Doug Hood Mining

Stockton Mine – Earth dam and stormwater sump update

July 12, 2021

The earth dam and stormwater containment sump under construction by Doug Hood Mining Ltd at Stockton Mine are nearing completion

The 610,000 bcm engineered embankment is approximately 90% complete

With a final crest level of RL737m, the completed embankment will be 30 metres high.

A synthetic liner placed on a 200mm compacted fines layer will be installed on the final upstream face.

The spillway will be lined with a rock rip-rap layer.

The excavation of the mine water treatment sump provided the majority of the drilled & blasted rock for the dam. Sump construction is also nearing completion with inlet and outlet structures still to be constructed.

The bulk earthworks prime fleet was an EX1900 excavator (190 tonne) and 5 x 777D (100 tonne) dump-trucks, with the PC1250 excavator and A45G articulated dump-trucks used for fill placement on the narrowing final dam lifts.

A D9R bulldozer with GPS was used on the dam crest for fill push out and level control.  

Final batter trim is being achieved with an EC380 excavator also fitted with GPS.

D8T bulldozers are being used to track roll the final surface prior to the placement of the compacted fines layer. Articulated 45 tonne dump-trucks and smaller excavators were used when carting unsuitables from the dam footprint preparation, and other miscellaneous ancillary works associated with the various stages of dam construction.

A Montabert rock breaker fitted to an EC290 excavator was used to break up any oversize rock to incorporate in the dam fill lift layers.

Dam crest with final lift in progress

Downstream face with crest at RL737m

Trimming upstream batter and final lift placement

Dam floor cleanup of pockets of unsuitable materials & replacement with clean fill

D8T track rolling downstream batter slope

D8T track rolling upstream batter slope

Sump load-out with PC1250

Sump floor with last flitch to complete dam crest

Dam crest rising in background

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