HRSD 24″ Forcemain Abandonment
The Job
HRSD‘s Virginia Beach Boulevard Forcemain Replacement project installed more than a mile of new pipe to replace an aging 24″ force main. The owner specified forcemain abandonment using grout.
The Challenge
The original alignment was outside the pavement limits. Over time due to extensive widening, most of the pipe was now under the roadway. The areas not under the roadway crossed under significant commercial & residential development.
To avoid the risk of utility strikes digging access pits, and disruption to traffic and citizens, the number of access points needed to be limited.
The Forcemain Abandonment Solution
CJGeo grouted more than 7,000LF of the 24″ pipe over a period of four working days onsite, using CJFill-Ultra Lightweight. The CJFill-UL completely filled each run of pipe. This was verified by uniform material venting from the far end of each run. Run lengths for the forcemain abandonment ranged from 450LF to more than 2000LF.
The CJFill-UL for this project was generated onsite using the wet batch process. Wet batching uses slurry delivered to the site by ready mix trucks. This method was best here because of very limited access at each of the placement points. The relatively short runs also lean towards wet batching.
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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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Facing a similar challenge to this multiplate tunnel grouting 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.
Sewer Collapse Sinkhole Repair
The Job
This sewer collapse sinkhole repair project is located in central Virginia. When the operators of a tire and auto shop noticed a sinkhole developing next to their building. They weren’t sure what to do. After an employee crawled into the hole and discovered that he could stand up underneath their building, the owner reached out to the city. City crews determined that a 20″ VCP combined sewer & storm pipe had collapsed under the structure, roughly 25′ below grade.
The Challenge
An on-call contractor for the city installed a new manhole and rerouted the pipe around the building. However, addressing the sinkhole was out of their businesses’ scope. The project manager reached out to CJGeo, who visited the site and recommended DCP testing to better quantify the extent of the problem.
The Solution
DCP testing showed that outside of the large hole on the surface, there was little deep disturbance. Working with the city’s consulting engineer, CJGeo developed a grouting plan to install two different CJGrouts. 20SDB in the bulk voids near the surface. And 35NHV61 for soil grouting to address voids within the underlying ground near the failed sewer line.
While onsite for just 6 hours, a CJGeo crew completed the work with zero disruption to the businesses’ operations.
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Facing a similar challenge to this sewer collapse sinkhole repair 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.
Tunnel Abandonment – Boston
THE JOB
A plumbing contractor hand tunneled 140LF of 4’x5′ tunnel under two apartment buildings near Boston, Massachusetts. In preparation for a renovation project, a structural inspection was performed. The structural inspection revealed the slab floors which were tunneled under were not designed as structural slabs. The structural engineer directed the property owner to immediately fill the tunnels to restore structural integrity.
THE CHALLENGE
The tunnel abandonment work had to be completed during the winter, and while one of the two affected buildings was occupied. The non-occupied building was also in the process of asbestos abatement and a full gut renovation.
Due to the plumbing running through the tunnels, an excavatable grout was required. Also, the grout had to be low exotherm in order to not affect the new PVC plumbing.
THE SOLUTION
CJGeo proposed polyurethane grouting for the tunnel abandonment. Polyurethane grouting can be performed in any weather, is low exotherm, and can be placed in very thick lifts. The specific grout chosen was a low exotherm bulk void filling polyurethane.
CJGeo mobilized a polyurethane grouting truck with more than 9000 pounds of polyurethane grout, due to the unknown exact volume of the tunnels. During an 8″ snowstorm, CJGeo abandoned both tunnels in a single day. The unoccupied building was grouted via holes drilled through the floor. The tunnel below the occupied building was free sprayed from inside the tunnel. All tunnels were kept under negative pressure ventilation in order to address installation odors.
CJGeo placed 4100 pounds of polyurethane grout into the two tunnels.
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Communication Jack & Bore Grouting
The Job
The Sandston area, just outside of Richmond, Virginia, is at the crossroads of major north/south data transmission lines, and transoceanic data transmission lines. This jack & bore grouting was done to support a road crossing connecting two new data centers.
The Challenge
As part of the construction of a new, multi-billion dollar data center, a utility contractor bored two, 48″ steel casings under a roadway & adjacent wet utilities for a road crossing. Each of the casings had up to 20 different PVC conduits held in place using casing spacers. The contractor needed a grout that could be placed at minimal pressure while ensuring complete fill without damaging the conduits.
To avoid carrier pipe buoyancy, the maximum allowable grout density for the annular space grouting was 45lb/cuft.
The Solution
CJGeo mobilized a cellular grouting crew to the site and did the jack & bore grouting on both pipes in a single day. The peak grouting pressure was 5psi, and confirmation of fill was achieved when uniform cellular concrete was vented from the 12 o’clock position on the opposite end of each bore. 38PCF CJFill-ST was used to achieve the design strength of 200psi at 28 days.
CJFill-ST is heavier than CJFill-Ultra Lightweight, which is the most common cellular grout that CJGeo uses for annular space grouting. However, in the case, the municipality specified a higher compressive strength due to the proximity of multiple other critical utilities.
CJGeo used wet batch on this project due to the low volume and proximity of a ready mix plant. Wet batch typically has lower peak heat of hydration, which is helpful when grouting around PVC.
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Facing a similar challenge to this communication jack & bore grouting project? Give us a shout or shoot us a text. Click the state marker for the location of the project for contact info for the appropriate rep.
