ARCHIVED REPORTS_REMEDIAL ACTION REPORT

Home Browse Search

Tracy Pump Station Remedial Action Report January 4,2012 Penecore advanced borings SB-20 through SB-49 to depths ranging from 3 to 10.3 feet bgs. SAIC observed visual evidence of hydrocarbon-affected soil, which may correlate with high concentrations of PAHs, in SB-20, SB-21, SB-27, SB-28, SB-29, SB-32, SB-33, SB-33a, SB-38, SB-39, SB-41, SB-42, SB43, and S1345. SAIC collected soil samples adjacent to the lateral and vertical extents of the PAH-affected soil and submitted them to Calscience for laboratory analysis. Analytical results for the COPCs are summarized in Tables 1 and 2. Groundwater was encountered between 8 and 10 feet bgs. ' The boring locations and lateral extent of affected soil, based on field observations, are depicted on Figure 2. The boring logs,which describe Unified Soil Classification System soil classifications,photoionization detector readings,and observations, are provided as Appendix F. Boring locations were surveyed for Iongitude and latitude coordinates within a 5-foot range using a Global Positioning System with reference to the World Geodetic System 1984 coordinate system and datum. 3.3 SITE REMEDIATION ACTIVITIES SAIC delineated the extent of PAH affected soil as shown on Figure 3. Remedial Construction ' Services, L.P. (RECON), a licensed general contractor, initiated site activities on October 17, 2011, and completed activities on November 10, 2011. SAIC observed RECON perform the following: • Operate excavation and earth-moving equipment to remove approximately three feet of native topsoil and stockpile it on site for replacement after completion of the excavation activities; ' a Operate excavation and earth-moving equipment to remove PAH-affected soil to the pre- determined excavation limits and to direct-load the affected soil into waste hauling trucks; ' • Backfill the excavation using clean fill; • Compact the backfill in shallow lifts using a sheepsfoot roller and drum compactor to ' achieve a 90-percent compaction rate (minimum)from the bottom of the excavation to 3 feet bgs. Compaction testing was performed by Smith--Emery; • Resurface the excavated area with approximately 3 feet of native topsoil; • Restore site to original condition(move imported gravel to an area approved by the property owner, rip areas of the agricultural field that were compacted by the trucks and equipment, reimburse property owner for professional grading by a contractor of his choice). SAIC collected three 4-point composite soil samples from the native topsoil stockpile to confirm that the concentrations of PAHs are comparable to concentrations elsewhere on site and is suitable for site use. The samples were analyzed by Calscience for PAHs by EPA Method 8270 using SIM. The analytical results are provided in Table 5 and the analytical report is included as a component of Appendix D. RECON encountered debris(bricks,metal piping) in the northwestern portion of the excavation on October 21, 2011. The soil in this portion of the excavation also contained a material that appeared to be asbestos in this portion of the excavation. SAIC arranged for a California 1 4 SAIC 1