Equipment: Astec® DD3238 and a StraightLine® 4″ Air Hammer System.
Ground conditions:Clay soil with 3 x 10+ foot diameter granite boulders in the bore path.
Project: water service requiring a minimum 3-feet of cover that totaled 90-feet in length. Entered the ground at a minus 18%, drilled conventionally until a boulder was encountered, engaged the hammer and drilled through the rock, exited the ground at a plus 25%.
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