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George F. Schuler, Inc 1705 N. Broadivay, Stockton, California August l7, 1993 Phase I Remedial Report Page: 3 The borings were logged under the direct supervision of a registered professional using the Unified Soil Classification System (Appendix D). The color, texture, moisture, plasticity, consistency of the earth materials, pertinent soil or bedrock characteristics, and any evidence of contamination were noted. All water-bearing zones and the depths at which they were encountered were noted on these logs. i All borings were drilled in such a manner as to prevent cross contamination i between strata. Exploratory soil borings within the unsaturated zone were backfilled with a cement and three percent (3%) Bentonite mixture. Borings into the saturated zone were terminated approximately 8 feet beneath the top of the aquifer in a clay to prevent penetration into a deeper aquifer. Upon termination., the boring into the saturated zone was completed as a monitoring well and backfilled with concrete grout, after a Bentonite seal had been placed. The boring for the monitoring well was of a diameter at least 4 inches greater than the 2 inch diameter of the well casing to be used. The cuttings from the drilling operation were containerized on-site during drilling for proper disposition. The proper method of disposal will be dependent upon results of laboratory analysis. This disposal will be the responsibility of the client unless other arrangements have been made. 3.2 Well Construction All materials used in well construction were thoroughly cleaned prior to introduction into the boring. A 2- inch diameter well casing (PVC) with end cap and factory perforations for placement in the saturated zone was placed in the boring. The screen and filter pack sizes are as noted in the well construction drawing. The casing and end caps were threaded; no PVC cement was used. The filter pack extends two feet above the perforated zone. A Bentonite seal 2- to 3- feet thick was placed in the annular space above the filter pack followed by a ' cement grout to the surface. Seal and filter pack elevations may vary based on the underlying geology (Appendix D). 3.3 Well Development and Sampling The wells were developed until the well water appeared clear of sediment, or until an appropriate number of well volumes (based upon the judgment of the responsible professional) had been evacuated. The water produced during well development was containerized and left on-site in 55-gallon drums for disposal as hazardous waste if deemed necessary upon receipt of laboratory results. Disposal will be the responsibility of the client unless other arrangements have been made. The wells were allowed to stabilize for twenty-four (24) hours prior to sampling.