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CLEARWATER G R Q U •P, I N C. 2.3 Installation of Monitoring Wells and Vapor Extraction Wells The PHS Workplan Review stated that only one monitoring well should be installed in a downgradient position (on the north side of Lafayette Street), and that the remainder of the work should be conducted using push point assessment tools. However, in a subsequent telephone conversation with Mr. Ron Rowe, it was agreed that a downgradient well could be installed in a later stage of work (i.e. during installation of additional monitoring wells or SVE wells). No groundwater monitoring wells or SVE wells will be installed at the subject location during the next phase of work. Instead, a cone penetrometer test (CPT) rig and a hollow stem auger rig will be used to obtain subsurface samples. After the existing excavation has been backfilled and compacted, Clearwater will conduct a subsurface investigation by advancing six CPT borings and one continuously sampled boring using a hollow-stem auger rig. Locations of the '0 CPT borings (CPT-1 through CPT-6) and the continuous core location (SB-7) are shown on the attached revised Site Plan. 2.3a Hollow-Stem Auger Boring Soil boring SB-7 will be advanced adjacent to the excavation using a hollow- stem auger rig. Soil will be sampled continuously from the surface to 50 or 55 feet bgs using a 3.25-inch diameter, 5-foot long continuous sample barrel. �� Samples will be selected from representative strata and and screened using an FID, but no samples will be chemically analyzed. �44V Up to 4 samples will be submitted to a soil laboratory for analy$is of soil permeability (to water) and soil moisture content using ASTM 13534. These samples will be collected from representative strata using a split-spoon sampler lined with six-inch long brass sleeves. The laboratory results obtained for permeability to water will be used to estimate the permeability to air, as requested by the PHS. • 3 D105WPAdd 10/95