Wambo Coal AEMR 2010-2011 - Peabody Energy

2010-2011 AEMR3.3 Erosion & SedimentControl3.3.1 Environmental ManagementErosion and sedimentation is managed inaccordance with WCPL Erosion and SedimentControl Plan (ESCP), a requirement of ConsentConditon 32, Schedule 4 of DA305-7-2003. TheESCP is a component of WCPL’s Site WaterManagement Plan as required under Condition 30,Schedule 4 of DA305-7-2003. The main principlesof the ESCP include: Separation of runoff from disturbed andundisturbed areas where practicable; Construction of sediment structures orutilisation of existing mine water storages tocapture runoff up to a specified design criterion;Construction of surface drains to facilitate theefficient transport of surface runoff. Drains aredesigned using trapezoidal or parabolic crosssections;andProgressive rehabilitation stabilisation of mineinfrastructure areas.These principles take into account the generalrecommendations for site drainage works presentedin “Managing Urban Stormwater – Soils andConstruction Volume 1” (Landcom 2004).A number of strategies are used on site for erosionand sediment control including:The establishment of diversion banks on theupstream side of the site to divert clean wateraround the site and into natural drainage lines;The establishment of sediment fencing asrequired on the down-slope side of soilstockpiles;The use of a street sweeper to remove dirt andmud from mine access roads;Monthly monitoring of all sediment controlstructures and maintenance when required;Limiting clearance and disturbance of thenatural environment; andProgressive rehabilitation across site.3.3.2 Environmental PerformanceMonthly inspections of sediment control structuresas well as inspections following rainfall events of 20mm or more in a 24 hour period are conductedacross the mine by WCPL personnel andcontractors. During these inspections, sedimentcontrol structures are inspected for capacity,structural integrity and effectiveness.The routine removal of sediment from a number ofthe sediment control structures, including HalesCrossing Sediment Dam was undertaken during thereporting period. As discussed in the last AEMR, aplan of works to remove coal sediment from a seriesof purpose built sediment dams around the CHPPand product stockpile areas was scheduled for2011. Dredging to remove coal fines and increasethe dam capacity within the Gordon Below FranklinDam commenced in June 2011. The recovered coalfines were reprocessed through the CHPP. The establishment of catch drains inaccordance with relevant criteria (outlined in theESCP) to direct sediment-laden water intosediment control structures; The strategic placement and design ofsediment control structures on site to treatsediment laden water before it leaves site;The placement of hay bales along catch drainsto control the velocity of flow and preventscouring;The establishment of sediment ponds orutilisation of existing mine water structures totreat sediment laden water;Dredging GBF Dam in June 2011During the reporting period WCPL completed aremedial rehabilitation program within the NWCDiversion. Please refer to Section 5.1.4 for furtherdetails about the NWC Diversion rehabilitationworks.Page 47