CBBT Sheet Pile Pregrouting
The Job
This sheet pile pregrouting project is located in the Chesapeake Bay. 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 launch & receiving work is on man-made islands in the Chesapeake Bay. The islands are dense 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. This was 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. This is in order to excavate the receiving pit for the tunnel boring machine. The construction team was concerned about inducing settlement of the adjacent roadway. They reached out to CJGeo about performing compaction grouting under the footing for the original tunnel’s portal wall. This was after the wall had been demolished down to grade.
The Solution
CJGeo performed compaction grouting utilizing an NSF-certified potable water contact plural component CJGrout 35NHV 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. There was only nominal movement of the foundation and roadway.
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8″ Pipe Abandonment
The Job
This 8″ pipe abandonment project is located outside of Washington, DC. 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 CJFill-Ultra Lightweight (CJFill-UL) 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.
By cutting the pipe at three locations, it was split into roughly equal segments. Each of around two thousand six hundred feet. 30lb/cuft CJFill-Ultra Lightweight is easily pumpable this distance without yield loss.
To do this same work with flowable fill would have required approximately thirty five access points. This would be to split the pipe into roughly thirty six segments around three hundred feet, each. Even then, pumping flowable fill three hundred feet through eight inch pipe is very difficult. By using CJFill-Ultra Lightweight for this pipe abandonment project, the general contractor saved about two weeks off of their schedule, and tens of thousands of dollars.
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Union County Annular Space Grouting
The Job
This Union County annular space grouting project is located in North Carolina, near Charlotte. Due to a rapidly increasing population, Union County, North Carolina installed a new raw water intake. It required a nearly 11 mile long raw water line to supply a water treatment plant.
The Challenge
There are dozens of road crossings along the alignment. 17 crossings are jack & bore, and require annular space grouting per NCDOT requirements. Given the length of the project, there weren’t any ready mix providers who could cover this entire annular space grouting in North Carolina project.
The Solution
CJGeo has multiple NCDOT approved mix designs, for CJFill-UL. CJGeo sourced material from two different ready mix providers. Each annular space on all crossings was grouted per NCDOT requirements. CJGeo has approved mix designs with the North Carolina Department of Transportation that cover the entire state. From the Outer Banks to Asheville, Raleigh/Durham, Wilmington & Charlotte, CJGeo has you covered.
The density for this work was 30lb/cuft CJFill-Ultra Lightweight. 30lb/cuft CJFill-Ultra Lightweight breaks above NCDOT’s minimum 125psi at 28 day unconfined compressive strength requirement for annular space grout. Because the project volume on this job is relatively low per crossing, CJGeo used ready mix for the raw slurry. Ready mix typically isn’t best for large placements. But for small, spread out placements like this project, is a great fit.
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24″ Water Main Abandonment
The Job
This 24″ water main abandonment project is located in Fairfax, Virginia. Fairfax County is part of the rapidly expanding Northern Virginia region. As part of a large transportation project, 2000 linear feet of 24″ water main were being 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. VDOT’s minimum 28 day unconfined compressive strength requirement is 30psi.
The Solution
CJGeo grouted each run of pipe using 30lb/cuft CJFill-Ultra Lightweight low density controlled low strength material. Each CJFill-UL 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.
The 28 day compressive strength of 30lb/cuft CJFill-Ultra Lightweight cellular grout is 150psi. This significantly exceeds VDOT’s minimum compressive strength for controlled low strength material (flowable fill).
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Facing a similar challenge to this 24″ water main abandonment project that CJGeo completed using CJFill-Ultra Lightweight cellular concrete? Give us a shout or shoot us a text. Click the state marker for the location of your project for contact info for the appropriate rep.
Neuse River Annular Grouting
The Job
This annular grouting project is located in North Carolina. 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 40lb/cuft CJFill-Standard 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.
By using cellular grout instead of a traditional high unit weight grout, CJGeo designed three lifts out of the placement. This is because carrier pipe buoyancy is a function of the displaced mass. When the grout is less than 1/3 the density of traditional grout, deeper lifts are possible without floating the new carrier.
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Dairy Branch Annular Space Grouting
The Job
CJGeo’s Dairy Branch annular space grouting project is located in North Carolina. Charlotte Water’s Dairy Branch Tributary Sewer project is an approximately $30mm capacity improvement project to address increasing population density.
The Challenge
As part of the project, the tunneling contractor mined a 430LF tunnel ranging from 58″ bore to a four foot arch. 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. This annular space mix design is weighs around 30lb/cuft, so falls withing CJGeo’s CJFill-Ultra Lightweight range. The tunnel was completely dry, so displacing water was not a concern. It took less than two hours to place all 275 cubic yards of grout into the annulus.
Peak pumping pressure was less than five psi. Complete water filling of the carrier pipe provided more than a two time factor of safety for buoyancy control. CJFill-Ultra Lightweight cellular grout is sometimes called foamed concrete fill.
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New York Annular Space Grouting
The Job
This New York annular space grouting work is part of the Bay Park Conveyance Project. The Bay Park Conveyance Project is using a combination of microtunneling and slip-lining. This is to redirect 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. The pipe runs 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 is night work. 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 CJFill-Ultra Lightweight 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.
