Tub Crossing Repair
The Job
This tub crossing repair was done for a short line railroad in New Jersey. The sandy soils of South Jersey are great for growing produce and mining pure silica sand. While most of the produce is shipped by truck, a lot of the silica is shipped by rail. The rails inevitably cross the roads, and many of the crossings are at grade.
The Challenge
A short-line railroad was experiencing significant settlement and pumping of multiple precast modular crossings in the Vineland & Millville areas. Each crossing saw significant truck traffic, primarily from aggregate mining, and also significant heavy haul rail traffic from transporting sand.
Voids below the panels were holding water due to poor drainage. Each time a truck or train passed over the panels, they deflected downwards. This deflection pumps base material out from under the crossing, causing settlement.
The Solution
Working with a rail maintenance contractor, CJGeo performed polyurethane grouting on a total of four precast tub crossings in the area, using CJGrout 40NHL. Each crossing repair took a single day. Polyurethane grouting allowed for the immediate resumption of automobile traffic, and rail traffic. Th CJGeo crew installed supplemental bolting to address the deterioration of the panels resulting from the extensive movement of the panels.
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Industrial Short Line Tub Crossing Repair
The Job
This short line tub crossing repair project is located in Baltimore, Maryland. Sparrows Point, in Baltimore, Maryland is a brownfield site. It’s transforming from being steel manufacturing to industrial and logistics use. From it says as a heavy manufacturing facility, there is an extensive freight rail network throughout the site, with many grade crossings subject to significant heavy truck traffic & heavy haul rail traffic.
The Challenge
A precast tub-style grade crossing on a road feeding a metals recycling plant developed a 2.5″ belly. The local FRA inspector instructed the railroad to correct the settlement.
The Solution
CJGeo performed structural polyurethane grout injection to fill voids below the panels. And then lift them back into their correct alignment. The work took just a few hours, without disruption to the rail or auto traffic.
CJGrout 40NHL is a four pound per cubic foot geotechnical polyurethane grout. It’s specifically designed for high dynamic load environments like rail, port, and airfield traffic. CJGeo’s crews use 40NHL for modular grade crossing repairs to ensure the longest life repair possible.
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NC Tub Crossing Repair
THE JOB
This NC tub crossing repair project is located in Charlotte, North Carolina. The 8′ long panels of tub-style grade crossing settled. As a result, MOW placed a speed restriction on the crossing. This affected passenger schedules. The settlement affected three panels. The belly in the slabs was approximately 2 inches. The crossing deflected slightly with heavy truck traffic. The crossing deflected significantly with rail traffic.
THE CHALLENGE
The repair had to be completed in just a few hours, to avoid disruption to rail traffic. The repair had to allow for immediate resumption of rail traffic, and tolerate tamping of the adjacent truck during the repair. Additionally, the tub crossing repair had to be done in a manner that did not disturb the adjacent asphalt pavement.
THE SOLUTION
High-density geotechnical polyurethane grouting to stabilize and lift the affected modular grade crossing panels. Geotechnical polyurethane grouting is far superior to mudjacking, in that the process is faster, and can more easily ensure a complete filling of voids under the crossing panels. Lifting precision of fewer than 0.1 inches is standard.
A CJGeo modular grade crossing repair crew filled the voids and corrected settlement in a few hours. During the tub crossing repair, the rail system used a tamper on the approaches. This helps ensure the longevity of the grouting repair. The structural polymer grouting process used here is sometimes referred to as slab jacking.
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Industrial Driveway Crossing Repair
The Job
This industrial driveway crossing repair project is located in Frederick, Maryland. MARC’s Brunswick Line’s Frederick extension passes through multiple industrial sites & driveways. This particular crossing served as the driveway of a ready mix concrete operation, so saw extensive high dynamic loading in a wet environment.
The Challenge
The repair had to be performed without disrupting either rail or industrial traffic. There was a four-hour window between the last morning train and the first evening train for performing the repair to the eight modular tub crossing panels. The settlement was up to two inches, with extensive spalling.
The Solution
CJGeo’s crew installed supplemental bolts due to replace the OEM center panel anchors, and then grouted the crossing in the mid-day window, without disruption to any stakeholder. The structural polymer grouting work took less than a day onsite. The work was done between the morning and evening commuter trains, but multiple freight trains used the crossing during the repair.
CJGrout 48NHL was the grout of choice. CJGrout 48NHL is formulated specifically for high, dynamic loading environments, such as rail crossings, and airfields. It provides superior bearing capacity, excellent resiliency to dynamic loads, and is great for correcting differential settlement between panels. Because it is relatively low mobility, CJGrout 48NHL is unlikely to affect adjacent pavement.
