Secaucus Lightweight Fill
The Job
This Secaucus lightweight fill project is located just across the Hudson River from Manhattan. It’s part of a completely gut of an existing 100,000 square foot distribution and logistics building. While the ground in Secaucus is terrible, the real estate is valuable because of its close proximity to New York City, and also at the core of the dense, urban North Jersey market.
The Challenge
Since original construction in the 1970s, the floor of the building has settled nearly two feet. This is due to underlying compressible, organic soils. As the underlying soils consolidated, and the floor settled, two subsequent floors were poured on top of the existing floor. Varying thicknesses of recycled concrete and other base materials were used to level over the differentially settled previous floors in preparation for the new floor pours.
The goal of the full gut was to build a food grade space. This is to bring the building into a more profitable sector. To do this, minimizing the amount of future settlement was important. Reports from multiple consulting geotechs in the past recommended undercutting and lightweight fill placement as a viable option for achieving this goal. The CMAR reached out to CJGeo about designing and implementing an undercut and lightweight fill program. This was based on our experience on similar projects in the Secaucus area.
The Solution
CJGeo’s inhouse geotechnical engineer worked with the CMAR’s geotechnical consultant. We used RocScience’s Settle 3 program to design an undercut program that would bring anticipated settlement to no more than 1.5 inches. Given the global subsidence of the area, along with rising ground water levels and increasing flood chances, buoyancy was also a design consideration. The total system (floor, base stone & lightweight fill) had to have a minimum 1.1 factor of safety against uplift in fully inundated condition. As an added measure of safety, given the very large footprint of the fill, limited permeability soils immediately below the lightweight fill, and disruptions associated with any buoyancy, CJGeo recommended not factoring infiltration into reduced buoyancy.
The final design includes a 42 inch undercut, followed by placement of 32 inches of CJFill-Ultra Lightweight foamed concrete fill. CJGeo mobilized a single dry batch plant to the site, and placed approximately 8,500 cubic yards of CJFill-Ultra Lightweight material. Production was as high as 1100 cubic yards per day.
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Wet Well Lightweight Fill
The Job
This wet well lightweight fill project is located at HRSD’s Nansemond Treatment Plant, in Suffolk, Virginia. As part of an extensive capital improvement project, the Nansemond Treatment Plant is being upgraded to accept increased flows. The additional flow will be coming via the Hampton Roads Sanitation District’s Hampton Roads Crossing (HRX) project.
As part of the upgrades, a large wet well requires abandonment filling. The structure bears on deep foundation piles, and underlying soils are extremely poor. Therefore, the structure requires low density, self-consolidating fill instead of traditional flowable fill.
The Challenge
The Construction Manager At Risk evaluated multiple lightweight fill materials. Geofoam would provide the least additional load, but due to safety concerns from access into the structure, would not be practical. Foamed glass aggregate fell below maximum allowable densities, but would be difficult to place and compact in the tight space. Expanded shale would be too heavy, and very difficult to place and compact.
The Solution
CJGeo worked with the CMAR, along with the geotechnical and structural engineers to design a fill program which would minimize density, maximize safety, and be optimal for cost and schedule.
CJGeo mobilized a 200cy/hour cellular grout plant to the site, and placed 430 cubic yards of 25lb/cuft CJFill-Ultra Lightweight foamed concrete fill. To manage lateral loads on the walls during placement, two ten foot deep lifts brought the fill to finish elevation.
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NYC Cellular Concrete
The Job
This NYC cellular concrete project is located at the William McCray Playground in Manhattan. The existing playground had experienced significant subsidence, which damaged the already outdated equipment.
The entire playground was demolished, in order to install a new updated facility, including play equipment, basketball court and spray equipment.
The Challenge
Design documents called for three feet of 25lb/cuft lightweight fill material over roughly 4,000 square feet of the site. Two options were given to contractors; 25lb/cuft cellular concrete or foamed glass aggregate.
Logistics for any work in Manhattan are tricky. Challenges include truck traffic limitations, constraints on work time and noise, and the narrow, congested streets. There was no room on the site for any stockpiles.
The Solution
The customer determined using 25lb/cuft CJFill-Ultra Lightweight fill by CJGeo would be the lowest risk, most economical, and fastest method allowable by specification. Because the equipment for generating foamed concrete fill is mobile and compact, the tight site wasn’t a problem.
CJGeo brought in just four loads of cement in order to generate the approximately 550 cubic yards of foamed concrete material. Cold temperatures didn’t affect the operation; it froze the night between the two pours, and also the night afterwards. No tenting or protection is required.
The day following the second pour, the customer was able to start placing pavement base on top of the cellular concrete.
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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 injection grouting with 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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