Lightweight Fill Over Waterline
The Job
This lightweight fill over waterline project is located north of Baltimore, Maryland, in Edgewood. It is part of a modernization and widening of I-95. This includes replacement of multiple bridges crossing I-95, including Clayton Road. Clayton Road is a rural, two lane roadway. However, I-95 in this area is a very heavily traveled, critical piece of the east coast megalopolis infrastructure.
About half of the City of Baltimore’s raw water supply parallels I-95 in this area. It runs through a 108″ PCCP raw water main that originates at the Susquehanna River, a few miles north of the project site.
The Challenge
As part of replacing the Clayton Road bridge over I-95, the bridge clearance was increased. To facilitate this, the approach/departure embankments had to come up a few feet. On the west end, this was not a problem; there are no underlying utilities or compressible soils.
On the east end of the bridge, however, the 108″ PCCP raw water main passes under the roadway embankment, in an area where grades needed to come up by an average of three feet. The pipe cannot see any additional load.
The Solution
Two potential solutions for this challenge are using lightweight fill to balance loads, or install a pile-supported load transfer slab bridging over the pipe. Lightweight fill was the fastest and most economical option.
CJGeo mobilized a single dry batch plant to the site. Over the course of six days onsite CJGeo poured 2,000 cubic yards of CJFill-Ultra Lightweight load reducing fill. The fill mass is roughly 10 feet thick at the deepest. At 25lb/cuft, this balances the loads within the zone of influence of the pipe. The pipe sees no increase in loads despite up to 4 feet of additional elevation over it.
Due to CJGeo’s exclusive use of high shear mixing, the contractor was able to place aggregate base on top of the CJFill-UL the following day.
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Fairfax Polyurethane Grouting
The Job
This Fairfax polyurethane grouting project is located at a commercial building used for medical office space in Merrifield, Virginia. The facility is a clinical site for a large regional hospital operator. It houses a primary care and community outreach practice.
The Challenge
The building was built in the 1980s, and will eventually be torn down. However, over the past few years after build out, the floor along the exterior wall settled about 0.75 inches. As the floor settled, the interior finishes along the wall started to cause functional issues for the users. Most of the cabinet and desk drawers were racked and unable to completely close, and office chairs were always trying to roll towards the wall.
The tenant reached out to the owner/property manager, who brought in a forensic structural engineer to investigate the problem and recommend a repair. The structural engineer reached out to CJGeo for recommendations.
Due to the clinic schedule, all demo, grouting, and finish restoration had to be completed in no more than two days. The area of impact is about 1200 square feet.
The Solution
CJGeo recommended CJGrout 28FDL to the structural engineer due to the relatively narrow zone of settlement, and nominal loads due to the light duty use of the space.
A single CJGeo polyurethane grouting crew filled the voids below the floor, lifted back into place and turned it over to the general contractor in fewer than four hours onsite. The general contractor then replaced the VCT and LVP floor tiles that CJGeo drilled through to perform the grouting. The space returned to normal use the following day, without the chairs moving on their own.
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Seawall curtain grouting
The Job
This seawall curtain grouting project is located at a secure facility in North Carolina. It is owned and maintained by the federal government.
The Challenge
The facility is located along a tidal waterway, and has a pre-cast concrete panel seawall protecting it from the adjacent waterway. The soils in the area are beach sand. Numerous sinkholes developed over time at the top of the seawall, which is just over half a mile long. The structure extends up to 17 feet from the cast-in-place cap down to the mud line, with mean high tide roughly six feet below grade. In other areas, the mud line is as close as five feet to below water. The seawall retains an airfield taxiway, runway, and extensive sensitive other infrastructure elements.
The original design for the seawall repair called for performing jet grouting along the entire length of the wall. This caused concerns from an environmental perspective, due to the difficulty in containing highly mobile material behind the wall, and also the equipment required for jet grouting, given extensive sensitive structures adjacent to the wall.
The Solution
CJGeo worked with the general contractor to analyze two different alternative repairs:
- permeation grouting with an acrylic grout
- curtain grouting with geotechnical polyurethane
Based on cost, timeline, and environmental concerns, CJGeo and the general contractor determined that curtain grouting with geotechnical polyurethane was the best alternative to jet grouting. Fundamentally, curtain grouting effectively coats the backside of a wall or structure with plastic, kind of like a waterproofing membrane, but without having to excavate.
Working together, the solution was presented to the owner. The owner determined that the value engineer alternative was preferable to the original design based on:
- water quality risk management – CJGrout 22SHV is certified for potable water contact, and does not contain PFAS. CJGrout 22SHV does not contain any cement, which can quickly change the pH of water, affecting aquatic life
- top side footprint – no drilling equipment is needed in this case. This eliminates obstructions for the airfield operation, and eliminating surface disturbances and surcharge loads on the wall
- cost – the value engineer alternative was accompanied by a savings of approximately $1.7 million
CJGeo mobilized a single polyurethane grouting crew to the site. Over a period of three months, CJGeo successfully performed the seawall curtain grouting work.
