FAQs

Q. What area do you cover?
A. Anywhere in the North Island including offshore islands.
   
Q. What is the largest diameter pile you can drill?
A. Depending on ground conditions, but we have drilled 3600mm diameter into the Waitemata Sandstone - refer bored piles.
   
Q. How deep can your drilling rigs drill?
A. It depends on what drill rig is used.  Our pendulum rigs can drill up to 10m, our MTrack drilling rig can drill up to 20m - depending on diameter and our Soilmecs can drill large diameter piles down to about 45m - refer Great South Road, Penrose.
   
Q. Can you drill into rock?
A. Yes.  We have special drills and core barrels for drilling hard material - refer access shafts.
   
Q. What about unstable ground - can you drill, place reinforcing and pour concrete into wet, sandy or sloppy ground?
A. Spiral Drillers Civil has all the equipment and expertise to install either temporary or permanent caissons into unstable ground.  Piles can then be de-watered or concrete placed under water using the tremmie method - refer Ormiston Road bridge.
   
Q. With your pile driving rigs, what size and types of pile can you drive?
A. The smallest pile driver is designed for the installation of ‘pin piles’.  This machine can be taken inside a building with a minimum head height of 2,500mm to drive pin piles.  Our intermediate sized machines are track mounted with either 780Kg or 1200Kg hammers capable of driving timber, steel or concrete piles up to 9m long under the hammer.  If it is larger pile driving that is required we have a number of large crane mounted pile driving hammers that can drive up to 25m under the hammer.  We also have 6 tonne drop hammers to be used on a crane suitable for bottom driving steel caissons - refer pile driving.
   
Q. I noticed that you mentioned screw piles on your web site, can you tell me what they are and their advantages or disadvantages.
A. A screw pile is basically a steel hollow heavy wall shaft with either 1, 2, or sometimes 3 steel flights welded to the bottom of it.  This is screwed into the ground using a high torque rotary in a similar way to a cork screw or a wood screw into timber.  The shaft can be extended as it is screwed into the ground to achieve required depths.  The advantage of this system is that it can be installed with no vibration and there is no need for spoil removal.  This system is not suited to rocky ground - refer groundforce pamphlet.
   
Q. If you start a job and find that the drilling conditions differ from what you expect, can you solve the problem promptly.
A. Yes.  Our on site crews are fully trained and experienced in all aspects of piling and we have a fully equipped workshop where we can build or modify equipment at very short notice.  Our engineers can also attend to on site issues - refer home.