HVO 2009 Annual Environmental Management Report - Final

Coal & Allied – Hunter Valley Operations
Parnells Dam (W3)
Parnells Dam (W3) at Hunter Valley West Pit is a large out of pit mine water storage dam that receives water
pumped from West Pit. Parnells Dam collects runoff from its own surface area and a small catchment. The
dam operates as a discharge dam under the HRSTS. The recorded pH ranged from 8.9 to 9.4 in 2009, and
the average pH of 9.1. EC remained stable throughout with year with an average EC of 4,204μS/cm. TSS
ranged from 2 to 99mg/L, averaging 25.5mg/L, which is typical of saline mine water and varies subject to both
weather conditions and pumping regimes.
WOOP Dam (3S)
The WOOP Dam (Dam 3S) is a sediment dam settling runoff from the western out of pit dump at HVO South.
The WOOP dump catchment consists of equal parts mature rehabilitation and natural regrowth. The dams
primary function is the capture of water for settlement treatment before being released offsite. Activities
associated with mining have returned to this catchment in the reporting period. Generally the water sampled
in this dam is consistent with fresh water runoff. This dam was not accessible for fourth quarter sampling due
to renewed mining activities. An average pH of 8.6 was consistent throughout the year with EC remaining in a
range between 750μS/cm and 1,180μS/cm in 2009 due to cycles of rainfall and evaporation. The average
TSS was 16.3mg/L.
W9
W9 (Dam 14W) is located at the Newdell Coal Loader facility and prevents runoff from the coal stockpiles and
old CPP area from entering Pikes Creek. W9 recorded a 75 per cent sample capture rate with no sample in
December. As such the trend should be regarded as coming from an evaporating basin. The pH of the dam
water ranged from 7.7 to 8.2 in 2009. The average pH of 7.9 was lower than the 2008 average of 8.2. The
maximum EC of 11,100μS/cm occurred in March and the minimum EC of 9,000μS/cm in June. TSS was
minimal during the first period of 2009