T Wall Lightweight Backfill
The Job
This T wall lightweight backfill project is located in Boston, Massachusetts. The bridge is located on the Lowell Line, within the MBTA‘s Commuter Rail Maintenance Facility.
The Challenge
CJGeo has been involved in this alternative delivery project since 2020, helping to optimize the use of CJFill-Ultra Lightweight fill to facilitate constructing a new embankment over underlying compressible soils.
In this specific location on the project, curved T walls were installed along the curved alignment (different radius) of the existing embankment. A sheet pile SOE retains the existing embankment. Due to highly irregular spaces, limited access, lightweight aggregate, such as foamed glass, would be exceptionally difficult to install and ensure adequate compaction.
The Solution
CJGeo proposed 26lb/cuft CJFill-Ultra Lightweight as the optimal material for the T wall lightweight backfill. The lowest 4′ is CJFill-High Permeability. Because CJFill is a self consolidating fill, there’s no compaction required. This practically eliminates chances of backfill consolidation. On a curved, relatively high speed commuter rail alignment, settlement could be quite risky if it were to occur.
For the first phase, CJGeo mobilized a single dry batch cellular grout plant. The work took a total of five days.
Speak With An Expert
Facing a similar challenge to this T wall lightweight backfill 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.
Hobas Pipe Backfilling
The Job
This Hobas pipe backfilling project is located in Baltimore, Maryland. It is one of the last steps in an emergency storm drain collapse project.
The Challenge
The original design for this project was to slip line a roughly 100 linear foot length of 108″ brick sewer that had collapsed. There was a massive void above the pipe, which was going to be filled with CJFill-Ultra Lightweight after the new pipe was slid in. However, the soil collapsed and the repair turned into an open cut repair.
The pipe is more than 100 years old, and was installed in a rock trench, the walls of which were uneven and unstable. Extensive rock bolting and stabilization was installed to facilitate the installation of the pipe. In order to ensure uniform bedding and stability of the new pipe, Hobas and the EOR recommended backfilling the pipe to at least 1′ above the crown with self-consolidating fill.
150lb/cuft flowable fill would have resulted in tremendous uplift forces on the pipe, unless installed in impracticably thin layers.
The Solution
CJGeo proposed cellular grout as an alternative, in order to reduce the uplift while decreasing the number of lifts.
Due to water infiltration near the invert, the first lift was done using 65lb/cuft CJFill-Under Water. Once the first lift was in place, the placement was switched to CJFill-Standard.
All material was generated onsite from bulk cement using CJGeo’s colloidal dry batch generation process.
Speak With An Expert
Facing a similar challenge to this Hobas pipe backfilling 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.
USACE Pipe Abandonment
The Job
This USACE pipe abandonment project is located in Muncie, Indiana. The project was part of a locally-administered stormwater improvement project. Because the pipes pass through a US Army Corps of Engineers levee, abandonment of the existing culverts had to be performed to USACE specifications.
The Challenge
New pipes and an endwall wall had been in place for a few months. All paving restoration was done, and the original pipe discharged through the new endwall. Specifications for USACE pipe abandonment call for cellular grout with a minimum of 300psi unconfined compressive strength at 28 days, 100psi penetration resistance at 24 hours, and minimum wet cast density of 45lb/cuft (CJFill-Standard).
The Solution
The contractor reached out to CJGeo due our expertise in cellular concrete placements with tight specs and discerning owners.
CJGeo mobilized a wet batch cellular grout crew to the site, and filled the two pipes in about an hour. Aerix Industries supplied the Aerlite-iX preformed foaming agent. Wet batch method was best due to the relatively low volume of the placement. Both runs of pipe are 36″ CMP. The first run is 73 feet, the second run 103 linear feet, for a total of 47 cubic yards.
CJGeo successfully filled the two runs of pipe. Confirmation of fill was venting of uniform grout out of the 6 & 12 o’clock ports on each end of both runs.
Speak With An Expert
Facing a similar challenge to this USACE 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.
NCDOT abandonment grouting
The Job
This NCDOT abandonment grouting project is located outside of Chapel Hill, North Carolina. The abandonment grouting is the final step in a gravity main replacement project. The scope requires filling 3,023 linear feet of 24″ RCP gravity sewer with NCDOT-approved flowable fill.
