Laserfiche WebLink
GSI Job No.: 14� G S T <br /> 1 <br /> Issued: 15 November 2017 <br /> ENVIRONMENTAL <br /> Following completion of soil boring advancement, temporary soil gas probes will be installed at <br /> approximate depths of 5 and/or 15 feet bgs to facilitate the collection of soil gas samples. Soil <br /> gas probes will be constructed using nominal 1/4-inch diameter Teflon tubing connected to a <br /> porous polyethylene soil gas sample probe, which will be set within approximately 1 foot of #3 <br /> sand placed around the sample probes from approximately 4.5 to 5.5 feet bgs (for the 5-foot <br /> probes; deeper probes will be constructed similarly with adjusted depths and backfilled with <br /> granular bentonite hydrated with potable water in 1-foot approximate lifts between probe depths). <br /> The remainder of the boring annular space will be backfilled with granular bentonite hydrated with <br /> potable water in 1-foot approximate lifts to create a seal. <br /> After the probes have equilibrated for at least 2 hours, soil gas samples will be collected and <br /> analyzed in a state ELAP certified laboratory for VOCs using US EPA Method 8260B (modified <br /> for soil gas analysis) or US EPA Method TO-15. <br /> Following completion of sampling activities, the temporary soil gas probes will be destroyed by <br /> removing the probes and filling the borings with granular bentonite hydrated with potable water. <br /> The surface of each boring will be patched with concrete or cold patch asphalt to match <br /> surrounding conditions. <br /> 6.0 QUALITY ASSURANCE AND QUALITY CONTROL (QA/QC) PROCEDURES <br /> Specific QA/QC procedures will be followed in the field and laboratory as part of the soil and soil <br /> gas sampling and analysis. These procedures will include laboratory blank samples, laboratory <br /> duplicates, and laboratory spike samples. Data from the QA/QC samples will be evaluated to <br /> assess precision, accuracy, completeness, and data usability. The QA/QC review will be <br /> performed in general accordance with US EPA guidelines. <br /> 7.0 DATA EVALUATION AND REPORTING <br /> Field activities and analytical results will be summarized in a report that will be submitted to the <br /> Water Board. The report will include data summary tables, figures showing sample locations, <br /> lithologic boring logs, and an interpretation of subsurface lithologic and environmental conditions. <br /> VOC data will be compared to risk-based screening criteria for commercial land use, including <br /> the potential for vapor intrusion, and for threat to underlying groundwater. If the results of this <br /> phase of investigation indicate the need for additional shallow soil and soil vapor assessment at <br /> stepped-out lateral locations, additional sample locations will be discussed with the Water Board. <br /> An additional phase of shallow investigation, if warranted, will be conducted using the <br /> methodologies described in this Work Plan. <br /> If the results of this investigation suggest the need for deeper assessment to characterize the <br /> extent of VOC impacts at the Site, recommendations for additional investigation will be included. <br /> Site Investigation Work Plan <br /> Park Woods Cleaners <br />