While traditional trenching has been used for decades, Horizontal Directional Drilling (HDD)—also called directional drilling—is now the preferred solution for many fiber optic projects. FO-VC2 JOINT USE - VERICAL MIDSPAN CLEARANCES 48. FO-RI JOINT USE RISER. Drilling holes for fiber optics may seem like a daunting task, but with the right tools and techniques, it can be a surprisingly simple and efficient process. The Contractor will generally be liable. The Fiber Optic Association, Inc. (FOA) was founded in 1995 to help develop the workforce to build the fiber optic networks to support a rapid expansion in communications and the Internet. TYIA We use flex fiber where you can pull the connector a 3/8" hole is all we do but we.