Regulatory Decision 002: Using unbound pulverised fuel ash and furnace bottom ash in construction

This Regulatory Decision (RD) is valid until 1 June 2025 by which time it will be reviewed. You should check back at that time to ensure the RD 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

If you comply with the requirements below, we will allow the use of unbound pulverised fuel ash (PFA) and furnace bottom ash (FBA) in specified circumstances without the need for an environmental permit.

The Waste Protocols Project considered whether a generic end of waste position could be developed for the use of unbound PFA and FBA. The work concluded that a quality protocol, setting out the end of waste criteria for the production and use of unbound PFA and FBA, could not be produced at this time. Industry is currently working with Natural Resources Wales to assess the impact of use of unbound PFA in the environment.

This Regulatory Decision allows unbound PFA and FBA to be used in construction under specified conditions without an environmental permit pending the findings of the field work being undertaken by the Equal project. When the findings have been reached, this Regulatory Decision will either be amended or withdrawn.

This Regulatory Decision covers only the final use and associated storage of unbounded PFA and FBA in construction projects such as embankments, road building and the construction of flood defences. If you carry out any treatment of PFA/FBA, or if you store these materials anywhere other than at the place of final use, or if you are carrying out a disposal activity, you will need a permit. Our position is that unbound PFA and FBA remains waste until it has been put to its final use.

If you cannot comply with the conditions in this RD, you need to apply for an environmental permit.

Conditions you must comply with 

Storage must be secure and be at the place of final use.

Storage must not:

• exceed 50,000 tonnes
• be for longer than 6 months
• be on a principal aquifer
• be within 500 metres of any borehole or well used to supply water for drinking or domestic food production
• be within 500 metres of a Groundwater Dependent Terrestrial Ecosystem unless a leachate collection system is in place

The use of waste

• must not exceed 100,000 tonnes for the entire construction project; We will apply a common-sense approach to whether something is a single project or has been artificially divided, for example the construction of a road or highway would normally be a single project even if described as being split into several phases. Similarly, the construction of a noise bund, creation of a golf course or construction of a flood embankment would normally be a single project.
• must be for a recovery activity and not for disposal. Find out whether an activity constitutes recovery or disposal

The use of waste must not be within:

• groundwater Source Protection Zones 1 or 2
• 50 metres of any spring or well, or of any borehole used to supply water (including private water supplies)
• 50 metres of a site that has relevant species or habitats protected under the Biodiversity Action Plan that Natural Resources Wales considers at risk to this activity
• 500 metres of a European Site, Ramsar site or a Site of Special Scientific Interest (SSSI)
• 50 metres of a National Nature Reserve (NNR), Local Nature Reserves (LNR), Local Wildlife Site (LWS), Ancient Woodland or Scheduled Ancient Monument
• 250 metres of the presence of Great Crested Newts where the location of the waste deposit is linked to breeding ponds of the newts by good habitat. Good habitats are those that provide plenty of cover and shelter for the newts in hot or cold weather and a good supply of invertebrates. The types of habitats that can support great crested newts includes scrub and woodland, rough grasslands and linear features such as hedges stone walls and railway lines with a variety of refuges for the newts to use

The operator must notify Natural Resources Wales of the proposed activity

• at least 10 days before delivery of the waste to the site begins for uses of greater than 5,000 tonnes
• at least 5 days before delivery for uses of less than 5,000 tonnes

The notification must include as a minimum

• the operator's name and contact details; the location of where the PFA or FBA is to be used to include grid reference
• quantities to be used (in tonnes)
• duration of the project; details of the activity
• confirmation that the use of the waste complies with the conditions of this Regulatory Decision

For uses >5000 tonnes detailed scheme drawings (plans/cross sections) showing original and final levels are required to be submitted.

• The waste must be suitable for use and must meet the required civil engineering standards
• The waste must not be mixed with other wastes
• The waste may only be mixed with non-wastes if the mixing improves its use or application
• All other waste controls such as duty of care and waste carriers registration will still apply

If you consider your material has met the end of waste test, visit our find guidance on the end of waste test and how to seek our views.

Enforcement

This RD does not change your legal requirement to have an environmental permit for a waste operation when using unbound pulverised fuel ash and furnace bottom ash in construction.

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