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Light Rail Tub Crossing Repair
This light rail tub crossing repair project is located in Charlotte, North Carolina. It is part of Charlotte’s CATS system.
THE JOB
A suburban grade double-crossing was rebuilt to address poor drainage infrastructure in the area. This included installing two different culverts adjacent to the crossing panels, and then resetting all of the panels which had to be removed for the culvert installation. During routine track inspections, the panels showed signs of deflection up to one inch with rail traffic. The system’s track division was concerned that pumping of the crossing panels would lead to destabilization of the base, and settlement. At the lower elevation end of the crossing, there was extensive evidence of sub-base material being pumped out from under the crossing within two weeks of the crossing reconstruction. 368 track feet were affected.
THE CHALLENGE
Work had to be completed during non-revenue hours, between 0200 & 0430 over two nights. There was also a high probability of the voids below the panels being waterlogged.
THE SOLUTION
High-density polyurethane grouting to stabilize the grade crossing panels. Specially-formulated hydro-insensitive void filling (high-mobility) grout was proposed in order to ensure complete filling of voids below the panels, whether waterlogged or dry.
CJGeo successfully stabilized the crossing during the two-night work period.
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Railroad Sinkhole Stabilization
The Job
This railroad sinkhole stabilization project is located in Martinsburg, West Virginia. During the installation of a 42″ jack & bore casing below a three-track Class 1 railroad, ballast started showing in the spoils. Soon afterward a sinkhole appeared between tracks 2 & 3, 15 feet above the casing. The jack & bore installation was stopped, and the contractor reached out CJGeo requesting an emergency mobilization.
The Challenge
CJGeo had to mobilize with very little notice, and work had to be performed adjacent to an operational track.
The Solution
CJGeo mobilized two polyurethane compaction grouting crews, who were on the road in less than an hour. Within four hours of the sinkhole formation, CJGeo was onsite with more than 250CY of material placement capacity.
CJGeo successfully grouted the sinkhole, using CJGrout 20SDB. Rail traffic continued on adjacent tracks, and the face of the bore was restored, allowing the jack & bore operation to safely restart. CJGeo performed this repair using a polyurethane grout with an elastic modulus similar to the existing soil in order to prevent creating a hard spot in the rail. CJGrout 20SDB was the best fit grout for railroad sinkhole stabilization project because:
- it cures to 95% strength within 15 minutes
- doesn’t impede auger boring
- is highly mobile, so will pass through ballast easily
- doesn’t have lifting capacity, so wouldn’t move the adjacent tracks
- is formulated for bulk placements without charring
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Tunnel Abandonment – Boston
THE JOB
A plumbing contractor hand tunneled 140LF of 4’x5′ tunnel under two apartment buildings near Boston, Massachusetts. In preparation for a renovation project, a structural inspection was performed. The structural inspection revealed the slab floors which were tunneled under were not designed as structural slabs. The structural engineer directed the property owner to immediately fill the tunnels to restore structural integrity.
THE CHALLENGE
The tunnel abandonment work had to be completed during the winter, and while one of the two affected buildings was occupied. The non-occupied building was also in the process of asbestos abatement and a full gut renovation.
Due to the plumbing running through the tunnels, an excavatable grout was required. Also, the grout had to be low exotherm in order to not affect the new PVC plumbing.
THE SOLUTION
CJGeo proposed polyurethane grouting for the tunnel abandonment. Polyurethane grouting can be performed in any weather, is low exotherm, and can be placed in very thick lifts. The specific grout chosen was a low exotherm bulk void filling polyurethane.
CJGeo mobilized a polyurethane grouting truck with more than 9000 pounds of polyurethane grout, due to the unknown exact volume of the tunnels. During an 8″ snowstorm, CJGeo abandoned both tunnels in a single day. The unoccupied building was grouted via holes drilled through the floor. The tunnel below the occupied building was free sprayed from inside the tunnel. All tunnels were kept under negative pressure ventilation in order to address installation odors.
CJGeo placed 4100 pounds of polyurethane grout into the two tunnels.
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Bridge Approach Polymer Grouting
The Job
This bridge approach polymer grouting project is located just outside of Washington, DC. The George Washington Memorial Parkway connects Washington, DC with Fairfax and Alexandria Counties in Virginia. Originally designed as a scenic route, the road has transformed into a heavily used commuter route in and out of Washington. The road runs along the Potomac River, with bridges crossing deep ravines, including Windy Run.
The Challenge
Our biggest challenge with this project was making sure this heavily populated commuter route was completed in a timely fashion.
