Wambo Coal AEMR 2010-2011 - Peabody Energy

2010-2011 AEMR2.8.1 Water Supply and UseContinuity of water supply to the CHPP, Open Cutand Underground is important for the processing ofcoal and the operation of the mine. During thisreporting period the site water balance for themining activities was recalculated. This waterbalance is presented in Table 2.5.WCPL manages its water supply through a numberof on site water storage dams. The mine routinelyobtains water from the Hunter River Licence(Number 20AL200631), Wollombi Brook Licence(Number 20SL033872), the Wollemi andHomestead goaf areas and from rainfall runoff.WCPL’s annual water catchment generally matchesoperational water requirements for CHPP and OpenCut usage. In 2009-2010, minimal water wasextracted from the Hunter River to supplementextraction via the Wollombi Brook pumps. Waterextracted from Wollombi Brook (and the HunterRiver) is used to supply the fire suppression systemand underground oprerations.2.8.2 Surface Water ManagementTo minimise the potential for water quality impactsfrom mining operations, a network of water storageshas been established to separate the clean water(runoff from undisturbed areas) and dirty water(runoff from disturbed areas). Rainfall runoff fromundisturbed areas is diverted away from miningareas. Runoff from areas disturbed by mining isdiverted into the onsite dams for use across the site.West Cut Dam and Area C Dam have now beendewatered and are now only sumps.The wash down and runoff water from the CHPPand adjacent stockpiles is accumulated insedimentation ponds which feed into the GordonBelow Franklin Dam network. The Gordon BelowFranklin Dam network is designed to slow the flowof the water and encourage the precipitation of finesediment to drop out. The sediment ponds arecleaned out on a regular basis using a variety ofmethods including dredging and truck andexcavator. Water from these dams is returned to theEagles Nest Dam. A new dredging programcommenced in late 2010 to remove excesssediment from the CHPP dam network.Water stored in South Wambo Dam, Chitter Damand Eagles Nest Dam complex is used in the coalwashing process and for dust suppression at theCHPP.Water is pumped to tank fill points in the Open Cutto allow water carts to fill and assist in dustsuppression. Water for this process is pumped fromthe storage dams and the Homestead Pit (North)decant dam.2.8.2.1 Water Balance & ModelingIn March 2010, WCPL completed a detailed reviewof the operations water balance. The water balanceis based on monitoring data from numerous waterflow meters on site and information provided byWCPL technical personnel.In addition, a comprehensive predictive site waterand salt model was finalised in February 2011, inaccordance with recent development consentrequirements. The completed water model includesa predictive accounting system for water and saltbudgets.2.8.2.2 NWC Discharge ReportIn April 2008, the North Wambo Creek (NWC)Diversion Plan was approved by DoPI, DTIRIS andNOW, subject to a number of approval conditions. Inaccordance with the approval conditions for theNWC Diversion Plan, WCPL must prepare andsubmit a flow assessment report after each flowevent down the diversion.In early June 2011, significant rainfall resulted increek flows down South Wambo Creek, StonyCreek and North Wambo Creek, including flowsdown the NWC Diversion. At the time of writing theAEMR, WCPL has engaged a consultant tocommence a flow assessment report of the NWCDiversion in accordance with the approvalconditions for the diversion. The results of the flowassessment report will be provided in the nextAEMR.NWC Diversion Flow Event June 2011Page 32