Somerville self-performs surface casing installations up to 60 inches in diameter. Surface casings are required to isolate unconsolidated formations (gravel and cobble layers) and to ensure full fluid return back to the rig. This unstable ground can be disastrous while drilling as this material can lock into place in the cavity created by the downhole tooling and prevent the tool from moving forward and backward. A surface casing is installed at a designed angle and driven down until it can be seated into bedrock. The conductor barrel provides a clean hole that will not fill-in or erode during construction, and is designed based on the size of the product pipe being pulled back once the crossing has been completed. Typically, a pneumatic ramming tool rams the conductor barrel into the ground, the pipe is rammed into place and another segment is welded on. The length and depth of the surface casings are dictated by entry angle, ground conditions and size of the pipe rammer. Depending on the angle and ground conditions an auger boring machine can be used to clean out the casing, if not the HDD rig can clean out the casing with a forward reamer.