Specialty geotechnical drilling contractor Holocene Drilling of Edgewood, WA recently completed work on an interesting project for Sound Transit’s U-220 TBM Tunnel Project at the University of Washington Campus in Seattle. Their scope included drilling and installing inclinometers and borehole extensometers to monitor possible ground movements related to the tunneling operation. They were also retained by Hayward Baker to perform borings after jet grouting to verify the size and condition of the jet grout block. [Source: National Driller. Image: Holocene Drilling]