Doug Hood Mining

Stockton Mine – Fines retention dam

August 31, 2020

In early 2020 Doug Hood Mining Ltd was tasked with constructing a fines retention dam for BT Mining at Stockton Coal Mine.
The dam embankment will require approximately 500,000 m3 of drilled and blasted bulk material excavated with an EX1900 primarily from a stormwater sump excavation and carted 1km using multiple 777D dump trucks.
D8 and D9 dozers and smaller ancillary plant will be used in the sump borrow area and for controlling layer depth and compaction in the dam embankment.
A french drain will be constructed beside adjacent batters at the downstream toe of the dam.

 
Construction work commenced with dam floor footprint clean up.

Initially, a small plant fleet comprising an EC390 excavator and multiple A45G articulated dump trucks excavated unsuitable material over footprint margins which included cleaning out gullies and localised blasting of steep faces.

A crew on the ground using water and air blasting techniques cleaned back to competent rock.

 
 
 
Excavating the margins of a coal floor and pockets of unsuitable material in gullies down to rock:

Air blasting to expose all interfaces:

Water blasting to remove a fine silt layer:

As cleaning progressed graded material was placed on selected rock interfaces:

Compaction trials were used to develop a methodology to confirm “layer lift height” and material size:

The haulroad was extended and widened and larger culverts were installed:

Drilled and blasted bulk material for the dam embankment utilises a plant fleet including an EX1900 excavator and multiple 777D dump trucks:

Rock breaking will be used as required to utilise oversize rock in the fill to achieve compaction of the fill at layer thickness of 1.5m:

Vertical in-situ rock edges are taken back to 45 degrees via drill and blast to ensure target compaction of initial layer lifts to all surfaces:

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