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Pipelines & Tunneling

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

Nashville Annular Space Grouting

The Job

This Nashville annular space grouting project is located at Nashville’s Central WWTP, which is undergoing extensive improvements to provide service to a growing population.

The Challenge

As part of an upgrade, 400LF of 66″ pipe was slip lined. Once the carrier pipe was selected, the space around its 57.1″ OD needed to be filled.

The Solution

CJGeo proposed using CJFill-ST at 45lb/cuft for this Nashville annular space grouting project. CJFill-ST is batched onsite directly from bulk cement, eliminating supply chain issues with ready mix.

Because the selected CJFill-ST only weigh 45lb/cuft, buoyancy control of the new carrier is simple. By filling it with water, it won’t float during grouting. This allowed CJGeo to grout the entire annulus in a single lift. Single lift grouting significantly reduces the likelihood of partial fills, fouled injection tubing, or trapped voids.

A CJGeo crew placed the 87CY of CJFill-ST in less than an hour to perform this Nashville annular space grouting project. CJFill-ST can be made two ways; wet batch or dry batch. With wet batch, a ready mix truck brings the base slurry to the site, and the foam is either added to the truck, or injected downstream of a pump. For dry batch generation, which was used here, a mobile batch plant mixes the cement and water onsite. The mixing quality using dry batch is significantly better than wet batch.

This project had a relatively high compressive strength requirement due to new foundation installation adjacent to the slip lined pipe. With cellular concrete, there are two ways to increase compressive strength–increase the cement content by increasing the density, or increasing the quality of the mix. Since annular space grouting projects are very sensitive to carrier pipe buoyancy control, increasing mix quality is a better option than increasing density. CJGeo’s three mobile batch plants all use high shear colloidal mixing. Colloidally generated material can have 28 day strengths up to two times ready mix batched material at the same density & cement content.

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BNA Culvert Abandonment

The Job

As part of a Nashville International Airport’s BNA Vision project, several hundred feet of culvert needed to be filled with grout. The culvert abandonment work is part of installing a new drainage system to accommodate a new terminal.

The Challenge

Due to long runs with no intermediate access, the engineer specified cellular concrete as the abandonment grout. Access to the site was across an active taxiway, so the fewest deliveries possible was very important. The minimum design requirements were:

  • 28 day compressive strength minimum = 100psi
  • maximum wet cast density = 35lb/cuft

The Solution

To address the need to limit the number of deliveries, CJGeo performed the culvert abandonment using CJFill-UL . CJFill-UL is batched onsite directly from bulk cement. By using bulk cement onsite, there were no concerns about hot loads of ready mix. A single semi was able to deliver all the raw material for the placement.

Each of the runs on this project is greater than 250LF. By using highly mobile grout, there are no questions about the pipes being completely full. CJFill-UL is so mobile it will flow by gravity up to a few hundred feet. The material is always pumped. This allows for placement from either the high or low end of individual runs. Because the density of the material is very low, it takes very little additional pressure to place from the low end.

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Facing a similar challenge? 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.

Parsippany Annular Space Grouting

The Job

This Parsippany annular space grouting project is part of a microtunneled installation of 48″ sanitary line in two runs under an interstate. Each tunnel is 60″ diameter, one was 725LF, the other 530LF. They shared a shaft. The project’s goal is to replace an aging stretch of large diameter gravity sewer that runs parallel to the interstate.

The Challenge

The owner specified a grouted annular space for the tunnels. The long pumping distance and relatively tight annulus drove the need for a highly mobile, lightweight grout.

Cellular grout is advantageous for annular space grouting because:

  • it’s primarily air, so takes little energy (pressure) to pump, which virtually eliminates risk of damaging the carrier pipe(s) during grouting
  • it’s significantly lower density than traditional grouts, which reduces the buoyancy of carrier pipe(s)
  • cellular grout is made onsite, reducing risk exposures from the ready mix supply chain when mosts placements are “you only get once chance to do this right” type of jobs

The Solution

CJGeo placed 270CY of 35lb/cuft CJFill-ST (36ksf unconfined compressive strength) cellular grout to fill the annulus on both tunnels. Because the shared shaft wasn’t easily accessible, grouting was performed from each end towards the shared shaft over two back to back days.

