Site-specific risk assessment and management of point and diffuse sources - Environmental Deterioration and Contamination: Problems and their Management - page 367

diffuse source contaminant was the arsenic. The main pollution transport pathways
were soil erosion by runoff and direct spillage of arsenic into the surface water during
heavy rainfall, slow percolation of water through the waste into the groundwater and
transportation of pollution by dust.
As seen from the above characteristics the modes of diffuse transfer in a mining
watershed may include the following:

- Diffuse seepage in the immediate vicinity of point discharges such as AMD or
acidifying waste dumps and diffuse waste sources as well as runoff water;
- Runoff from mine waste dumps rich in pyritic material both in metal mine (Vol-
ume 5) and in coal mine waste dumps which can produce AMD with much higher
Fe concentrations than deep mine drainage due to the greater atmospheric contact
in the mine waste heaps (Younger & Banwart, 2002 and Younger et al., 2002);
- Re-mobilization of previously deposited waste material in both in-stream (Volume
5) and floodplain sediments (Mayes et al., 2005). Studies of metal mine contam-
ination (principally Pb and As, which are largely transported in adsorbed form
on sediments in neutral to alkaline waters) have highlighted the longevity of con-
taminated sediments as secondary diffuse pollution sources in river basins (Gruiz
et al., 2000; Mayes et al., 2005);

- Transportation by dust .

6.2 Risk management approach of diffuse pollution
from mining
Risk management of diffuse pollution from mining, similar to nonpoint source
pollution of any other origin, uses a watershed-scale approach supported by GIS.
The PECOMINES (Inventory of Mining Sites in Central and Eastern European
Pre-Accession Countries, 2004) project (2013) developed a concept for regional impact
assessment by linking the site/source-related indicators (information comes from exist-
ing databases) with spatial information at watershed scale by utilizing the results
of satellite remote sensing techniques such as CORINE Land Cover, GISCO river
networks and watersheds, European Soil Database.
The recommended uniform risk management methodology for mine waste follows
a tiered approach (shown in Figure 10.13) and standardized data acquisition from the
existing conventional databases, as well as a uniform questionnaire for the identifica-
tion of mine sites and hot spots (Sommer et al., 2006). The information is compared to
an independent remote sensing identification, which is based on the principal compo-
nent analysis of anomalies in ferro-oxy-hydroxides and secondary clay minerals on the
surfaces. This method based on the results of geo-referenced Landsat TM reflectance
channels is suitable for rapid screening of accumulations and distribution of mining
materials bearing increased acidification potential. Sommer (2004) summarized the
advantages of remote sensing for mine waste identification as “the remotely sensed
anomalies are obtained independently from existing ground truth and add value by
filling gaps in existing records and databases and improving spatial coherence.''
In the risk management practice, the watershed-scale GIS approach requires that
the contaminant emission of any point within a contaminated area be studied and
forecasted within the watershed. In the traditional risk management practice, applied