Wambo Coal AEMR 2011-2012 - Peabody Energy

2011-2012 AEMR
Table 5.2 – Maintenance Activities on Previously Rehabilitated Land
Nature of Treatment
Area Treated (ha)
Report
Period
Next
Period
Comment/Control Strategies/Treatment
Detail
Additional erosion control
works (drains re-contouring, rock
protection)
0
As
required
For the next reporting period WCPL will be
developing an annual maintenance rehabilitation
program.
Soil Treatment (detail – fertiliser,
lime, gypsum etc)
Treatment/ Management (detail
– grazing, cropping, slashing etc)
Re-seeding/ Replanting (detail –
species density, season etc)
Repairs to subsidence induced
cracking
0
0
0
0
As
required
As
required
As
required
As
required
For the next reporting period WCPL will be
developing an annual maintenance rehabilitation
program.
For the next reporting period WCPL will be
developing an annual maintenance rehabilitation
program.
For the next reporting period WCPL will be
developing an annual maintenance rehabilitation
program.
Subsidence cracking repaired along site internal
access roads.
Adversely Affected by Weeds
(detail – type and treatment)
0
As
required
See Section 3.8 for to weed control measures on
other WCPL owned land
Feral animal control (detail –
additional fencing, trapping,
baiting etc)
0
As
required
While no work is proposed directly on rehabilitated
areas, work will be conducted on other WCPL
owned land. Refer to Section 3.8.
5.1 Rehabilitation of Disturbed
Land
5.1.1 Open Cut
Landform reshaping consists of re-contouring
overburden dumps to the designed shape for final
rehabilitation. The bulk shaping of overburden is
undertaken using bulldozers. Reshaping results in
a stable landform incorporating slopes and drainage
which blend in with the surrounding natural
topography. Slope stability is integral to
rehabilitation design and the objective during
rehabilitation planning is to design all slopes to a
gradient of ten degrees or less. Slopes steeper than
ten degrees may be necessary in some locations to
ensure rehabilitation merges seamlessly with
adjacent undisturbed land.
Once bulk reshaping is completed, the landform is
deep-ripped to approximately 300mm, and then the
final trim and rock raking are undertaken. The
ripping loosens up any near surface strata within the
landform that have been compacted during
placement, aiding root penetration during vegetation
establishment.
The final trim smooths out any wash-outs, rough
edges, temporary access tracks, local steep
topography and prepares the surface for
revegetation. Rock-raking removes exposed
surface rock greater than 200 mm in diameter. This
raking is usually done along the contour, leaving a
textured surface that assists with erosion
minimisation until vegetation can be established.
Ameliorants, if required, are applied to the trimmed
overburden surface prior to topsoil spreading.
Topsoil stripped ahead of mining will be applied to
the reshaped surface in an even layer generally not
less than 100mm. Topsoil is placed using rear
dump haul trucks, or ejector trucks, and spread with
dozers or graders. Once spread, the topsoil surface
will be disc or chisel cultivated to create a textured
surface which assists in trapping surface runoff,
provides seed entrapments and creates
microclimates favourable for seed germination.
Where biosolids are used, cultivation also integrates
the topdressing material, which is a requirement of
the EPA biosolids handling guidelines.
Following surface preparation, vegetation
establishment across the rehabilitated area is
commenced. The aim of revegetation is to minimise
erosion and facilitate the development of the postmining
land-use, be it agricultural production or
habitat/ecosystem enhancement.
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