Planning4Minerals header
  Influence of EU
 Role of central government
 Role of regional bodies
 Enviro protection/heritage
 Role of elected members
 Local communities
 Planning process
 Future aggregate sites
 Commercial interests
 Planning permission
 Enforcing planning rights
 Natural and built heritage
 Noise and vibration
 Transport and traffic
 Air quality
 Water resources
 Mineral waste
  What are aggregates?
 Resources vs Reserves
 Location of aggregates
 Quarry design/restoration
 Aggregate process
 Aggregate testing
  Aggregates use
 Supply and demand
 Value to economy
 Regional supply issues
 Local economy
 Transportation issues
 Site map
 Notes for trainers

Water pumping from workings below the water table

Why are water resource issues important to councillors?

Water ultimately underpins the survival of life on Earth. Alongside the potential environmental impacts, alterations to water flow patterns, the volume of water available, and the quality of water, can have significant implications for many water users, from those that rely on it for business purposes through to those whose interest is focused on leisure activities. The Environment Agency is consulted following the submission of an Environmental Impact Assessment to the Mineral Planning Authority. The Agency's comments will influence the planning decision and contribute to the planning conditions that might be imposed on the operator to ensure that environmental effects on the water resources will be minimised.

What are water resources?
Surface water and groundwater are both essential parts of the natural cycle of water that underpins the survival of life on Earth.
There are two principal types of water resource: surface water and groundwater, both of which are essential parts of the natural cycle of water (the cycling of water between the atmosphere, the land surface and underground) which ultimately underpins the survival of life on Earth. Surface waters include ponds, lakes, drainage ditches, streams, rivers and the sea. Groundwater is the water below the surface, held in, and moving through, the soils and rocks. The term 'water table' is used to describe the depth below which rock is totally saturated with groundwater. Groundwater eventually resurfaces via springs, streams or connections with rivers and other surface waters. High quality groundwater is often abstracted for use in private and public water supplies.

The natural cycle of water

The water cycle.

What are the potential impacts of aggregates production on water?
The potential impacts of aggregates production relate to three broad categories, namely changes in groundwater characteristics; changes in surface water characteristics; and contamination of surface and/or groundwaters.

Changes in groundwater flow and volume:

  • Boreholes created during initial field studies to confirm the quality and extent of the aggregate may generate 'short-circuits' that allow groundwater to move between previously isolated areas of underground rock, leading to changes in the subsurface flow of water. Boreholes may also act as points of entry for contaminants from the surface environment if not properly sealed.
  • Soils and overburden are important temporary stores of groundwater as it moves down to the rock below. When they are stripped prior to aggregate extraction, groundwater storage for the area can be reduced.
  • The efficient extraction of aggregates normally requires conditions to be reasonably dry so that machines can work safely and effectively. Operations often extend below the water table and pumping (known as dewatering) is required to prevent flooding. This depresses the water table to below the level at which aggregate is being extracted, but gives rise to potential problems such as loss of groundwater for use in private or public water supplies, drying up of local abstraction wells, reduced flow in surface waters supplied by the groundwater and effects on the habitats that these surface waters support.
  • Restoration of a worked-out site also has implications for groundwater, particularly if the excavated void is allowed to flood, resulting in changes to the direction and volume of groundwater flow.

Changes in surface water flow and volume:

  • As noted above, groundwater is often encountered as excavation continues and the workings become deeper. In most cases dewatering is necessary for efficient excavation to proceed. The pumped water is often discharged into surface water, which can increase flow rates and erosion downstream.
  • At some sites, the operator may have an abstraction licence, allowing it to use surface waters in its aggregate production process (for example in a washing plant). Abstraction may be of particular importance during the drier summer months when on-site sources of water such as settling ponds cannot supply the volumes required. Water abstraction may reduce downstream flows.
  • Pumped discharge or high volumes of run-off from a site during periods of heavy rainfall can increase the potential for downstream flooding.
  • The discharge of water containing high levels of suspended solids can cause changes to the bed of the receiving water through deposition of additional sediments.
  • Disturbance, removal or diversion of surface waters such as ponds, streams and rivers to improve access to aggregates and prevent flooding of the site are sometimes necessary. This affects both surface water flow and volume and can damage any wildlife habitats associated with these waters.
Contaminated water supply

A river contaminated with fines (clay particles) from a nearby quarry.

Contamination of surface and groundwaters:

  • Like any other piece of land, aggregates sites receive a certain amount of rainfall and this water runs over the site's surface into ponds, lakes streams and rivers or seep downwards to form groundwater in the rocks underlying the site. Water quality can deteriorate through contact with bare ground or sources of contamination or spillage of contaminants into the water. Since water normally needs to be discharged from sites, usually to surface watercourses, any reduction in water quality can cause impacts beyond the site boundary or on the wider groundwater resource in the area.
  • In some cases, particularly coastal operations, dewatering can draw in salty water from adjacent groundwater zones reducing the quality of local groundwater. Any salty water pumped during dewatering is also likely to cause problems with respect to its discharge to surface waters.
  • Potential contaminants include suspended solids (fine particulates that have been transferred to surface run-off); petroleum products such as fuels and oils; sewage (particularly at isolated sites where connection to the sewer system is not possible); nitrates derived from the use of explosives and other chemicals such as acids and alkalis used on site).
  • Without appropriate measures to protect and manage water, contaminants can be widely dispersed, affecting the quality of surface and groundwaters and the habitats and wildlife that they may support. Contamination may also constrain the use of water for commercial or amenity purposes.
The potential impacts of aggregates production on water resources can be broken down into three broad categories: changes in groundwater characteristics; changes in surface water characteristics; and contamination of surface and/or groundwaters. Alterations to flow patterns, volumes and quality of both surface and groundwaters can have significant implications for water availability and use by others and the health of freshwater ecosystems.

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