Water Pollution and Land Contamination
Water pollution and land contamination are important considerations in the process of aggregate recycling.
Environmental Protection Regime
Controlled waters (streams, rivers, canals, marine environment and groundwater) have statutory protection under the Water Resources Act 1991 in England and Wales and, from April 2006, the Water Environment (Controlled Activities) Regulations 2005 (CAR) and amendments in Scotland. It is an offence to make a discharge to controlled waters without the permission or consent of the regulators of these areas, which are the Environment Agency and Scottish Environmental Protection Agency respectively.
Consent to Discharge
Discharge is normally controlled by means of consent to discharge, which specifies the maximum concentration allowed for a range of possible pollutants. Under the Environment Act 1995, the Environment Agency has the right to recover costs involved in the investigation, clean-up and possible prosecution for polluting controlled waters.
The Environmental Regulator can serve a works notice on any person causing or knowingly permitting poisonous, polluting or noxious matter to enter controlled waters, or to prevent pollution from occurring, and have the right to access premises for inspection. The regulators are also able to control discharges of dangerous substances (mineral oil, range of metals, solvents and ammonium compounds) to groundwater under the Groundwater Regulations 1998 and the Scottish Water Environment (Controlled Activities) Regulations 2005 (CAR) and amendments.
The new Groundwater Regulations is currently under review and any new changes in the regulation is expected to be implemented in February 2009.
The discharge of certain substances is specifically controlled through the black (list 1) and grey (list 2) lists under the EC Dangerous Substances Directive 76/464/EEC and prescribed in the Environmental Protection Act 1990 and the Water Environment (Controlled Activities) Regulations 2005 (CAR) and amendments. Water companies act under the Water Industry Act 1991 and its regulations with respect to the discharge of drainage to sewers, and this includes restrictions of the discharge of dangerous substances (List 1 and 2).
There are provisions under Part III of the Environmental Protection Act 1990 for the control of contaminated land as a Statutory Nuisance and section 57 in the Environment Act 1995 specifically deals with historically contaminated land. Also consult the Contaminated Land (Scotland) Regulations 2005 (SSI 2005/658).
Planning Control
The planning authority is required to consider matters relating to water and land pollution under the Town and Country Planning Acts, and regulations and planning conditions may cover the following:
- Measures to ensure the protection of ground and surface waters
- Ensuring the capacity of the sewerage system to take site drainage
- Arrangements for drainage of waste waters from the working area
- Arrangements for the storage and handling of fuel and lubricating oils
- Adequacy of protective measures on site for dealing with incoming waste that may not only include inert waste
- Arrangement for the storage or disposal of unwanted waste
- The programme for sampling and monitoring of discharges including record keeping.
Pollution is the release from any process of substances that are capable of causing harm to human health, property and other living things. Water pollution can occur to any watercourse, such as a river, stream, canal, lake or pond, or to groundwater.
The pollution of groundwater is of the most concern in relation to the pollution of land. If land is polluted through recycled aggregate operations, there can be environmental implications for subsequent use of the land.
Recycling Operations
Water pollution associated with recycled aggregate operations can arise from the following causes:
- Separation, screening and processing of waste material - Rain and dust suppressions sprays on waste will cause solids to be released into the drainage. In the case of recycled aggregates, the solids will principally be concrete dust, rock dust, sand, silt and clays;
- Lime within the concrete dust may dissolve within the water to create an alkaline solution, but the pH is unlikely to be raised significantly due to the quantity of lime present.
- Oil, solvents and other contaminating material could be carried with the suspended matter
- Contaminants which are soluble in water, for example road salt, may also pollute the water.
Processing of the aggregates to a finer grade may expose contaminants held within the material into the air, this in turn may enhance solubility into water.
Storage of feedstock, and of unwanted or recycled non-aggregate materials
Contaminants are often held within the finer grade material of the aggregate, such as silts and clays, and so processing of feedstock will concentrate the contaminants in finer product types, held in storage bays.
Similar processes will occur within storage as described for the processing of waste, although the residence time may be much greater. Therefore the water entering or contained in the material will become more concentrated with dissolved substances, in particular road salt and lime from the concrete.
