SITE HISTORY - Laserfiche WebLink

Home Browse Search

enviros® excavation was performed in this area prior to sample collection and is discussed in Section 7.2. Soil samples ST-1 and ST-7 were collected on April 25, 1996 at a depth of 3 fbg. These samples were collected from beneath former generation steel product lines encountered during product line removal and replacement activities. A total of approximately 100 lineal feet of former generation product lines was removed. Plate 3 shows the locations of the soil samples,product line trenches, and the former dispensers. Soil samples ST-1 and ST-6 through ST-10 were ND for TPPH and benzene. Sample ST- 2 contained 3.7 ppm TPPH and 0.011 ppm benzene. Samples ST-1, ST-2, and ST-6 through ST-10 contained MTBE concentrations ranging from ND to 0.12 ppm. All soil samples collected from beneath the former fuel dispensers and USTs, and from the product line trenches, were below regulatory action limits for Total Lead. The laboratory analytical reports are presented in Appendix A. Chemical analytical data are summarized in Table 1 and presented on Plate 3. 7.0 OVER-EXCAVATION ACTIVITIES AND SAMPLING RESULTS 7.1 UST Area Over-excavation and Sampling Upon verbal approval from the SJCPHS representative,over-excavation was performed laterally in the area of sample SE-8. Soil samples SE-9 and SE-10 were collected from the western and southern sidewalls, respectively, at a depth of 18 fbg (Plate 3). These soil samples were ND for TPPH,BTEX, and MTBE. Approximately 15 cubic yards of soil were generated during over-excavation activities in this area. 7.2 Product Lines and Fuel Dispenser Over-excavation and Sampling Upon excavation of the northwest dispenser island,Enviros and SJCPHS representatives noted visible staining and a strong petroleum odor. With verbal approval from the SJCPHS, an additional 20 cubic yards of soil were excavated before activities were halted by American to protect the structural integrity of the adjacent canopy. Soil samples ST-3 through ST-5 were collected from the sidewalls and beneath the former northwest dispenser island(Plate 3). ST-3 through ST-5 contained TPPH concentrations ranging from 18 to 6,800 ppm,benzene concentrations ranging from ND to 9.2 ppm, were ND for MTBE, and were below regulatory action levels for Total Lead. Chemical analytical data are summarized in Table I and presented on Plate 3. 8.0 MONITORING OF SOILS FROM NEW TANK EXCAVATION During excavation of the new UST tank pit, American encountered former generation product lines and debris. As requested by the SJCPHS, Enviros screened approximately 450 cubic yards of soil generated from the new UST excavation using a Photo Ionization Detector(PID). The majority of soil generated during these activities did not contain petroleum hydrocarbons based on PID screening and was used for backfill in the former UST excavation. Approximately 5 cubic yards of soil from the new UST excavation had slight detections on the PID and was placed in stockpiles for off-site disposal. 370 3