Doublestar Drilling (DSD) was awarded the main scope of work installing HSS Micropiles over 9 Tower Structures. After being awarded, the scope of work increased and an additional 16 HSS Micropiles were added to make the total drilled length of 1536m.
Each tower was designed with 4 legs and each leg had 4 micropiles. In total Doublestar installed and grouted 160 micropiles. The diameters of the HSS Micropiles are 217mm with a rock socket bond length up to 3.2m and consisted with #14mm Threadbar bar.
With the uneven ground conditions, this caused longer times for drilling equipment to set up and the ongoing change of soil conditions (i.e. fractured bedrock , etc.) which lead to higher overages in grout due to fractures in geology.
DSD dedicated a night shift crew to ensure that equipment kept warm and running throughout the night. This helped with cutting down the set up/start time of each morning shift and preventing equipment shut downs and thus DSD was successful in extreme cold working conditions and all of the power line structures were completed in 26 days of drilling.