Borehole design alternatives in pastefill applications

The success of a paste underground distribution system (UDS) is dependent on the proper installation, operation, and maintenance of its boreholes. The boreholes, particularly the surface boreholes, required over the life of the mine, represent both the greatest cost and risk to the UDS. While hydraulic and operational aspects of paste boreholes have been presented in multiple publications, design, installation, and maintenance aspects have not been widely discussed. The decision to proceed with a certain borehole design is typically based on the local project team’s knowledge or the local equipment available to drill and install the borehole infrastructure. Often a particular borehole design is selected without a complete understanding of the future operational and maintenance challenges that will arise from the design decisions. This paper covers the major design aspects of paste boreholes, presenting both advantages and disadvantages of various design options, so that readers may make informed decisions before implementing a particular solution for their paste project. This paper is a revised version of a paper presented at the 14th International Symposium on Mining with Backfill in 2024.