the biodegradation capacity of the subsurface environment The calculations ' performed for Site #1 indicate that the biodegradation capacity is more than adequate to address the low levels of TPH and BTEX constituents currently present in ground water, with or without the continued addition ' of ORC Tank Site #2 Activities performed at Former Tank Site #2, located at 1325 West Weber Avenue include • Removal of a 500-gallon fuel UST (1991), • Installation of soil borings and four monitoring wells for site characterization (1992), • Excavation of hydrocarbon-contairung soils (1993), a Further characterization of the residual TPH levels within the excavations (1994), I • Quarterly monitoring of ground water chemical quality during the period April 1992 to April 1998, and • Ground water remediation consisting of ground water extraction (3 events during the period 1993 through 1994) and the installation of ORC socks A description of these activities is provided below 1 i I 3-5 I