North Second Street Bridge Natural Gas Main Replacement Project

Cleary Gas Main Replacement
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In late 2020, Clarksville (TN) Gas and Water (CG&W) issued an award for a unique 6-in. gas main relocation project that included the replacement and removal of an existing 6-in. gas main to Cleary Construction Inc. A 400-lf portion of this gas main was hanging under the 2nd Street Bridge spanning the Red River near the intersection of 2nd Street and Kraft Street.

CG&W worked with a team of consulting engineers to design the replacement of 740 ft of 6-in. gas main that included this 400-ft bridge crossing, 110 lf of directional bore under 2nd Street, and three mainline hot taps with stopple connections. This gas line replacement allowed CG&W to eliminate the existing 6-in. steel gas line hanging under the bridge, which was deteriorating at an accelerated pace.

While this project wasn’t a large monetary contract, it required a unique, innovative, and specialized skill set. Cleary Construction Inc. successfully completed this project at the end of 2020 and turned it over to the owner in a timely manner.

Challenges and Innovative Ideas

Due to the proposed location of the gas line bridge hanging (5-7.5 ft from the edge and under the bridge deck) along with the very high volume of traffic over the bridge, Cleary Construction was faced with a serious challenge of how to construct this line under the bridge safely and efficiently. After reviewing the options of shutting down a lane of traffic to allow for the utilization of a snoop truck and/or hydra platform to work under the bridge, Cleary leaned on its previous utility bridge hanging experience and opted to build a wood deck under the bridge across the bridge beams. This OSHA-approved grade wood decking allowed the hangers and gas line to be installed under the bridge without worsening the major traffic issue that was present at the project location.

The second challenge that Cleary faced on the project was how to get the 6-in. steel gas pipe that is typically fabricated in 40-ft lengths welded together, X-rayed and tested under the bridge, which was the only constructable option. To solve this challenge, Cleary customed designed an innovative lift platform to be used in conjunction with a standard Lowell-type forklift. Cleary chose to have the steel gas pipe delivered in 20-ft lengths, which was exactly the separation between the girder braces at the only place where the pipe could be welded, tested and installed under the bridge. The welding personnel stayed on the platform while being lifted up with one 20-ft in length joint of pipe at a time. Once being lifted to the deck height (approximately 30 ft in height), the pipe was slid on the deck rollers to butt against the pipe that was already installed on the hanger rollers. The pipe was then welded and slid through the hangers over to a second manlift where a World Testing representative performed the X-ray testing. Once the testing was complete, the pipe was again slid across the rollers above the wood decking where Cleary personnel coated and placed the shrink wrap around the welds. This process was completed 20 times until the 400 ft of gas line was completely installed under the bridge.

At this point, Cleary faced the last, but quite possibly the biggest, challenge on the project: how to remove the old existing gas line and hangers from under the center of the bridge. This existing line that was obviously installed during the bridge deck construction and was some 80 ft from the edge of the bridge. The line was out of reach for a standard snoop truck, and it would take a lane closure for an extended period of time to utilize a hydra platform to remove the existing line/hangers. Cleary again used its experience to deck between the girders to provide a platform under the existing line that allowed the pipe and hangers to be removed very efficiently and safely.

Subcontractors, Suppliers and Equipment

Cleary Construction Inc. worked with multiple trusted suppliers and subcontractors on this project. The primary gas materials including the Power-Crete coated steel pipe and appurtenances as well as the cathodic protection stations, pipe hangers, and TD Williamson tapping tees/stopples were supplied by trusted vendor, Consolidated Pipe and Supply. The Simpson Strong Tie-hanger epoxy was supplied by HD Whitecap. The backfill stone was supplied by Vulcan Materials Company. Kelsey Unland with Meridian Safety provided the supplementary OSHA compliance and training. Trusted subcontractor, Brooks Excavation Contractor LLC, performed the challenging horizontal directional drill, while Badger Daylighting performed the trenchless methods to locate and verify the depth of the existing fiber optic duct bank to be drilled under. Longtime Cleary subcontractor Johnny Storm Paving completed the asphalt replacement, while another trusted sub, SJ Patterson, installed the gas hot tap with stopple connections.
Superior Traffic Control provide the traffic control set up. Sunbelt Rentals supplied some supplementary construction equipment. Tompkinsville Industrial Repair Inc. fabricated the custom designed lift platform. Jeff Harbison provided the welding, while World Testing provided the X-ray testing, as well as the operator qualification training and submittals packages.

Project Benefits

This replacement project benefitted the client and the community by eliminating a deteriorating 6-in. steel gas main, part of which was exposed and suspending under a highly traveled bridge. Not only did this project eliminate a big liability issue for Clarksville Gas and Water, it made the community a safer environment for the public.

“This was one of the most high-profile and successful projects for the City of Clarksville Gas Department in 2020 thanks to the expertise, out-of-the box thinking, and constant fluid coordination provided by the entire Cleary Construction Inc. team,” wrote Tyler Hayes, City of Clarksville. “The most impressive part of this project was the installation and removal plans Cleary developed – a plan that allowed us to remove 400 lf of gas main under the center of the bridge and install 400 lf of new gas main under a separate location under the bridge, all while working during normal business hours and not stopping traffic for one second.

“During design, it was envisioned that our contractor would use a snoop truck or a hydra platform to access the underside of the bridge and ultimately the existing and new gas main. After the project was awarded to Cleary Construction Inc., conversation was immediately opened between Cleary’s project manager (Allan Farris), Cleary’s job superintendent (Jeremy Gray), and our Clarksville gas team. Through a combination of on-site visits and discussions between Cleary Construction and the Clarksville gas team, along with coordination with TDOT Structures Department, Cleary proposed constructing the temporary construction platform that allowed us to install the entire new pipeline and remove the existing pipeline without affecting traffic and to be completed 100% underneath the bridge, and 100% safely. These innovations by Cleary Construction’s team allowed them to complete this project ahead of schedule and on budget.

“From the bid phase, through the post-bid/pre-contract phase, and ultimately the construction phase, it was clear that Cleary Construction Inc. was an incredibly knowledgeable company that placed a ton of emphasis on doing nothing short of quality work. Their project manager (Allan Farris) and superintendent (Jeremy Gray) both had great communication skills with not only myself, but my inspectors in the field. … They approached a potentially very dangerous and technically challenging project with common sense and attention to detail which ultimately led to an incredibly safe work environment that turned out an absolutely phenomenal end product.”

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