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i <br /> Mr.Rusty Benkosky,Stantec Consulting Corporation March 23,2009 <br /> Well Installation Data Package Project No.E443-01 <br /> Former ARCO Station No.443,Stockton,CA <br /> Page 2 <br /> the grout seal; as a result, the augers were stopped until it was time to extract <br /> another section of auger. Soon after this practice began, the drill rig broke <br /> down, ultimately forcing the driller to abandon 80 feet of 18-inch hollow- <br /> stem augers as the grout solidified in the annulus between the augers and the <br /> conductor casing. A variance to leave the augers in the ground indefinitely <br /> was granted by SJCEHD via a telephone conversation on January 29, 2009. <br /> • The 10-inch diameter hollow-stem augers appeared to be in danger of binding <br /> with the conductor casing, possibly leading to the casing spinning and <br /> compromise of the grout seal. Due to these concerns, it was decided to drill <br /> past the conductor using 8-inch hollow-stem augers to conduct soil sampling, <br /> then to drill and set the well using a mud-rotary drill rig. <br /> Chronology of Events: f <br /> Data Submittal Prepared/Reviewed by: Allan Dudding/ Steve Carter <br /> Phone Number: (530) 676-6008 <br /> Date: August 6, 2008 <br /> On-Site Supplier Representative: Allan Dudding <br /> Scope of Work Performed: Underground Service Alert markings were painted around <br /> proposed on-site well locations. <br /> Variations from Work Scope: None noted <br /> Unusual Field Conditions: None noted <br /> I <br /> Date: December 1,2008 <br /> On-Site Supplier Representative: Allan Dudding <br /> Scope of Work Performed: Located utilities in proposed locations for MW-5 and MW-8. <br /> Cleared MW-5 to 10 inches diameter and 5 feet bgs and MW-8 to 20 inches diameter and <br /> 5 feet bgs using airknife. <br /> Variations from Work Scope: None noted <br /> Unusual Field Conditions: None noted <br /> Date: December 2, 2008 <br /> On-Site Supplier Representative: Allan Dudding <br /> Scope of Work Performed: Drill MW-8 pilot boring using 10-inch diameter hollow-stem <br /> augers to 95 feet bgs. Ream borehole with 18-inch diameter augers to 60 feet bgs. <br /> Variations from Work Scope: Due to the likelihood of heaving sands of 65-80 feet depth, I <br /> continuous sampling was not carried out as planned, instead sampling continued at five- <br /> foot intervals. <br /> Unusual Field Conditions: Heaving sands present from approximately 65 to 85 feet bgs <br /> during drilling of the pilot boring. <br /> K:tBP-ARCO ExecuteW43\2009 Data packages\Amo 443_Well Installation—Dam Package.doc If <br /> I <br />