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Austin Road Landfill Appendix B Contaminant Plume Characterization Report Field Procedures _ ® At subsequent boring locations,soil cores were collected approximately every 10 feet using an 18-inch split barrel sampler. In addition,up to three groundwater samples were collected—one sample from the shallow aquifer zone and one sample from the deep aquifer zone--at depths which target the highest probable concentrations of _ PCE. These sampling depths were determined based on rapid turn-around analysis of samples collected in the transect's initial boring. B.1.2 Sample Collection The following subsections provide descriptions of the sampling methodologies used during the - field portion of this study. Hew Drilling Company was selected to provide drilling services. The hollow stem auger drilling rig was a Central Mine Equipment(CME)-75 or equivalent,capable of reaching the required depths. _ The hollow stem auger was either a hydraulically or mechanically powered drill rig which simultaneously rotates and axially advances a hollow stem auger column. Each of the joints between auger sections was properly connected. The rig and the hollow stem augers were decontaminated following the procedures in Section 13.2 prior to drilling the first boring and after each boring was completed. The washdown was performed at the on-site decontamination facility. Groundwater Sampling Depth discrete groundwater samples were collected at the specified aquifers in the borings of each -- transect using a Hydropunch®sampler. The Hydropunch®is a stainless steel sampling device which is hydraulically driven ahead of the hollow-stem augers into undisturbed soil at a sufficient ' distance to perform groundwater collection(1%-2 feet). For sample collection,the Hydropunch®is fitted with a dedicated stainless steel tip which seals the bottom opening of the sampler during advancement and then releases as the sampler is retracted to expose a screened opening. After the sampler is retracted about one foot,groundwater enters an internal chamber through a synthetic,reed-type check valve. After a waiting period sufficient to allow the internal chamber to fill(field judgment will be used to expedite this process),the sampler is retrieved. At the ground surface,sampled groundwater was transferred from the internal chamber to volatile organic compound(VOA)sample vials. Results from VOC sampling had a 24-hour turnaround. QA/QC samples were taken as prescribed by EPA guidance. The Hydropunch®sampler was - decontaminated prior to its next use as described in Section 13.2. Aquifer Soils by Split-Barrel Core Samplers _ Soil samples were collected using 5-foot long,split-barrel core samplers on the initial borings of each transect. The split-barrel samples were collected continuously from approximately 10 feet above the water table(at depths starting at 60 to 75 feet below ground surface)and extending down e CDM Camp Dresser&McKee CS 010809 B- W:WEPORTSGTOCKTOMARLPIUMEBBUPPXB.WPO City of Stockton 140855.0006