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NNW i Ms. Lori Duncan October 3, 2003 Page 4 of 7 Monterey sand from the bottoms of the wells to approximately 1.5 feet above the tops of the screens. The remaining annular space will be completed with 2 feet of hydrated bentonite overlain by concrete grout. Each well will be fitted at the surface with a locking cap and water tight, traffic rated well box. Drilling and well installation will be conducted under the supervision of California Registered Geologist. The borings will be sampled at 5-foot intervals for soil classification and possible analytical testing. All soil samples will be classified in accordance with ASTM Designation D2488-90, which is equivalent to the Unified Soil Classification System. We anticipate submitting soil samples collected from the capillary fringe from each well for chemical analysis. Additional samples may be submitted for analysis, dependent upon field evidence of contamination. Soil samples selected for analysis will be immediately capped, labeled and placed in an ice chest for transport to the laboratory. Soil samples selected for analysis will be submitted to a State-certified laboratory under chain of custody protocol. The samples will be analyzed for total petroleum hydrocarbons as gasoline (TPHg) using EPA Method 8015B; benzene, toluene, ethylbenzene, xylenes (BTEX) using EPA method 8021 B, and gasoline oxygenated additives and lead scavengers using EPA method 8260B. Drill cuttings will be placed on and covered with plastic sheeting or placed in DOT approved 55- gallon drums. Water generated from equipment decontamination will be contained in labeled DOT approved drums. The soil and/or drums will be stored on site pending laboratory results and the development of disposal options. Investigation of Vertical Extent of Groundwater Contamination Vertical Assessment of Adsorbed Plume The vertical extent of the adsorbed plume has already been defined. Analytical results of a soil sample collected at a depth of approximately 15 and 25 feet bgs from boring SB3, which was adjacent to the former UST, contained no detectable petroleum hydrocarbons or gasoline additives (Table 1). No additional investigation of the extent of the adsorbed plume is warranted. Vertical Assessment of Dissolved Plume Ground Zero previously submitted a partitioning analysis derived from site specific data that predicted that dissolved contaminant concentrations at depth in the source area were below laboratory detection limits (Ground Zero letter October 3, 2002). EHD did not agree with the analysis. While the soil distribution coefficient concept has long been used to predict contaminant partitioning, we will concede that EHD has a valid point in that models are not definitive. To address EHD's concern that the partitioning analysis does not adequately demonstrate that the woolsey.chUreports/workplan.mws