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NOW, Ift-4 Four exploratory borings (B-1, B-2,B-3 and B-4) were drilled and sampled in April 2003 around the former underground tank pit at the WWCF. The soil samples collected showed that contaminants were not detected. Groundwater samples showed very Low levels of dissolved TPHD, with one relatively elevated level of 33,000 micrograms per liter(ug/1)TPHD in.B-2 in a downgradient location. BTEX, MTBE and related oxygenates were not revealed in any groundwater sample. On the basis of this data collected for this study, limited leakage from the former underground tank had occurred, and is attributed to overspill. The dissolved plume has migrated a short distance downgradient of the former tank pit to the north-northwest. New WWCF construction occurred between 2003 and 2007 that changed the site geography at the former UST site area. Wright relocated the 2003 boring positions to conduct the 2008 subsurface study. Wright completed additional soil and groundwater sampling and 2000-foot radius well search for the former underground diesel tank at the WWCF in late 2008 (see References). The 2000400t radius well search showed that there were no municipal or domestic drinking water wells within the search area and nearby wells are listed as either industrial or irrigation wells. The regional groundwater flow direction is estimated to be northerly. WWCF and industrial waste ponds bounded the site to the north, east and south and it is likely that seepage from these ponds may affect the local groundwater flow at the project site. However there was no monitoring well information available at that time to assess the local groundwater flow direction. Soil and groundwater samples collected in 2008 and only analyzed only for TPHD since previous analysis had shown that gasoline and related fuel compounds had not been detected. TPHD dissolved concentrations were relatively low in groundwater. Boring B-6 drilled adjacent to Boring B-2 showed only 170 Ug/1 (compared to 33,000 Ug/l at B-2 in 2003) a significant decrease. The laboratory reported that the TPHD was higher boiling than typical diesel fuel. Wright's conclusion from this data was that a large contaminant problem was not indicated, and only a small dissolved residual and possibly degraded TPHD plume was present. Scope of Work 2.0 Rationale for New Monitoring Well Location Wright discussed the results with the SJC/EHD representative who requested and one groundwater monitoring well to be installed at this time. Data from. a previous WWCF site study by CH2M Hill made available to Wright in 2009 shows that shallow groundwater monitoring wells are present on the Wastewater Plant site(see CH2M Hill 2008 Annual Monitoring Report, Figure 20, June 2008 Shallow Groundwater Elevations). Wells MW-HP-7 and MW-HP-8 are located downgradient from the proposed new monitoring well location. The groundwater flow direction in the immediate project site area appears to be northwesterly on the 2008 CH2M. Hill map. The "regional" flow direction is northerly in the larger Wastewater Plant area according to CH2M Hill data(see Figure 1). Page 2 of 5