Diaphragm Wall Technique Used in a Different Way â€“ Cutting Trenches up to 823 ft (251 m) for an Exploration and Bulk Sampling Program-Paper

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In 2019, a trench cutter system was adapted for bulk sampling at the Star Kimberlite deposit in Saskatchewan, Canada. Unlike its usual role in constructing underground walls, the equipment excavated ten trenches to depths of 225–251.1 m, reaching a commercial trench-cutting depth record. The program aimed to collect high-quality, diamond-bearing Kimberlite samples for processing.<br /><br />The system combined a BC 50 trench cutter, specially designed hose handling, slurry treatment equipment, and a Kimberlite Separation Unit. A 2017 suitability test helped establish sample-quality criteria and guide equipment settings. Before excavation, deep guide walls stabilized loose upper soils. The team then separated overburden from Kimberlite, screened and washed the Kimberlite, and packed samples into bags for secure storage.<br /><br />Operations faced variable geology, including loose sands, cohesive clays, silt, cobbles, and boulders. These conditions caused cutter-wheel clogging and wear, while fine material affected slurry properties and trench stability. Careful slurry management, equipment adjustments, and continuous optimization of cutting parameters were therefore essential. Sample intervals also required system clean-outs to prevent mixing and preserve sample integrity.<br /><br />The project involved more than 2 km of cutting over 126 days. It produced 6,848 bags—about 8,271 wet tonnes—of Kimberlite, with more than 95% of samples meeting the high-quality criterion by the end of the season. Trenches were surveyed and backfilled, with procedures adjusted after the original Kimberlite backfill material proved unsuitable.<br /><br />The successful demonstration led to plans for 14 additional trench locations in 2020. The project showed that trench-cutter technology can support deep, controlled bulk sampling and may have broader applications in mineral exploration and mining.

Keywords

Star Kimberlite

trench cutter

bulk sampling

diamond exploration

kimberlite

Saskatchewan

slurry management

mineral exploration

deep trenching

sample quality