ARCHIVED REPORTS_XR0009061 - Laserfiche WebLink

Home Browse Search

1 ' Union Ice Company, 425 North Union Street, Stockton, California Phase II Rewtsed Site Assessment, Installation of Oct 28, 1993 Monitoring Wells and Quarterly Groundwater Report Page 2 ' The work was carried out between January 14 and 21, 1992 One (1) soil boring was drilled to a depth of 35 feet through the former location of Tank#4 A second boring was ' started through the Tank #3 excavation, but was abandoned at ten feet due 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 The remedial excavation in the tank #4 area (figure 2A) was conducted from April 22 to April 28, 1993 This excavation was terminated to the west by the railroad right-of-way, and to the north and east by buildings Wall and floor samples were taken and sent for analysis Some fingers of residual contamination remain in the excavation sidewalls and are shown on Figures 2A, 6A, 6B and 7A, however, testing of the floor of the excavation detected no remairung contamination 3.0 Scope of Work From June 22 through June 25, 1993, WBF, Inc installed three (3) additional monitoring wells (NM-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 lust 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 linut and aid in the r gradient determination Laboratory soil samples were collected from the borings at five- f foot intervals including the capillary fringe (Table 1) 3.1 Drilling I Permits were obtained as necessary for all wells before drilling began The borings were accomplished using a hollow stem flight auger no less than 3 114-inch i d and 7 112-inch o d All drilling equipment was thoroughly steam-cleaned before drilling began, to prevent r the introduction of contamination from off-site, and between borings to prevent cross-contamination The borings were logged by WHF's on-site geologist, under the direct supervision of a registered professional, using the Unified Soil Classification System (Appendix G) The color, texture, moisture, plasticity, consistency of the earth materials, blow counts, pertinent soil or bedrock characteristics, and any evidence of contamination were noted I