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s CLEARWATER ( It () L I' ] N C £vvuanmentaf Services ' In addition to the four confirmation soil borings, all on-site monitoring wells were sampled for the first quarter 2000 monitoring event This round of sampling should provide useful data for the evaluation of the lateral and vertical extent of dissolved-phase groundwater contamination The vertical extent of any residual contamination was addressed by the sampling of the two sparge wells, these wells are screened at a deeper interval than the other wells, thus providing information regarding any deeper groundwater contamination Methods Confirmation Soil Borehole Drilling and Soil Sampling Prior to drilling, a permit for the soil borings was obtained from the SJCPHS/EHD All fieldwork was performed in accordance with Clearwater's Field Procedures (attached) Prior to initiation of drilling activities, Clearwater and drilling subcontractor personnel reviewed and signed the Site Safety Plan On March 10, 2000, Clearwater supervised Fast-Tek g u Engineering Support Services in drilling the four g PP g soil borings (CB1 through CB4) (Figure 2) Fast-Tek, a C-57 licensed contractor based in Point Richmond, California, used a truck mounted Geoprobeg 5400 direct push drill-rig equipped with 2-inch diameter drill-rod to advance the soil borings All borings were drilled to a total depth of 30 feet bgs lieEach boring was continuously cored with PTEG liners Portions of each soil sample were retained for visual lithologic description by a Clearwater geologist using the Unified Soil Classification System A total of 17 soil samples (four from CB1, CB3, and CB4, and five from CB2) were selected and retained for laboratory analysis These samples were covered with teflon lined plastic end caps, labeled, documented on a chain-of-custody form, and placed on ice in a cooler for transport to the project laboratory The samples selected for laboratory analysis came from several depth intervals, including one from the bottom of each boring, 30 feet bgs Boring logs and well construction diagrams are attached Soil cuttings and auger/sampler rinseate were stored on-site in labeled 55-gallons drums pending future removal and disposal Groundwater Gauging and Sampling On February 7, 2000, all on-site wells (MW-1 through MW-7, and SW-1 and SW-2) were monitored RW-1 could not be sampled due to its being partially filled sediments Additionally, a water sample was collected from the on-site domestic well (DW) An electronic water level indicator was used to gauge depth to water accurate to within ±0 01-feet All wells were checked for the presence of SPH prior to purging No measurable thicknesses of SPH were observed in any of the wells The wells were purged until sampling parameters (e g temperature, pH and conductivity) stabilized, which occurred by approximately three wetl casing volumes Groundwater monitoring and well purging information was recorded on Gauge Data/Purge Calculations and Purge Data sheets (attached) ZBI07C Conf Borings/GWMR 1(100 3 Mach 27 2000