Site-specific risk assessment and management of point and diffuse sources - Environmental Deterioration and Contamination: Problems and their Management - page 358

Figure 10.11 Inverse application mode at watershed scale, GIS-based transport and fate model to
calculate the maximum permissible emission.

- Second step : using generic (from legislation) or setting site-specific quality criteria

(PNEC, ADI) for the users in the compliance points.
For the purpose of establishing the site-specific quality criteria ( ADI ) the exposure
parameters of the site-specific receptors in the compliance point should be known
or assessed. According to Ferguson et al. (1998) where waters are historically
polluted, site-specific approaches based on groundwater and surface water uses are
preferred. For aquifers that have a potential for drinking water extraction, drinking
water standards are often used as remedial targets. However, where groundwater
is not considered to be a usable resource, the quality of the surface water bodies
into which it discharges, or the impacted air, soil or plant and animal products
to which the food chain elements and humans are exposed via nutrition, may
represent the quality objectives.

- Third step : characterization of the source and of the transport pathways.

A description of the source and the transport pathway is needed as input for
the transport and fate model. This step includes the selection and description of
the relevant physico-chemical, geochemical, hydro-geological properties of the
source, of the dominant transport pathways taking into account the partition
between physical phases, sorption-desorption, dissolution-precipitation, rate of