Gully #2 at Glen Bowen Station… the gully scarp averages 2.5m-3m high.
THE actively-eroding footprint of Gully 2 has a perimeter of about 1km, with an internal area of 1.1ha.
The banks of the gully scarp are on average 2.5-3m high. The drainage lines within the gully all converge to a single drainage line discharging into the Bowen River.
The Gully 2 remediation design consists of the following works:
- Reshaping of the northern and central complex gully networks into two stabilised and free-draining basins that involves bank battering and topography reshaping through cut to fill-and-compaction earthworks operations.
- Reshaping of the southern complex gully network into a third stabilised and free-draining basin.
- Reshaping of a small alluvial gully adjacent to Basin 3.
- Construction of three rock cut-off walls at the downstream extent of each of the three basin reshaping works.
- Construction of rock check dams in the beds of the three reshaped basins.
- Treatment of all the reshaped surfaces to consist of:
- application and incorporation of gypsum to all reshaped and disturbed surfaces;
- spreading topsoil stripped from the footprint of the works; and
- applying soil ameliorants, fertiliser and drill seeding.
Gully #4 at Glen Bowen Station… it covers an area of almost 5ha.
Gully 4 is about 200 metres from Gully 2.
Gully 4 differs from the other gullies of interest on Glen Bowen Station, having an upstream catchment approximately four times the size of the gully’s footprint.
The actively eroding footprint of Gully 4 has a perimeter of about 1.2km, with an internal area of 4.8ha. The banks of the gully scarp are on average 0.6m high.
The Gully 4 remediation design consists of the following works:
- Rock chutes designed to move flows to the bed of the gully and prevent future migration of gully heads from occurring.
- Earth bunds to be constructed on either side of each rock chute to direct flows to the crest of the rock chutes.
- Reshape the gully network into two stabilised and free-draining basins by battering banks and reshaping land features to reduce water flows and to prevent ponding occurring on the sodic and dispersive soils.
- The reshaping of shallow gullies and gully scarps to manage runoff.
- Construction of a series of rock check dams to help control flow velocity and to trap sediment allowing the structures to act as drainage and sediment control devices.
- Cover treatment will include cornet matting, hydromulch, hay or bagasse (depending on availability) to achieve 50 per cent cover of the disturbed footprint prior to the first wet season.
- Amelioration will also include spreading of an ameliorate mix of topsoil, fertiliser and gypsum, based on soil sample results.