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Annular Space Grouting Projects

By applying unique solutions to increase the safety and longevity of our environment.

Garden State Parkway grouting

The Job

As part of ongoing large diameter culvert rehabilitations and replacements, four new bored stormwater crossings and the original culvert they replaced needed to be grouted. The tunnels ranged from 120″ down to 74″, for a total of 312CY, and the abandonment required 405CY.

The Challenge

Grout needed to meet the minimum strength requirements of the owner, and ideally needed to be light enough to facilitate single lift annular space grouting.

The Solution

CJGeo’s preconstruction team worked with the general contractor to design a grouting program which facilitated single lift abandonment of the original culvert, and single lift grouting of the four various annular space runs. CJGeo utilized onsite dry batching to generate 30lb/cuft CJFill cellular concrete.

Union County Annular Space Grouting

The Job

Due to a rapidly increasing population, Union County, North Carolina installed a new raw water intake, which required a nearly 11 mile long raw water line to supply a water treatment plant.

The Challenge

While there were dozens of open cut road crossings along the alignment, 17 crossings were bored, and require annular space grouting per NCDOT requirements. Given the length of the project, there weren’t any ready mix providers who could cover the entire project.

The Solution

CJGeo has multiple NCDOT approved mix designs, CJGeo was able to source material from two different ready mix providers, and grout the annular space on each crossing per NCDOT requirements.

Neuse River Annular Grouting

The Job

The City of Raleigh’s Neuse River East Parallel Interceptor project involves the installation of miles of large diameter gravity sewer. Two road crossings required 120″ tunnels for installation of the 96″ HOBAS pipe.

The Challenge

While neither tunnel was very long, due to the 10′ diameter tunnels, grouting needed to be performed in two lifts. This allowed buoyancy control of the HOBAS carrier pipes to be maintained with partial water filling, and eliminated the need to perform hold down blocking during the carrier pipe installation.

The Solution

CJGeo proposed an NCDOT approved cellular grout mix due to passage through an NCDOT right of way, and then grouted the two tunnels each in two lifts. Fill was confirmed with uniform grout vented out the 12 o’clock vent position at the far end of each tunnel.

Dairy Branch Annular Space Grouting

The Job

Charlotte Water’s Dairy Branch Tributary Sewer project is an approximately $30mm capacity improvement project to address increased density.

The Challenge

As part of the project, a 430LF tunnel ranging from 58″ bore to a 4×4 arch was mined. The carrier pipe was 36″ ductile iron, and required annular space grouting using a mix which wouldn’t float the carrier pipe, and would be able to entirely fill the tunnel at low pressure.

The Solution

CJGeo proposed an NCDOT approved cellular grout mix due to passage through an NCDOT right of way, and then placed the 275CY of grout in a single lift over two hours at approximately 5psi of placement pressure.

Bay Park Annular Space Grouting

The Job

The Bay Park Conveyance Project is using a combination of microtunneling and slip-lining to redirect treated 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 running 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 must be performed at night, and 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 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.

To address material logistics, each night’s cement consumption is staged locally during the day, and then shuttled in to each placement location during the pours.

SW Florida Annular Space Grouting

The Job

City of Fort Myers’s South AWWTF Reclaimed Water Transmission Main.

The Challenge

Two 52″ tunnels with 32″ DIP carriers requiring annular space grouting. Tunnel 1 was 170LF, Tunnel 2 was 607LF. The

The Solution

CJGeo grouted both tunnels utilizing cellular grout with 250psi at 28 day compressive strength.

Brentwood Annular Space Grouting

The Job

As part of large water main installation, a 970′ tunnel, ranging from 60 to 78″ in diameter was mined through a small mountain. A 42″ DIP carrier pipe was then installed by the tunneling contractor.

The Challenge

The annular space needed to be filled with grout to ensure long term stability of the carrier pipe, and of the surrounding ground in an area where the tunnel was hand mined through soil with rib and lagging.

The Solution

CJGeo proposed and installed 25lb/cuft cellular grout for the annular space grouting. By generating material onsite directly from bulk cement, using a dry batch plant, the 425CY annular space was filled in fewer than five hours.

UNO Annular Space Grouting

The Job

As part of a sewer upgrade, three tunnels were mined between four shafts, in Athens, Georgia. Tunnel lengths ranged 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 cellular grout. Batching was performed utilizing an onsite dry mix plant, which was fed directly by bulk cement trailers, minimizing the required laydown area on a very tight site.

Because of the very low grout density, the carrier pipe only needed to be braced by filling it partially with water.

NY Thruway HDD Annular Space Grouting

The Job

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 required the casing to be back-grouted, and the casing pipe’s annular space grout filled.

The Challenge

The proposed back-grout had to be pumpable 830LF at very low pressure, dense enough to displace the 10PPG 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 casing background for the displacement of the 10PPG (75lb/cuft) drilling mud, and 25lb/cuft 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.

Upham Brook Annular Space Grouting

The Job

A sewer trunkline expansion in Richmond, Virginia required five bored road crossings ranging from 60″ to 72″.

Tunnel lengths ranged from 200LF to nearly 600LF and were mined through rock using slurry micro-tunneling.

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.

The Solution

CJGeo proposed 38lb/cuft non-permeable cellular concrete to meet the designer’s 200psi 28-day compressive strength requirement.

Over four different mobilizations, CJGeo successfully placed approximately 900CY of annular space grout.

Cellular concrete generation was performed using wet batch continuous generation. Wet batch generation was chosen due to the relatively small daily volume of material placement and very constrained sites.

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