Fort Lauderdale Permeation Grouting
The Job
This Fort Lauderdale permeation grouting project is located next to Port Everglades. Port Everglades is a crucial piece of Florida’s infrastructure, with annual economic impact exceeding $30 billion dollars per year. The tunnel, which is being mined with a 72″ MTBM, crosses under Eisenhower Boulevard from the George T Lohmeyer Wastewater Treatment Plant towards the Broward County Convention Center.
The tunnel is more than 20′ below grade, below the water table, in limestone with pockets of silty sand.
The Challenge
On this project, the microtunneling contractor had two tunnel crossings. On the first, they elected to not pre-grout their break in & break outs through the SOE. This resulted in a significant water and soil inflow event during the first break in. This crossing, under the entrance to the cruise port and between two other pieces of critical infrastructure, would not tolerate any surface disturbances associated with a flooding event.
The contractor reached out to CJGeo about stabilizing the launch & retrieval shafts to ensure stability during the launch & retrieval processes, by performing permeation grouting.
The Solution
CJGeo proposed permeation grouting of the limestone with an acrylic grout to ensure stability of the launch & retrieval shafts. Permeation grouting with acrylic grout ensures uniform permeation, and displacement of groundwater. It also ensures that the soils are sufficiently bound together to not fail while cutting the launch & retrieval holes in the sheet pile.
CJGeo installed the sacrificial tubing for this installation from the shaft. Occasionally, sonic drilling is useful for pre-grouting, but in this case, it was more economical and less disruptive to go through the shaft walls.
CJGeo performed the permeation grouting work in a single shift at each shaft.
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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.
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Spillway Undersealing
The Job
This spillway undersealing project is located at a dam in Tuckahoe, Virginia. The dam is owned and maintained by a home owner association, and is approximately 45 years old.
The Challenge
The lake, which is is approximately 7.5 acres, drains through a 24′ RCP pipe that maintains the lake at the lip of a large concrete spillway that only occasionally sees flow. The lake dropped about two feet, which was an immediate cause for concern. A consulting engineer specializing in dams inspected the structure, and determined that a flowpath had opened under the spillway. This flowpath allowed water to drain under the structure at an elevation below the primary outlet.
This obviously caused concerns about the stability of the earthen structure. The consultant recommended that the owner work with CJGeo to perform polyurethane grouting to address the voids and restore flow to its designed routes.
The Solution
CJGeo worked with the consultant to design a polyurethane grouting program to address two different problems:
- water piping along the outside of the concrete-encased 24″ RCP outfall
- bulk voids under the 6″ thick concrete secondary spillway structure
To address the piping along the pipe, CJGeo proposed injecting CJGrout 22SHV geotechnical polyurethane grout along the entire pipe alignment using driven sacrificial tubing. Because the pipe was relatively shallow and the soils relatively soft and uniform, percussion installation of tubing was sufficient, and no sonic drilling was needed.
To address the voids under the larger surface spillway structure, CJGeo also proposed grouting with CJGrout 22SHV geotechnical polyurethane grout. Here, grout installation was through mechanical packers installed in 5/8″ holes drilled through the concrete.
A three person polyurethane grouting crew took less than a day to perform all of the grouting. Confirmation of fill was grout extruding from numerous points at the top and bottom of the spillway, as well as cross-hole communication.
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Collapsed CMP Abandonment
The Job
This collapsed CMP abandonment project is located at a paper mill near Richmond, Virginia. The pipe drains a relatively large area of the site under the primary road into the facility. Onsite personnel noticed that flow through the structure diminished significantly with time.
The Challenge
The first thought was that the pipe had just filled slowly with sediment. To address this, the mill hired a jetting contractor to clean the pipe. The jetting equipment ran into an obstruction inside the 36″ corrugated metal pipe. The obstruction turned out to be a nearly complete collapse.
The mill hired a consulting civil firm to design a replacement crossing, who then reached out to CJGeo for options to abandon the collapsed pipe.
The Solution
The first thought from the consultant was to sonic drill down to the pipe at three locations, drop and grout 2″ PVC pipes in, and install cellular grout through the pipes.
CJGeo thought this could work, but had concerns about the environmental risks. The pipe has quite a bit of fall, so the low end would see quite a bit of head, which increases the likelihood of leaks out of the embankment. These leaks can be hard to predict, and if they occur, very difficult to contain.
CJGeo recommended abandoning the CMP with CJGrout 22SHV geotechnical polyurethane as a lower risk, faster alternative. The consultant agreed with CJGeo’s recommendation to use polyurethane grouting to reduce costs and environmental risks.
CJGeo mobilized a geotechnical polyurethane grouting crew to the site. It took a few hours to fill the pipe. Despite being significantly lighter than the water & muck in the pipe, the CJGrout 22SHV still displaced all of this material because it expands and is only moderately mobile.
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TBM Intervention Permeation Grouting
The Job
This TBM intervention permeation grouting project is located in Virginia. It is part of a highway tunnel installation project to increase capacity on a bridge tunnel.
