Planning Horizontal Directional Drilling for Pipeline Construction

4.2 Construction Risk
Success of an HDD installation is dependent upon the ability of the project team
to minimize the causes of failure. The risks associated with each crossing will
vary according to many factors. These include but are not limited to:
• inadequate planning;
• lack of contingency planning;
• inexperienced field personnel;
• overestimation by the contractor in the firm’s abilities;
• insufficient quantity and size of equipment onsite; and
• inadequate knowledge of subsurface conditions.
(CPWCC 1999)
Construction risk on a project can be minimized by ensuring that sufficient
planning is conducted and an adequate geotechnical investigation is carried out.
Another means of addressing risk on a project is through the type of contract that
is used (see Section 9.1).
Table 1 summarizes some of the more common problems associated with HDD
and identifies the construction risks associated with each.
Table 1 - Construction Risks Associated with an HDD
Potential HDD Difficulty Construction Risk
Loss of drilling fluid Variable depending on volume and connectivity to surface or
water body.
Loss of circulation Complete loss of circulation indicates a loss of drilling fluid
(see above).
Drilling mud seepage directly
into watercourse
Drilling mud seepage onto land
and then into watercourse
Sediment load and deposition with possible adverse effects
on fish, fish habitat, hydrology and downstream water users.
Sediment load and deposition with possible adverse effects
on fish, fish habitat, hydrology and downstream water users.
Additional adverse effects on wildlife, vegetation, soils,
heritage resources and current land use may occur on land.
Collapsed hole Loss of topsoil and unexpected widening of the area of
disturbance. Extended duration of disturbance is likely.
Washout of cavities and
collapse of right-of-way
Loss of topsoil and unexpected widening of the area of
disturbance.
September 2004 Planning Horizontal Directional Drilling for Pipeline Construction Page 4-2