Regulatory Decision 044: Using unbound incinerator bottom ash aggregate in construction activities

This Regulatory Decision (RD) is valid until 31 January 2025 by which time it will be reviewed. You should check back at that time to ensure the Regulatory Decision is still valid.

NRW can withdraw or amend this RD before the review date if we consider it necessary. This includes where the activities that this RD relates to have not changed.

Regulatory Decision

This RD applies if you use unbound municipal incinerator bottom ash aggregate (IBAA) in certain construction activities. It also covers the storage of IBAA in relation to its use.

Unbound IBAA includes IBAA in hydraulically-bound mixtures (HBMs). A HBM is where IBAA is mixed with water and a binder such as cement to form a mixture which then sets.

For the purpose of this RD a surface water body is a relevant territorial water, coastal water or inland freshwater (as defined by the Water Resources Act 1991).

This RD does not apply to any other activity, even if it is under the same legislation. You may still need other permits or licences for other activities you carry out.

Conditions you must comply with 

Using IBAA may produce hydrogen so you must take appropriate safeguards.

You must:

• follow the hydrogen safeguarding guidance in the Material Safety Data Sheets
• comply with the guidance Dispose of business or commercial waste
• comply with hazardous waste controls if you identify these wastes
• store unbound IBAA safely and securely
• follow the Health and Safety Executive precautions on the use of IBAA or other equivalent measures
• keep records for 2 years that show you have complied with this RD – you must make these records available to Natural Resources Wales on request

For each delivery, the producer must confirm (by doing risk assessments) that the supply meets all the conditions in this RD and records in writing the:

• date of supply
• name and contact details of the producer and distributors (as applicable), including the site of production’s address
• quantity supplied (by weight or volume)
• statement from the producer that the material meets the relevant standard for an end use specified in this RD and has been supplied for that use

You must give a copy of this record to the end user of the unbound IBAA. Both parties must:

• keep the record for a minimum of 2 years
• make each record available to Natural Resources Wales on request

You must not store or use unbound IBAA within:

• a groundwater source protection zone 1 or 2
• 50 metres of any spring or well, or any borehole used to supply water, including private water supplies

You must make sure your activity does not endanger human health or the environment.

You must not:

• use, or supply for use, IBAA underneath any residential building or garden
• store IBAA for more than 6 months before use
• cause a risk to water, air, soil, plants or animals
• cause a nuisance through noise or odour
• adversely affect the countryside or places of special interest

All aggregate products must comply with BS EN 13242 or any revision of that standard. You need to pay for this standard.

Building a road sub-base

You can use an unlimited quantity of unbound IBAA to build a road sub-base providing:

• the width of the IBAA emplacement is not more than 40 metres
• the road, cycleway or footpath is asphalt, concrete or other low permeable material

Pipe bedding

You can use up to 510 tonnes of unbound IBAA as pipe bedding in any single construction project. This does not apply to anything that has been artificially divided.

Building a construction or structural platform

You can use IBAA to build a construction or structural platform that is on average one metre thick. It must be at least 25 metres from a surface water body. At least 95% of it must be entirely covered by a low permeability surface or building.

The amount of IBAA you can use depends on the distance to a surface water body as shown in the following table.

Enforcement

This RD does not change your legal requirement to have an environmental permit for a waste operation when using unbound incinerator bottom ash aggregate in construction activities.

However, NRW will not normally take enforcement action if you do not comply with the need for an environmental permit if you meet the requirements in this RD.

In addition, your activity must not cause (or be likely to cause) pollution of the environment or harm to human health, and must not:

• cause a risk to water, air, soil, plants or animals
• cause a nuisance through noise or odours
• adversely affect the countryside or places of special interest