The Challenge
During mining, the TBM, which is more than 40′ in diameter, began to pull pieces of sheet pile & wire rope through the face. To prevent further damage to the machine, tunneling was stopped. The machine encountered the debris approximately 250 feet short of the exit structure, underneath a constructed island.
The island is built out of relatively loose beach sand that’s commonly available in the area. The crown of the machine is approximately 25′ below grade, with the invert of the machine being about 70 feet below grade. Mean high tide is also about 25′ below grade.
In order to facilitate a hyperbaric intervention, the contractor needed a solid plug in front of and around the machine face. The criteria for the plug included:
- easily excavatable, to prevent issues for the TBM upon resumption of mining, and also to ensure that divers doing the hyperbaric intervention wouldn’t have issues removing grouted material in the case of grout entry into the machine face.
- low viscosity, to ensure uniform permeation into the soils in front of the machine, though they were relatively course (only 1% fines)
- readily available, in order to meet the incredibly short schedule requirement
The Solution
CJGeo proposed permeation grouting to create the plug using acrylic grout. Acrylic grout is:
- readily available through the mining supply chain
- very low viscosity, so well suited for permeating sands
- forms a stiff gel that’s stable, but still easily hand-excavatable
To perform permeation grouting up to 75 feet below grade, CJGeo proposed sonic drilling to install Tube-a-Manchette (TAM) pipes.
Due to the compressed timeframe, CJGeo subcontracted a sonic driller to install 86 different TAM wells, ranging from 25 to 75 feet deep. Once the first 10 TAM tubes were in place, CJGeo started placing acrylic grout through up to 10 simultaneous TAM pipes, using straddle packers and a PLC-controlled grouting system.
CJGeo was onsite within 10 days of the first call. Then, over 23 calendar days, CJGeo successfully installed more than 85,000 gallons of acrylic grout, at rates of nearly 15 gallons per minute.
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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.
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Yonkers Polyurethane Grouting
The Job
This Yonkers polyurethane grouting project is located in Yonkers, New York. The project is part of a renovation of a multi-tenant strip center into a single discount grocery tenant.
The Challenge
During construction, someone on the general contractor’s team thought that areas of the floor sounded hollow. Tapping on the floor, it sounded like a drum. The contractor reached out to CJGeo, and we recommended performing a few cores in the hollow sounding areas.
Coring revealed extensive voids in two areas of the building footprint. Both were along the side exterior walls. In one area of the floor, the voids were up to 4′ deep. The apparent cause for the voids was a longstanding problem with below slab plumbing when the space was a deli and dry cleaner.
The Solution
After the cores were used to confirm the size and extent of the voids, CJGeo recommended CJGrout 20SDB geotechnical polyurethane grout to fill the voids.
CJGrout 20SDB is ideal for filling large voids below floors because it is low exotherm. Many foams used for polyurethane grout are not well suited for filling very large voids.
A plumber installed new sanitary lines below the floor after CJGeo completed the void filling. The void filling only took a single day onsite. It’s important to fill voids first so that cutting new plumbing trenches doesn’t cause catastrophic, unexpected settlement.
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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.
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Tunnel Shaft Sinkhole Grouting
The Job
This tunnel shaft sinkhole grouting project is located in Newport News, Virginia. It is located outside the gate for Pier 2 at Newport News Shipbuilding, home to the deactivated USS Enterprise (CVN-65). As part of water and sewer upgrades in the area, multiple shafts were excavated to facilitate guided pilot tube bores.
The Challenge
At a shaft in the middle of an intersection, the dewatering well driller was unable to maintain circulation. This resulted in incomplete dewatering points. During excavation of the ring beam and liner plate shaft, the floor blew out after excavating through a fat clay layer. The fat clay is underlain by a highly permeable flowing sand.
When the floor blew out, the shaft, which is roughly 30 feet diameter, settled up to a foot on one side, and the shaft flooded in a few minutes. Multiple large sinkholes opened up around the perimeter of the shaft.
The Solution
The utility contractor, who was sinking the shaft, reached out to CJGeo for a solution. The only way to salvage the situation was to adequately dewater the site, which was even less possible due to the extensive voids around the shaft.
CJGeo visited the site, and made a few recommendations. First was to grade the site to direct the surface water away from the structure. There were multiple blocks of surface stormwater flowing directly into the area around the shaft. Second was to perform polyurethane compaction grouting around the entire structure to fill voids under the pavement and around the liner plates.
CJGeo mobilized a geotechnical polyurethane grouting crew to the site the following day. Using CJGrout 35NHV61, the crew filled approximately 70 cubic yards of sinkholes. Grout uniformly migrated through the liner plates, indicating that voids were continuous around the perimeter, and across the full depth of the shaft.
After CJGeo completed the grouting work, the dewatering contractor was able to successfully drop four wells around the shaft. By dewatering the underlying flowing sands, the contractor was able to resume excavating the shaft.
A few weeks after stabilizing the shaft, the two tunnels were successfully completed from the shaft. A CJGeo cellular grouting crew then grouted the annular space on both tunnels.
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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.
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