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.