Types of River Crossing Methods
Horizontal Directional Drilling Intercept Method (Joint Venture Proposal)Utilizes two drilling rigs on either side of the river that drill towards each other. Drill head control and positioning systems allow for steering of the drill heads, which intersect 100 feet beneath the river bottom. This method is often used for long distance crossings and the placement of pipelines far below river corridors does not disrupt fragile river ecosystems. This method is environmentally the safest method of crossing the river. THIS IS THE PROPOSED METHOD OF THE SACAGAWEA PIPELINE.
Pipeline Pull Method – Open Trench Method
This method pulls the pipe across the river from one side, as it is assembled on the opposite bank. The pipe is then laid into a 3’ to 4’ trench along the river bottom, backfilled, and covered with concrete mats. Dredging often results in water & river bottom degradation. This method has a larger environmental footprint, and the pipe is more exposed to damage from 3rd party impacts, including ship anchors and underwater debris. If a leak does occur, pipe is just a few feet from entering the river.
Pipe is routed along existing bridges and water crossings. This type of crossing poses risk to bridge traffic, and there are environmental risk as waterways are exposed to spills. Pipe is exposed to 3rd party impact, the most common form of damage to pipelines. Increasing governmental regulation is being focused on this type of crossing.
Often used in remote areas when HDD boring is not possible due to subsurface issues, length and/or pull load of the pipe. Pipe exposure is an environmental risk.