New York Annular Space Grouting
The Job
This New York annular space grouting work is part of the Bay Park Conveyance Project. The Bay Park Conveyance Project is using a combination of microtunneling and slip-lining. This is to redirect effluent discharge from Western Bay to an existing ocean outfall several miles away.
The Challenge
Approximately 7 miles of the discharge pipe is being sliplined into an existing 72″ riveted iron pipe. The pipe runs underneath the Sunset Highway. Access pits are between 700LF & 3000LF apart, requiring annular space grouting placements ranging from 200CY to 850CY.
Due to maintenance of traffic concerns, all grouting is night work. There is nowhere to stage materials onsite.
The Solution
Working with the design and construction teams, CJGeo designed a 30lb/cuft, 150psi at 28 day compressive strength CJFill-Ultra Lightweight cellular grout for the annular space grouting. By using dry batch mixing onsite, CJGeo is able to achieve the compressive strength required, and place the distances required in the very short nightly placement windows.
Pipe jacking is the installation method for the carrier pipe, so there are no casing spacers. Because there are no casing spacers, water filling is the buoyancy control method. With water fill and a grout density significantly lower than water, the carrier uplift factor of safety is approximately 2.5 times.
To address material logistics, each night’s cement consumption is staged locally during the day. The cement is then brought to each placement location during the pours.
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SW Florida Annular Space Grouting
The Job
This Florida annular space grouting project by CJGeo is located in For Myers, Florida. The work is part of the City of Fort Myers’s South AWWTF Reclaimed Water Transmission Main. The goal of the project is to facilitate the beneficial reuse of treated wastewater, primarily for uses such as irrigation which historically utilized drinking water.
The Challenge
The majority of this pipeline uses open cut installation. However at two road crossings with extensive existing buried utilities, trenchless installation is most appropriate. The first crossing is 170 linear feet. The second crossing is 607 linear feet. Each tunnel is 52 inches in diameter steel. The reclaimed water line is 32 inch diameter ductile iron pipe.
The Solution
The tunneling contractor for this project was under contract to provide turn key installation, including annular grouting. The tunneling contractor reached out to CJGeo, knowing that CJGeo’s CJFill cellular grout could:
- fill each annulus in a single lift
- not over-pressurize or damage the brand new carrier pipe
- not float the brand new carrier pipe
CJGeo took two days onsite to grout both tunnels (one day per tunnel). The final design for the grout on this Florida annular space grouting project was 38lb/cuft CJFill-Standard, with a 250psi unconfined compressive strength at 28 days. While the Florida DOT’s minimum strength for cellular grout is only 80psi at 28 days, the designer wanted a higher strength grout than the minimum acceptable by the DOT.
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Tennessee Annular Space Grouting
The Job
This Tennessee annular space grouting project is located in Brentwood. Brentwood is part of the Nashville metro area, which is rapidly expanding. As part of large water main installation, a 970′ tunnel, ranging from 60 to 78 inch diameter was mined through a small mountain. To ensure long term service improvements, a 42″ DIP water line occupies the tunnel.
The Challenge
The tunnel support is wood lagging, which is not permanent. Therefore, the annular space requires grouting to ensure long term stability of the new water line and adjacent ground.
Because the Nashville market is so hot, it’s really hard to get any concrete deliveries, let alone specialty mixes. The tunneling contractor knew that they would be hard pressed to self-perform the grouting using flowable fill. This was if they could even get material. So, they reached out to CJGeo about performing the annular space grouting with cellular grout made onsite with one of CJGeo’s custom mobile cellular batch plants.
The Solution
CJGeo proposed and installed 25lb/cuft CJFill-Ultra Lightweight cellular grout for the annular space grouting. By generating material onsite directly from bulk cement, using a dry batch plant, the 425CY annular space grouting took fewer than five hours.
Buoyancy control on this project was very easy. Because CJFill-Ultra Lightweight cellular grout is so much lighter than water, filling the carrier with water was sufficient to ballast the pipe against uplift during grouting. No casing spacers or top blocking needed. The American Concrete Institute classifies CJFill-Ultra Lightweight as low density controlled low strength material.
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Georgia Annular Space Grouting
The Job
This Georgia annular space grouting project is located in Athens, Georgia. The project involves three tunnels connecting four shafts. Tunnel lengths range from 116LF of 700LF, with diameters between 58.5″ ID to 9×9 arch segments.
