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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Toe Drain Abandonment
The Job
This toe drain abandonment project is located outside of Washington, DC. Lake Whetstone is an approximately 30-acre manmade impoundment located in Montgomery County, Maryland. The approximately 1000LF earthen dam provides stormwater runoff control and recreation.
As part of a retrofit program of the embankment, two 8″, perforated CMP toe drain pipes need to be grouted for a minimum of 100LF, under active flow.
The Challenge
Each of the two, 100′ long pipes needed to be grout filled. The pipes are only could only be accessable from the downstream end of the pipes. One pipe had nominal flow, and the second pipe had approximately 10GPM of flow. Each discharges through an end wall structure at the stilling basin.
The Solution
The project designer, Gannett Fleming, specified NSF Section 61 certified grout (potable water contact) for the abandonment grout. Due to the “one-shot” nature of the project, above-ground mockups, including sacrificial pipe installation, chemical grout cup testing, yield analysis, and visual inspection, were all required prior to the start of grouting.
While most abandonment grouting uses high mobility cement grout, like CJFill-Ultra Lightweight, chemical grout was the best option for this abandonment. Chemical grout’s reaction speed (and therefore mobility) is controllable onsite by variable catalyst dosing. This helps ensure minimizing any migration of grout into adjacent structures or waterways.
CJGeo performed the onsite mockup testing and analysis, and then grouted the two pipes in place successfully over a period of two days onsite.
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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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Chemical Underpinning
The Job
This chemical underpinning project is located outside of Pittsburgh, Pennsylvania at a manufacturing facility. Water began to seep through the floor of the shop, break room, and bathrooms inside a manufacturing facility. The investigation determined that a water line had broken, and weekend soils below the floor, causing the settlement. Voids were also present below the floor.
The Challenge
The client’s primary concern was addressing the stability of the area without affecting normal usage.
The Solution
CJGeo proposed chemical grouting to stabilize the weakened soils, along with structural polyurethane grouting to fill voids. Previous repairs to address floor settlement had been completed, so a hydro-insensitive undersealing polyurethane grout was used to ensure stability without lifting the slab.
Due to saturated soils, CJGrout 35NHV was the best material for filling voids immediately below the floor. 35NHV is a normal speed, hydro-insensitive geotechnical polyurethane, specifically formulated for void filling applications. It provides high bearing capacity, and minimizes the chance of undesirable lifting during installation.
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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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Warehouse Floor Water Intrusion Repair
The Job
This warehouse floor water intrusion repair project is located in Columbua, South Carolina. An area of the floor inside of a produce processing facility experienced water intrusion through joints in the floor. Considerable amounts of process water were dumped on the floor each day, and unsealed joints in the floor allowed water to collect under the floor slab.
The floor was showing signs of slab curl from poor control of the curing process after placement. With dynamic loading from material handling equipment, water was pumping through the joint onto the floor. Due to the slab curl, the floor was effectively acting as a diaphragm pump. The facility’s health & safety staff was concerned that the water could introduce contaminants to the food processing area.
The Challenge
The proposed repair had to perform well in saturated conditions, allow for near immediate resumption of material handler equipment, and ensure a long-term fix. Since no settlement had occurred, the grout material had to be able to seal the very small voids, displace water, and not exert any lifting forces on the floor.
The material & process also had to be perform well at cold temperatures–the facility is at 34 degrees year-round.
The Solution
CJGeo proposed chemical grouting using a hydrophilic prepolymer grout. Chemical grouting is ideal for saturated environments and helps to ensure complete stabilization and sealing of floors.
A single CJGeo chemical grouting crew mobilized to the site and performed the slab foundation repair work in a few hours. The water intrusion grouting work started after the second shift. The grout set to tolerate material handling equipment before the start of the first shift.
The following day, the facility reported no water extrusion under material handler traffic.
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