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Stephen Donell - 4 - 31 January 2014 d. Interior North Patch The Interior North Patch TW-4 boring log shows increasing PID readings from approximately 5 to 12-ft bgs. Only the 5-ft bgs and 25-ft bgs samples were selected for analysis. Soil samples from TW-4 at 5-ft contained 16,700 mg/kg of TPH. The March 2012 sampling results for soil boring SB-112, at the north-eastern corner of the patch, contained 68,600 mg/kg of TPH at 10-ft depth. March 2012 soil vapor samples contained perchloroethylene (PCE) and trichloroethylene (TCE) at levels below the California Human Health Screening Level (CHHSL) for commercial setting, but above the residential CHHSL of 0.2 ug/L for PCE. The contaminated soil will need to be removed and confirmation samples taken to document clean soil margins. 2. The approved Work Plan (Section III. E. Soil Sampling for Chemical Analyses) stated that two of five samples collected from each well borehole and submitted for analyses would be based on field PID readings. The soil samples analyzed for TW-2, TW-4, and TW-3 do not comply with the approved Work Plan as discussed below: a. Table 2 -Soil Results TPH by Carbon Chain Identification contains results for each of the two samples selected for analysis from the eight monitoring wells and four temporary wells. The table shows that all wells were sampled at the same depths of 5-ft bgs and 25-ft bgs, with the exception of MW-1 which also analyzed the sample from 20 ft bgs. The Report boring logs show increasing PID readings from approximately 5 to 12-ft bgs in both wells. Although the samples from 12 feet had the highest PID readings, only the 5-ft bgs and 25-ft bgs samples were selected for further analysis at TW-2 and TW-4. b. Table 2 shows only one PID sample was submitted for analyses for TW-3. Groundwater results from TW-3 contained elevated chloroform, 1,2-DCP, and DCBP, as shown in Table 4 of the Report. Site characterization and resampling for VOCs is necessary to assess impacts at TW-3. 3. The discussion of prior investigations in Section 3.3 includes sampling results without providing the corresponding data location points (such as MW-1, SB-112, etc.) for constituent concentrations. The section needs clarification of the corresponding data point locations for discussed results. 4. The second paragraph of section 4.2.4, Survey of Groundwater Monitoring Wells, contains information regarding the catch basin survey. This information should be moved to section 4.4 Site Topography and Surface Drainage. 5. Section 4.4 Site Topography and Surface Drainage does not adequately characterize the site drainage system. The surveyor retained to survey elevations of eight stormwater catch basins was unable to perform the work due to blockages and standing water in several basins. The survey report, included as Appendix E in the Report, fails to adequately describe if the various drains are connected and where they flow, or if there are potentially dry wells. Surface drainage survey problems include: a. Catch Basins 1 and 8 (CB 1 and CB 8) were completely plugged with debris therefore no invert measurements were obtained for either catch basin. b. Catch Basin 3 and Catch Basin 4 (CB 4) had standing water.