Consolidation grouting for Shaft Collar Construction

Compaction Grouting for Shaft Collar Construction

Case description

A new mine shaft was being constructed through deep overburden consisting of heavy clay layers on top of fractured bedrock.

The general contractor had driven sheet piles into bedrock and was in the process of excavating the shaft collar when soil migration was observed at the interface between sheet pile perimeter wall and underlying rock strata, resulting in a delay in construction.

The contractor was able to excavate within the shaft collar on day shift but overnight and on weekends, the surrounding clays would gradually seep through openings beneath the sheet piles and partially refill the shaft collar.


Vertical steel pipes were driven with the pile driver down to the bedrock interface around the outside of the sheet pile perimeter and a thick cement grout was injected to compact disturbed soil conditions and create stable lenses of cement grout at the overburden/rock interface. As compaction grouting progressed and increased grouting pressures were achieved, the vertical grout pipes were systematically raised to create columns of stable material within a few meters above the bedrock interface.

Following compaction grouting operations around the perimeter of the shaft collar, the general contractor was able to complete shaft collar excavation to bedrock interface without further creep of surrounding clay materials and to proceed with shaft collar construction.

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ground improvement under a 90-years building in SoHo, NY

Ground Improvement Beneath Old Building Foundations

Case description

A property developer acquired two adjacent buildings in the SoHo area of New York and was in the process of constructing new roof-top penthouse and adjacent structures.

To support the additional structural building loads, building design engineers required that soil conditions beneath the existing 90-year-old building foundations be improved by soil grouting operations.

The geotechnical contractor engaged by the property developer retained Peter White to design the cement grouting operation, provide rental cement grouting equipment and accessories and to supervise the startup of grouting operations by the contractor’s personnel.


As anticipated, drilling quickly revealed that foundation conditions were not as shown on the original construction drawings, so the contractor’s drilling and grouting methodology was quickly adapted by Peter according to the existing site conditions.

Cement grouting was successfully undertaken using microfine cement to achieve satisfactory penetration and consolidation of the existing foundation soils without causing uplift or damage to the existing building structures.

The cement grouting equipment selected for this project was small and portable for moving through various sub-basement rooms where grouting operations were undertaken but with appropriate discharge volume and pressure for the encountered site conditions.

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workers at dam jobsite for consolidation grouting

Consolidation Grouting for Tailings Dam Construction

Case description

Upgrades to an existing tailings storage facility included construction of a water diversion channel and related berms to divert groundwater, as well as the construction of a new embankment dam downstream of the original tailings dam to satisfy current environmental standards.

The scope of work involved the construction of a bedrock foundation grout curtain over a length of 200 m and to a depth of 10 m into rock.

A major engineering challenge was to complete the grout curtain into bedrock beneath a deep rock trench that was filled with saturated soil that the general contractor was unable to excavate due to proximity to the original tailings dam.


The general contractor retained Peter White to provide grouting engineering services, cement grouting equipment and accessories, and to supervise and direct all aspects of grout curtain construction utilizing the contractor’s own personnel.

The contractor constructed a thick concrete pad within the deep rock trench.

Drill holes of 3-inch diameter were drilled through the concrete pad as required using a hydraulic top-hammer drilling rig.

Ready-mix high-density cement-slag grout mix was delivered by ready-mix trucks from a local batch plant and injected beneath the concrete pad to displace saturated soil situated between the concrete pad and underlying bedrock.

After a few days of injecting ready-mix cement-slag grout, the underlying zone between the concrete pad had been adequately consolidated that holes could be drilled down to bedrock and used for conventional cement grouting operations.

Within a few additional days of conventional cement grouting as directed by Peter, ground conditions had been improved sufficiently that drill holes could be advanced to bedrock to successfully complete final stages of grout curtain construction.

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Bitumen/cement based injection to stop water inflows in a drainage tunnel below an open pit

Water Cutoff Grouting for Deep Drainage Tunnel

Case description

A major tailings inflow in an underground drainage tunnel, which peaked at approximately 7,000 l/sec needed to be sealed.


