How Spectra Energy Crosses Rivers & Streams

Categories of Bodies of Water

Bodies of water such as streams and rivers are classified by the Federal Energy Regulatory Commission (FERC) into three categories:

  1. Minor
    Includes all streams less than or equal to 10-feet wide at the water’s edge at the time of construction.
  2. Intermediate
    Constitutes perennial stream crossings greater than 10-feet wide, but less than 100-feet wide at the water’s edge at the time of construction.
  3. Major
    Includes crossings of more than 100 feet wide at the water’s edge at the time of construction.

Methods of Crossing

There are four basic methods for crossing bodies of water. The techniques for each are site-specific:

  1. Open-Cut Wet-Ditch Method
    The open-cut wet-ditch method of construction consists of digging an open trench in the stream bottom, laying the prefabricated length of pipe necessary to reach bank to bank and then backfilling.
  1. Open-Cut Dry-Ditch Method
    The open-cut dry-ditch method of construction uses flume pipe(s) to transport the stream across the disturbed area, which allows trenching to be done in drier conditions.
  1. Dam & Pump-Around Method
    The pump-around method of construction can act as a substitute to the open-cut dry-ditch method of construction. It may be employed on small, low-flow streams where the dry-ditch method cannot be employed because of site-specific conditions. In application, small sand bag dams are constructed both upstream and downstream around the work area across the stream channel. Stream flow is then diverted around the work area using gasoline-powered pumps and hoses.
  1. Horizontal-Directional Drilling (HDD) Method
    The tools and techniques used in the HDD process were developed in the oil well drilling industry. The rigs use similar components, with the major difference being that the pipeline rig is equipped with an inclined ramp.

Installation of a pipeline by HDD is generally accomplished in two stages:

  1. The first stage consists of directionally drilling a small diameter pilot hole along a designed directional path. The path of the drilling string is tracked and directed using surface monitoring systems. The surface monitoring system determines the location of the probe downhole by taking measurements from a grid or point on the surface. This allows the operator to follow the designed directional path.
  2. The second stage involves enlarging the pilot hole to a diameter that will accommodate the pipeline. The enlargement process involves the use of hydraulic cutting with jet nozzles and downhole hydraulic motors (also called “mud motors”) used to cut harder soils. It can take several passes to enlarge the hole to the required diameter, typically 42 inches for a 24-inch pipeline.