Drilldown: Protecting rivers during pipeline construction

Pipelines transport energy products across the country through a variety of landscapes. Sometimes they must cross rivers.

Protecting the environment, which includes waterways and other environmentally sensitive areas, is a top priority for Canada’s pipeline companies. This focus on environmental protection has sparked innovation, advances in technology and the development of non-invasive pipeline construction techniques.

Trenchless crossings are a key tool when pipelines must cross rivers, roads, railways and other environmentally sensitive areas. One of the most common methods of trenchless crossings is Horizontal Directional Drilling (HDD).


What is Horizontal Directional Drilling?


In simplified terms, conventional pipeline construction essentially involves clearing the pipeline route, digging a trench, lowering the pipe into the hole, replacing the removed soil and remediating the area back to its original state.

With HDD, the pipe is carefully threaded through a tunnel underneath the river or other obstacle. This eliminates the need for digging trenches and using equipment, which means the environmentally sensitive area is not disturbed.


How does HDD work?


While each crossing is unique and requires its own carefully designed engineering plan, there are basic steps involved in HDD.

First, a drill rig is set up on one side of the crossing. From there, a pilot hole is drilled underneath the river, following a carefully designed drill path. Next, that tunnel is widened until it is about 12 inches larger than the diameter of the pipe. On the opposite side of the crossing, the pipe is assembled and welded. When it’s ready, the pipe is attached to the drilling equipment and carefully pulled back through the tunnel.

This process is completed using advanced technology and highly trained technicians. They use specialized equipment to guide the pipe, ensuring the angle, depth and exit point precisely follow the engineering plans.


How does using HDD in pipeline construction protect the environment?


HDD is non-invasive and has minimal impact on the environment. The only impact is the work area on either side of the crossing. That work area is created to accommodate the heavy equipment needed for the HDD process. Once the work is completed, the area is completely restored to its previous state.

No physical activity takes place in the waterway – everything happens underground. This means there is no impact to the river or riverbanks and zero disturbance to fish and wildlife.

HDD is often used by members of the Canadian Energy Pipeline Association (CEPA) to avoid or limit environmental impact. Here are some recent examples of how HDD has been used while constructing pipelines in Canada: