Review Topic - Reducing the Environmental Effect of Aggregate Quarrying on the Water Environment

Quarrying, both for aggregates and other minerals, can potentially have a wide range of both positive and negative impacts on many different aspects of the water environment. In most cases, the adverse effects can either be anticipated and prevented, or at least reduced to an acceptable level by means of careful assessment, planning and monitoring, and through the timely implementation of appropriate mitigation measures. Similarly, potential benefits on the water environment can be optimised if the opportunities are foreseen and planned for from the outset.

The ALSF has supported considerable research into ways of improving the assessment, monitoring and mitigation of these potential impacts, and into ways in which improvements can be achieved. The ‘benchmark’ review aims to bring together the key findings of that research and to highlight the ways in which the findings can be used by quarry operators, regulators and others to reduce the environmental footprint of aggregate quarrying on the water environment. The report also identifies specific gaps in essential knowledge or good practice guidance in these areas which may need to be addressed by future work.
 
The key issues involved can be summarised for each of the three ‘life-cycle’ phases of the quarrying process: planning and design, operations and post-closure.

Planning and design phase

In recent years, the importance of the water environment has risen high on national and European policy agendas. In particular, the Water Framework Directive (WFD) has placed increased emphasis on the need for holistic catchment management, with requirements for the protection and improvement of both groundwater and surface water, and with the maintenance or enhancement of water-dependent ecosystems being seen as one of the highest priorities. In this context, one of the most important aspects of minimising the adverse effects of quarrying on the water environment must involve giving due consideration to the strategic importance of mineral extraction alongside all relevant social, economic and environmental issues in both regional scale and local spatial planning.

ALSF research in the area has provided both policy recommendations and guidance on how this can be achieved, along with more detailed guidance on site-specific development control. This has included the use of a risk-based approach to the development of impact assessment, mitigation and monitoring. Underpinning all of this is a need to understand the way in which the water environment actually works and how quarrying operations can affect those natural processes. This is an area of very active research and increasing practical interest, particularly in terms of the policy-driven need to gain a better understanding of interactions between groundwater, surface water and ecosystems. The first part of the review thus provides a summary of the current ‘state of the art’ knowledge and ongoing research in these areas.

Operational phase

The operational phase of aggregate quarrying runs from the first implementation of a minerals planning permission through to the completion of restoration and immediate aftercare works. Potential impacts and opportunities for improvement can be found throughout all of these stages. Recent research in these areas, from the ALSF and elsewhere, is reviewed in relation to the effects associated with: Excavation and Stockpiling; Quarry Dewatering; Site Processes and Management; and Quarry Restoration. In each case, the review provides an outline of the issues involved and summarises the findings of recent research that have helped to improve understanding or to develop better ways of doing things, so as to minimise impacts and/or to encourage the type of enhancement required by European legislation. Separate chapters at the end of the report provide reviews of investigation, impact assessment and monitoring techniques which may be used throughout the lifetime of quarrying operations to help avoid or control any adverse effects.

Post-closure phase

The post closure phase of aggregate quarrying relates to the period of after-use, following the completion of extraction, restoration and aftercare. Unlike many other impacts associated with mineral working and transportation, certain impacts on the water environment are likely to persist long after quarrying itself has ceased, particularly those associated with any permanent change in topography. Research and good practice in this area are covered specifically in Chapter 9 of the review but, in order to control these long-term effects there is a need for the restoration design and subsequent after-use options to be borne in mind and planned-for, initially at the planning and design phase and throughout the operational phase.

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