To meet the client’s time requirements, UEA mobilised a D100 x 120 (45 tonne) HDD drill rig and DFE 300gal/min cleaning system to undertake the pilot bore. A steering engineer was engaged to ensure the bend radius of the pipe was not compromised. Completion of the pilot bore confirmed that ground conditions were estuarine sand with low clay content at depth. For the reaming process UEA mobilised a D300 x 500 rig and DFE 700 gal/min cleaning system. Scheduling of the reaming works were based on the day and time that pipe could be strung out across the access road, in order to maintain the only heavy vehicle access to Port Hunter.
A 750mm open reamer was utilised for the pre-reaming pass in conjunction with a comprehensive mud program designed to help carry out solids and help to maintain hole stability in the sand. The bore was surprisingly stable with returns maintained for 90% of the ream, a testament to the importance of good mud in these ground conditions.
Pipe was successfully installed with pullback pressures less than 10 tonnes.
For more information about this project or UEA Trenchless, please send enquiries to Steven Hopkins.