Environmental guidance for your business in Northern Ireland & Scotland

Concrete and grout

Grouting and using concrete on construction sites

Cement powder, workable concrete and grout are extremely alkaline. You may also hear this referred to as a high pH.

There are several construction processes that risk contaminating water in this way.

Where shafts are to be sunk wet (ie material is removed from below the water level in the shaft), there is a risk of the water in the shaft becoming highly alkaline when the concrete base is poured.

When using dry-mix concrete to set kerbs or paving, water that runs off may be alkaline and, if so, needs to be contained.

Civil engineering works that use workable concrete close to watercourses or groundwater, such as cast in situ piling or bridge works.

Cement powder, workable concrete and grout can be highly polluting to water if released into the environment.

What you must do

If you are using concrete or grout, ensure that they are contained within your working area and do not enter any watercourses or surface water drains.

If you are mixing grout on site, construct a suitable barrier around mixing areas, supply lines and around working areas to prevent its escape.

Run-off from concrete operations and concrete wash out water are highly alkaline, which can cause water pollution.

Concrete also contains chromium, which is potentially polluting not only to watercourses but also to groundwater.

Trucks, hoppers, mixers and concrete pumps that have contained concrete must be washed out in a contained area away from watercourses, surface water drains, storm water drains, grids and channels to prevent pollution.

Where possible, store and reuse washout water.

You can contact the Northern Ireland Environment Agency (NIEA) or SEPA to find out if you are in an area where groundwater is vulnerable to pollution.

Contact your environmental regulator

If you are working in an area where groundwater is vulnerable to pollution, ensure that concrete washout water is contained and removed from site for treatment as liquid waste.

If you are pumping concrete or grout into the ground, keep records of the quantity that you are using. If you find that you are using larger quantities than you expected it is possible that these materials are escaping into the ground and potentially polluting groundwater.

Good practice

Only order the amount of concrete or grout that you need. Where you have several smaller areas that require concrete, plan your works so that you can pour more than one of these areas at once.

When preparing method statements and risk assessments, include information on:

  • testing the water prior to disposal
  • treating the water if necessary to reduce its alkalinity
  • how the water will be disposed of.

Supply good quality gloves for people working with concrete to reduce the quantity of gloves that you have to order and later dispose of.

Follow the pulverised fuel ash quality protocol in Northern Ireland

The pulverised fuel ash (PFA) and furnace bottom ash (FBA) quality protocol means that PFA and FBA will no longer be classified as waste when used in bound and grout applications, providing you meet the criteria set out in the quality protocol. This means PFA and FBA can be used without waste management controls.

For example, if it is not classed as a waste, you do not need to transport it using a waste carrier or with a waste transfer note.

The quality protocol for PFA applies in Northern Ireland.

GOV.UK: Pulverised fuel ash quality protocol

SEE ALSO: Settlement tanks, Protecting groundwater during drilling and boring

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