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I� In the vicinity of RAP excavations 15136 and 15139, located in Area 15, a previously unknown UST was discovered. This discovery and subsequent removal action required a modification to j the analytical,sampling program. The UST removal activities and over-excavation was performed with regulatory oversight by the SJCEHD. The 15136 UST excavation activities are discussed in Section 5.2.3. r Table 10 presents the estimated excavation soilexcavation volumes presented in the RDIP and estimated soil excavation volumes for each completed RAP excavation based on the final excavation dimensions. All RAP excavations were advanced to at least the dimensions proposed in the RDIP, and over half of the RAP excavations were extended beyond the dimensions j proposed in the RDIP. I , 5.2 RAP Hot Spot Excavation Results In general, the soils encountered at the RAP excavations are gravelly and debris-rich fill material described below. • Artificial fill that is composed of clayey gravel to gravelly silty sand with construction debris, metal, glass, and brick fragments. The fill is present at the ground surface and o I below foundations and pavement. Where present,the fill generally extends to 1 or 2 feet i bgs, with a maximum depth of approximately 4 feet bgs. 1 • Medium coarse-trained sands lie below the fill and are sometimes present at the surface. l These silty sands are brown, with 10 to 30 percent fines, extend to approximately 3 feet bgs where present. • Fine-grained clays lie below the silty sands. The clays and silty clays, are dark brown 4 and plastic with trace sands and gravels. The clays and silty clays extend to approximately 18 feet bgs, the maximum excavation depth. i Groundwater was only observed in UST excavation in 15136 at an approximate depth of 18 feet bgs (Figure 12). Groundwater samples were not collected or analyzed during the excavation I 25971025.DGD 12 11 August 2005