The Challenge
This gravity main runs entirely in a cross-country backwoods right of way. Along the alignment, there are a few road crossings, which require the NCDOT approved material.
Because the new pipe is in the same right of way, there are multiple locations where new and old pipe alignments cross. This breaks it into a collection of smaller runs, as opposed to one continuous run of pipe.
The Solution
If this was one continuous run of pipe, it would be a great candidate for dry batch generation cellular grouting. The 352CY project volume would only take about two hours to fill.
However, being broken into multiple, shorter runs in the middle of the woods, meant that wet batch equipment was more appropriate from an access and productivity perspective.
CJGeo mobilized a wet batch crew to the site, and it took them two days to complete the work. There were a total of 11 runs of pipe and six placement points. The longest run was 1113 linear feet, the shortest only 56.
Speak With An Expert
Facing a similar challenge to this NCDOT abandonment grouting 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.
NCDOT pipe abandonment
The Job
This NCDOT pipe abandonment project is located outside of Wilmington, North Carolina. It is part of a large highway improvement project to improve capacity in the rapidly expanding southern coastal North Carolina area.
The Challenge
NCDOT requires grout fill for most abandoned pipes within their right-of-way. Traditionally this is done using flowable fill mixes. Using flowable fill for short abandonment is generally pretty simple.
However, this project has more than 100,000 linear feet of pipe ranging from 6″ to 36″ to fill. Most flowable fill mixes won’t go more than a couple hundred feet in best cast conditions. The utility contractor was looking at having to dig up to five hundred access points to place flowable fill. That’s incredibly time consuming and costly.
The Solution
The utility contractor reached out to CJGeo about performing the abandonment grouting on this project, using low density cementitious material (cellular concrete).
Due to the highly variable pipe diameters and run lengths, CJGeo proposed a mix of wet batch and dry batch cellular concrete generation.
Wet batch was used for the lower volume runs. Dry batch is best suited for large volume runs. Over the course of a few months, CJGeo mobilized multiple times to fill runs as long as a mile at a time.
Speak With An Expert
Facing a similar challenge to this NCDOT 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.
Ohio Annular Space Grouting
The Job
This Ohio annular space grouting project is located in Akron. It is part of the Northside Interceptor, being constructed by Granite Construction. The total project budget is about $215 million, to construct 6,660 linear feet of 16.5′ diameter segmental liner tunnel.
While the main tunnel is single pass, there are multiple tie-ins to the structure, some of which are open cut, and another which is a microtunnel. The microtunnel is 530 linear feet of 48″ pipe.
The Challenge
Plans call to grout the annulus between the carrier pipe and microtunnel casing with 600psi at 28 day material. A lean concrete mix to achieve this compressive strength would be significantly heavier than water. This can cause significant headaches managing carrier pipe buoyancy, as the heavier the grout, the greater the uplift during grouting.
The Solution
CJGeo proposed a 55lb/cuft CJFill-Standard mix to meet the compressive strength requirement, while minimizing carrier pipe buoyancy. Because the proposed material is less dense than water, filling the carrier pipe with water during the grouting process keeps the carrier pipe in place.
A CJGeo dry batch cellular grout crew placed 119 cubic yards of 55lb/cuft CJFill-Standard over two hours to fill the annular space in a single lift. Cellular concrete is also referred to as foamed concrete fill.
Speak With An Expert
Facing a similar challenge to this Ohio annular space grouting 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.
Indiana Pipe Abandonment
The Job
This Indiana pipe abandonment project is located in Anderson. Anderson is in central Indiana, near Indianapolis. The project is a water main relocation out of a park.
The Challenge
Plans call for safe loading the pipe being replaced. It’s important to fill abandoned utilities to prevent them from being groundwater conduits, or eventually failing completely. This can cause significant amounts of settlement, and transport soils long distances, neither of which is desirable.
The Solution
Using traditional flowable fill would have required close to 10 access points to place material into the pipe. This would have torn up a bunch of the park that the pipe ran though, and taken quite a bit of time.
CJGeo proposed filling the pipe from a single access point near the middle, using CJFill-Ultra Lightweight cellular grout. The beauty of cellular grout for abandonment is that it’s pumpable thousands of feet. In this case, the first run was 770 linear feet. The second run was 488 linear feet.
