3D geological modelling to aid efficient remedial works design and planning

Upper Chelburn is a 200 year old impounding reservoir with northern and southern earth-fill embankments. The works at Upper Chelburn form part of a targeted risk reduction strategy implemented by United Utilities (the client) termed ‘Portfolio Risk Assessment’ which when used in conjunction with their ‘Toolbox’ assessment highlights key risks to be addressed to reduce the probability of failure to an acceptable level.

Extensive ground modelling has been successfully applied to inform the design of permeation grouting; new spillway; sheet-piling and wave-bund. This has added-value throughout the design and further, by engaging the construction team, client, and subcontractor throughout the delivery of the works. The modelling has enabled both the grouting and sheet piling solutions to be highly targeted, reducing both programme and cost whilst also allowing for the effective design and management of temporary works design for a large historical landslip present on the site.

As a portion of the works requires a third party to be satisfied as to the quality of the recorded output, constant tracking of the developing solution throughout the works has allowed for greater client, construction team, and subcontractor engagement, as well as greater overall confidence in the output provided. Ultimately the contract records have been used to achieve sign-off of the works as a whole, to satisfy a client commitment to OFWAT.