HVO 2009 Annual Environmental Management Report - Final

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Coal & Allied – Hunter Valley Operations CGW49 CGW49 is located in alluvium north and upslope of CGW6 on the western side of Carrington. The pH at CGW49 averaged 7.5 in 2009. A spike in pH values was noted from CGW49 (pH. 8.1) in September 2009, however this spike was consistent with bores in the vicinity and within historical ranges for groundwater located in this alluvium area. CGW49 EC levels averaged 3,647μS/cm for the 2009 reporting period. CGW49 EC levels trended around 7,000μS/cm before the flood event of June 2007. Subsequent sampling results indicate that the EC values have levelled out to approximately 4,000μS/cm. This indicates some mixing with the lower EC water from upslope aquifer recharge after the flood event. Water levels at CGW49 where recorded at an average depth of 9.07m (61.4m AHD). The water level remained consistent throughout 2009. CGW51A The pH at CGW51A averaged 7.2 in 2009. This value is consistent with historical data that since 2006 which recorded pH values between 6.8 and 7.7. CGW51A EC levels averaged 11,185μS/cm for the 2009 reporting period. This value is closely aligned with historical EC data (around 13,000μS/cm) prior to the flood events of June 2007 and suggests aquifer water quality is returning to normal conditions. The minimum EC of 6,980μS/cm was recorded in the last quarter of 2009. Water levels at CGW51A where recorded at an average depth of 13.97m (55.4m AHD) through 2009. CGW52 CGW52 is targeted to follow groundwater levels associated with the Broonie 1 coal seam. The mean pH at CGW52 was 7.2 in 2009. This value is consistent with historical data that since 2006 which recorded pH values between 6.8 and 7.7. CGW52 EC levels decreased from 6,120μS/cm at the start of the reporting period to 2,450μS/cm at the end of the reporting period. It is unknown whether this drop is an anomaly or represents a change in groundwater source. The standing water level in CGW52 has trended downwards from 15.4m (54.9m AHD) in 2005 to 24.96m (45.3m AHD) in 2009. During the 2009 reporting period this trend continued with water levels falling to a maximum of 26.04m (44.1m AHD) possibly influenced by closer mining activity. CGW52A The pH at CGW52A averaged 7.6 in 2009. This value is consistent with historical data since 2006 with pH values between 6.8 and 7.7. CGW52A EC levels have trended down from a high of 9,090μS/cm February 2007 to an average value of 3,887μS/cm for the 2009 reporting period. This gradual trend downward may be influenced by continued river seepage following initial flushing of salts from the 2007 flood event. Water level recovered from 12.1m (58.2m AHD) to around 11.4m (58.8m AHD) after the out of bank flood event of June 2007. This level held steady until January 2009 when a decline commenced to reach a minimum of 11.97m (58.3 mADH) in July 2009. The reason for a rise to 9.94 m (60.3 mAHD) in January 2010 is unknown. CGW45 Recorded as dry and reported to maximum available depth. No samples were able to be extracted. CGW46 Recorded as dry and reported to maximum available depth. No samples were able to be extracted. AEMR 2009 99
Coal & Allied – Hunter Valley Operations CGW54 CGW54 is located in the Broonie 1 coal seam. CGW54 is no longer monitored due to a bent casing and blockage. Samples for pH and EC analysis from CGW54 were only available during the last quarter of 2008. It is therefore difficult to establish trends based on the data available. CGW54A The pH at CGW54A remained in an average range around 7.4 in 2009. This value is consistent with historical data that since 2006 suggest pH values between 6.8 and 7.7. CGW54A EC levels fluctuated around an average EC value of 6,337μS/cm for the 2009 reporting period. A significant drop in EC was observed between the March and July monitoring period, from a maximum recorded EC of 8410μS/cm to the yearly low of 3500μS/cm. Following this sample, the September and December monitoring results show a returning trend to normal EC conditions. Water levels at CGW54A where recorded at an average depth of 10.6m (57.8m AHD) through 2009. North Pit and Alluvial Lands Groundwater With mining and rehabilitation completed at North Pit, monitoring of restored alluvial with a series of piezometers and bores DM1 to DM6 commenced in 2004 to establish water levels and quality located on the mined side of the levee bank. Sampling is undertaken quarterly subject to safe access. DM5 and DM6 were unable to be sampled in 2009 due to bore damage. Samples for analysis of EC were not collected for site DM1 with no free water present. Monitoring results for 2009 are shown in Table 35 and Figure 48 to Figure 50. Table 35: Groundwater Results from North Pit & Alluvial Lands for 2009 Location EC (S/cm) Average Min Max Average Min Max pH DM1 (Weir 1 Piezo) NA NA NA NA NA NA DM2 (Weir 2 Piezo) 10,253 10,000 10,500 6.6 6.5 6.9 DM3 8,325 8,180 8,630 6.9 6.7 7.2 DM4 4,833 4,540 5,130 7.7 7.7 7.8 Groundwater Monitoring pH Results for North Pit and Alluvial Lands Piezometers Recorded pH values in 2009 remain within historical values of 6.5 and 8.0 pH units (Figure 48). AEMR 2009 100
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HVO 2009 Annual Environmental Management Report - Final

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