Derivation of a Methodology for the Assessment of Groundwater Recovery Times to Achieve Good Status: Tests for Feasibility and Disproportionate Cost
WFD25

October 2004

Key Words: Groundwater, Recovery Timescales, Water Framework Directive Executive Summary

This project was initiated by the Scotland and Northern Ireland Forum for Environmental Research (SNIFFER). Its purpose was to propose a framework for the technical and economic assessment of groundwater recovery timescales to achieve Water Framework Directive ‘good environmental status’.

This document is a research and development (R&D) report and is not, therefore, formal guidance for the Environment Agency (England and Wales), Scottish Environment Protection Agency and Environment Heritage Service of Northern Ireland. This document is intended to form a starting point which will help to inform the above agencies in the assessment of groundwater recovery timescales.

Under the Water Framework Directive timescale, good environmental status for surface water and groundwater bodies is to be achieved by December 2015. An extension to the timescales of two river basin management plan cycles (i.e. up to December 2027) can be invoked to allow phased achievement of the environmental objectives provided that no further deterioration in the status of the affected water body occurs.

In addition, less stringent objectives can be set for a groundwater body where achievement of the environmental objectives by 2027 are technically unfeasible or disproportionately expensive. These less stringent objectives must be the least possible deviation from the ‘good groundwater status’ and it is intended that the objectives would work towards ‘good environmental status’ for the water body. Applications for both timescale extensions and for less stringent objectives will require technical and economic justification to Europe.

Groundwater bodies likely to require less stringent objectives will be identified in the initial characterisation reports (December 2004) and the actual less stringent objectives will be specified in each river basin plan. Failure to achieve these less stringent objectives would be a breach of the WFD.

The requirement for either timescale extensions or less stringent objectives will depend on the type, history and extent of the existing pressure (chemical or quantitative) and the ability of the groundwater body or affected receptor to recover from this pressure under an implemented measure or combination of measures.

A clear conceptual understanding of processes within the groundwater body is important todetermine the level of uncertainty in the groundwater recovery estimation. Key influences on the recovery time of the groundwater body will be the residence time within the overlying strata and unsaturated aquifer and the rate of flushing through the saturated aquifer.

A framework is presented which details the assessment process from initial characterisation, through further characterisation to the submission and revision of the river basin management plans.

For the initial characterisation, a basic assessment is proposed which will, through categorisation primarily based on expert opinion, identify those groundwater bodies likely to require timescale extensions or less stringent objectives. This basic assessment uses a risk scoring matrix system to consider the influence of the pressure giving rise to failure to achieve ‘good status’ and the likely recovery timescales for the recovery of the groundwater body or affected receptor.

For the further characterisation and revision of the river basin management plans more detailed assessments are proposed which will provide an estimation of the times to achieve good environmental status (recovery times) and less stringent objectives, where required. The detailed assessments will consist of three tiers of calculation where Tier 1 is a simple calculation; Tier 2 is a spreadsheet based flushing cell (chemical) or aquifer response calculation and Tier 3 is a distributed model. Tools for the implementation of these three tiers are suggested. It is intended that these tiers are implemented sequentially and that the subsequent tier is utilised where the uncertainty in the outcome from the previous tier justifies it.

Lastly, a framework for the economic justification of proposed recovery measures is detailed. It will be necessary to present reasons of disproportionate cost to the European Commission where technically feasible measures are not implemented and where this leads to requirements for either a timescale extension or the setting of a less stringent objective.

It is proposed that the cost-effectiveness of measures can be assessed by considering the range of likely costs, the expected impact on concentrations of contaminants or quantitative status by 2015, and the timescale thought to be required to meet WFD environmental objectives.

Copies of this report are available from the Foundation in electronic format on CDRom at 20.00 + VAT or hard copy at 35.00, less 20% to FWR members.

N.B. The report is available for download from the SNIFFER Website