An unusual application of directional drilling was recently completed in Alaska.
The Pruhs Corporation of Anchorage used a Ditch Witch JT7020ts directional drill to install a siphon pipe to control the level of a lake.
The 8ha lake had risen, causing problems for nearby houses and damage to roads.The project is believed to be the first time directional drilling has been used for such an installation.
To install the pipe, a 120m pilot bore was made, extending 35m into the lake at a depth of 4.5m below the existing lake level.
After the drill bit reached its exit point, divers, working from a barge in the lake, removed the bit and installed backreamers and pipe.
Because of difficult soil conditions (gravel, cobble, and boulders), several attempts were necessary to complete the pilot hole, and backreaming and product pullback had to be made in one pass.