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1 Union Ice Company, 425 North Union Street, Stockton, California Phase II Additional Site Assessment, Installation of Sept 9, 1993 Monitoring Wells and Quarterly Groundwater Report Page. 2 1 Additional Phase 11 work was designed and proposed to determine the vertical extent of soil contamination in the vicinity of Tanks #3 and #4, which were known to have leaked Furthermore, one (1) of the borings was completed as a monitoring well to establish the groundwater table at the site and check for possible contamination The work was carried out between January 14 and 21, 1992 One (1) soil boring was drilled to a depth of 3 5 feet through the former location of Tank#4 A second boring was started through the Tank #3 excavation, but was abandoned at ten feet Clue to caving of the pea gravel backfill A third boring was then drilled approximately 10 feet north of the excavation site and completed as a monitoring well (MW-1) at a depth of 75 feet The groundwater level was found to be at approximately 62 feet below ground level 3.0 Scope of Work From June 22 through June 25, 1993, WHF, Inc installed three (3) additional monitoring wells (MW-2, 3, & 4) on this site (Figure 2) All three (3) wells were drilled to 80 feet - water table of approximately 65 feet plus 15 feet of screened interval The first well, MW- 2 was located south of the Tank #3 excavation, approximately 56 feet south of MW-1, between the curb and sidewalk MW-3 was installed dust south of the Tank #4 excavation and approximately 118 feet west of MW-1 The third well, MW-4, was installed at the southeast corner of the site, approximately 43 feet south of MW-2 MW-4 was an approved addition to the work plan, as MW-2 had hydrocarbon odor in the soil samples from 40 to 65 feet MW-4 could establish a zero contamination hunt and aid in the gradient determination Laboratory soil samples were collected from the borings at five- foot intervals including the capillary fringe (Table 1) 33 Drilling Permits were obtained as necessary for all wells before drilling began The borings were accomplished using a hollow stem flight auger no less than 3 1/4-inch i d and 7 1/2-inch Io d All drilling equipment was thoroughly steam-cleaned before drilling began, to prevent the introduction of contamination from off-site, and between borings to prevent cross- contamination IThe borings were logged by WFF's on-site geologist, under the direct supervision of a registered professional, using the Unified Sod Classification System (Appendix G) The color, texture, moisture, plasticity, consistency of the earth materials, blow counts, E E