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0 • the detection limit. As both of these borings were located within or adjacent to the former UST cavity,there is no indication that a substantial amount of diesel fuel leached downward into the higher permeability part of the Riverbank sand. Item 7. Delineation and Characterization of the Channel Deposit in the Modesto Formation The last item that warrants finther discussion is EHD's comment that it was unable to find information that delineates or characterizes the channel deposit within the Modesto Formation. This information was extensively developed in the 1996 Problem Assessment Report. Several figures presented in that report illustrate and characterize the channel deposit within the Modesto Formation. In total, twelve figures and several pages of text were presented illustrating the geometry and facies of this channel and its relationship to soil and groundwater contamination. These figures were subsequently updated in the First Quarter 1999 Report after GT-10 and GT-11 were drilled. The channel was shown in cross section in text figure 10 and in appendix figures A-1 through A-4 of the assessment report. A three-dimensional view of the channel was given in the fence diagram in text figure 6, which utilized all of the borings that had been drilled up to that time. Figure 7 provided a map view of the channel, showing the depth to its base and illustrating its nearly linear northeast-southwest trend. This map was also used as a base map for four isocontour maps of the extent of gasoline and diesel in soil at specific depths (Figures 11-14). Lastly, a sediment facies map showing the distribution of permeability belts within the channel (based primarily on grain size and sorting) was included as appendix figure A-6. These figures were successfully used to select optimum drilling locations for GT-10 and GT-11 in 1999, demonstrating the validity of the earlier interpretations regarding the trend of the channel deposit and the location of the most highly impacted soil. hi its November 17 letter to Gillies Trucking, EHD conceded that agency staff had not reviewed these older reports in exhaustive detail, and this may explain why EHD staff is not aware of the data on the channel deposit. Further study of these documents should answer EHD's remaining questions regarding this issue, and we are not proposing any additional investigation into the character or extent of this channel at this time. 4.0 PROPOSED TASKS AND PROCEDURES EHD's November 2002 letter provided a list of several recommended tasks that should be completed in order to move the characterization of the site toward completion. These are addressed in this section,though not in the order listed by EHD. Task 1.Downhole Camera Survey Both the California Department of Water Resources and the company who originally drilled the Gillies domestic well (Clark Well, Inc.) were contacted several years ago in order to obtain a well construction diagram for the well. Neither could supply the requested