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Paved Slope Void Filling
The Job
This paved slope void filling project is located in Interstate 95, near Rocky Mount, North Carolina. The work is part of a bridge rehabilitation for the North Carolina Department of Transportation.
The Challenge
One of the bid items for the project is filling voids below the paved slopes protecting the embankments below the bridge structures. There are two bridges; each carrying two travel lanes over a set of railroad tracks and a rural roadway.
The slopes are quite steep; effectively 1:1. Specifications call for a 3lb/cuft geotechnical polyurethane for the void filling.
The Solution
The general contractor awarded the polyurethane grouting work to CJGeo due to our extensive experience performing geotechnical polyurethane grouting on transportation projects.
CJGeo mobilized a single polyurethane grouting crew to execute the paved slope void filling work. The crew used CJGrout 35NHV geotechnical polyurethane to completely fill all of the voids. Cutoff criteria for the project was cross-hole communication.
Due to the very steep slope, CJGeo installed working platforms and used tie-offs to ensure safety of our crew.
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Jersey Turnpike Polyurethane Grouting
The Job
This Jersey Turnpike polyurethane grouting project is located next to Secaucus Junction in North Jersey. It is part of a larger paving and rehabilitation project. The work location is the exit departure slabs for the 15X tollbooth over Penhorn Creek.
The Challenge
The departure slab (closest to the toll booth) for this structure settled about six inches. The adjacent barrier walls are integrated into an MSE wall, which has an open graded stone reinforced zone. The cause of the settlement is due to consolidation of underlying soft soils, which are prevalent in the area.
Before CJGeo’s involvement in the project, the design engineer consulted with a chemical grout manufacturer representative. This person designed a grouting program to address voids below the pavement and within the underlying soils, up to eight feet below grade.
The Solution
The general contractor awarded the polyurethane grouting work to CJGeo due to our extensive experience performing geotechnical polyurethane grouting on transportation projects.
CJGeo mobilized a single polyurethane grouting crew to execute the plan designed by the chemical grouting manufacturer representative. It took a single crew two onsite shifts to perform about 7200 pounds of polyurethane grouting. The material was equivalent to CJGrout 48NHL.
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North Carolina Polyurethane Grouting
The Job
This North Carolina polyurethane grouting project is located at Elon University. It is part of the Innovation Quad project, being built by Whiting Turner.
The Challenge
The site concrete contractor poured a large set of steps near the entrance of the new building. The steps are approximately thirty feet wide, and have roughly eight feet in rise. The steps are constructed over fill material, including site soils and dense graded crushed aggregate.
During a precipitation event, the grading at the top of the steps directed a significant amount of water towards the top of the steps. The water had nowhere to go other than below the steps. This washed out a significant amount of material, and also caused consolidation of some backfill material.
The Solution
The project’s geotechnical consultant recommended the general contractor reach out to CJGeo to address the voids below the steps. They also recommended performing DCP testing as a minimally invasive way to check the bearing capacity of the underlying materials after the erosion event.
The most suitable polyurethane grout for this project was CJGrout 20SDB. CJGrout 20SDB is a high mobility grout designed specifically for undersealing and bulk void filling, with lifting ability designed out in order to manage risk of displacing the brand new structure.
CJGeo mobilized a single polyurethane grouting crew to the site. They started by performing DCP testing, which uncovered voids within the top three feet of fill material immediately below the steps. The crew used sacrificial tubing to ensure that these voids were completely full, along with the voids immediately below the steps.
Confirmation of fill was material returning to the surface.
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Slurry Wall Gap Closure Grouting
The Job
This slurry wall gap closure grouting work is part of CJGeo’s continuing permeation and water control work at the RiverRenew project in Alexandria, Virginia. At an outfall structure that will pull wet weather flow from an existing CSO, which is a roughly 8’x8′ box culvert. It is currently suspended from a large beam and webbing. The beam spans a roughly 40′ wide excavation between two parallel slurry walls. The slurry wall gap is approximately 20 feet wide.
The Challenge
Excavation at this location has continued to uncover seams of highly permeable sand and gravel. The material is quickly recharging due to close proximity to the Potomac River. It also recharges with ground water flowing through the bedding stone below the box culvert from the uphill catchment area.
The Solution
Due to ground-level obstructions, drilling from the surface into the grouting zone isn’t possible. CJGeo designed a percussion-driven sacrificial tubing plan to install the grout. No sonic drilling needed.
The grout curtain is approximately two feet thick. It is fourteen feet deep. It is located about two feet behind the desired face of excavation.
All of the work was done from a mud mat installed by the contractor. Evaluated grouts included:
- colloidal silica grout, which would perform well from a permeation perspective, but likely be susceptible to washout. Colloidal silica would also potentially not perform well during lagging installation due to the friable nature of treated soils, and high groundwater head
- acrylic grout, which has performed very well onsite in previous work.
CJGeo mobilized to the site and completed the permeation grouting over a period of a few daytime shifts. This allowed the contractor to resume excavation within the structure.
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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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