The devil in the details

Abstract

Small HDD projects are often advertised for bid with limited design. Owner agencies will sometimes rely heavily on the winning contractor to design the bore geometry, work areas, and pipe stiffness or thickness, all while acquiring permits and limiting impacts to the public. While contractor-designed projects have been successful, many have also led to significant change orders, claims, and litigation. Requiring the contractor to provide design services is ill-advised, unfair to the contractor, and often leads to costly issues and delays. Contractors typically do not employ professional engineers, do not provide design services, and may not fully comprehend the nuanced challenges and risks of the project. As subsurface infrastructure and surface facilities become more crowded, requiring a contractor to design a project in a low-bid scenario increasingly leads to conflicts during construction, resulting in costly delays and change orders. This paper discusses common pitfalls encountered on small HDD projects and how these hazards can be addressed and mitigated during design. Topics discussed in the paper include geotechnical investigations, bore geometry, work areas, performance requirements, and early feasibility analysis of the project and constraints. Past HDD projects are cited to illustrate the topics discussed. Identification and mitigation of potential problems during the design phase can limit the number and severity of unexpected problems during construction.