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1 CreologicalTeckxicslrrc. Page 8 Sinclair Trucking Project No.: 1030.2 August 11,2005 It appears as if excavation reached the southwest and northeast boundaries of contamination. Contamination was thinning out toward the north and west. The location of soil sample SW- East had heavy staining and appeared to be the area of the leak. The bulk of the soil contamination was found above 13.5 feet as indicated by the bottom sample. At the time excavation was halted, the project had already slightly exceeded the amount of soil removal allowed by the SWRCB. Under the SWRCB's explicit soil removal restrictions a quantity of contaminated soil had to be left in place. 2.7 Area Restoration The lower portion of the excavation pit was backfilled using imported fill dirt. The upper five feet was backfilled with the stored clean overburden. The upper three feet was compacted at a 90% compaction rate. The excavation area was covered with road base to bring it back to the original condition and provide control for fugitive dust. 2.8 Monitoring Well Installation—Replacement 1 The new water table monitoringwell MW-1R was installed using an 8.00-inch outside ( } g diameter continuous flight hollow stem auger owned and operated by ResonantSonic International (RSI), a C-57 licensed driller. Permits were secured as necessary and the local regulatory agency was notified 48 hours prior to commencing work. ' Soil cuttings were placed in the excavated soil stockpile and stored on site until disposal was arranged. A professional geologist under the supervision of a licensed registered geologist supervised all drilling, sampling, and well construction activities. ' The shallow monitoringwell was constructed using 2,0 inch diameter PVC n g casing with flush ' threads. Groundwater was encountered at approximately 12.5-feet below grade. Well construction is outlined below and attached in Table 2: Summary of Well Construction. A surface seal was achieved by pumping a neat cement grout (augmented with <4% bentonite) ' via a tremie tube. The well was secured with a locking watertight cap encased in flush mounted traffic rated well box. ' Well ID DiaJTD Screen I Slot Sand PackTrans. Seal Grout Seal MW-1R 1 2"/20' 20-10' 0.010" #3 sand 20-8' 8-6' 6'- surface ' The monitoring well was developed (using mechanical surging and pumping methods) approximately one week after installation. The well was purged and groundwater samples collected on April 11, 2005. Details of the groundwater sampling of MW-1R are discussed ' in GTI's: 2nd Quarter 2005 Groundwater Monitoring Report dated June 28, 2005. All development and purge water has been containerized in 55 gallon DOT approved containers and stored on site until their disposition can be arranged.