WORK PLANS - Laserfiche WebLink

Home Browse Search

Lee Higgins _2- • 21 September 2011 , • 990 Beechnut Avenue, Tracy purposes 1. Based on the pre-excavation analytical findings, the outline of the excavation was established. In October and November 2010, AMEC staff directed the excavation, transport of affected soil to a certified landfill for disposal, collection of confirmation samples, and backfill and grading. According to AMEC's remediation Report: • Excavation/grading permits were obtained from the City of Tracy and other appropriate agencies were notified. An English and Spanish work notification brochure was provided to residents within about one block of the work site. • Approximately 4,024 tons of affected soil was removed from an excavation having dimensions of approximately 60 feet by 240 feet with an average depth of six feet bgs. A small discolored area, about 40 feet square, in the south part of the excavation, was excavated another foot deeper and one confirmation sample was collected. • Based on the pre-excavation and confirmation sampling results, affected soil containing TPHc including the area of elevated PAHs concentrations exceeding the environmental screening levels was removed. Excavated soil was transported with non-hazardous manifest for disposal at the Class II Forward Landfill near Manteca. • Analytical results for the additional confirmation samples collected were non-detect or below the environmental screening levels, and the Site remedial goals considered for a commercial/industrial risk scenario. • Immediately following completion of the excavation, backfill and re-grading was completed using the excess soil contained in the Site soil mound, to match previously existing surface grade. No other visually affected soil was observed during backfill/grading. • Grading and compaction was completed and density tests conducted under direction of an AMEC staff engineer. Results of density tests indicated backfill compaction was 90 percent or greater. The Site perimeter security fencing was re-established. • Subsequent calculations provided by AMEC staff estimated that approximately 30 percent of the total volume of soil removed was impacted by the residual TPH compounds. Based on the high and low range of TPH concentrations reported, the estimated the volume of PAH/TPHc material removed was approximately 141,375 pounds including the PAHs targeted for removal. • After the excavation and backfilling activities were completed, irrigation lines were re- installed, the area was reseeded in accordance with City of Tracy requirements. — Environmental Screening Levels, California Regional Water Quality Control Board, San Francisco Bay Region, May 2008, Screening for Environmental Concerns at Sites with Contaminated Soil and Groundwater, Interim Final.