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� I A S S O C I A T E S ! N C 21 Drilling Activities " 21.2 Hollow Stem Auger Drilling Activities On September 23, 24, 25, and 30 2002, a geologist from ATC supervised the advancement of five soil borings, MW4 through MW8 A site plan with soil boring locations is shown on Figure 2 Hollow stem auger drilling was conducted by Cascade Drilling, Inc (State C57 license no 717510) Soil borings MW4 through MW8 were advanced to approximately 65 feet bgs and completed as 2-inch diameter groundwater monitoring wells Soil samples were collected from each soil boring at five-foot intervals The soil samples were ' collected using a 2-inch diameter split-spoon sampler containing three brass tubes A field geologist logged drill cuttings and soil samples utilizing the Unified Soil Classification System Descriptions of soil types encountered and sample collection intervals are included on the soil boring/well construction logs contained in Appendix B Drill cuttings were temporarily stored on site in DOT approved 55-gallon steel drums The bonngs were subsequently completed as groundwater monitoring wells MW4 through MWS The monitoring wells were constructed of 2-inch inside diameter schedule 40 PVC well screen and casing A 0 010-inch well screen slot and #2112 sand pack was used, approximately ' six sacks of sand per well A cement grout mixture was used to seal the wells in accordance with California Well Standards (December 1981) To protect the integrity of the wells, a locking, watertight well plug was installed on each well and a watertight wellhead labeled "monitoring ' well" was set in concrete over each well Well construction details are presented on the boring logs contained in Appendix B Descriptions of soil types encountered, field observations, and sample collection intervals are presented on the well logs contained in Appendix B ' 2.1.2 Cone Penetrometer Testing Drilling Activities Cone Penetrometer Testing (CPT) drilling was conducted on October 1, 2002, by Gregg Drilling & Testing, Inc (State C57 license no 485165) Two CPT borings, CPT1 and CPT2, were advance at the locations shown on Figure 2 Cones mounted with sensors at the tip were advanced into the soil using direct push rods The sensors on the cone tested the response of the soil to the force of the penetrating cone and allowed the subsurface stratigraphy to be characterized The cones and rods were advanced by a hydraulic press with a down pressure capacity of approximately 25 tons Borings CPT1 and CPT2 were advanced to approximately 120 feet bgs and 139 feet bgs, respectively, utilizing a truck-mounted CPT rig A copy of the Gregg Drilling Cone Penetration Test Data is included in Appendix B w lwordpro1625831reportslWell_mstail_rpt doc 3