Provided technical grouting expertise during plugging of drainage tunnel located 500 feet below abandoned open pit filled with tailings using cement grout, polyurethane and hot bitumen grouting materials.

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large grout curtain contruction for Antamina tailings dam

Large Grout Curtain Construction Project

Case description

Building the Antamina mine in Peru required the construction of a 1,000 m long x 130 m high concrete-face, rock-fill tailings starter dam to impound water for start-up of milling operations and for subsequent retention of tailings.

The sedimentary bedrock geology consisted of siltstones and mudstones with interbedded limestone layers, including various discontinuities such as faults and open joints.

The grout curtain for the tailings starter dam required 40,000 m of drilling and injection of 2,800 tonnes of cement.

It was critical that the grout curtain be completed to the required performance standards prior to the winter rainy season to impound sufficient water for startup of the mill.

The project engineers were concerned that the dam contractor did not have sufficient expertise and resources to accomplish the required scope of grouting work on schedule and retained Peter White to provide ongoing technical support for the contractor’s grouting operations.


Working with the owner’s engineering team and the contractor’s construction crews, Peter White was involved in all aspects of the tailings starter dam grout curtain, providing hands-on direction of grouting operations being undertaken by various specialty subcontractors.

In addition, Peter quickly designed and site-fabricated real-time grout monitoring equipment with computer-based data collection to provide relevant grouting and water testing information for review and analysis by the project engineering team.

After months of around-the-clock drilling and grouting work, the tailings starter dam grout curtain was successfully completed on schedule in advance of the winter rainy season. The Antamina mill was commissioned on schedule the following year.

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Pipeline Abandonment using cement grout

Sewer Pipe Decommissioning using Cement-Bentonite Grout

Case description

As part of the remediation of the Sydney Tarponds and Coke Ovens site, two large-diameter concrete drainage pipes were to be decommissioned by filling with low-strength cement grout.


A general contractor contacted Peter White for engineering assistance to develop a grouting plan and to prepare a list of required equipment and bill of materials for decommissioning of two drainage pipes.

Peter recommended a low-strength cement-bentonite grout mixture for this application to complement existing grouting equipment owned by the contractor.

Bentonite slurry was prepared in advance and hydrated overnight using a series of portable plastic tote tanks.  Decommissioning operations were accomplished under Peter’s supervision using diaphragm pumps to transfer bentonite slurry to the grouting plant where dry cement was mixed and the resulting cement-bentonite mixture pumped to fill the respective concrete drainage pipes.

The general contractor’s crews successfully completed cement-bentonite work within each pipe at a high rate of production, completely filling each pipe within a few hours.  The cement-bentonite grout produced a stable, thixotropic and cohesive mixture.

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test cell

Soil Stabilization for Test Cell Excavation

Case description

A multinational equipment manufacturing company required a deep foundation to be excavated through granular soils with a high water table for installation of a new test cell within an existing plant facility, without disrupting adjacent equipment operations or causing settlement of building structures. Due to space constraints and ongoing equipment operations, conventional deep foundation shoring systems could not be utilized within the existing manufacturing plant.


A sleeve pipe grouting plan was designed and implemented by our grouting engineers to consolidate perimeter walls around the proposed deep excavation using water-activated polyurethane resin.

Where possible, sleeve pipes were installed at a spacing of 18 inches apart to a depth of 10 feet around the perimeter of the proposed excavation. At locations where various obstructions precluded sleeve pipe installation, conventional open drill holes were systematically drilled and injected using down stage techniques to complete soil stabilization around the perimeter of the excavation.

Water-activated, low-viscosity polyurethane resin with low accelerator dosage was systematically injected by our grouting specialists at a flow rate of 1/2 gallon per minute through each sleeve pipe port and drill hole to effectively permeate and stabilize the surrounding soil.

Upon completion of soil stabilization grouting work, the general contractor was able to proceed with test cell excavation and foundation construction as planned without encountering any delays or problems.

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