In situ foundation improvement for upstream raising of embankments using dried tailings

Autonomous tailings operation

Ground improvement via dewatering methods can provide significant savings in the order of A$ 1,000,000

for a moderate upstream-raising foundation-improvement programme.

Such works should only be considered with a geotechnical engineering programme that includes

investigation, design and monitoring.

Ground improvement using in situ dewatering equipment (MudMasters) has been successful for the

preparation of foundations for the upstream raising of embankment walls. This method does rely heavily on

climatic conditions and requires a detailed ‘daily time step’ plan to maximise drying rates during drier

months. Evaluating this progress daily using a range of different and inexpensive techniques allows

operational activities to be tailored to suit the conditions.

The provision of additional equipment does not always mean increased dewatering/drying rates and requires

ongoing supervision/monitoring to avoid “repulping” dried tailings. It is by maximising the value from the

necessary equipment that the greatest benefits will result. The AMC plan includes dewatering

patterns and frequency rates to suit site conditions and tailings composition and rheology specifically.

It is suggested that when considering ground improvement of tailings for upstream construction, the

owner provides sufficient contingency for conventional ‘bridging layers’ in areas where greater than 8 m of

consistently very soft tailings exist (i.e. without any harder/dense layers throughout). Conventional bridging

layers may include the use of rock fill/high strength geotextiles/geogrids. It is noted that before these

methods are adopted, a deep recovery/dewatering method could be tried (and modified accordingly to suit

site conditions) using available MudMaster equipment. It is only when negligible strength gain is observed

that the alternative methods would be adopted.

This process has been successfully used at several sites.

See the full white paper:

in_situ_foundation_improvement_upstream_embankment_raising_dried_tailings.pdf

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