Hydrogeological Criteria

The Geological Survey of Ireland Recommended Approach to Site Selection

The Geological Survey of Ireland has, in conjunction with the Department of Environment and Local Government and the Environment Protection Agency, drawn up a groundwater protection scheme matrix for landfill siting. The matrix provides a cross-reference between vulnerability, source protection and resource protection.

Four groundwater vulnerability categories are used– extreme (E), high (H), moderate (M) and low (L). Examples of each are given in Table 1. These ratings are not scientifically precise; they are based on pragmatic judgements, experience and limited technical and scientific information. However, provided the limitations are appreciated, vulnerability assessments are an essential element when considering the location of potentially polluting activities. As groundwater is considered to be present everywhere in Ireland, the vulnerability concept is applied to the entire land surface. The ranking of vulnerability does not take into consideration the biologically-active soil zone, as contaminants from point sources are usually applied below this zone, often at depths of at least 1m.

The vulnerability concept and vulnerability maps are useful in landfill site selection. Firstly, they indicate and are a measure of the likelihood of contamination if a leak occurs from a landfill site. Secondly, they enable landfill sites to be located in relatively low vulnerability and therefore in relatively low risk areas, from a groundwater point of view. Thirdly, they allow an initial indication of the likely engineering measures required to prevent contamination.

Table 1: Vulnerability Ratings

GSI/DoELG/EPA document (Word Document, 33 kbs)