Disposal of unwanted material
If unwanted material is unsuitable for purposes other than aggregate production, i.e. recycling is not a viable option, then it must be disposed to a licensed waste management site, where leachate will be controlled.
Transport of material
In wet conditions, the delivery and tipping of materials and the moving of materials around site by loaders and dump trucks will be a major source of suspended solids in run-off. Likewise, dust from vehicles, which accumulates on the roads, will be suspended in run-off after rainfall, or by water used in dust suppression equipment. Therefore in recycling aggregate operations, where it is likely vehicles will become dirty, it will be necessary for vehicles to pass through wheel washers before entering the public highway. The washings will likely contain an amount of highly suspended solid.
Operation of plant and vehicles
Recycling aggregate operations will use powered machinery, fuel oil, lubricating oil and grease in various plant, equipment and vehicles on site, which have the potential to contaminate water or land. Storage of these fuels in tanks or drums may also be a cause of potential pollution problems during filling, dispensing and if leaking or spillage were to occur. Solvents, like degreasers, and detergents could also be a potential contaminant to water or land during plant and vehicle maintenance.
All of the above can have an effect on the following receptors and environmental resources:
Controlled waters - These have statutory protection and it is an offence to make a discharge to controlled waters without the permission or consent of the regulator.
Effects on people - Industrial and agricultural use, or potable water supply by water companies and others, can be disrupted or generate health risks respectively. Aggregate operations based on sandstone, gravel or chalk quarries are especially at risk of causing pollution of groundwater, whereas those underlain by impermeable rock strata are considerably less liable to cause pollution. Therefore, reference is required to the Policy and Practice for the Protection of Groundwater 1992 (as revised in 2002) and the Environmental Agency should be consulted if a site is to be located on the former.
Nature conservation - Aquatic plants, invertebrates (insects, larvae, shrimps etc.), fish and birds can suffer detrimental effects from highly suspended solid loads and oil/solvents in water.
The means of avoiding or mitigating the main potential water and land pollutants are discussed below:
Suspended solids
Suspended solids can be controlled during the recycling process or measures can be used to remove solids at discharge:
- Hardstanding areas, which are attributed to reducing the generation of suspended solids in water, should be provided on site roadways and areas subject to operational use.
- Arranging site layout and managing vehicular movements so as not to travel close to water courses or drive over non-hardstanding areas.
Move self propelled tracked crushers and screens to operate close to stockpiles to reduce vehicle movements. - Keep roads and wheels clean to help prevent fine material from being distributed.
- Implement control measures to avoid discharge of suspended solids to water courses, subject to approval of the planning authority and agreement of the Environment Agency, through: segregated drainage, silt traps, settlement pools, filtration systems (microstrainers, filters or filter presses),which may be used with flocculant, partial recirculation of screened or partially treated drainage for wheel washing or onto land for irrigation (upon agreement reached with the planning authority).
Water Contamination and Land Contamination from Fuel and Lubricating Oils
This is not unique to recycling aggregate operations. Pollution Prevention Guidance leaflets are issued by the Environment Agency. However some examples of common sense precautions to take are:
- Storage of the minimum quantity of lubricating oil and fuel on site and within one area.
- Proper and secure bunding.
- Provision of equally secure measures on any mobile equipment used for refuelling permanent plant that cannot travel to the designated refuelling area.
- Use of an impermeable area fitted with a boundary drain with oil separator for the designated refuelling area.
- Service and maintenance programme on all vehicles and plant to avoid leakage or spillage of oil or fuel to the ground.
- Scheduled maintenance programme for emptying and servicing oil separators on site.
- Provision of sand to treat small areas of spillage, for its removal and disposal.
- Holding and use of oil absorbent mats and/or bunds for dealing with accidental spillages to water.
- Written procedures to be followed for dealing with oil spillage.
Water Pollution and Ground Contamination from Unsuitable Material
Management should pay close attention to the sourcing of material in particular if general construction and mixed skip waste (from which aggregate material can be gained from sorting) is coming on site. The operator may be left with paint pots, containers of solvents etc. and so it is of utmost importance that the delivery and unloading of waste for recycling is supervised, to ensure compliance with the site requirements so that only acceptable material is received.
Pollution controls are needed to ensure that materials are retained in the correct bays or storage areas, to prevent contamination.
