This paper is concerned with two case histories of wastewater quality management in underground coal mines in the
Illawarra region. The first investigation briefly presents an analysis of mine water discharge having an extremely high
concentration of suspended solids and consistently high barium concentrations, averaging, 14.4 mg/I Barium, over the
sampling period. A laboratory study of chemical precipitation processes has indicated that about 91% of barium could be
removed by using ferric sulphate and lime. On the basis of the information obtained from the environmental audit
process an alternative water treatment and reuse system incorporating 51% reduction in the water consumption with 32%
less off-site discharge has been suggested (Thomas, 1995).
The second case history is concerned with the storm water management at a mine situated in the Illawarra escarpment
where only 20% of the wastewater generated in the colliery is discharged off-site. Computer modelling of the storm water
system showed that 75% of the clean runoff becomes contaminated through poor management practices and causes the
process wastewater treatment system to fail in wet weather. Suggested improvements include relatively simple alteration
to the coal wash filtration dams which are expected to reduce the periods of inefficient operation of these dams by 95%.
The use of storm water diversion channels and detention basins can reduce the overflow volumes by 70 - 100 % for a ten
year ARI (Average Recurrence Interval) storm event (Wingrove 1996).