SOE Closure Manchette Grouting
The Job
This SOE closure Manchette grouting project is located in Alexandria, Virginia. It is part of the RiverRenew project, a large CSO project.
The Challenge
As part of this project, a diversion structure and drop shaft were being installed to pull flow off of an existing sewer tunnel. The box tunnel is around 8′ wide. The SOE will facilitate installation of the diversion chamber. Excavation within the SOE called for closing the gap between slurry wall panels. This is to be done under the existing structure with steel lagging.
However, the closure is below ground water table. The “marsh” deposits soils require stabilization prior to excavation. The conceptual design from the owner called for permeation grouting tied into an underlying clay layer. The clay layer is approximately 50′ below existing grade.
The Solution
CJGeo proposed performing the permeation grouting to cut off ground water flow and stabilize the soils for excavation using an acrylic grout. Due to the relatively deep required depth, traditional percussion driven installation tubing wasn’t possible.
To ensure accurate placement at depth, CJGeo used the TAM grouting method. TAM grouting, or Tube-a-Manchette, uses special grout casing installed by drilling to grout through.
CJGeo performed this SOE closure Manchette grouting work over a period of two weeks.
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Massachusetts Lightweight Fill
The Job
This Massachusetts lightweight fill project is located at Boston’s Logan International Airport. It is part of Logan Forward continuing improvements to the airport.
The Challenge
As part of this project, the general contractor installed two cast-in-place barrier walls. The space between the barrier walls is between four and nine feet. The walls are curving, have non-vertical faces, and bear on a curving, non-horizontal existing podium slab. The gap between the walls needed to be filled in order to pour a housekeeping slab spanning between the walls.
This work is all on an existing podium structure. So, the fill density between the two walls had to be as low as possible.
The Solution
CJGeo proposed filling between the two walls with CJGrout 20SDB. 20SDB has a similar density and compressive strength to typical expanded polystyrene (EPS, or Geofoam) blocks. However, unlike geofoam blocks, 20SDB:
- is pumped, so doesn’t require trimming, and fits to any shape
- expanded onsite, so logistics are significantly simpler
- cures within a few minutes, so is still quick
- not affected by petroleum products
A CJGeo polyurethane grouting crew took a single shift onsite to install the 64 cubic yards of CJGrout 20SDB. The general contractor began installing the topping slab the next day.
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Detroit Michigan Annular Space Grouting
The Job
This Detroit Michigan annular space grouting project is located near Van Dyke Avenue & 8 Mile Road. The project owner is Great Lakes Water Authority, and the project is part of the PCI-4 rehabilitation.
The Challenge
As part of the rehabilitation of this large diameter sewer, three different liner systems had to be installed. The longest section of single liner type is approximately 800 linear feet. The concrete sewer’s inner diameter is approximately 17.5 feet. The outer diameter of the liner that the installer subcontracted the annular space grouting to CJGeo on is approximately 16.5 feet.
Based on the theoretical average inside diameter of the existing sewer, the annulus is almost exactly one cubic yard per linear foot.
The Solution
The pipe runs at full charge at least once per day, so there was a high likelihood of accumulated water in the annulus. To displace this water and ensure consistent bearing of the pipe, CJGeo proposed 75lb/cuft CJFill-Under Water. While this density of CJFill cellular grout significantly exceeds the 300psi at 28 day compressive strength requirement, it facilitates displacing solids from the annulus.
To help manage buoyancy, once the first lift was in place, the wet cast density of the cellular concrete on this Detroit Michigan annular space grouting project was reduced to 45lb/cuft CJFill-Standard. Reducing the wet cast density significantly reduces uplift, which allows taller lifts.
CJGeo used an onsite dry mix batch plant to generate the cellular concrete and pump it up to five hundred feet in the sewer line.
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Michigan Pipe Abandonment
The Job
This Michigan pipe abandonment project is located in Grand Rapids, Michigan. As part of the Coldbrook Pumping Station decommissioning project, 2250LF of 48″ pipe, and 2300LF of 60″ pipe were specified for grout filling.
The Challenge
The primary challenge for the general contractor on this project was the sheer volume of abandonment grouting. The project also had a significant amount of smaller diameter pipe, but it was in shorter runs, so was easy for them to self-perform with flowable fill.
The Solution
CJGeo proposed using 25lb/cuft CJFill-Ultra Lightweight cellular concrete. CJFill-Ultra Lightweight can be pumped thousands of feet per placement. This eliminates the need for most intermediate access points. Placement points on this project were in the driveway of a fire station, next to a new riverwalk project, and also on the grounds of the pumping station.
