New Jersey permeation grouting
The Job
This New Jersey permeation grouting project is located in Elizabeth, New Jersey. It is at a large wastewater treatment plant owned by the JMEUC.
The Challenge
During installation of a new building on site, a large excavation was required. Primarily comprised of H piles and wood lagging, it crossed a 24 foot wide influent conduit. The influent conduit is a double barrel box structure, cast in place on 12 inch thick bed of open graded stone.
During test pitting to the bottom of footing elevation, the test pit appeared to be tidally influenced. The site is immediately adjacent to a creek that feeds into the Elizabeth River. At high tide, and due to the permeability of the stone layer, inflow into the test pit was not controllable, and was higher than the footing elevation.
Specific challenges here included:
- potentially high velocity water flows due to tidal influence
- 12 foot minimum spacing of grout holes due to structure wall locations
- potential fouling of bedding stone with fines
The Solution
The general contractor reached out to CJGeo about grouting the stone bed. The structure is 24 feet wide, but only has a single, eight inch wall down the middle.
CJGeo proposed that a coring contractor drill a two inch core down through the center and side walls from the surface. This gave us three access points to place grout from at each location.
Due to the large grout hole spacing, CJGeo selected acrylic grout. Acrylics are excellent for this type of application because they are exceptionally low viscosity (pump & flow pretty much like water).
A single CJGeo chemical grouting crew performed the acrylic grouting over two days onsite. Afterwards, infiltration into the excavation was down to a submersible garden hose pump. The use of acrylic grout ensured that:
- coverage was uniform despite the large distance between placement points
- any fines fouling the bedding stone were uniformly bound together, immobilized & made impermeable
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Outfall Leak Grouting
The Job
This outfall leak grouting project is located near Emporia, Virginia. The work is located at two different stormwater ponds at an industrial scale solar facility. The facility is owned by Dominion Energy.
The Challenge
This facility has a mix of both dry and wet ponds. At two wet ponds, leaks developed along the outfall pipes, which prevented them from holding water long term. During a precipitation event, water would build up, but then afterwards, slowly drain out by piping alongside the outfall pipes. In order to turn over the facility to the owner, the contractor needed to address the leaks to ensure the ponds functioned as designed.
The Solution
Due to the small diameter of the pipes, they weren’t accessible from the inside. CJGeo proposed grouting along the pipe alignments using single component expanding chemical grout. The pipes are reinforced concrete.
To facilitate this, CJGeo drove sacrificial injection tubes along both sides of each of the two pipes. No grout returned to the inside of the pipes, which confirms that the root cause of the problem was poor control of the backfill, as opposed to problems with the pipe joints. When bedding isn’t properly installed, and backfill properly compacted, water can flow outside of stormwater pipes, which is what was happening here.
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SOE Leak Grouting
The Job
This SOE leak grouting project is located in Alexandria, Virginia. It is part of the RiverRenew project, which is a large CSO tunnel and drop shaft project. This location is immediately adjacent to the Woodrow Wilson Bridge, and the Potomac River.
The Challenge
At a drop shaft location, the contract installed two parallel slurry walls between an existing combined sewer box culvert and a drop shaft to the new tunnel. During excavation of the pit, two high volume leaks, each around 125GPM opened up below the existing conduit.
The customer installed road plates to stabilize the area, and pumped flowable fill behind the road plates. This provided short term stability to the area, but did not address the high velocity flow of water through an unanticipated open graded sand seam that was causing the leaks.
The Solution
CJGeo mobilized a grouting crew capable of performing both high volume geotechnical polyurethane grouting and acrylic permeation grouting at the same time for this SOE leak grouting work. The first step was to install CJGrout 35NHV61 to fill voids which had washed out immediately behind the road plates.
After grouting the bulk voids and slowing the velocity of the leaks, CJGeo installed acrylic grout up to 20 feet behind the slurry wall face. The only way to reliably stop water flow through sands is to bind them together with a very low viscosity grout. The acrylic grout installed on this project has a viscosity less than 10 centipoise. This allows it to uniformly permeate the sands, react into a cooked egg white consistency, and make the treated sands impermeable.
