J. D. Hair & Associates, Inc. offers a full suite of trenchless engineering services, including HDD and Direct Pipe design along with associated analysis, site investigation, construction monitoring, and consulting services. 

  • hdd crossing design

    We are the industry leader in the design of horizontally directionally drilled pipeline crossings and have been key members of design teams for some of the most significant and challenging pipeline projects ever completed. Since its founding in 1987, JDH&A has consulted on more than one thousand HDD crossings in locations ranging from Alaska to Australia.

    Crossing Design

  • direct pipe crossing design

    Direct Pipe is a relatively new trenchless installation method that combines a surface mounted pipe thruster with a tunnel boring machine to excavate a borehole and install a product pipe or casing in a single pass. In certain locations, subsurface conditions, and areas where inadvertent drilling fluid returns pose a serious concern, Direct Pipe can offer advantages over HDD. In the past few years as the Direct Pipe method has been implemented in North America, we have been at the forefront of the technology, producing Direct Pipe crossing designs and monitoring Direct Pipe construction operations in the field.

    Direct Pipe versus HDD

  • hydrofracture analysis

    Due to an increasing focus on minimizing environmental impact, it has become standard practice in the HDD industry to evaluate the potential for drilling fluid to inadvertently flow to the surface due to hydrofracture. We evaluate the risk of inadvertent returns due to hydrofracture by comparing the confining capacity of the soils overlying the drilled path to the annular pressure necessary to conduct HDD operations. By completing a hydrofracture evaluation early in the design process, we are able to optimize the crossing design to reduce the potential for inadvertent drilling fluid returns resulting from hydrofracture.

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  • feasibility assessment

    In some instances it is necessary to determine if crossing an obstacle by HDD is feasible. We approach this question from two perspectives. First, is HDD technically feasible? That is, can the proposed crossing be installed using today's tools and techniques? Once this question is answered, the issue becomes one of cost. Is HDD economically competitive with other crossing methods? We address these questions by preparing preliminary crossing designs using publically available data and assuming conditions where necessary. Technical feasibility is demonstrated primarily by comparing the proposed crossing with previously completed installations. Economic feasibility is assessed by producing detailed cost and duration estimates for comparison against alternative crossing methods. The results of these efforts are typically delivered in a feasibility opinion letter with supporting engineering drawings and analysis.

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  • pulling load and stress analysis

    The loads imposed on a pipeline during HDD installation may exceed those involved with its operation. Therefore, analysis of pipe stresses resulting from installation loads is a crucial component of the HDD crossing design process. We routinely perform detailed pipe stress analysis to confirm that pipe material selected on the basis of operating loads can also withstand installation loads. Our experience in this area also allows us to support our clients with design and analysis of downhole components and preparation of pipeline handling procedures. 

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  • pull section geometry analysis

    With HDD crossings being completed in increasingly challenging locations, pull section handling can require considerable planning and analysis. We analyze geometry and loading scenarios taking into account the proposed line pipe specifications, pipe handling equipment, topography, and existing infrastructure to determine appropriate lift points. This analysis aids in constructability and minimizes the potential for pipe damage.

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    Our construction monitoring efforts focus on communication and documentation. We believe it is important that HDD operations are clearly documented for reference and action both during and after construction. We accomplish this with daily progress and spot check reports. These reports are prepared by our engineer at the crossing location and distributed to appropriate parties by email. Progress reports provide a breakdown of the contractor's progress as measured by drilled or reamed footage along with a detailed summary of construction operations. Spot check reports document specific aspects of HDD operations and address conformance with applicable drawings, specifications, and HDD industry standards.

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  • site survey

    The first step in defining the obstacle to be crossed is to survey the site. Depending on the nature of the obstacle, this may involve hydrographic as well as topographic surveys. For small crossings, we perform site surveys using our own personnel. For larger crossings, we produce detailed survey specifications for use in subcontracting local or specialized surveying firms. The results of site surveys are presented on the design plan & profile drawing.

  • Geotechnical investigation

    Characterization of the subsurface material in which a crossing will be placed is critical. We apply our extensive HDD engineering experience in designing a subsurface exploration program tailored to each crossing. This starts with preparation of a preliminary design which we use to layout the spacing and depth of exploratory borings. Field and laboratory soil tests are specified. The results of these efforts are pulled together into a detailed geotechnical investigation scope of work for use in subcontracting geotechnical specialists. Geotechnical information is summarized on the design plan & profile drawing. 

    Click here for a technical paper on subsurface investigation for HDD installations

  • Construction Contracting

    We routinely provide technical specifications governing specialized HDD activities to complement our crossing designs. These specifications are provided in draft form for integration by our clients into their standard construction documents. Alternatively, we can produce a stand alone construction document that also includes technical specifications governing operations that support HDD activities.

  • Permitting Support

    In today's highly regulated construction environment, it is important to accurately describe the impact of proposed HDD operations. We support our clients in this effort by preparing permit applications and assembling technical data required for submission to federal, state, and local authorities.