CJGeo mobilized a dry batch cellular grout plant to the site, and made around 200 cubic yards per hour of CJFill-Ultra Lightweight to finish this Michigan pipe abandonment project. Each run was up to 2500 feet long at a time. The abandonment work took five days onsite. By utilizing on site dry batching, a snow storm and cold overnight temperatures did not affect the work.
After the crew was completed with this work, they moved to Detroit to perform annular space grouting on a 17′ diameter CSO outfall structure.
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Pregrouting for Hand Mining
The Job
This large CSO project in Alexandria, Virginia required pregrouting for hand mining. The hand mining was to install a new pipe below an existing influent tunnel, which is on piles. The hand mined tunnel was to connect two a secant pile shaft to a slurry wall pit, which are roughly 25′ apart.
The Challenge
The challenges on this project included:
- no drilling allowed without pre-probing
- 3′ thick secant pile walls
- unknown exact pile support layout of influent tunnel
- fully saturated soils
- potential debris in backfill under existing influent tunnel
The Solution
CJGeo proposed performing the permeation grouting using acrylate. Acrylate is exceptionally low viscosity, so well suited to the organic, fine-grained soils. Previous permeation grouting on the project was done with acrylamide. However, acrylamide is neurotoxic and carcinogenic, so the owner was happy to learn about acrylate, which has very similar properties, but is not neurotoxic or carcinogenic.
To avoid drilling, CJGeo developed a pushed/driven probe grouting installation. This approach uses 1/2″ diameter steel tubing driven to depth, and then grouted through during extraction.
The 3′ thick secant pile walls didn’t pose too much of an issue, clearance holes were drilled with hand-held percussion drills.
Drilling wasn’t allowed. The owner and design team were concerned about potentially hitting and damaging the pile foundation. Because there was the potential for debris, there would be no way to distinguish debris from a pile until it was potentially too late. By using groutable probe rods, CJGeo avoided all of this risk.
The fully saturated soils had relatively low permeability, and the site was constrained on two sides by the existing SOE structures. Performing permeation grouting when below the water table you’re limits the placement rate by the ability to displace the existing groundwater. Because of the water-tight walls on two sides of this pregrouting for hand mining application, take was slower than originally anticipated.
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New Jersey Pipe Abandonment
The Job
This New Jersey pipe abandonment project is located in northern New Jersey. First, the general contractor installed a new force main by micro tunneling. After the the new micro tunneled force main was in service, the existing force main had to have grout filling. The pipe is 24″, and about 6300 feet long.
The Challenge
The pipes ran underneath an existing roadway, so digging access points for flowable fill installation would have been expensive, time consuming, and disruptive to traffic. The general contractor recommended CJFill as an alternative to the controlled low strength material that the township typically uses.
In addition to the old force main abandonment, a wet well structure also required abandonment. The original plan was to use flowable fill, however there were concerns about inducing settlement if the fill material was heavy.
The Solution
CJGeo proposed using 25lb/cuft CJFill-Ultra Lightweight cellular concrete. CJFill-Ultra Lightweight can be pumped thousands of feet per placement. This eliminates the need for most intermediate access points.
CJGeo mobilized a dry batch cellular grout plant to the site, and made around 150 cubic yards per hour of CJFill-Ultra Lightweight to finish this New Jersey pipe abandonment project. Each run was up to 2500 feet long at a time. The abandonment work took two days onsite. After the abandonment grouting was done, the CJGeo crew did the wet well abandoning work with 25lb/cuft CJFill-Ultra Lightweight.
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Pennsylvania Pipe Abandonment
The Job
This Pennsylvania pipe abandonment project is located at a drinking water reservoir near York, Pennsylvania. As part of a dam reconstruction, the existing outfall pipe was specified for grouted abandonment.
The Challenge
The existing outfall pipe is 48″ cast iron pipe, and approximately 200 feet long. The pipe passes approximately 45 feet below the crest of the earthen embankment, concrete core dam structure. To ensure that the pipe would not serve as a conduit for water after abandonment, the specification calls for cellular grout with a maximum permeability of 1×10-6 centimeters per second.
During design, there were concerns about leaks in the pipe draining out some of the cellular concrete after placement stopped, but before it reached initial set. To address this, a secondary grouting program using chemical grout was designed to top off any void volume in the outfall pipe after the cellular grout set.
The Solution
CJGeo proposed using 60lb/cuft CJFill-Standard cellular grout for the abandonment. 60lb/cuft CJFill-ST exceeds the minimum compressive strength requirement, and has less than 1×10-6 cm/sec permeability.
