Pipe Ramming

Communities around the world routinely install underground utilities of various types, sizes, and purposes. Pipelines are installed everywhere and by a variety of construction methods, the most common of which is open trench excavation. Trenchless methods for new utility installations are often attractive to project owners and are sometimes required by regulatory agencies and property owners because they reduce impacts to the surface, existing structures, and infrastructure. This introductory chapter summarizes the benefits of trenchless construction methods. Trenchless methods, equipment, and guidance systems improve and change over time, and contractors continue to develop innovative new techniques. Therefore, it is important for design engineers to keep abreast of available trenchless methods and tooling to systematically evaluate options. An overview of the key concepts discussed in this book is also provided.

This chapter addresses pneumatic and hydraulic powered pipe ramming, which is widely used for installation of steel casings and cross-country steel pipelines, primarily at crossing locations. It provides a clear explanation of the capabilities and limitations of pipe ramming; outlines important design and construction considerations; and investigates potential problems and prevention measures to instill confidence in the science and art of pipe ramming. The two major categories of pneumatic or hydraulic pipe ramming are closed-face and open-face. Except for the ramming hammer and the pilot tube, the tooling is relatively inexpensive, and, in many cases, contractors adapt and reuse equipment, making it even more cost-effective. For these reasons, more projects are using pipe ramming in conjunction with pilot tube guidance. Pipe ramming is used in applications with a horizontal orientation, but it can also be used for inclined and vertical applications.

This chapter provides peer review of the planning/design process for making good design choices. The parameters that help to determine the applicability and constructability of a potential pipe ramming project are described. The engineer of a project is encouraged to consider all trenchless methods before concluding that the pipe ramming method is the best construction method available. It is recommended that the owner and the engineer visit the proposed site during the initial planning phase and then periodically throughout design to identify site conditions and constraints. In the planning phase of a project, a preliminary geotechnical investigation should be performed to identify general conditions and any special subsurface conditions. Pipe ramming projects should be planned with attention given to the benefits and constraints that are unique to this construction process. Pipe ramming can be a more economical choice than traditional open-cut construction when all costs are considered.

Communities around the world routinely install underground utilities of various types, sizes, and purposes. Pipelines are installed everywhere and by a variety of construction methods, the most common of which is open trench excavation. Trenchless methods for new utility installations are often attractive to project owners and are sometimes required by regulatory agencies and property owners because they reduce impacts to the surface, existing structures, and infrastructure. This introductory chapter summarizes the benefits of trenchless construction methods. Trenchless methods, equipment, and guidance systems improve and change over time, and contractors continue to develop innovative new techniques. Therefore, it is important for design engineers to keep abreast of available trenchless methods and tooling to systematically evaluate options. An overview of the key concepts discussed in this book is also provided.

This chapter presents a discussion of design specific to construction with pipe ramming. It provides a summary of the design tasks, namely, planning and permitting; exploration, design considerations; and design documentation. The planning and permitting process assesses the interaction of the pipe ram construction with anticipated and assumed subsurface and environmental conditions, to identify and manage risks of encountering hazards in the context of project cost, schedule, environment, and safety. Explorations of surface and subsurface conditions are part of the due diligence field studies necessary to support assumptions that site surface layout, subsurface utility, and subsurface conditions are suitable for pipe ramming. All trenchless projects should require some form of documentation, such as assumptions, data, and analyses, to demonstrate that the basis of design is founded on industry standards of professional care. Design documentation of a pipe ramming project is typically used to clarify the project features and assumptions for retaining an independent contractor to schedule a project and determine its cost.

This chapter is based on the traditional design-bid-build process. During bidding, interested bidders should review the bid documents. After reviewing the contract bid documents and referenced documents, the general contractor prepares and submits a bid based on the estimated building cost and schedule. The contractor performing the pipe ramming prepares and provides detailed submittals in accordance with the requirements of the specifications. The standard safety procedures that are followed in tunnel construction should also be followed in pipe ramming projects. The extent to which the subsurface conditions, including geotechnical conditions and potential buried objects, are identified prior to construction depends on the comprehensiveness of the site investigation during the design phase when traffic control or management of traffic plans may be developed and included in the bid documents.

This chapter presents case histories of past pipe ramming projects. Often, published case histories only showcase the longest, largest, most complex, and most challenging projects. The trend of publishing pipe ramming case histories based on diameter and drive length is discussed. A table is compiled that includes both common and less-common pipe ram projects involving utility crossings, culvert installations, conductor casing installations, horizontal directional drilling assists, and pipe extractions. Information is provided on when each project was completed, as well as purpose, location, casing diameter, drive length, length of the casing sections, wall thickness, hammer size, ground type, pipe ram position relative to the groundwater table, and available information on grade. References are included to provide more information.