Added value:
Halcrow is the designer to Edmund Nuttall Ltd for the construction of a Hydraulic Isolation Barrier for a shaft some 65m deep currently used for storage of intermediate and low level waste at the Dounreay Nuclear Establishment.  To facilitate the removal of this waste from the shaft the groundwater inflow currently 350m3/day is to be reduced to a manageable flow of less that 15m3/day as a result of the barrier construction.

The project includes the development of suitable grout materials and injection techniques together with the design of a substantial working platform located on the shoreline.

Due to the uniqueness of the project, extensive detailed design of the pre-works site trials was an inherent requirement for project success and included:
>>Off site materials prequalification testing
>>Off site methodology testing
>>Site characterisation of the trials area
>>Grouting field trials
>>Post trials demonstration

The combination of Halcrow expertise in computer modelling, geological interpretation and
materials science plus Edmund Nuttall’s expertise in grouting installation has enabled a
seamless service to the ultimate client UKAEA.

The thorough and advanced nature of the process has enabled the number of boreholes
required for the hydraulic isolation of the shaft to be reduced from a preliminary figure of 352
to an actual number of 165 on this £16m project.

Innovation:
The contract is based on target cost that aligns the commercial interests of the ultimate client
UKAEA, Edmund Nuttall and Halcrow.  All parties work closely together to achieve the
optimum balance between technical excellence and cost. 

Team work:
The project is a model of team working not only between Halcrow and Edmund Nuttall Ltd but
also specialist sub-contractors.  The work requires the specification of leading edge materials
and installation techniques.

Seamless teamwork is essential and Halcrow staff embedded in Edmund Nuttall’s site team
is a beneficial feature of this project.