CJGeo used onsite dry batching to generate the cellular grout for this Parsippany annular space grouting project. Dry batch generation uses bulk cement, eliminating risks associated with the ready mix supply chain. Cellular grout made using the dry batch process is also much higher quality, which allows CJGeo to get higher strengths with lower densities. This lowers pumping pressure, buoyancy, and costs.

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Facing a similar challenge? 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.

Dumfries Pipe Abandonment

The Job

This utility relocation included abandonment grouting as part of a VDOT roadway reconstruction and realignment of US Route 1 in Dumfries, Virginia. This Dumfries pipe abandonment job is located in a rapidly growing town in Northern Virginia. US Route 1 is a major local traffic corridor, as well as a bailout route for I-95 congestion.

The Challenge

1,575LF of pipe, a combination of 54″ & 60″ needed to be completely filled with grout. Due to sequencing, the pipe was underneath new roadway at the time of abandonment. So, the fewer the number of access points, the better.

The Solution

CJGeo placed 995CY of 25lb/cuft CJFill-Ultra Lightweight cellular grout to completely fill the pipe run. The material was placed in a single day, from a single access point near the center of the pipe run.

To facilitate such a large placement in a single day on this Dumfries pipe abandonment job, CJGeo used dry batch generation. Dry batch generation mixed water with bulk cement onsite, using a mobile batch plant. CJGeo’s mobile batch plants are designed specifically to generate cellular concrete. They generate preformed foam at the same time as making the cement slurry. The preformed foam and cement slurry pass through an in line mixer, at up to 200CY/hour.

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Facing a similar challenge? 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.

Lightweight Pipe Backfill

The Job

This lightweight pipe backfill is part of the City of Alexandria’s RiverRenew project, its largest in history. The project includes installation of new interceptors, and a large CSO/conveyance tunnel.

The Challenge

A pile-supported, concrete-encased interceptor needed to be backfilled. Due to the pile support capacity, the maximum allowable density of the backfill was 90lb/cuft.

The Solution

To bring the average backfill density to 90lb/cuft, CJGeo proposed filling between the SOE & concrete encasement with 30lb/cuft CJFill-High Permeability (HP). CJFill-HP has very high permeability, so reduces buoyancy when saturated when compared to other lightweight fill materials. CJGeo successfully filled between the concrete encasement and SOE with 145CY of CJFill-HP. The placements was done in a single, 6′ deep lift in less than an hour.

To facilitate the fast placement speed, CJGeo used a mobile batch plant to generate the CJFill-High Permeability cellular grout onsite. Onsite generation blends dry, bulk cement onsite with water, using custom batch plants which also make generate the preformed foam on site. The cement slurry is around 110lb/cuft, and the preformed foam is around 2.5lb/cuft. CJGeo’s batch plants utilize colloidal mixing, which ensures the highest quality cement paste, and therefore the highest quality finished product possible.

The use of very low density material then allowed the client to backfill on top of the structure with normal unit weight material while maintaining the average 90lb/cuft density through the full depth of the fill column.

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Facing a similar challenge? 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.

Valve Vault Infiltration Grouting

The Job

This valve vault infiltration grouting project is part of the Purple Line project in Maryland. A large diameter water line was relocated, with the tie-in done inside a 10′ diameter vault that was about 20′ deep. The vault structure, which is precast, and set inside a line plate shaft, was leaking at multiple joints and at a poured in place pipe penetration closure.

The Challenge

The vault structure wasn’t concentric in the shaft. This left little room to pour the closure around the pipe penetrations. One of the penetrations leaked, causing the structure to completely fill with water. Per specifications, it needed to be dry.

Most of the shaft was backfilled with 57 stone. Highly permeable backfill material can make water control grouting particularly difficult. When grouting to seal relatively tight leaks in a structure, the less permeable the adjacent soils the better. All grouts want to take the path of least resistance, and with highly permeable backfills, that often means traveling out into, and permeating, the backfill material instead of into tight cracks and water passageways.

The Solution

CJGeo proposed grouting the infiltration points with CJGrout-35NHV61. 35NHV61 is a hydroinsensitive, plural component geotechnical polyurethane, certified for potable water contact. 35NHV61 is a moderately mobile grout, selected to minimize mobility into the 57 stone backfill and reduce material loss during grouting.

