Spillway Bridge Grouting
The Job
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, which caused large sinkholes to form adjacent to and under the roadway pavement, and 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 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.
Hotel Basement Water Intrusion Grouting
The Job
A hotel in Baltimore had a continuously wet floor in the basement utility room. Water was oozing out from under the power feed bank housekeeping slab, which had been poured 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 had been done under the presumption that surface water was flowing down the outside face of the basement wall, and 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, which included re waterproofing approximately 500sqft of wall, 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 250sqft floor was then undersealed with grout, which extruded up through the joint between the wall and floor, and also through various cracks in the floor.
Upon completion of the grouting by CJGeo, the conduit pit was dry, and there are no longer any leaks.
Launch Shaft Permeation Grouting
The Job
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 to bind the soils together in order to make them 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 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.
MTBM Recovery Grouting
The Job
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, and tail of the machine was under the outside lane of the interstate. The machine was approximately 15′ below ground water level, and there was extensive ground water infiltration into the sheet pile rescue shaft.
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.
While the desire was to increase the stability of the soils, the treated soils needed 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, significantly reduce their permeability, but still facilitate hand excavation in an underwater confined space.
Because the failure mechanism of the MTBM was unknown, CJGeo grouted the zone between the MTBM face and the rescue shaft, 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, and 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.
8″ Toe Drain Abandonment
The Job
Lake Whetstone is an approximately 30-acre manmade impoundment located in Montgomery Village, Maryland. It is utilized for stormwater runoff control, and also recreation, with an approximately 1000LF earthen dam.
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, underactive flow.
The Challenge
Each of the two, 100′ long pipes needed to be grouted full, but could only be accessed from the downstream end of the pipes. One pipe had nominal flow, and the second pipe had approximately 10GPM and discharged 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.
CJGeo performed the onsite mockup testing and analysis, and then grouted the two pipes in place successfully over a period of two days onsite.
Acid Drainage Grouting
The Job
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.
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. 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.
Chemical Underpinning
THE JOB
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.
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 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.
Sand Filter Joint Sealing
The Job
Two underground stormwater sand filters at an apartment community wouldn’t hold water. The structures, which were assembled from 10′ diameter metal pipes needed to pass a water loss test 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 were bedded in washed #57 stone and were connected to the stormwater drainage system, so subject to live flow.
The Solution
Sprayed high-density polyurethane/polyurea hybrid to seal the joints internally. In addition, chemical grouting for joints that had been repaired previously using internal bands and polyethylene seals. The chemical grouting repair was designed to minimize the loss of chemical grout into the surrounding stone beds. The previously-installed internal seals and bands were left in place and encapsulated in the joint sealant.
CJGeo’s large diameter pipe repair crew installed chemical grout to seal the leaking joints. Immediately after the sealing was performed, the structures were tested by the municipality. Neither structure leaked any water after CJGeo sealed the joints.
Warehouse Floor Water Intrusion Repair
The Job
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. With dynamic loading from material handling equipment, water was displaced through the joint onto the floor. 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 performed at cold temperatures–the facility is maintained 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 work in a few hours. The work started after the second shift and was completed in time for the grout to set and tolerate material handling equipment at the start of the first shift.
The following day, the facility reported no water extrusion under material handler traffic.
HDPE Pipe Joint Sealing
THE JOB
A large sinkhole opened up in the parking lot of a manufacturing facility. The sinkhole was adjacent to a cast-in-place stormwater drop inlet structure. The structure was 14VF deep and was fed and discharged by 54″ HDPE pipes, requiring HDPE pipe joint sealing.
Facility maintenance personnel had been monitoring the sinkhole and noted that it was growing rapidly. Inspection of the pipe revealed that there were joint failures at the first joint out from the manhole and deterioration of the parging. The parging between the HDPE and concrete pipe had failed to the point of significant amounts of soil washing out during rain events.
THE CHALLENGE
The repair had to be done without disrupting traffic in the parking lot. It also had to provide a long-term solution to the failed pipe joints.
Along with gently filling the voids around the HDPE pipe without deflecting or damaging it, the repair material had to have enough expansive force to thoroughly seal the small cracks and leaks in the parging between the HDPE pipe and concrete structural walls.
THE SOLUTION
Chemical grouting using both prepolymer chemical grouting and plural component polyurethane grouting.
Chemical grouting was chosen for injection through the joints of the HDPE pipe. Prepolymer chemical grouting uses single component polyurethane grouts with exceptionally long gel times. This virtually eliminates localized expansive pressure, which could further damage the HDPE pipe, which was already out of round.
The plural component structural foam was used for void filling the large sinkhole that extended from the bottom of the structure to the surface.
Prepolymer chemical grout was injected through the joints in the HDPE pipe. This successfully sealed the bell and spigot joints without causing further deflection of the pipes.
The large sinkhole void was grouting using plural component polyurethane grouting. A low exotherm structural foam was chosen due to the very large size of the void. Structural foams are important in situations where there are very large voids in areas subject to traffic loading.
