— Micro Piles are small diameter piles that can be installed in a variety of soils from non-cohesive, poorly-graded granular soils, to cohesive plastic clays. Also known as mini piles, pin piles, needle piles or root piles, micro piles can offer a viable alternative to conventional piling techniques, particularly in restricted access or low headroom situations. A micro pile foundation system may be advantageous in areas where large boulders are sporadic in the subsurface, as the small diameter micro piles may be able to be installed around such boulders. Micro piles are installed using water flush rotary drilling or rotary percussion drilling techniques. Measuring between 6 and 12 inches in diameter, micro piles consistently achieve capacities of 20 to 100 tons, with special installations up to 200 tons. Micro pile drilling methods generate minimal disturbance or vibration to adjacent structures, making micro piles an excellent underpinning alternative.