The Solution
CJGeo proposed polyurethane compaction grouting using CJGrout 30NHL. CJGrout 30NHL’s design is for improving the bearing capacity of loose soils similarly to cementitious compaction grouting. Grouting is done on 4’ centers, at 5’, 10’ & 15’ below grade. Top-down grouting ensured maximum densification of underlying soils. This grouting program was generally prescriptive, but with ground movement of 0.5 inches cutoff criteria.
CJGeo installed approximately 25,000 pounds of CJGrout 30NHL to increase the bearing capacity of the embankment soils. Due to polyurethane grout’s nearly immediate cure, CJGeo helped ensure that ground improvement stayed out of the critical path of this accelerated project. Pre & post grouting DCP testing showed improvement in soil density.
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Dam Outfall Pipe Seep Grouting
THE JOB
This dam outfall pipe seep grouting is located in Fairfax, Virginia at Northern Virginia Community College. A 36″ RCP outfall pipe for a dam terminated at an end wall. As part of a dam rehabilitation, small seeping leaks at the end wall/pipe joint needed to be stopped. The leaks had to be stopped so the wall could be resurfaced.
The engineer specified chemical grouting.
THE CHALLENGE
Access to the area was quite difficult. It was more than 150 feet from the closest vehicle access, which was only accessible by 4×4 vehicles down a steep slope.
While unknown during the planning of the chemical grouting repair, what was thought to be 36″ RCP was actually a larger diameter RCP that had been lined with steel casing pipe. An interior poured-in-place concrete liner had been installed afterward.
THE SOLUTION
Super low viscosity prepolymer chemical grout was selected. This was for two reasons: 1) the ability to easily pump more than 150LF from the lay-down area. 2) the ability to seek out and stop leaks through very tight cracks in the structures.
Prepolymer chemical grouts are water-reactive, so can be injected into active water flows. The grout expands when it comes into contact with the water, which seals the leak.
The initial grouting plan was to install the chemical grout through the pipe wall starting beyond the first joint. However, because the pipe had been cased, placement had to be done through the end-wall structure only. Multiple injection holes were drilled through the end wall structure, and the chemical grout was pumped through the end-wall structure.
Extensive catalyzation was used to first seal the leaks at the end wall and then chase the water flow pathways up along the outside of the pipe. The job was messy due to the forced proximity of the injection points and the leaks. But all the leaks were successfully stopped.
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1 Mile 36″ Waterline Abandonment
THE JOB
CSX crews were surfacing the mainline track in Baltimore when the tamping equipment struck an object immediately below the ties. Investigation revealed that it was a manhole associated with nearly 6000LF of 36″ water main primarily running immediately below the tracks. The municipality relocated the waterline. Next, they had to fill the pipe from just two intermediate points. There were three sections of pipe; 1200LF, 1600LF & 2900LF. Various potential solutions for the watermain abandonment included:
- threading sacrificial tubing and grouting on the way out, and
- pumping flowable fill from the manholes,
However, none were economical or could guarantee a pipe abandonment below the railroad.
THE CHALLENGE
The project designer, OBG, identified cellular concrete as a potential solution to the problem and reached out to CJGeo to determine its feasibility. CJGeo confirmed the appropriateness of cellular concrete and set out to create a grouting plan. Coordination between the utility contractor and slurry provider (the site was too small to set up a batch plant) was crucial to ensure that the runs of pipe were all successfully filled in a single shot each. With train frequencies of 3-4 per hour, if the operation didn’t work and the pipes were only partially filled, there was no opportunity to create intermediate access points to finish grouting a section of pipe.
Based on the required bearing capacity and production requirements, CJGeo proposed 22lb/cuft CJFill-Ultra Lightweight cellular concrete for abandonment. With a 25psi break strength at 28 days, the mix provided the required strength, met the CSX utility occupancy standard for abandonment, and maximized expansion in order to ensure the longest run, which required nearly 1000CY of the finished product, could be grouting in a single shot.
THE SOLUTION
CJGeo mobilized a 150CY/hour cellular concrete crew to the site and performed the two shorter runs the first week. The project was broken into two different weeks due to the criticality of ensuring the longest run was filled completely without issue. The first two runs allowed CJGeo, the GC, railway flaggers, railway operations, and the slurry provider the opportunity to work out any kinks in operations during the lower risk placements.
The following Tuesday, starting at 0600, Chaney Enterprises delivered the first of 24 loads of slurry. Overall, the work took three days. CJGeo generated & pumped a total of 1710 cubic yards of cellular concrete to successfully complete the waterline abandonment.
This project would have been much easier using a mobile batch plant, which we now have three of.
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