A. H. Beck Foundation was contracted to install an 11.5 foot diameter x 130 feet permanent casing for an access shaft at the Prosperity Mine near Petersburg. Unstable soil conditions encountered at the site required the use of bentonite slurry to ensure a stable excavation during the drilling and casing placement process. Due to a high water table, A. H. Beck Foundation had to set and grout an 18 foot diameter surface casing before drilling a 14 foot diameter shaft down 130 feet in order for the 11.5 foot diameter finish casing to be set with the proper grout cover, as required by North American Drillers. The 11.5 foot permanent casing was set in one continuous piece and weighed over 177,000 pounds. A 500 horse power crane attachment type drilling unit manufactured by Beck was used to drill the full 14’ diameter excavation after the pilot / alignment shaft was dug with the same rig.
OWNER: 5 Star Mine
GENERAL CONTRACTOR: North American Drilling