|Protecting water resources
The protection and management of water resources is an essential element of any programme to minimise the environmental impacts of aggregates extraction. The regulation of water resources in England and Wales is relatively complex, covered by a number of statutory organisations, and a constantly developing regulatory framework, which now largely falls in line with that adopted by the European Commission. Key pieces of legislation include the Water Resources Act 1991, the Land Drainage Acts (1991 and 1994), the Salmon and Freshwater Fisheries Act 1975, the Water Environment (Water Framework Directive) Regulation 2003 (England and Wales) and Groundwater Regulations 1998.
|The protection and management of water resources is an essential element of any programme to minimise the environmental impacts of aggregates extraction.
A number of bodies and organisations are involved in the management and regulation of water. In England and Wales the principal agency is the Environment Agency, whose responsibilities include granting licences and consents for existing water abstractions and for the discharge of ground and surface water from site to controlled waters such as streams and rivers. When an Environmental Assessment (EA) for a site is being prepared, the Environment Agency will be consulted following its submission to the Mineral Planning Authority (MPA) and its comments will influence the planning decision. If planning permission is granted, the EA will contribute to the planning conditions that might be imposed on the operator by the Mineral Planning Authority to ensure that environmental effects on the water environment will be minimised.
Measures that an operator can implement include:
|The regulation of water resources in England and Wales is relatively complex. The constantly developing regulatory framework now largely falls in line with that adopted by the European Commission and a number of bodies and organisations are involved in the management and regulation of water. In England and Wales the principal agency is the Environment Agency, but other organisations that may play a role include the local government drainage department, English Nature and the Countryside Council for Wales and interest groups such as Wildlife Trusts, RSPB and sailing or angling clubs. Ultimately, however, responsibility lies with the operator to ensure that the impacts of aggregates production on water resource availability and quality are minimised.
Managing groundwater flow and volume (NECESI/The Environment Practice, 2004):
- Locate the site away from areas likely to be affected by dewatering or lowering of the water table.
- Limit the working depth to reduce the need to depress the water table.
- Dewater small areas in sequence rather than the whole site at once to minimise changes to the water table (and also reduce the volume of water being discharged to surface waters).
- Replace the pumped water back into the groundwater system elsewhere on the site to maintain overall size of groundwater resource.
- Change the extraction methods so that the aggregate can be effectively removed from a wet environment - this approach however is only possible for sand and gravel sites and not hard rock quarries where drilling and blasting are necessary.
- Use water pumped from beneath the workings to supply private or public consumers whose wells have been affected by dewatering or to 'top up' surface waters where flows have decreased.
Protecting surface water flow and volume:
- Avoid the removal or diversion of surface water features unless absolutely essential and the economic benefits outweigh the environmental impacts.
Thickeners can be used to quickly settle fine particles from suspension allowing rapid recycling of water on site.
- Minimise abstraction from surface waters by recycling water within the operation. This approach can also be used to reduce the discharge of potentially contaminated water.
Water remediation and recycling at Cliffe Hill Quarry.
- Where diversions are necessary, they should mimic as closely as possible the characteristics of a natural system to promote the natural development of replacement habitats for animals and plants.
- Manage the discharge of water to surface watercourses by providing storage capacity within the site boundary in the form of ponds or even the quarry bottom. This storage capacity is particularly important during periods of heavy rainfall when it may not be possible to discharge water of suitable quality due to elevated levels of suspended solids.
- Ensure that discharge volumes and flows comply with discharge consents.
Preventing contamination of surface and groundwaters:
All of these measures should be underpinned by an appropriate water-monitoring programme to check whether preventative and remedial measures are delivering the necessary performance and to identify where changes may be necessary to protect surface and groundwater resources.
- The prevention of water contamination should be the first priority. Where prevention is not possible, control measures should be put in place to control or treat water to prevent the discharge of contaminated water. Preventative measures can include minimising the area of disturbed land (to control the transfer of particulates to surface run-off) or waste tips exposed to rainfall and keeping clean run-off from undisturbed areas separate from other potentially contaminated site water.
- Construction and lining of ditches around the site boundary should be undertaken to reduce lateral movement of water from adjoining areas if this is considered to be a significant source of on-site water.
- Boreholes should be grouted to prevent the migration of water and backfilled as soon as they are no longer required to minimise the risk of contaminants entering from the surface environment.
- Settling ponds and lagoons should be used to remove suspended solids prior to the discharge of water. At many aggregates sites, suspended solids are the principal water contamination issue.
- Petroleum products such as fuels and oil, and other chemicals used on site should be stored so that any spillages are contained within the immediate area and cannot enter surface or groundwaters.
- Sites should not accumulate rubbish, waste oil, other waste materials or general rubbish likely to result in water contamination. These should be removed for recycling or appropriate disposal as soon as possible.
- On-site sewage treatment should be designed and constructed to appropriate standards.
- With the exception of low-tech settling ponds and the separation of oil and water using simple physical separators, most treatment options are expensive with respect to capital and operating costs, and may require an extended period for construction and commissioning (i.e. not immediately available for treatment duties). The potential cost of treatment emphasises the importance of preventative and control measures, not just from an environmental perspective, but also from a cost-control perspective.
- Response procedures should be in place to deal with spills if they do occur.
NECESI/The Environment Practice. 2004. Drainage and Water Quality. Chapter 3 (Section B-I) in Environmental management guidance manual for SME aggregates companies . March 2004. Available from NECESI, University of Durham, Unit 1R, Mountjoy Research Centre, Stockton Road, Durham DH1 3SW.
Sources of Further Information
- Goodquarry.com - Water: Click here
- Thompson, A, Easton, P H, Hine, P D and Huxley, C L 1998. Reducing the effects of surface mineral workings on the water environment. A guide to good practice . Symonds Travers Morgan, ISBN 0 9522345 9 9.
- Wardrop, D R, Leake, C C and Abra, J. 2001. Practical techniques that minimize the impact of quarries on the water environment. Trans. Inst. Min. Metall. (Sect. B: Appl. Earth Sci.), 110 , January-April, pp B5-B14.