Winning No-Dig Show Papers Highlight Trenchless Technology Lessons

Geopolymer spray applications for rehab work and lessons learned on high-risk HDD projects are the focus of presentations from the 2021 NASTT No-Dig Show named winners of the Outstanding Trenchless Paper Awards

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The North American Society for Trenchless Technology (NASTT) recently named the winners of its Outstanding Trenchless Paper Awards. The papers were presented at the 2021 NASTT No-Dig Show in Orlando, Florida, earlier this year.

Winning in the Rehabilitation category was a paper about a stormwater culvert rehab project in Columbia, South Carolina, by Bill Sharpe, business development manager of Inland Pipe Rehabilitation of Columbia, South Carolina, and Joe Royer, vice president R&D for GeoTree Solutions of Spartanburg, South Carolina.

In the fall of 2017, the city of Columbia, South Carolina, placed a publicl bid project for major upgrades to a critical water treatment plant. The scope of work included the rehabilitation of multiple existing brick arch stormwater culverts ranging from 4x6 feet to 8x8 feet. Columbia Water did a comprehensive investigation of the rehabilitation options available, including a 2012 pilot study, and selected a geopolymer mortar spray-applied system as the means for structural rehabilitation. The project consisted of three separate culverts, originally constructed in the 1820s within the treatment plant, that carried stormwater runoff underneath the emergency water reservoir, clear well and canal before discharging into the Broad River. The paper brings attention to the use of geopolymers and spray applications as an important part of the trenchless industry.

“The work we at GeoTree Solutions and our contracting partner on this project Inland Pipe Rehabilitation have done to develop the technology showcases viable solutions for large-diameter projects,” Royer says.

Winning in the New Installations category was a paper focused on key lessons about horizontal directional drilling work by Kimberlie Staheli and Jake Andresen, engineers at Staheli Trenchless Consultants of Seattle, Washington. 

“I have thought about putting this together for years,” says Staheli, who was introduced to trenchless technology on her first job after college with a microtunneling contractor. “The industry was so new that it really excited me. The more I learned, the more I realized that I had a shot of making a difference.”

Staheli says she has seen the industry in an ongoing state of rapid transformation for more than 20 years and believes it is an industry where an engineer can continuously learn and grow.

“I see engineers specifying things that are not constructible. Then when we get there to perform risk management inspection, we have to work through the issues in the field. I wanted engineers to be aware of how the designs need to be changed in the field to avoid claims,” Staheli says.

The paper focuses on how HDD technology is being stretched to projects that have significant challenges that are not often considered on standard HDD projects. Many of these projects carry high risks and challenges due to geotechnical conditions, site constraints, locating interference and risk of hydrofracture that are not evident to people who have only worked on standard HDD projects. The paper presents a number of case histories and illustrates lessons learned on high-risk projects.

The 2021 winning papers (and all other NASTT No-Dig Show papers) are available in the NASTT product store. The authors of both papers will also be giving encore presentations of their work at the 2022 NASTT No-Dig Show in Minneapolis, Minnesota. Visit the conference website.



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