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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48 Inch RCP Joint Repair
The Job
This 48 inch RCP joint repair project is located in Raleigh, North Carolina. The pipe is located at a commercial facility. The slope covering the pipe experienced a slope failure. Upon inspection, six joints were showing signs of soil infiltration and water exfiltration.
The Challenge
The primary challenge for the general contractor on this project was minimizing cost and time. It would have been expensive and disruptive to excavate the pipe. Cover depths were up to 15 feet, and there was a road that would be impacted by excavation, as well.
The exfiltration from the leaking joints was washing away bedding material and adjacent backfill. This caused significant amounts of erosion, and destabilized the slope soils by completely saturating them.
Piping outside of reinforced concrete pipe is an ideal candidate for polyurethane grouting.
The Solution
CJGeo worked with the general contractor and owner’s civil engineering to design a grouting program to repair the pipe. The general concept for this 48 inch RCP joint repair project was to backgrout the pipe with rigid geotechnical polyurethane grout. CJGrout 35NHV61 was the grout of choice; it can be injected directly into flowing water, provides nearly 10ksf in compressive strength, and migrates into both large and small voids with ease.
A CJGeo polyurethane grouting crew took a single day to perform the repair. The average circumferential void around the pipe was nearly nine inches. Cutoff criteria were:
- grout hole to joint communication
- cross hole communication
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Box Culvert Void Filling
The Job
This box culvert void filling project is located near Fredericksburg, Virginia. The Virginia Department of Transportation owns and maintains the structure, which conveys a stream under a rural divided highway. As part of a rehabilitation project, extensive cracking in the structure (a double barrel six foot by six foot box), was being patched with repair mortar, and some cracks epoxied.
The Challenge
At the start of project, the general contractor discovered extensive voids outside of the structure. These voids were allowing significant amounts of the stream flow outside of the box culvert (piping). This was cause for concert regarding the specified repair mortar application and epoxy injection.
The general contractor reached out to CJGeo about filling the voids with grout prior to the patching and repair operation.
The Solution
CJGeo proposed grouting all the voids outside of the box culvert with CJGrout 35NHV61. 35NHV61 is a hydro-insensitive, structural polyurethane grout. Its NSF61 potable water certification makes it excellent for work on drainage structures.
The owner, Virginia’s Department of Transportation, required water testing before, during and after grouting. This water testing specifically looks for MDI. All of the water testing, which was performed by a third party environmental laboratory, found zero MDI in any of the water samples.
It took three days onsite to complete the grouting. Some hairline cracks that were still damp after the bulk box culvert void filling work. CJGeo grouted these cracks with a hydrophilic chemical grout to make them completely dry.
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8′ CMP Joint Grouting
The Job
A spec warehouse was planned for a vacant piece of land which had 1700LF of 8′ CMP running through it. The pipe was 10 years old. Because the site was vacant, there was no maintenance. Nearly every joint showed signs of soil infiltration, and there were massive sinkholes along the entire alignment. Given the depth, size, and short work window, the contractor sought out a CMP joint grouting repair alternative to replacement.
The Challenge
To avoid replacing the entire run of pipe, the joints had to be sealed. There were 80 pipe joints and 12 pipe to structure joints to seal. The pipe crossed under a roadway, and then crossed the site at an angle. The downstream end of the pipe transitioned to new 96″ RCP.
The Solution
In preparation for the repair, CJGeo had to educate the town, contractor, owner & consulting engineers that polyurethane grouting is an effective CMP repair method.
CJGeo mobilized a polyurethane grouting crew to the the site. Over the course of a week onsite, the crew performed all of the CMP joint grouting.
CJGeo used CJGrout 20SDB geotechnical polyurethane. 20SDB is a high mobility geotechnical polyurethane, so seeks out and fills even the smallest of voids outside of pipes. Because it’s highly mobile, it doesn’t deflect or damage the CMP that needs repair.
The manholes also had significant defects. Made of non-parged sewer brick, they leaked extensively. To address the widespread infiltration through the structures, CJGeo sprayed the interior of each structure with CJGrout 60FDC. 60FDC is a hybrid polyurethane/polyurea spray coating. For durability, the 60FDC was coated with polyurea. The 20SDB, 60SDB & polyurea coating were all installed using the same equipment, significantly reducing costs.
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Multiplate Tunnel Grouting
The Job
This multiplate tunnel grouting project is located in Asheville, North Carolina. During a real estate transaction, civil engineers walked a 1400LF run of 14′ diameter multiplate tunnel running underneath a strip center and multiple outparcels.
A previous inspection had indicated impending section loss of the pipe due to corrosion and had recommended grouting of incidental voids, but no work had been performed at that time.
The pipe, which had up to 20′ of cover, bypasses a large stream and runs under 200LF of building footprint, the main entrance roadway, two out-parcels, and ties into an NCDOT box culvert to discharge.
The Challenge
Significant debris was present in the pipe, and access was exceptionally difficult. Because dewatering was not practical, all work proposed had to be performed underflow.
The Solution
CJGeo proposed polyurethane backgrouting using plural component CJGrout material, specifically CJGrout 35NHV61.
CJGrout 35NHV61 is a hydro insensitive, moderate mobility grout. It’s designed for backgrouting in wet environments, and is certified for potable water contact.
Despite a bear wandering into the pipe during repairs, CJGeo crews successfully backgrouted the pipe to address piping and erosion outside of the structure over a period of two weeks. More than 40,000 pounds of CJGrout 35NHV61 were needed for this 14′ CMP repair project.