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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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Sheet Pile Joint Sealing
The Job
This sheet pile joint sealing work is part of the Thimble Shoals parallel tunnel project. The project is located between Islands 1 and 2 of the Chesapeake Bay Bridge Tunnel. The Chesapeake Bay Bridge Tunnel crosses the opening of the Chesapeake Bay, connecting Norfolk/Virginia Beach and the Eastern Shore.
The Challenge
Water was leaking out of a joint in the precast splash wall adjacent to the TBM slurry separation pit. Any time it rained, precipitation landing in the slurry pit would flow out of gaps in the sheet pile wall. It then passed through the roughly 3′ of soil between the sheet pile wall and splash wall, and then out through joints in the splash wall.
The Solution
CJGeo proposed using a single component, hydrophilic chemical grout to seal the joints. Hydrophilic grout is best for this particularly repair because:
- the area is rather dynamic, so hydrophilic’s ability to flex and stretch without tearing helped to ensure longevity
- the area is constantly exposed to moisture, so dimensional stability is not a concern.
A CJGeo chemical grouting crew of three people completed the sheet pile joint sealing repairs in less than a day. Some chemical grout extruded out through the joint in the splash wall. It was broken off flush with the surface and disposed of offsite.
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Valve Vault Infiltration Grouting
The Job
This valve vault infiltration grouting project is part of the Purple Line project in Maryland. A large diameter water line was relocated, with the tie-in done inside a 10′ diameter vault that was about 20′ deep. The vault structure, which is precast, and set inside a line plate shaft, was leaking at multiple joints and at a poured in place pipe penetration closure.
The Challenge
The vault structure wasn’t concentric in the shaft. This left little room to pour the closure around the pipe penetrations. One of the penetrations leaked, causing the structure to completely fill with water. Per specifications, it needed to be dry.
Most of the shaft was backfilled with 57 stone. Highly permeable backfill material can make water control grouting particularly difficult. When grouting to seal relatively tight leaks in a structure, the less permeable the adjacent soils the better. All grouts want to take the path of least resistance, and with highly permeable backfills, that often means traveling out into, and permeating, the backfill material instead of into tight cracks and water passageways.
The Solution
CJGeo proposed grouting the infiltration points with CJGrout-35NHV61. 35NHV61 is a hydroinsensitive, plural component geotechnical polyurethane, certified for potable water contact. 35NHV61 is a moderately mobile grout, selected to minimize mobility into the 57 stone backfill and reduce material loss during grouting.
CJGeo mobilized a three person crew to the site, and performed the valve vault infiltration grouting over a few hours.
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Spillway Bridge Grouting
The Job
This spillway bridge grouting project is located in Toano, Virginia. Toano is between Williamsburg and Richmond. Two DOT-maintained bridges crossing two privately owned dam spillways had to be closed because of extensive undermining of the spillways.
The undermining was allowing nearly all of the flow to happen below the spillway slabs. This caused large sinkholes to form adjacent to and under the roadway pavement. It also led to some settlement of the spillway slabs.
The Challenge
There was very little room to work–just under 4′ of clearance below the bridge beams. Also, the velocity of the water through the voids below the structure was quite high.
The Solution
CJGeo proposed a combination of plural component polyurethane grouting to address the water flows and voids, and hydrophobic chemical grout placed directly into cracks. A single CJGeo grouting crew was able to complete the repairs in a day (roughly 2500sqft of work, and approximately 4500lbs of CJGrout 35NHV61 polyurethane, plus 30 gallons of hydrophobic chemical grout). Dye testing during and after the grouting work confirmed that no more leaks were present under or around the spillway structures.
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Hotel Basement Water Intrusion Grouting
The Job
This basement water intrusion grouting project was at a hotel in Baltimore, Maryland. It had a continuously wet floor in the basement utility room. Water was oozing out from under the power feed bank housekeeping slab. The housekeeping slab sits directly on top of the floor slab. There were two presumed point sources:
- the unsealed joint between the floor and the wall,
- and the power feed conduit wall penetrations.
The pit where the power conduits came through the wall and turned up into the power feed cabinets was 18″ deep, and always full of water.
