TITLE:
Hydrochemistry of Surface and Groundwater in the Vicinity of a Mine Waste Rock Dump: Assessing Impact of Acid Rock Drainage (ARD)
AUTHORS:
Francis Krampah, George Lartey-Young, Peter O. Sanful, Oscar Dawohoso, Austin Asare
KEYWORDS:
Waste Rock Dump, Acid Rock Drainage, Surface Water, Ground Water, Wassa East District, Water Quality
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.7 No.1,
January
22,
2019
ABSTRACT: Acid Rock Drainage (ARD) is a well-known problem related to the mining
industry due to its hazardous environmental effects. Metal-rich drainage and
acid effluent transmitted from mine waste dumps compromise environmental
quality of groundwater and surface water systems destroying aquatic life and
increasing human health risks. This study was aimed at assessing the acid and
metal drainage potential from the Subriso East Rock Dump (SERD) located in
the Wassa East district of Ghana on ground and surface water quality in the
catchment using a system of monitoring boreholes, reference boreholes and
river samples. Water samples were collected from deep and shallow monitoring
boreholes and surface water within the immediate environs of the SERD
from August 2012 to February 2013 for laboratory and statistical analysis.
Parameters analyzed include sulphate, alkalinity, Arsenic (As), Manganese
(Mn), Iron (Fe), Zinc (Zn), Copper (Cu), Cadmium (Cd), Mercury (Hg),
Aluminum (Al), Silver (Ag) and lead (Pb) and their concentrations compared
with Ghana Standards Authority (GSA) GSB (2009) and WHO (2017) standards.
Results indicate that surface and groundwater were not impacted by
the SERD possibly because there was no generation of acid or metal-loaded
effluent from the SERD into the environment. Physicochemical variables between
monitoring boreholes did not differ significantly from conditions in
the reference boreholes. Similarly, comparison of upstream and downstream
river conditions did not yield any statistical significance (p > 0.05). Mn and
Fe concentrations were above the WHO (2017)/GSB (2009) standards. Heavy metal concentrations in surface and groundwater were below detection limits
except manganese and iron whose concentrations exceeded the recommended
guidelines. No significant environmental impacts exist that could be
attributed to the waste rock dump and may be as a result of engineering designs
and mechanisms which prevent acid generated water from reaching the
external environment. Furthermore, the geology of the study area potentially
could be slightly inert having the potential to generate ARD under appropriate
conditions. Again, the young age of the waste rock dump is a factor that
may contribute to ARD generation under appropriate condition. Routine
monitoring of groundwater and surface water sources is required to determine
future acid generation of the SERD and its environmental impacts. The
results of this study will assist decision makers and environmental managers
to plan effectively to mitigate future impacts as mining waste rock dumps are
known to increase in acid generation potential with age.