CLL used its air operated downhole hammer for the 800mm diameter piles to retain the basement excavation of a building. A downhole hammer was required at the site because of the Volcanic Basalt Lava flow from Lake Pupuke.
While the downhole hammer works well in hard rock, there was also an overburden layer of collapsing fractured rock. Temporary casings were used to prevent the piles from collapsing above the competent basalt.
The job was carried out successfully using a SR45 Soilmec with the downhole hammer attached and five high volume air compressors.