CJGeo mobilized a three person crew to the site, and performed the valve vault infiltration grouting over a few hours.

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Facing a similar challenge? 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.

8′ CMP Joint Grouting

The Job

A spec warehouse was planned for a vacant piece of land which had 1700LF of 8′ CMP running through it. The pipe was 10 years old. Because the site was vacant, there was no maintenance. Nearly every joint showed signs of soil infiltration, and there were massive sinkholes along the entire alignment. Given the depth, size, and short work window, the contractor sought out a CMP joint grouting repair alternative to replacement.

The Challenge

To avoid replacing the entire run of pipe, the joints had to be sealed. There were 80 pipe joints and 12 pipe to structure joints to seal. The pipe crossed under a roadway, and then crossed the site at an angle. The downstream end of the pipe transitioned to new 96″ RCP.

The Solution

In preparation for the repair, CJGeo had to educate the town, contractor, owner & consulting engineers that polyurethane grouting is an effective CMP repair method.

CJGeo mobilized a polyurethane grouting crew to the the site. Over the course of a week onsite, the crew performed all of the CMP joint grouting.

CJGeo used CJGrout 20SDB geotechnical polyurethane. 20SDB is a high mobility geotechnical polyurethane, so seeks out and fills even the smallest of voids outside of pipes. Because it’s highly mobile, it doesn’t deflect or damage the CMP that needs repair.

The manholes also had significant defects. Made of non-parged sewer brick, they leaked extensively. To address the widespread infiltration through the structures, CJGeo sprayed the interior of each structure with CJGrout 60FDC. 60FDC is a hybrid polyurethane/polyurea spray coating. For durability, the 60FDC was coated with polyurea. The 20SDB, 60SDB & polyurea coating were all installed using the same equipment, significantly reducing costs.

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Facing a similar challenge? 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.

Atlanta cellular concrete

The Job

This Atlanta cellular concrete installation is part of Atlanta Watershed Management’s Niles Avenue Sewer Improvements project. The project took approximately 2500LF of microtunneling to install a new 18″ sewer main.

The Challenge

A 72″ microtunnel was chosen, which required approximately 1200CY of annular space grouting. Operations were challenged by the pandemic hitting in the middle of the project.

The Solution

CJGeo proposed 30lb/cuft CJFill-UL cellular grout for the annular space grout. This allowed the contractor to avoid mechanical buoyancy control during grouting operations during single lift grouting. Buoyancy control of the carrier was one of the driving factors for using CJFill-Ultra Lightweight for this Atlanta cellular concrete project. Because the tunnels had a good amount of slope on them, grouting in multiple stages would have been impractical. Flowable fill would have floated the carrier pipe, even if it was full of water.

Over two mobilizations, CJGeo generated the cellular grout onsite and placed it via shafts which were up to 40 feet deep. CJGeo chose wet batch generation due to the project volumes.

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Facing a similar challenge? 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.

66″ Water Main Abandonment

The Job

This 66″ water main abandonment is part of the The Purple Line’s construction. The Purple Line is a light rail line project in suburban Maryland. It will 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 was built over approximately 3000LF of 66″ PCCP water main. To avoid any future maintenance problems under the rail alignment, a new line was put in adjacent to the embankment. The old line had to be completely full of grout.

Due to construction sequencing, the embankment installation happened before the water line relocation.

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 CJFill-Ultra Lightweight cellular grout. Because the embankment was already in place, the entire 3000LF stretch was accessible 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. This 66″ water main abandonment took four days to complete, and didn’t disrupt any of the adjacent construction activities.

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Facing a similar challenge? 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.

Garden State Parkway grouting

The Job

This Garden State Parkway grouting project is located near Middletown, New Jersey. 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 Ultra Lightweight cellular concrete.

CJFill is a type of Low Density Controlled Low Strength Material, or LD-CLSM. The “low density” comes from using preformed foam, in this case Aerlite-iX, as a substitute for aggregate. This significantly reduces the unit weight, which exponentially increases pumpability. In this case, all 405 cubic yards of abandonment grout were placeable at once.

Because CJFill LD-CLSM is significantly lighter than water, each annular space grouting run was doable in a single lift. Filling each carrier pipe partially with water was all it took to facilitate this.

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Facing a similar challenge to this Garden State Parkway 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.

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