ARCHIVED REPORTS XR0010860 - Laserfiche WebLink

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Moderate to severe flowing conditions were encountered in some boreholes which required drilling methods to be alternated between push and auger drilling depending upon the severity of the flowing condition. Some soil samples were not recovered in instances of severe flowing since the sampler could not be advanced to the desired depth. The boreholes were drilled with a truck mounted hollow stem auger and/or direct push drilling equipment. All drilling equipment and sampling tools were cleaned prior to arriving, between driving samples and before leaving the site. The augers were advanced to the desired sampling depth interval,and a drive split spoon sampler was driven ahead of the drill bit. The sampler was then retrieved and dissembled. The soil filled brass or acetate liners retained for chemical analysis were sealed with Teflon® paper and plastic endcaps, labeled, logged onto chain-of-custody forms and place in a chilled ice chest on crushed ice. Drill cuttings were drummed and left on-site. The boreholes were logged using the Unified Soil Classification System under the supervision of a registered geologist. Additional lithologic information was collected to describe the subsurface geology. Soil samples were field screened for presence of contaminants by checking for presence of odor and staining, and a photoionization meter was used for soil field vapor measurement use. Soil samples were collected at minimum five-foot intervals, with additional samples collected at intervals of obvious contamination and at stratigraphic features of interest using field discretion. Upon completion of the borehole drilling and collection of information, all boreholes were backfilled with grout,placed from the bottom to top of the borehole with a tremie line. Field Modification of Workplan for Borehole Locations The PHS EHD representative and field geologist discussed the sampling as the borehole drilling and sampling progressed on March 17, 2000. Field observations indicated that contaminants were not widespread and a modification to the field work and sampling was approved by PHS EHD in the field. One boring(originally proposed furthest north under the canopy)was deleted. One boring was moved to a location lateral from the two former tank pits to search for possible lateral contaminant migration in that area(see Figure 1). Reconnaissance Groundwater Sampling Groundwater from each borehole was sampled using push or drill rods or hollow stem auger as temporary casing in the uppermost aquifer. Depth to groundwater measurements were made to the nearest one-one hundredth of one foot from existing grade, and also checked for the presence of separate phase product. The groundwater sample was carefully collected with a clean disposable bailer and poured into the appropriate laboratory prepared container with minimum cavitation and headspace. Each water sample was labeled,logged onto a chain-of-custody form, and placed in a chilled ice chest on crushed ice. Off-Site Water Well Domestic water for the lavatories is obtained through an agreement with Calaveras Cement, the property owner on the west side, who has an industrial well used in concrete batch operations. Wright's scope of work included collection of water samples from the Calaveras Cement well(Water Weil), located at 8181 1 lth Street(just west of the M&M building). Water Well sampling used the faucet.near.the_well head-and the.existing-pump in the-well. The water sample was collected after first clearing the faucet for thirty seconds, then filling the laboratory prepared containers with minimum cavitation and headspace. The water sample was labeled, logged onto a chain- of-custody form,and placed in a chilled ice chest on crushed ice.