Wambo Coal AEMR 2010-2011 - Peabody Energy

2010-2011 AEMRUnited Collieries PiezometersThe United Collieries network of piezometersdisplayed largely static water levels for most of thereporting period. With the exception of P1, P11,P12, P13 and P15, all otherpiezometersperiodically exceeded their respective maximumwater level depths. The overall trend at the end ofthe reporting period displayed recovering waterlevels approaching their respective criteria. Goodrainfall in June 2011 was likely to have influencedthis recovering trend.3.5.2.2 pHThe results for pH analysis of the groundwatermonitoring network are provided graphically andtabulated in Appendix 2D.The pH values for groundwater in wells GW02,GW08, GW09 and GW11 remained within theGWMP trigger levels during the reporting periodwith pH values averaging from 6.6 to 8.8. Thegroundwater wells GW02 and GW11 located on theBrosi’s property are subject to the ANZECC criteriafor “Raw Waters for drinking purposes subject tocoarse screening”. GW02 and GW11 were withinthe ANZECC pH range of 6.5-8.5 for the wholemonitoring period.All pH values recorded during the 2010-2011reporting period for the 100, 200 and 300 seriesremained within the pH trigger limits. These valuesin contrast to the last reporting period when the pHat P202 and P301 periodically fell below theirrespective pH trigger limits.All pH values recorded during the 2010-2011reporting period for the United Collieriespiezometers remained within their respective pHtrigger limits as listed in Table 3.2.3.5.2.3 Electrical ConductivityThe results for EC analysis of the groundwatermonitoring network are provided graphically andtabulated in Appendix 2D.Groundwater wells GW02, GW08 and GW11remained within the GWMP trigger levels for ECduring the reporting period, with the exception ofGW09. The recorded EC at GW09 fell below theminimum EC criterion of 1500S/cm with a result of459S/cm for December 2010, with an annualaverage 1085S/cm.The measured EC in the 100 and 200 piezometerseries stayed relatively static during the reportingperiod. The measured EC for P106, P109, P110,P111, P114, P202 and P206 remained within theirrespective criteria for EC. The EC at P116periodically dropped below the EC criteria of1500S/cm during the reporting period with a resultof 1315S/cm for August 2010 and an annualaverage of 1790S/cm. The EC results recorded inthe 2010-2011 reporting period for both the 100 and200 piezometer series were consistent with ECresults recorded in the 2009-2010 period.The measured EC in the 300 series piezometersduring the reporting period remained relativelystatic. The measured EC values at P301 fell belowtheir minimum EC trigger level of 8500S/cm withan annual average 3117S/cm and a minimum ECvalve of 2420S/cm for June 2011. The EC resultsrecorded in the 2010-2011 reporting period for the300 piezometer series were consistent with ECresults recorded in the 2009-2010 period.The United Collieries monitored piezometersgenerally remained within their respective ECcriteria levels during the reporting period. A numberof United’s piezometers returned EC values wellbelow their respective minimum EC trigger levels.The EC results recorded in the 2010-2011 reportingperiod for the United Collieries piezometers wereconsistent with EC results recorded in the 2009-2010 period.3.6 Contaminated Land3.6.1 Environmental PerformanceThe highest potential for land contamination atWCPL is from hydrocarbons. The main areas withthe potential for land contamination are thehydrocarbon storage and refuelling areas. Allhydrocarbon storage areas are routinely inspectedas part of WCPL Environmental ManagementSystem (EMS). All hydrocarbon storage areas atWCPL, with the exception of the decommissionedunderground unleaded fuel tank at theadministration area, are managed within bundedareas. These concrete bunded areas are regularlymonitored and maintained, reducing the risk of anyhydrocarbon spillage. The decommissionedunderground unleaded fuel tank has previouslybeen pressure tested to ensure its integrity issatisfactory.During the 2009/2010 reporting period, WCPLdeveloped a detailed scope of works to remove theold underground unleaded fuel tank and itsPage 57