Pipe jacking is the installation method for the carrier pipe, so there are no casing spacers. Because there are no casing spacers, water filling is the buoyancy control method. With water fill and a grout density significantly lower than water, the carrier uplift factor of safety is approximately 2.5 times.
To address material logistics, each night’s cement consumption is staged locally during the day. The cement is then brought to each placement location during the pours.
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SW Florida Annular Space Grouting
The Job
This Florida annular space grouting project by CJGeo is located in For Myers, Florida. The work is part of the City of Fort Myers’s South AWWTF Reclaimed Water Transmission Main. The goal of the project is to facilitate the beneficial reuse of treated wastewater, primarily for uses such as irrigation which historically utilized drinking water.
The Challenge
The majority of this pipeline uses open cut installation. However at two road crossings with extensive existing buried utilities, trenchless installation is most appropriate. The first crossing is 170 linear feet. The second crossing is 607 linear feet. Each tunnel is 52 inches in diameter steel. The reclaimed water line is 32 inch diameter ductile iron pipe.
The Solution
The tunneling contractor for this project was under contract to provide turn key installation, including annular grouting. The tunneling contractor reached out to CJGeo, knowing that CJGeo’s CJFill cellular grout could:
- fill each annulus in a single lift
- not over-pressurize or damage the brand new carrier pipe
- not float the brand new carrier pipe
CJGeo took two days onsite to grout both tunnels (one day per tunnel). The final design for the grout on this Florida annular space grouting project was 38lb/cuft CJFill-Standard, with a 250psi unconfined compressive strength at 28 days. While the Florida DOT’s minimum strength for cellular grout is only 80psi at 28 days, the designer wanted a higher strength grout than the minimum acceptable by the DOT.
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Rising Mains 48″ Abandonments
The Job
This Pittsburgh pipe abandonment project is located within the city of Pittsburgh, Pennsylvania. It is part of the Rising Mains No 3 & 4 replacement project. Plans call for filling with grout roughly 1575LF of 48″ water main.
The Challenge
The abandonment was specified for traditional controlled low strength material (flowable fill). However the contractor had doubts about being able to successfully perform the pipe abandonments with flowable fill. These concerns were based on access limitations, ready mix delivery limitations and the roughly 20′ of elevation change over the length of the pipe.
The Solution
The contractor reached out to CJGeo about using low density controlled low strength material (LD-CLSM). CJGeo evaluated the pipeline as-builts and recommended a CJGeo 25lb/cuft CJFill-Ultra Lightweight cellular concrete mix design. 25lb/cuft CJFill-Ultra Lightweight’s average 80psi compressive strength at 28 days (ASTM C495) is ideal for abandoning the pipes. The low density maximizes yield (finished volume per ton of cement), and provides adequate bearing capacity in most situations.
Using onsite dry batching, CJGeo generated and placed 730CY of grout to successfully fill the pipe, which was access near the middle to create two segments. The work took two days onsite to complete. Onsite batching directly from bulk cement was advantageous on this project for the following reasons:
- economical – it costs significantly less than ready mix flowable fill
- speed – CJGeo made more than 100CY of CJFill-UL per hour
- safety – peak placement pressures were less than ten psi
- logistics – it only took five loads of cement, whereas flowable fill would have taken 92 loads
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Facing a similar challenge to this Pittsburgh pipe abandonment project that CJGeo completed with CJFill-Ultra Lightweight cellular grout? Give us a shout or shoot us a text. Click the state marker for the location of your project for contact info for the appropriate rep.
Power Station Pipe Abandonment
The Job
This power station pipe abandonment project is between Richmond & Lynchburg, Virginia, along the James River. Dominion’s Bremo Bluff Power Station was taken off line in 2019. As part of complete decommissioning, demolition and site restoration took place in 2022.
The Challenge
Power stations typically have extensive pipes for cooling water circulation. At Bremo Bluff, the buried cooling pipe network consists for four, four foot diameter pipes, connecting to a junction box. Total linear footage of the forty-eight inch pipes is about six hundred linear feet.
Due to the remote location, the demolition contractor knew that it would be difficult to get timely deliveries of the nearly 40 loads of flowable fill needed to fill the pipes.
The Solution
The demolition contractor reached out to CJGeo for consultation on the best type of flowable fill for the pipe abandonment work. CJGeo recommended 25lb/cuft CJFill-Ultra Lightweight. 25lb/cuft CJFill-Ultra Lightweight has a 28 day compressive strength (ASTM C495) greater than 50 psi. This met the owner’s requirements.
25lb/cuft CJFill-Ultra Lightweight is nearly 80% air content. Therefore, each twenty-five ton load of cement delivered to the site turns into nearly 150 cubic yards of finished product. Due to this on-site expansion, instead of needing nearly 40 loads of ready mix flowable fill, the work only needed two loads of cement.
CJGeo generated and placed approximately 300CY of CJFill-Ultra Lightweight cellular concrete to fill the junction box and pipes. CJGeo made all of the material over a few hours onsite, using dry batch generation.
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Facing a similar challenge to this power station pipe abandonment project? Give us a shout or shoot us a text. Click the state marker for the location of your project for contact info for the appropriate rep.
