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Stantec 1%001 y, <br /> September 29,2009 <br /> Page 2 of 3 <br /> Reference: Well Permit Application Packet <br /> Soil Borings <br /> Stantec will advance five direct-push soil borings (B-11 through B-15) at approximate locations <br /> illustrated on the attached figure. The total depth of each of the soil borings is anticipated to be <br /> approximately 15 feet bgs; however, if observed chemical impacts appear to extend deeper than 15 <br /> feet, up to three soil borings may be extended to 30 feet bgs. Soil borings will be cored <br /> continuously from approximately 5 feet bgs to total depth. Recovered soils will be screened for the <br /> presence of volatile organic vapors using a photoionization detector, and logged in accordance with <br /> the Unified Soil Classification System. <br /> Stantec will collect up to three soil samples from each soil boring for chemical analysis, and an <br /> additional two soil samples from soil borings extended deeper than 15 feet bgs. Soil samples <br /> retained for laboratory analysis will be based on field observations of chemical impact <br /> (discoloration, chemical odors, and/or elevated volatile vapor concentrations). If no field evidence <br /> of chemical impact is observed, soil samples will be collected to provide a representative vertical <br /> gradient of chemical concentrations in soil. Soil samples will be analyzed for the following <br /> constituents: <br /> • Total petroleum hydrocarbons (carbon-range speciation) by EPA Method 801513; <br /> • Volatile organic compounds by EPA Method 826013, prepared using EPA Method 5035 for <br /> samples collected using EnCore-style hermetically sealed sample vials; and <br /> • Semi-volatile organic compounds (SVOCs) by EPA Method 8270C SIM. <br /> Following sample collection, the soil borings will be backfilled with a neat cement grout, except as <br /> described in the following section. <br /> Vapor Sampling Probes <br /> Dual-nested vapor sampling probes will be installed three of the soil boring locations. Default vapor <br /> probe locations are illustrated on Figure 3; however, the actual locations of the vapor probes will be <br /> based on observations made during advancement of the direct-push soil borings. At each location, <br /> soil vapor collection probes will be installed at depths of five and 12 feet bgs. Stantec proposes <br /> converting three of the direct-push soil borings into vapor sampling probes by backfilling the <br /> borehole between 15 feet and 12.5 feet using hydrated granular bentonite (Volclay). However, if soil <br /> borings are extended deeper then 15 feet bgs, Stantec will backfill the entire borehole with neat <br /> cement grout, and install the vapor sampling points in a .new borehole advanced to approximately <br /> 12.5 feet bgs. This approach is intended to maximize field efficiency, and minimize the disruption to <br /> the neighboring property owner. <br /> The vapor sampling probes will be constructed with quarter-inch diameter NylaflowO tubing with a <br /> two-way valve connected at the surface end and a diffuser tip (one-inch filter) at the subsurface end. <br /> The vapor probe tips will be set at approximately 12 feet and five feet bgs with the diffuser tips <br />