ASCE MOP Addresses Direct Steerable Pipe Thrusting

Five-year Process Yields First-of-its-Kind Manual for Popular New Install Method

When it comes to new installation trenchless technologies, one of the youngest methods in the toolbox is the use of direct steerable pipe thrusting technologies for large diameter pipeline installations.

Direct Steerable Pipe Thrusting (DSPT) — commonly known as Direct Pipe — was first used in 2007 to install 48-in. diameter casing under the Rhine River.

“DSPT was developed by Herrenknecht AG, in Germany in the early 2000s under the trade name Direct Pipe with the first installation occurring in 2007. Subsequently it has gained increasing acceptance worldwide with more than 200 installations completed,” says Jonathan L. Robison, P.E., principal, GeoEngineers Inc. He adds that in addition to Herrenknecht’s Direct Pipe system, Prime Drilling GmbH makes a comparable system.

In 2010, the DSPT method made its U.S. and North American debut on a Florida Gas Transmission Co. project. REM Directional Inc. installed a 705-ft pipe string under Highway 70 in Arcadia, Florida as part of the utility’s Phase VIII Expansion project.

In 2014, Michels Canada was the first to use the method in Canada on a pipeline project. Michels installed a 1,122-ft, 42-in. pipeline under the Beaver River as part of the Inter Pipeline Ltd.’s Cold Lake and Polaris Expansion Program.

Early on, many conceptualized DSPT to be a hybrid of horizontal directional drilling (HDD) and microtunneling. Robison notes that the main innovation that differentiates DSPT and the already established new installation methods, is that the pipe thruster machine grips the outside of the pipe and pushes it into the ground. This, he notes, allows for long sections of steel pipe to be prefabricated, pre-tested, and installed- similar to HDD pipe strings.

“DSPT uses microtunneling technology to excavate the ground and remove the cuttings while installing welded steel pipe in a one-pass, typically along a curved profile. It provides a niche capability between HDD and conventional microtunneling,” says Robison. “Relative to HDD, DSPT can operate at lower annular fluid pressures (reducing inadvertent drilling fluid surface release risk), tackle tougher, granular ground conditions, and offer shorter and shallower installation geometry. Relative to conventional microtunneling, DSPT can launch and end close to or at the ground surface and can install welded steel pipe over much longer distance.”

While many DSPT projects have successfully been completed, a good practices type document had not been created for the method. To fill this void in the industry, the American Society of Civil Engineers (ASCE) Committee on Trenchless Installation of Pipelines (TIPS), as part of the Utility Engineering & Surveying Institute (UESI) convened a task committee to develop a manual of practice (MOP) for DSPT.
Robison was chair of the committee, which formally created, “ASCE Manuals and Reports on Engineering Practice, 155: Direct Steerable Pipe Thrusting.” Commonly known as ASCE MOP 155, the MOP was released in March 2023.

“As distinct from a conference paper or journal article, an MOP is a consensus document written by a group of industry experts and then subsequently peer-reviewed by a second group of industry experts,” says Robison. “Its purpose is to provide general information and specific due diligence, design and construction recommendations for project teams contemplating the use of the DSPT method.”

Jeff Scholl, P.E., vice president of J.D. Hair and Associates, served as vice chair of the committee and credits Robison with helping bring the MOP to fruition. He also notes some of the nuances between how different sectors of the underground construction industry viewed the DSPT method that made a document like MOP 155 necessary.

“Jon deserves all the credit in the world for managing the development of the MOP and keeping all the various personalities on task and keeping things moving and helping us build consensus,” Scholl says. “One interesting thing about the document is that Direct Pipe is still such a young technology, there really isn’t even established terminology yet. Depending on your background, whether HDD or tunneling, you might have differing opinions on what to call something. For instance: Is it an exit point or reception point? Drilling fluid or slurry? [What] do you call the pipe that is being thrust into the ground? Thrust section? Lots of work even on simple things like terminology.”

The process to create MOP155 began with a TIPS discussion in 2016. It was formally approved to proceed by ASCE in January 2018. The kickoff meeting for the MOP took place at the NASTT 2018 No-Dig Show in Palm Springs, California. In the ensuing five years, the MOP was written and reviewed by the primary authors (listed below) and a “cold eyes” peer review completed by a blue-ribbon committee before being approved and published by ASCE.

In addition to Robison and Scholl, the primary authors of MOP 155 are:

• Andrew Sparks, P.E., MOP Task Committee Secretary, Laney Directional Drilling
• Joachim Engelhardt, Herrenknecht AG
• Andrew Finney, P.E., Jacobs
• Norm Joyal, P.E., McMillen Jacobs Associates
• Chris Lamont, P.Eng., Associated Engineering Alberta Ltd.
• Michelle Macauley, P.E., LEG, Macauley Expert Services
• Mary Neher, P.E., Bennett Trenchless Engineers
• Matt Smith – Michels
• Nic Strater, PG, Brierley Associates
• Webb Winston, P.E., Williams

Helping contribute to the MOP and blue-ribbon panel are a cross-section of the underground infrastructure construction industry that includes academia, contracting, engineering, manufacturing and pipeline owners.

The 176-page MOP covers:

• History of DSPT;
• Overview of the DSPT method;
• Parameters that should be considered when determining the applicability and constructability of a potential DSPT project;
• Guidance on how to conduct site investigations that are critical to the DSPT process;
• Design process involved in the DSPT installation method, pulling techniques from both HDD and microtunneling;
• Installation stresses, evaluation, considerations, and calculations;
• Contract documents and forms, delivery methods, and potential legal issues associated with DSPT projects; and
• Overview of the construction phase of DSPT installations.

“As the DSPT technology has evolved beyond the proof-of-concept phase, and become increasingly accepted for applications around the world, an industry consensus document was needed to provide a reference for project teams to assist in the development, engineering, and delivery of DSPT installations,” says Robison. He adds that the document is designed not only for the engineering community but system owners, contractors, equipment manufacturers, academia and any other underground infrastructure construction stakeholders.

To help acquaint the construction community with the DSPT method and inform the industry of the availability of MOP155, Robison is leading a four-hour workshop on Aug. 13, at the UESI Pipelines 2023 Conference.

Those interested in ordering ASCE MOP 155, can visit asce.org/bookstore and search for MOP 155.

Mike Kezdi is the managing editor of Trenchless Technology.