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Work Plan for the
<br /> Former Two 20,000-Gallon USTs Location at Stockton AASF
<br /> California Army National Guard
<br /> 4.5 The results of the groundwater investigation conducted in February 2004(at B-1 and B-2)
<br /> beneath/adjacent to the southeast corner of the two former 20,000-gallon USTs location had no
<br /> detectable petroleum constituents(TPHG,TPHD,TPHJ,TPHG,BTEX,TAME,TBA,DIPE,ETBE,
<br /> MTBE,or lead)at concentrations greater than their respective reporting limits. The results of the
<br /> groundwater sampling from B-28 south of the two former 20,000-gallon USTs location,beneath the
<br /> previous spill location,had no detectable petroleum constituents(TPHG,TPHD,TPHJ,TPHG,
<br /> BTEX,TAME,TBA,DIPE,ETBE,MTBE,or lead)at concentrations greater than their respective
<br /> reporting limits.
<br /> 5.0 RECOMMENDATIONS
<br /> Based on the information obtained for the AASF, the following is recommended.
<br /> • Drill five soil borings and up to five contingent soil borings surrounding the location of the two
<br /> former 20,000-gallon USTs to provide data to determine whether TPHG,TPHD,BTEX,
<br /> oxygenates,and lead are present in the soil or groundwater.If groundwater samples show
<br /> concentrations less than action levels(comparison criteria), it may be appropriate to destroy the
<br /> existing three groundwater MWs 1-3 (with RWQCB concurrence).
<br /> 6.0 WORK PLAN
<br /> 6.1 This WP describes the strategy that will be used to characterize the levels of petroleum
<br /> constituents(including TPHG,TPHD, BTEX,oxygenates,and lead)concentrations in soil and
<br /> groundwater that may have originated from the former two 20,000-gallon USTs location. To assess
<br /> whether the soil and groundwater in the area of the two former 20,000-gallon USTs have been
<br /> impacted with petroleum constituents,hollow-stem auger(HSA)drilling and soil and groundwater
<br /> sampling is proposed.The proposed boring locations for this investigation are shown on Figure 6-1.
<br /> The sampling and analytical matrix is provided in Table 6-1.
<br /> 6.2 General field,drilling,sampling and analysis, documentation,and data review procedures and
<br /> strategies will follow guidelines presented in the CA ARNG Site Investigation Quality Assurance
<br /> Project Plan(QAPP)(Radian International,2000a). The QAPP describes quality assurance(QA)
<br /> activities to be performed,quality control(QC)samples to be collected,and procedures for equip-
<br /> ment decontamination and disposal of contaminated materials.All health and safety issues are
<br /> addressed in the CA ARNG Health and Safety Plan(Radian International,2000b). This WP follows
<br /> the guidelines presented in the California Code of Regulations Title 23 (Sections 2649 and 2672)
<br /> (Barclays Law Publishers,2000).
<br /> 6.3 Drilling and Sampling Activities.Five HSA borings will be drilled and sampled to determine
<br /> the extent of possible soil and groundwater impacts that may be present within the vicinity of the two
<br /> former 20,000-gallon USTs location.In addition,up to five contingency HSA borings(placed
<br /> approximately 50 feet from the initial boring locations)will be marked but not drilled and sampled
<br /> unless evidence of soil and/or groundwater impacts is determined from the initial five borings.All
<br /> HSA borehole locations will have soil samples collected within the native soil material and be
<br /> sampled down to groundwater,as described in Table 6-1.Groundwater samples will be collected at
<br /> the first zone of groundwater at or near the top of the water table by lowering a dedicated bailer
<br /> through the open augers.If heaving sands prevent this sampling methodology, it may be necessary to
<br /> set a temporary casing or use a HydroPunch or similar method,as described in the QAPP
<br /> (Sections 4.3 and 9.0). All borehole locations will be placed as presented on Figure 6-1;however,
<br /> KAWprocess\00251\CA ARNG\Stockton AASF WP\FINAL\WP text.doc 7 June 2007
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