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' Page 2 C,¢ological Teckxics tx� - Sinclair Trucking SCM&CAP Addendum Project No. 1030.3 July 12,2004 ' newer software program. Some problems arose during the procedure and are outlined below. ' 1. Some blow counts have changed in NfW-1: Two blow counts differ between the original borehole log presented in 1995 and updated MW-1 borehole log. The blow counts for the updated logs were copied from the original "field copy" of the borehole log. The ' field copy is difficult to read in some areas, and after review of the archived 1995 subsurface investigation report, we determined the interpretation of the field geologist should stand and the corrected borehole logs are attached. ' While reviewing the 1995 borehole logs we found discrepancies in the SB-1 borehole log. The change in blow counts in the borehole log of SB-1 was a typo from 1995. The borehole log made in the field during the drilling is attached for review. Mr. McDonald apparently transferred the time of sample collection and blow count data from the MW- 3 borehole log onto the SB-1 borehole log. t 2. Some of the original USCS designations have changed: As mentioned above, the new borehole logs were created from the actual field logs and field notes. These field documents do not contain USCS designations, and our interpretation of the soil descriptions was different than Mr. McDonald's. Unfortunately, our archived soil chip ' samples for the drilling events in 1995 are missing and therefore we are not able to compare the descriptions with actual soil samples. MW-3 provides a good example of the differences in interpretation. The five-foot sample collected in 1995 was described as a clay-silt mixture and very plastic. The USCS describes both ML and CL as having clay-silt mixtures, ML is slightly plastic and ' CL is low to medium plasticity. Mr. McDonald used the term "very plastic" which placed the soil sample as CL not ML,based on the USCS descriptor. Conclusion ' Upon further review of the 1995 data and the more recent soil boring data, we conclude that the unit should have a ML designation and the borehole logs have been corrected. ' The attached borehole logs (Appendix C of the June 2003 SCM) and cross section (replaces Figure 7 of the June 2003 SCM) have been revised. The revised borehole logs are included as Appendix A. A map showing the line of section is also attached as Figure 1 (replaces Figure 2 of the June 2003 SCM). 2.2 SJC/EHD Questions and Concerns ' The May 19, 2004 SJC/EHD letter states on page 2 that "... the switch of preferred method from excavation per the June 2003 CAP to AOP per the Addendum raises several questions and concerns." The numbers below correlate to the numbered concerns on pages 2 and 3 of ' the May 2004 county letter. 1. Estimate of the quantity of contaminated soil at your site: My original estimate of 700 cubic yards was based on soil analytical data and ' assumptions that may be difficult to achieve. These calculations suggest approximately 700 cubic yards of contaminated soil are present. The addendurn addresses some other