1. Directional drilling has traditionally been applied in telecommunications, electric installations, oil, forced water, sewer lines and gas distribution. More recently, HDD has been applied to horizontal environmental wells and geothermal systems. Contractors are developing new HDD applications every day. The directionally controlled horizontal drilling process was developed in the U.S. and is commonly used for crossing under natural or manmade obstacles, especially river crossings. This method has revolutionized complicated river crossings for pipelines, which were initially done by conventional dredging methods or were rerouted through long distances and crossed over at a bridge location.
2. Horizontal Directional Drilling has three basic stages as follows:
- Pilot drilling
- Back reaming
- Pulling back
3. Horizontal Directional Drilling has more advantages than Traditional open trench such as:
- Short set-up time and safety;
- Less negative impact on residents and – businesses or public places
- Less affect the environment;
- Surface disruption is minimized;
- HDD eliminates the need for removal, restoration and long-term costs associated with trench settlement
- In open areas, horizontal drilling provides an efficient method for crossing obstacles such as rivers, highways, rail tracks or an active runway.