The Challenge
In order to keep the carrier pipe from floating during grouting, the maximum allowable grout density was 70lb/cuft, and the minimum compressive strength was 200psi. Material had to be highly mobile, to facilitate placement through the 700LF of tunnel.
The Solution
CJGeo proposed 38lb/cuft cellular grout to the tunneling contractor. Over a period of three days, CJGeo batched and placed 1320CY of CJFill-Standard. Batching was performed utilizing an onsite dry mix plant, which was fed directly by bulk cement trailers. The minimizes the required laydown area on a very tight site.
Because of the very low grout density, the carrier pipe buoyancy control was simply water filling.
To address the transition from a round tunnel to an arch tunnel, CJGeo worked with tunneling contractor to design a sacrificial pipe venting system.
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NY Thruway HDD Annular Space Grouting
The Job
This HDD annular space grouting project is east of Buffalo, New York, under the New York Thruway. As part of distribution improvements, National Grid’s contractor bored 830LF through rock using HDD. The bore was 30″, with a 16″ HDPE casing, carrying three, 4″ HDPE conduits.
As part of the installation, the NY Thruway Authority call for casing back grouting, and the casing pipe’s annular space grout filling.
The Challenge
The proposed back-grout had to be:
- pumpable 830LF at very low pressure,
- dense enough to displace the 10 pound per gallon drilling mud, and
- provide sufficient strength to meet Thruway requirements.
The proposed annular space grout had to be:
- pumpable 830LF at very low pressure,
- light enough to not apply excessive pressure on the conduit pipes, and
- also provide sufficient strength to meet Thruway requirements.
The Solution
CJGeo proposed two different grout mixes to meet the project requirements. 85lb/cuft CJFill-Under Water casing backgrout for the displacement of the 10PPG (75lb/cuft) drilling mud. And 25lb/cuft CJFill-Ultra Lightweight annular space grout within the casing.
CJGeo’s crew mobilized to the site, and successfully performed the back-grouting and annular space grouting in a single day. A tremie pipe strapped to the HDD casing was used for the back grouting. By pumping the 85lb/cuft (11 pound per gallon) CJFill-Under Water to the low point, the drilling mud was floated out of the reamed hole annulus.
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Upham Brook Annular Space Grouting
The Job
This Upham Brook annular space grouting project is located in central Virginia. A sewer trunkline expansion in Richmond, Virginia required five bored road crossings ranging from 60″ to 72″.
Tunnel lengths are from 200LF to nearly 600LF. Mining is through rock using slurry micro-tunneling. One tunnel had mixed face conditions, which was unanticipated.
The design engineer required cellular concrete for annular space grouting due to run length, and buoyancy control of the carrier during grouting.
The Challenge
Not many; the longest run on this project, 600LF is a relatively short distance to push cellular concrete. Three of the four tunnels are round. The fourth tunnel is a combination of a round, MTBM-mined tunnel that transitions to a hand mined arch. The hand mine arch was to rescue the MTMB, which became stuck under a triple track CSX rail line. There was very poor access (the rescue shaft is in the CSX right of way).
The Solution
CJGeo proposed 38lb/cuft non-permeable CJFill-Standard low density controlled low strength material to meet the designer’s 200psi 28-day compressive strength requirement.
Over four different mobilizations, CJGeo successfully placed approximately 900CY of annular space grout.
The LD-CLSM generation was wet batch. Wet batch generation was chosen due to the relatively small daily volume of material placement and very tight sites.
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I-66 Annular Space Grouting
The Job
During the widening of Interstate 66 near the interchange with US-15, nine new culverts were installed by jack and bore, and one via direct jacking. The carrier pipes were a mix of spiral metal, precast concrete, and corrugated HDPE, and ranged in length from 150 to 350 feet.
The Challenge
The contractor, who was responsible for grouting, was concerned about carrier pipe buoyancy during grouting, and also run length. All work had to be done from one side of the interstate highway (three lanes in each direction, plus full-width shoulders and a median strip), as there was no access on the far side.
The Solution
CJGeo proposed 30lb/cuft CJFill-Ultra Lightweight cellular concrete for the annular space grouting mix design. Cellular concrete is the preferred material for annular space grouting because it is highly flowable, and reduces the chances of damage to carrier pipes in long placements. Its low unit weight also reduces carrier pipe buoyancy. CJGeo placed 350CY of cellular grout to successfully complete the jack and bore annular space grouting over three different mobilizations.
