HVO 2009 Annual Environmental Management Report - Final

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