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Pipelines & Tunneling

By applying unique solutions to increase the safety and longevity of our environment.

66″ Water Main Abandonment

The Job

The Purple Line is a light rail line project in suburban Maryland designed to increase connectivity within Maryland’s suburbs of Washington, DC. The project involves extensive utility relocation to facilitate installation of large embankments and the extensive infrastructure required for a double track rail corridor dropped into the middle of an already exceptionally congested/dense corridor.

The Challenge

As part of the project, a large MSE wall needed to be installed over approximately 3000LF of 66″ PCCP water main. In order to avoid any future maintenance problems under the rail alignment, a new line was installed adjacent to the embankment, and the old line needed to be abandoned.

Due to construction sequencing, the embankment was already in place well before the water line relocation was performed.

The Solution

CJGeo worked with the utility relocation contractor to design a grout mix and grouting program that provided sufficient bearing capacity to eliminate concerns about future stability. The ultimate design for the mix was a 100psi cellular grout. Given that the embankment was already in place, the entire 3000LF stretch had to be grouted from just two access points.

CJGeo used a 200CY/hour dry mix batch plant onsite to generate and pump the cellular concrete up to 1500LF to place the material. 2800CY of material were placed over a period of four days onsite with no disruptions to adjacent construction activities.

Garden State Parkway grouting

The Job

As part of ongoing large diameter culvert rehabilitations and replacements, four new bored stormwater crossings and the original culvert they replaced needed to be grouted. The tunnels ranged from 120″ down to 74″, for a total of 312CY, and the abandonment required 405CY.

The Challenge

Grout needed to meet the minimum strength requirements of the owner, and ideally needed to be light enough to facilitate single lift annular space grouting.

The Solution

CJGeo’s preconstruction team worked with the general contractor to design a grouting program which facilitated single lift abandonment of the original culvert, and single lift grouting of the four various annular space runs. CJGeo utilized onsite dry batching to generate 30lb/cuft CJFill cellular concrete.

CBBT Pregrouting

The Job

The Chesapeake Bay Bridge Tunnel’s Parallel Thimble Shoal Tunnel Project is constructing a second tunnel parallel to the original to reduce traffic congestion. All work is being performed from man-made islands in the Chesapeake Bay which are densely packed with utilities, equipment and operations facilities associated with the existing tunnel, which is in continuous use.

The Challenge

During previous phases, installation of sheet piling for tunneling activities and other driven elements induced consolidation of the loose sandy fill on the islands, causing settlement of duct banks, pavements and other structures, which were remedied by CJGeo using polyurethane compaction grouting.

In this case, sheet piles had to be driven immediately adjacent to the roadway in order to excavate the receiving pit for the tunnel boring machine. The construction team was concerned about inducing settlement of the adjacent roadway, so reached out to CJGeo about performing compaction grouting under the footing for the original tunnel’s portal wall, after the wall had been demolished down to grade.

The Solution

CJGeo performed compaction grouting utilizing an NSF-certified potable water contact plural component polyurethane grout. Cutoff criteria was 0.10 inches of movement of the foundation or adjacent roadway. Upon completion of the compaction grouting by CJGeo, sheet piling installation started, with only nominal movement of the foundation and roadway.

8″ Pipe Abandonment

The Job

As part of continuing waterline replacements, a utility contractor in Fort Washington, Maryland, needed to abandon 10,600LF of 8″ water main. The utility and DOT both require grouting of all utilities 6″ and larger taken out of service.

The Challenge

In order to minimize the number of placement points, the grout needed to be exceptionally mobile.

The Solution

CJGeo proposed a 30lb/cuft cellular grout, and worked with the client to design a grouting plan that would allow grouting all 10,600LF of pipe from just three access points. CJGeo performed the grouting over a period of two days, with no additional excavation required from the customer other than their original tie ins/disconnects.

Union County Annular Space Grouting

The Job

Due to a rapidly increasing population, Union County, North Carolina installed a new raw water intake, which required a nearly 11 mile long raw water line to supply a water treatment plant.

