Wambo Coal AEMR 2011-2012 - Peabody Energy

2011-2012 AEMR
3.3 Erosion & Sediment
Control
3.3.1 Environmental Management
Erosion and sedimentation is managed in
accordance with WCPL Erosion and Sediment
Control Plan (ESCP), a requirement of Consent
Condition 32, Schedule 4 of DA305-7-2003. The
ESCP is a component of WCPL’s Site Water
Management Plan as required under Condition 30,
Schedule 4 of DA305-7-2003. The main principles
of the ESCP include:
Separation of runoff from disturbed and
undisturbed areas where practicable;
Construction of sediment structures or
utilisation of existing mine water storages to
capture runoff up to a specified design criterion;
Construction of surface drains to facilitate the
efficient transport of surface runoff. Drains are
designed using trapezoidal or parabolic crosssections;
and
Progressive rehabilitation stabilisation of mine
infrastructure areas.
These principles take into account the general
recommendations for site drainage works presented
in “Managing Urban Stormwater – Soils and
Construction Volume 1” (Landcom 2004).
The use of a street sweeper to remove dirt and
mud from mine access roads;
Monthly monitoring of all sediment control
structures and maintenance when required;
Limiting clearance and disturbance of the
natural environment; and
Progressive rehabilitation across site.
3.3.2 Environmental Performance
Monthly inspections of sediment control structures
as well as inspections following rainfall events of 20
mm or more in a 24 hour period are conducted
across the mine by WCPL personnel and
contractors. During these inspections, sediment
control structures are inspected for capacity,
structural integrity and effectiveness.
The routine removal of sediment from a number of
the sediment control structures, including Hales
Crossing Sediment Dam was undertaken during the
reporting period. As discussed in the last AEMR, a
plan of works to remove coal sediment from a series
of purpose built sediment dams around the CHPP
and product stockpile areas was scheduled for
2011. Dredging to remove coal fines and increase
the dam capacity within the Gordon Below Franklin
Dam commenced in June 2011. The recovered coal
fines were reprocessed through the CHPP.
A number of strategies are used on site for erosion
and sediment control including:
The establishment of diversion banks on the
upstream side of the site to divert clean water
around the site and into natural drainage lines;
The establishment of catch drains in
accordance with relevant criteria (outlined in the
ESCP) to direct sediment-laden water into
sediment control structures;
The strategic placement and design of
sediment control structures on site to treat
sediment laden water before it leaves site;
The placement of hay bales along catch drains
to control the velocity of flow and prevent
scouring;
The establishment of sediment ponds or
utilisation of existing mine water structures to
treat sediment laden water;
The establishment of sediment fencing as
required on the down-slope side of soil
stockpiles;
Dredging Eagles Nest Dam in June 2012
During the reporting period WCPL commenced
rehabilitation program within the NWC Diversion
Stage 3. Please refer to Section 5.1.4 for further
details about the NWC Diversion rehabilitation
works.
Page 48