Record Jacking Project In San Antonio

By Jeff Griffin, Senior Editor | July 2012, Vol. 67, No. 7

“Subsequently, the back of the shaft was reinforced with one-inch thick ‘H’ beams, 1.5-inch limestone and 8 by 20-foot steel road plates,” Ritchards said. “This combination proved sound as jacking pressures reached 5,000 psi by the end of the project and there was no deflection in the backstop whatsoever.”

“When all were in place,” said Ritchards, “the string was only off by one-half inch.”

Installation of the new 11 by 9-foot box culvert was completed in January 2012, five months after work on the shaft was initiated. In addition to jacking the new culvert boxes, the project included installation of new concrete riprap for the drainage channel from Goliad Road to Interstate 37.

Ritchards said sizes of the boxes and length of the string set this project apart from others.

“Historically,” he said, “a string of boxes this diameter is much shorter, usually less than 100 feet. To my knowledge, no one has ever jacked a sting this size for a distance of 294 feet.”

Ritchards cited one man as instrumental in the successful completion of the project.

“BorTunCo Tunneling Superintendent Larry Robinson Sr. has more than 35 years of experience with hand mining operation,” said Ritchards. “His ability to plan and execute this monumental task was a direct reflection of his knowledge and determination to ensure this project was installed according to the spec. Larry never wavered in spite of the extenuating circumstances incurred that included ground conditions, weather, holidays and the work location and space constraints, all of which impacted the project at various times throughout construction.”

Founded in 1948, Boring & Tunneling Company of America first attracted the attention of the underground construction industry with its patented method of slurry boring. Over the years, BorTunCo has adopted other technologies as they developed and today offers services that include boring, tunneling, shaft construction, horizontal drilling, and construction consulting and management. The company is based in Houston, TX. The company’s founder, Gilbert Turner, held a long-time patent on slurry bore technology. In 2011, BorTunCo was acquired by Magnum Tunneling but still operates under the BorTunCo name.


BorTunCo, (832) 300-3333,

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