CJGeo mobilized a dry batch cellular grout plant to the site to complete this Pennsylvania pipe abandonment project. The crew performed the grouting in fewer than two hours. The dry batch plant generates the 60lb/cuft cellular grout onsite directly from bulk cement powder.
Placement was through sacrificial grout pipes installed by the general contractor. The GC also constructed masonry bulkheads on both ends of the structure.
Exploratory holes drilled in the bulkheads the following day confirmed uniform fill, and no need for the secondary grouting work.
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Michigan Water Main Abandonment
The Job
This Michigan water main abandonment project is located in Saginaw, Michigan. It is a 2900LF of 8″ grouted abandonment for the local municipality.
The Challenge
The utility contractor who installed the replacement water main was required to fill the old pipe with grout after tying in the new pipe. Because of the relatively small diameter, they were going to have to dig approximately 15 access holes if they used traditional flowable fill. The contractor really didn’t want to have to do that. So, they sought a highly mobile grout that would eliminate the need for digging access points.
The Solution
CJGeo proposed using CJFill-Ultra Lightweight cellular grout for this Michigan water main abandonment. Because the project volume is approximately 40 cubic yards. CJGeo proposed using wet batch generation, with a local ready mix provider supplying the raw slurry.
Wet batch generation is well suited for projects like this because the volume of slurry required is much less than a full load of cement. The equipment for wet batch generation is very portable–typically just two pickup trucks, one pulling a 20′ trailer with equipment.
Confirmation of fill for this Michigan water main abandonment project was material venting a fire hydrant at the far end of the placement. Pumping pressures were less than 20psi for the duration of the grouting process.
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Texas Annular Space Grouting
The Job
This Texas annular space grouting project is located in Lockhart, Texas. It is a 42″ treated water pipeline for the Alliance Regional Water Authority.
The Challenge
The annular space grouting for this tunnel was specified for cellular concrete. The minimum allowable compressive strength was 300psi at 28 days, when tested according to ASTM C495. The 42″ treated water pipeline was installed inside of a 60″ casing pipe.
The tunnel was approximately 460LF, and crossed under a frontage road and Texas State Highway 130, about 20 miles south of Austin.
The Solution
Due to the Texas cement market being extremely strained, CJGeo proposed using onsite dry batch generation to make the cellular grout onsite. This has a few advantages over using ready mix (wet batch generation):
- purchasing cement directly from a cement plant bypasses ready mix plant’s cement allocation limits
- bulk material doesn’t go bad onsite
CJGeo used a relatively high water:cement ratio to account for temperatures of 105 degrees during the placement and generation. This helped to ensure that material did not prematurely set during placement, and allowed CJGeo to generate and place all of the 40lb/cuft CJFill-Standard cellular grout material in just three hours.
Confirmation of fill for this Texas annular space grouting project was material venting from the 12 o’clock vent on the far end of the tunnel. Pumping pressures were less than 15psi for the duration of the grouting process.
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Microtunnel Contact Grouting
The Job
This microtunnel contact grouting project is located in Clarksville, Tennessee. It is part of a new water intake structure along the Cumberland River to improve the reliability of the city’s municipal water source.
The Challenge
Based on the overcut of about an inch, and length of the 450 foot long tunnel, the contact grouting volume was approximately 50CY. In order to efficiently place the grout against the roughly 40′ of head from the river that that the tunnel terminates in, high volume, high quality mixing was required.
The tunneling contractor reached out to CJGeo to use onsite colloidal batching to generate grout quickly, safely, and without the risks of using ready mix.
The Solution
CJGeo proposed using a 0.55 water : cement ratio slurry generated onsite with colloidal mixing for the contact grout. While there were nearby ready mix plants that could have supplied the job, mixing neat grouts in transit mixer trucks typically does not uniformly wet out the cement. This can make it very difficult to pump, and typically results in highly variable mixes. Because the grout is the same as the cement slurry used for making CJFill cellular concrete, CJGeo used a cellular concrete batch plant with the foam generator turned off.
CJGeo batched and placed 50CY of slurry over about 2.5 hours to complete the microtunnel contact grouting. Placement of the grout was through 2″ ports, and the grout displaced both the lubricating bentonite slurry, and significant amounts of water. Due to the exceptionally high mobility of colloidally mixed neat cement grout, CJGeo’s crew was able to grout the entire length of the tunnel from two ports located just in from the launch shaft.
Grout communication was confirmed through lubricating ports, visual confirmation from the casing pipe drying due to heat of hydration, and divers in the river witnessing grout at the tremied bulkhead.
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