The Challenge
Extensive exterior drainage work did not work. It presumed that surface water was flowing down the outside face of the basement wall. Then, through the unsealed floor:wall joint and/or into unsealed joints in the conduits and then through the conduit penetrations. The exterior drainage improvements re-waterproofed approximately 500sqft of wall. They slowed, but did not completely stop the water intrusion.
A forensic engineer overseeing the project reached out to CJGeo about performing chemical grouting inside of the utility room to underseal the floor, and to seal the conduit penetrations.
The Solution
CJGeo proposed chemical grouting utilizing a low viscosity hydrophobic prepolymer chemical grout.
Fibrous material soaked in grout was placed into the utility conduit openings to seal them against water intrusion. The grout injected through the floor extruded up through the joint between the wall and floor, and also through various cracks in the floor.
Upon completion of the basement water intrusion grouting by CJGeo, the conduit pit was dry, and there are no longer any leaks.
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Launch Shaft Permeation Grouting
The Job
This launch shaft permeation grouting project is located in Fort Myers, Florida. As part of a utility installation project, a 60″ MTBM was being launched from a shaft sunk in the middle of a nest of buried utilities, adjacent to an arterial roadway. Utilities included water, sewer, ITS, traffic signals, and others. The MTBM launch elevation was approximately 18′ below ground water.
The Challenge
The shaft installation contractor and adjacent open cut utility installations had experienced flowing sands, which had proven problematic. The tunneling contractor knew that without increasing the stability of the soils adjacent to 60″ hole they needed to cut in the sheet pile shaft walls, there would likely be significant loss of ground into the shaft, potentially damaging the adjacent utilities and roadway.
Soils excavated from the shaft were primarily fine sands, silty sands, and silt. Previous attempts at grouting the same soils with a prepolymer chemical grout had proven unsuccessful.
The Solution
CJGeo determined that acrylic grout would be the most appropriate. Acrylate can bind the soils together very well. This makes flowing silty sands stand vertically during cutting of the launch hold in the sheet pile wall.
Because acrylic grouts have single digit viscosities, they are able to permeate very find grained soils with ease, ensuring uniform stabilization.
CJGeo performed the launch shaft permeation grouting via holes cut in the sheet piling, and treated an approximately 8CY mass of soil. In addition to grouting the soils immediately adjacent to the launch hole, CJGeo performed leak stop grouting on numerous nuisance leaks throughout the joints of the sheet pile shaft.
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MTBM Recovery Grouting
The Job
This MTBM recovery grouting project is located in Florida. When a 42″ MTBM stopped advancing under the shoulder of I-75 in Miami, Florida, the tunneling contractor had to sink a shaft adjacent to the roadway, and then hand mine in to recover the machine.
The Challenge
The MTBM was stalled approximately four feet from where the recover shaft was sunk. The face of the machine was under the shoulder. The tail of the machine was under the outside lane of the interstate. The machine was approximately 15′ below ground water level. There was also extensive ground water infiltration into the sheet pile rescue shaft. Further complicating things, an intelligent transportation system duct bank runs right over where the machine came to a halt.
In order to ensure that the ground would be stable to facilitate hand mining in from the shaft while avoiding settlement of the interstate, the tunneling contractor reached out to CJGeo about increasing the stability of the soils.
The desire was to increase the stability of the soils. However, the treated soils had to be hand excavatable by divers working in a casing slightly larger than the MTBM. Soils in the desired treatment zone included lime rock, course sands and silty sands.
The Solution
CJGeo determined that acrylic grout would be the most appropriate to bind the soils together. This method would also significantly reduce their permeability, but still facilitate hand excavation in an underwater confined space.
The failure mechanism of the MTBM was unknown. So, CJGeo grouted the zone between the MTBM face and the rescue shaft. We then grouted a collar around the entire MTBM machine in case the machine needed to be completely uncovered.
CJGeo successfully performed the permeation grouting, then divers excavated back to the machine, freeing it. The grouted face held once the receiving ring was installed and the sheet pile wall cut. The treatment zone soil was easily excavatable for the divers.
In addition to grouting the soils, CJGeo’s crew also performed grouting of numerous nuisance ground water leaks through various joints in the sheet pile shaft.
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