It would be possible to grout the entire run in a single stretch, however there was already an excavation at this point to blind a connecting pipe, and there was a nearby fire hydrant.
CJGeo sent a dry batch plant to the site, and the grouting work took less than an hour of pumping to completely fill the pipe.
Speak With An Expert
Facing a similar challenge to this Indiana 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.
New York Pipe Abandonment
The Job
This New York pipe abandonment project is located in Newburgh, New York. Newburgh is on the Hudson River, about an hour upstream of New York City.
The Challenge
As part of a sanitary sewer upgrade project, 5,399 linear feet of gravity sewer ranging from 6″ to 24″ was specified for grout filling. The highest volume run was a 1,022 linear feet continuous run of 24″ pipe. The longest run was 1,469 linear feet of 18 inch” pipe. Each run did have intermediate manholes, but most manholes were a few hundred feet apart.
The Solution
Traditionally, the customer would have dumped flowable fill in the manholes in an attempt to completely fill the lines by gravity. However, many of the manholes were off road, and some of them were hundreds of feet apart. This makes gravity discharge of flowable fill into manholes unreliable for ensuring complete fill.
CJGeo proposed performing the abandonment grouting using 30lb/cuft CJFill-Ultra Lightweight cellular grout. Since cellular grout will flow much further at nominal pressures, CJGeo was able to place through multiple manholes at once, which significantly reduced access requirements.
Due to the relatively low volume on this project, continuous wet batch was the best method for generating the cellular grout for this project. Wet batch uses slurry delivered by ready mix truck, with Aerlite-iX added downstream of CJGeo’s slurry pump.
Speak With An Expert
Facing a similar challenge to this New York 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.
Underground Storage Tank Fill
The Job
This underground storage tank fill project by CJGeo is located at a food manufacturing facility near Harrisonburg, Virginia. The tank is 30 thousand gallons, and designed to store diesel to feed backup power generation for the facility. As part of an equipment upgrade, the tank is no longer in use, and had to be filled.
The Challenge
The best way to address unused underground storage tanks that aren’t removable is to fill them. If left empty and out of mind, abandoned empty tanks can cause serious problems, such as sudden collapse, which can significantly affect operations. Unfilled, out of use tanks can also accumulate groundwater, leading to potential environmental liabilities.
The Solution
CJGeo proposed 30lb/cuft CJFill-Ultra Lightweight (CJFill-UL) to fill the tank. CJFill-Ultra Lightweight is easily hand and machine excavatable to ensure that when the tank is removed in a few years that it’s not difficult.
While easily hand excavatable, CJFill-Ultra Lightweight still provides more than adequate compressive strength. In this case, total loads were just a few hundred pounds per square foot, whereas the CJFill material provides more than 17ksf of unconfined compressive strength. The American Concrete Institute publishes a removability modulus calculation which helps to quantify the ease of removal of controlled low strength materials, read more about it and how it relates to cellular concrete here.
It took CJGeo less than an hour to completely fill this tank. Confirmation of complete fill was uniform material venting from the tank vent ports.
Speak With An Expert
Facing a similar challenge to this underground storage tank fill 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.
North Carolina Annular Grouting
The Job
This North Carolina annular grouting project is located in Havelock, North Carolina. Havelock is home to Marine Corps Air Station Cherry Point. US 70 passes through Havelock, providing a critical link between New Bern and the coastal beaches of North Carolina.
The Challenge
As part of North Carolina DOT work to upgrade the capacity and increase safety of US 70, a number of wet utilities were upgraded and relocated. This required a number of jack and bore crossings of the existing roadway to avoid disrupting traffic. NCDOT requires annular grouting for jack and bore crossings of wet utilities, for anything with less than a 100 year design life.
The Solution
This project had two crossings needing annular space grouting. One was 120 linear feet of 42″ steel casing with an 18″ ductile iron pipe water line. The second was 86 linear feet of 42″ steel casing with an 18″ ductile iron water line.
A CJGeo cellular grouting crew successfully filled each of the two casings with CJFill-Ultra Lightweight cellular concrete in a few hours in a single day. Carrier pipe buoyancy was not a concern due the low density of the grout.
Speak With An Expert
Facing a similar challenge to this North Carolina annular grouting 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.