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Acid Drainage Grouting
The Job
This acid drainage grouting project is located in West Virginia. A 72″ CMP stream diversion pipe under a coal stockpile at a coal mine in West Virginia was experiencing acidic water infiltration. This was causing bypassed stream water to become acidic, so regulators required all of the stream flow to be pumped to treatment ponds and treated. This was expensive, and the flow volume was greater than the design capacity of the treatment system.
The Challenge
Access was quite challenging. The pipe was either 700LF or 1300LF from the nearest access points to the farthest grouting location. Additionally, the infiltrating water was pH 2.
Due to location, all personnel had to be MSHA 40 hour trained, and the company registered as a mine contractor with the state.
The Solution
CJGeo recommended a hydrophobic prepolymer chemical grout with an extensive performance history in high acidity environments. CJGeo crews sealed a combination of 20 joint leaks and point infiltration sources using the prepolymer chemical grout.
To address acidic water migrating through the stone dust backfill outside of the pipe, CJGeo crews then grouted an in-situ cutoff wall in the trench just downstream of the lowest leak using permeation grouting. Permeation grouting is optimal for creating small footprint cutoff walls because it typically doesn’t require large equipment. The mine operator installed two dewatering wells immediately upstream of the cutoff wall to intercept and pump out the acidic drainage, to keep it isolated from the stream water.
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RCP Pipe Sealing
THE JOB
This RCP pipe sealing project is located in Wake Forest, North Carolina. The asphalt parking lot over a 300′ run of 54″ RCP culvert kept collapsing. The public works department of the locality determined that the joints between the 4′ sticks of pipe had not been properly gasketed or seated during installation. The pipe saw the continuous flow of a small stream. Flow enters at an end wall and discharges into a box culvert that crosses a public street. The drop inlet at the downstream junction between the RCP culvert and box culvert also had a failed 18″ RCP culvert feeding it. This had been repaired multiple times using open trench excavation.
THE CHALLENGE
The municipality was looking for an affordable, proven, and non-disruptive solution. Replacement would have required removal of a structure, and prevented adjacent businesses from using their parking lot during the work. Relining was not practical due to multiple sewers and water utility lines crossing through the pipe. Significant joint offsets would have also made lining difficult.
Extensive voids were identified around the pipe through an inspection. Much of the water flow from the stream was passing under/outside of the pipe, causing the erosion and collapse of the overhead parking lot, and the floor of a storage building built over the pipe. Previous attempts at sealing the joints and filling voids around the pipe with concrete had failed.
THE SOLUTION
Polyurethane grouting fill voids around the pipe and seal the joints between the individual pieces of pipe, end wall and drop inlet. And, chemical grouting to treat a curtain at the upstream end to reduce subsurface flow, and at the downhill end to stabilize a joint in the failed small diameter RCP culvert entering the drop inlet.
CJGeo polyurethane grouting crews placed 50 cubic yards of CJGrout 35NHV61, hydro insensitive polyurethane and 45 gallons of polyurethane resin chemical grout for an upstream grout curtain over a period of three days to complete the repair. The repairs were all completed without disruption to the adjacent businesses or streets.
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15 inch RCP point repair
The Job
This 15 inch RCP point repair project is located near Richmond, Virginia. A 6′ deep sinkhole opened up adjacent to a stormwater manhole structure. The manhole was in an easement between two single-family homes and maintained by a municipality. Two misaligned joints were visible from the manhole and were the cause of the sinkhole.
The Challenge
The two misaligned joints were under up to 8′ of cover. The repair had to seal the two misaligned joints and fill the extensive voids around the pipe that resulted from years of erosion.
Due to extensive utilities in the area, and difficult access, the owner did not want to perform an open cut repair. While the misalignment was significant, the reduced flow from the misalignment was less problematic than an open cut repair.
The pipe is located approximately 150 feet from the nearest roadway, on a steep slope towards a resource protection area. All of these factors significantly increased the costs & disruption of an open cut repair.
The Solution
CJGeo proposed grouting via driven tubing to seal the joints in the pipe. An internal form was used to minimize the entry of chemical grout into the pipe.
CJGeo’s large diameter pipe repair crew installed CJGrout 35NHV geotechnical polyurethane to seal the two misaligned joints and fill voids. The repair took less than two hours, with no service disruptions. CJGrout 35NHV excels at repairing failed RCP joints because its reaction profile is designed for void filling, and it’s unaffected by water. The homeowners and owner were happy that the repair only took foot traffic and a lightweight 2″ hose bundle.
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Sand Filter Joint Sealing
The Job
This sand filter joint sealing project is located in Richmond, Virginia. Two underground stormwater sand filters at an apartment community wouldn’t hold water. The structure is four, twenty foot sticks of ten foot diameter CMP. It had to hold water before the property could come off the bond. Previous repairs attempted included the installation of internal joint rings and seals, which did not stop enough flow to pass the water loss tests.
The Challenge
The proposed repair had to accommodate multiple layers of previous repairs. The joints included four different materials–aluminized metal, galvanized metal, neoprene, and polyethylene. The structures are in a bed of washed #57 stone, and subject to live flow.
The Solution
Sprayed high-density polyurethane/polyurea hybrid to seal the joints internally. In addition, chemical grouting for joints with internal bands and polyethylene seals. A fast set reaction kept the chemical from migrating into and fouling the stone bed. The spay application and encapsulates the original repair’s joint seals.
CJGeo’s large diameter pipe repair crew installed chemical grout to seal the leaking joints. Then, each joint was sprayed with a hybrid polyurea-polyurethane internal seal. Immediately after the sealing was performed, the structure held water and passed the water loss test. Neither structure leaked any water after CJGeo sealed the joints.
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Facing a similar challenge to this sand filter joint sealing project? Give us a shout or shoot us a text. Click the state marker for the location of your project for contact info for the appropriate rep.
