Wambo Coal AEMR 2010-2011 - Peabody Energy

2010-2011 AEMRTopsoil stripped ahead of mining will be applied tothe reshaped surface in an even layer generally notless than 100mm. Topsoil is placed using reardump haul trucks, or ejector trucks, and spread withdozers or graders. Once spread, the topsoil surfacewill be disc or chisel cultivated to create a texturedsurface which assists in trapping surface runoff,provides seed entrapments and createsmicroclimates favourable for seed germination.Where biosolids are used, cultivation also integratesthe topdressing material, which is a requirement ofthe EPA biosolids handling guidelines.Following surface preparation, vegetationestablishment across the rehabilitated area iscommenced. The aim of revegetation is to minimiseerosion and facilitate the development of the postminingland-use, be it agricultural production orhabitat/ecosystem enhancement.5.1.1.1 Rehabilitation PerformanceDuring the previous reporting period, an Open CutMOP was approved for the period of 2010-2016.The Open Cut MOP covers all aspects of the OpenCut operations including mining, rehabilitation andtailings management.The total hectares of disturbance and rehabilitationat the commencement of the new MOP period (July2010) was 998.8ha and 270.3ha, respectively.Existing rehabilitated areas include the Whynot,Low-wall and Ridge Dump areas, RL160 Dump,Charlies Hole, Wombat Hill, and Radio Shack in thecurrent Open Cut plus older rehabilitation fromprevious Open Cuts.During the previous reporting period, approximately84.4ha was rehabilitated within the Open Cut. Thisessentially accounted for all available dump areaready for reshaping and rehabilitation. Furtherrehabilitation planned for the 2010-2011 reportingperiod was reliant on the completion of overburdendumps, particularly in the Rug/ Ridge dump area.Due to delays in overburden removal from theHomestead Pit (which was being placed on the Rug/Ridge dump), no significant dump areas wereavailable for reshaping, and no open cutrehabilitation was completed during the period.The major rehabilitation maintenance project wasthe remediation on the North Wambo CreekDiversion (NWC Diversion). Remedial works werecompleted between April and June 2011 andincluded the repair of several failed creek banks,wash outs, rock armoured structures and vehiclecrossing points (as listed in Table 5.2 and detailedin Section 5.1.3).5.1.1.2 North East Tailings DamThe rehabilitation of the area known as the NorthEast Tailings Dam (NETD) has been established asa stand alone project within Peabody’s Wambo CoalOperation. Initial works commenced at the NETDduring the 2008/2009 AEMR reporting period. Thedam, which was discontinued as an active disposalsite in 2004 following Department Approval underSection 127, has been the subject of a number ofstudies to identify a safe and viable method ofcapping the relatively weak surface. WCPL havebeen working together with Australian TailingsConsultants to develop a capping strategy utilisingreinforced geogrid and controlled layers of coarsereject and overburden placed by specialist lowground pressure equipment.The scope of the NETD capping project is torehabilitate the 1220m long by 200m widedecommissioned tailings storage facility.WCPL have investigated and evaluated the cappingmethod utilising purpose built low ground pressureequipment, in conjunction with Geotextilereinforcement. Extensive design works have beenundertaken to develop the concept and provideengineered solutions to cap the weak tailingssurface. The design has considered the strength ofthe current crust (verified through Shear VaneTesting), the equipment to be used and the cappingmaterial to determine the reinforcement and theplacement method required to ensure the safety ofthis operation.The planned rehabilitation for next year is 49 ha.This work is planned for the Rug/ Ridge Dump.All disused tailings dams are rehabilitated with theexception of the North East Tailings Dam, which iscurrently being capped for rehabilitation (seeSection 5.1.1.1).Page 84