Lesson Progress:

Causes of pollution

  • Deliberate or accidental leakage of substances (such as cement, silt, grout, sewage, chemicals, oils/greases or vehicle fuels) that soak into the ground or contaminate rivers, streams and ditches.
  • Discharge of contaminated liquids into drainage systems, both foul and surface water.
  • Deliberately or accidentally allowing waste material to escape from the site, through being wind-blown or through leakage, and contaminating adjacent land and/or watercourses.
  • Mixing contaminated, hazardous materials with other waste (for example, putting rags used to clean up an oil spillage in with general waste materials).
  • Mixing plasterboard or gypsum-based waste with biodegradable waste.
  • Allowing smoke, fumes or dust to contaminate the air and surrounding surfaces.
  • Causing too much noise, light or vibration, which can affect the quality of life of people who live or work nearby.

Why pollution occurs

  • Substances enter rivers, streams, ditches, drains or the ground because they aren’t stored correctly.
  • Not having properly protected, bunded (containment area that captures any leaks, preventing pollution) storage areas to contain any leaks or spills of harmful liquids (for example, oils, fuels and solvents).
  • Not protecting or covering stockpiles of hazardous or non-hazardous materials, resulting in them being blown by the wind and creating dust, or washed into the ground or watercourses by rainwater.
  • Failing to adequately protect waste material skips, resulting in rainwater washing harmful residues out.
  • Rain and muddy surface water running off site onto roads, into drains and watercourses.
  • Not having processes and equipment in place to report and control environmental incidents.
  • The poor maintenance of plant and equipment resulting in fuel and other leaks, excessive noise and/or air pollution.
  • The illegal burning of waste materials, and fly tipping.
A spill involving just one litre of oil can contaminate one million litres of drinking water.

Your part in preventing pollution

To avoid creating pollution you should always adhere to the following.

  • Follow the instructions in the control of substances hazardous to health (COSHH) assessment and any site rules when using any substance, particularly with regard to storage and disposal.
  • Keep the lids on tins of paints, adhesives and solvents when not in use.
  • Keep oils, fuels and chemicals within bunded areas when not in use.
  • Prevent spillages by careful handling and pouring of harmful liquids.
  • Keep harmful substances at least 10 m away from features such as watercourses, drains and ditches.
Pollution spreads easily

Spilt or leaking oils and fuel can be particularly damaging to the environment. It is possible for leaking substances to soak deep into the ground and pollute groundwater, which in some cases becomes domestic drinking water.

5 litres of oil can contaminate an area the size of two football pitches, damaging the nutrients within the soil that helps plant and crop growth. If it gets into surface water or groundwater, pollution may appear several miles away and could poison fish or other living organisms.

Spilt materials must be properly contained using absorbent materials, not washed down with detergent.

Refuelling site vehicles or construction equipment must be carried out by an authorised person. Where possible the refuelling should take place in a controlled area with a hard surface that prevents spilt fuel from soaking into the ground. The following points should be implemented if refuelling has to be carried out away from these areas, where the ground is unprotected.

  • A drip tray or absorbent mat must be used (it must be cleared of any spilt fuel afterwards by using absorbent spill clean-up materials).
  • Refuelling must take place at least 10 m from watercourses or drains. (Where 10 m cannot be achieved, speak with your supervisor who should then put in place further control measures.)
Pollution-absorbent mats, known as plant nappies, capture fuel and oil leaks, preventing ground pollution
Regulatory bodies recommend that refuelling is always carried out under supervision.

Where possible, refuelling should be carried out using a pumped supply through a nozzle fitted with an automatic cut-off to avoid over filling and spillages. Where necessary, funnels should be used to assist in preventing spills. Never leave a tank to fill unsupervised and always replace lids and caps on containers.

Do not dispose of harmful substances into drains or gullies. Site drain covers should be colour coded to show what type of fluid is allowed to pass through the drain.

BlueSurface water (such as clean, uncontaminated rainwater).
RedFoul water (such as sewage and silty run-off water).
Red ā€˜Cā€™Combined surface and foul water (both of the above descriptions).

If the product you are using displays this sign on the label or COSHH assessment then it is harmful to the environment. Any substances left over, including the container, must be disposed of in line with the COSHH information, regulations and site rules.

Concrete and cement washout is highly alkaline and can cause severe pollution. Water from washing out any mortar or concrete mixing plant or ready-mix concrete lorries must not be allowed to flow into any drain, watercourse or to ground. It should, in ideal situations, be recycled for further washout processes.

Waste concrete and washout water can be placed in a lined skip, allowing settlement of solids. If the appropriate environmental consents (permissions granted by the environmental agencies) are in place, the surface water can then be pumped to a foul sewer or taken away by tanker. To promote sustainability the settlement solids from the concrete washout can also be processed to reclaim the aggregate and be recycled for reuse into the works.

Washout areas should be designated and at least 10 m away from watercourses and drains.

If you are involved in pumping water out of an excavation (de-watering) you must be aware that silty water must be treated before it can be discharged into surface water drains, rivers, streams or ditches. Site management or your supervisor must make the decision whether the water is silty and needs treatment prior to discharge.

A lot of construction work takes place on what are known as brownfield sites. This means that the land has been built on or has been used for industrial purposes before, in which case it may contain hazardous substances. In most cases pre-construction surveys will have been carried out to identify any hazardous materials and your employer should include this information as part of your site induction. However, you must immediately stop and tell your supervisor if you find either of the following.

  • Soil that has a strange smell and/or appears to be oily.
  • Fragments or clumps of fibres that could be asbestos or other hazardous materials.

Pollution incidents

If you are involved in a pollution incident (such as a chemical spill or discharge of contaminated water), make an initial assessment of the risk. If you can take actions safely, make sure you have the correct personal protective equipment (PPE). If your assessment of the risk places you in danger, raise the alarm and inform your supervisor. Do not put yourself at risk.

If you are aware that an environmental incident or spill has occurred then act quickly and follow these simple steps: stop – contain – notify.

Stop further contamination with corrective actions (such as standing up oil drums or closing a leaking valve).

Spill kit deployed

Contain the contamination by using spill kits, building earth or sand bunds to prevent the contamination from spreading, making sure you direct flows away from unprotected drains.

Notify your supervisor or employer of an incident as soon as possible. Do not ignore or cover up the incident over fears of being blamed, as not reporting an incident can lead to far greater consequences.

As well as the points above the following steps should be taken.

Eliminate all sources of ignition. Do not switch plant or equipment on. Remove sources of heat and sparks.

Cover drains or inspection chambers to stop the substance entering unprotected drainage systems.

Check the spill has not reached any nearby drains, inspection chambers, watercourses, ditches, ponds or other sensitive areas.

Dispose of all contaminated materials (such as absorbent granules, soil or cleaning cloths) used to contain the spill in the correct hazardous waste skip.

Report the facts to your supervisor or employer, who will notify the appropriate Environment Agency and take action to prevent the incident reoccurring.