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CPVC Annular Space Grouting
THE JOB
This CPVC annular space grouting project is located in Leesburg, Virginia. Leesburg is outside of Washington, DC, and is a rapidly growing suburban community experiencing explosive growth of data centers, which is driving similar growth in water infrastructure. During the construction of commercial development, a 200LF of 16″ CPVC waterline was installed via jack and bore, through a 36″ casing. The casing crosses a suburban collector road, which is six lanes wide.
THE CHALLENGE
Due to site limitations, only one end of the pipe was accessible for grouting. The length of the placement was approximately 200LF. So, grout had to travel 200LF at low pressure while ensuring a complete fill without damaging the delicate carrier pipe material.
CPVC is relatively sensitive to heat of hydration, particularly when compared to ductile iron and fiberglass pipe materials.
THE SOLUTION
Due to the relatively low volume, and heat sensitivity of the pipe, CJGeo proposed performing this CPVC annular space grouting with wet-batched 30lb/cuft CJFill-Ultra Lightweight low density controlled low strength material.
To control carrier pipe buoyancy during grouting, the jack and bore contractor filled the CPVC pipe with water. This was accomplished by using pipe plugs. To address the inaccessible vent end, the customer stubbed a vent pipe to the surface prior to backfilling the bulkhead.
A CJGeo CJFill cellular grouting crew took less than one day to complete the grouting. Confirmation of will was venting of uniform material from the far end vent pipe.
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HDPE reline annular space grouting
THE JOB
A utility contractor installing 500LF of 48″ HDPE reline pipe through a 63″ CMP culvert required annular space grouting done at very low installation pressure yet able to ensure complete filling of the washouts outside of the CMP. This HDPE reline annular space grouting project is located in Baltimore, Maryland.
THE CHALLENGE
Due to traffic control limitations, only one end of the pipe was accessible for grouting. Therefore, all grout installation was done with up to 200LF of pumping to get to the bulkhead and then up to 500 feet of travel through the annulus via sacrificial grout tubes. Bulkhead leaks usually result from extensive voids outside of the host pipe. This pipe’s invert corrosion posed unique challenges for containing the annular space grout. CJGeo proposed cellular concrete for the annular space grouting. Cellular concrete is highly flowable. High flowability ensures low installation pressure, reduces flotation of lightweight carrier pipes, and ensures complete void filling outside of the host pipe. Using cellular concrete for annular space grouting was specified by the HDPE slip lining pipe manufacturer.
THE SOLUTION
CJGeo successfully performed this HDPE reline annular space grouting project over two days, in two lifts. Multiple lifts reduce the heat of hydration and carrier buoyancy. The cellular concrete-filled all of the voids outside of the host pipe. The peak pressure at the pump did not exceed 15PSI throughout the project. Therefore, the project was successfully completed without floating, deflecting, or damaging the HDPE slip line pipe.
CJGeo placed 30PCF wet cast density CJFill-Ultra Lightweight, with a 125psi compressive strength for this project. With a 24 hour penetration exceeding 50psi, 30PCF cellular concrete reduces buoyancy with its low unit weight, provides adequate strength, and rapid stability.
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North Jersey Annular Space Grouting
THE JOB
This North Jersey annular space grouting project is located in Paterson, New Jersey. A 30″ brick sewer in New Jersey started to unravel during an open excavation point repair. The municipal engineer directed the utility contractor to use welded HDPE pipe to reline the sewer instead of finishing the open cut point repair.
THE CHALLENGE
The HDPE slip lining contractor had four requirements for grouting:
- No more than 10psi grouting pressure, as measured at the bulkheads
- A mix which minimized carrier buoyancy
- Three day turnaround from notification to completion
- 200psi strength at 28 days
THE SOLUTION
CJGeo proposed 38PCF wet cast density cellular concrete for the annular space grouting. Cellular concrete is highly flowable. High flowability ensures low installation pressure. 38PCF cellular concrete reduces exerts 60% less buoyancy force compared to traditional weight grout. 38PCF cellular concrete reaches approximately 250psi at 28 days, when generated through the ready mix supply chain.
CJGeo mobilized to the site with two days’ notice. The CJGeo cellular concrete crew used continuous generation to generate and place the 38PCF cellular concrete to complete this North Jersey annular space grouting project. Peak pressure at the bulkheads never exceeded 5psi. All 500LF of the annulus was grouted in a single day, between four different manholes (three sections).
Confirmation of fill was uniform material venting at each bulkhead.
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