The Challenge

While there were dozens of open cut road crossings along the alignment, 17 crossings were bored, and require annular space grouting per NCDOT requirements. Given the length of the project, there weren’t any ready mix providers who could cover the entire project.

The Solution

CJGeo has multiple NCDOT approved mix designs, CJGeo was able to source material from two different ready mix providers, and grout the annular space on each crossing per NCDOT requirements.

24″ Water Main Abandonment

The Job

As part of a large transportation project, 2000 linear feet of 24″ water main needed to be relocated out of a highway right-of-way.

The Challenge

Due to phasing, the old water main was located under the existing roadway and could not be accessed, except for at one point near the center of the run. So, the abandonment grout had to meet VDOT’s minimum strength requirements for flowable fill, and be pumpable up to 1100LF at low pressure.

The Solution

CJGeo grouted each run of pipe using 30lb/cuft cellular concrete. Each placement took fewer than two hours, and required no additional traffic control, disruptions to other construction activities, or help from the utility contractor after they installed the bulkheads.

Neuse River Annular Grouting

The Job

The City of Raleigh’s Neuse River East Parallel Interceptor project involves the installation of miles of large diameter gravity sewer. Two road crossings required 120″ tunnels for installation of the 96″ HOBAS pipe.

The Challenge

While neither tunnel was very long, due to the 10′ diameter tunnels, grouting needed to be performed in two lifts. This allowed buoyancy control of the HOBAS carrier pipes to be maintained with partial water filling, and eliminated the need to perform hold down blocking during the carrier pipe installation.

The Solution

CJGeo proposed an NCDOT approved cellular grout mix due to passage through an NCDOT right of way, and then grouted the two tunnels each in two lifts. Fill was confirmed with uniform grout vented out the 12 o’clock vent position at the far end of each tunnel.

Dairy Branch Annular Space Grouting

The Job

Charlotte Water’s Dairy Branch Tributary Sewer project is an approximately $30mm capacity improvement project to address increased density.

The Challenge

As part of the project, a 430LF tunnel ranging from 58″ bore to a 4×4 arch was mined. The carrier pipe was 36″ ductile iron, and required annular space grouting using a mix which wouldn’t float the carrier pipe, and would be able to entirely fill the tunnel at low pressure.

The Solution

CJGeo proposed an NCDOT approved cellular grout mix due to passage through an NCDOT right of way, and then placed the 275CY of grout in a single lift over two hours at approximately 5psi of placement pressure.

Bay Park Annular Space Grouting

The Job

The Bay Park Conveyance Project is using a combination of microtunneling and slip-lining to redirect treated effluent discharge from Western Bay to an existing ocean outfall several miles away.

The Challenge

Approximately 7 miles of the discharge pipe is being sliplined into an existing 72″ riveted iron pipe running underneath the Sunset Highway. Access pits are between 700LF & 3000LF apart, requiring annular space grouting placements ranging from 200CY to 850CY.

Due to maintenance of traffic concerns, all grouting must be performed at night, and there is nowhere to stage materials onsite.

The Solution

Working with the design and construction teams, CJGeo designed a 30lb/cuft, 150psi at 28 day compressive strength cellular grout for the annular space grouting. By using dry batch mixing onsite, CJGeo is able to achieve the compressive strength required, and place the distances required in the very short nightly placement windows.

To address material logistics, each night’s cement consumption is staged locally during the day, and then shuttled in to each placement location during the pours.

SW Florida Annular Space Grouting

The Job

City of Fort Myers’s South AWWTF Reclaimed Water Transmission Main.

The Challenge

Two 52″ tunnels with 32″ DIP carriers requiring annular space grouting. Tunnel 1 was 170LF, Tunnel 2 was 607LF. The

The Solution

CJGeo grouted both tunnels utilizing cellular grout with 250psi at 28 day compressive strength.

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