Guidance

Using unbound incinerator bottom ash aggregate (IBAA) in construction activities: RPS 247

Updated 25 June 2024

Applies to England

This regulatory position statement (RPS) does not change your legal requirement to get an environmental permit for waste and groundwater activities when you use IBAA in:

• building a road sub-base
• building a construction or structural platform
• pipe bedding

However, the Environment Agency will not normally take enforcement action against you if do not comply with these legal requirements provided:

• your activity meets the description set out in this RPS
• you comply with the conditions set out in this RPS
• your activity does not cause (and is not likely to cause) pollution of the environment or harm to human health

When this RPS applies

This RPS applies if you use unbound municipal IBAA in certain construction activities. It also covers storing IBAA for later 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 RPS a surface water body is a relevant territorial water, coastal water or inland freshwater (as defined by the Water Resources Act 1991).

This RPS 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
• keep records for 2 years to show that you have complied with this RPS and make these records available to the Environment Agency on request

For each delivery the producer must confirm (by doing risk assessments) that the supply meets all the conditions in this RPS and record 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 RPS 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 the Environment Agency 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

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.

Distance to water body (metres)	Maximum tonnage (tonnes) (Dry)	Volume after compaction assuming 1.7T/m³ (m³)	Maximum surface area of a structural platform (m²)
25-49	4,420	2,600	2,600
50-99	6,800	4,000	4,000
100-149	13,600	8,000	8,000
150-199	20,400	12,000	12,000
200-249	27,200	16,000	16,000
250-299	34,000	20,000	20,000
300-349	40,800	24,000	24,000
350-399	47,600	28,000	28,000
400-449	54,400	32,000	32,000
450-499	61,200	36,000	36,000
More than 500	68,000	40,000	40,000

Pipe bedding

You can use up to 510 tonnes of unbound IBAA as pipe bedding in any single construction project. This does not apply if projects are artificially divided to allow multiple applications.

When you must check back

The Environment Agency will withdraw this RPS by 31 January 2025. You will need to check back then to see if it still applies or if you need to apply for an environmental permit or take appropriate alternative action.

The Environment Agency can withdraw or amend this enforcement position before it expires if they consider it necessary. This includes where the uses of IBAA in construction that this RPS relates to has not changed.

If you cannot comply with this RPS

If you operate under this RPS but think you may no longer be able to comply with its conditions, you must tell the Environment Agency immediately.

Contact the Environment Agency

General enquiries

National Customer Contact Centre
PO Box 544
Rotherham
S60 1BY

Email [email protected]

Telephone 03708 506 506

Telephone from outside the UK (Monday to Friday, 8am to 6pm GMT) +44 (0) 114 282 5312

Monday to Friday, 8am to 6pm.

Definitions of main terms

The following definitions only apply to this RPS.

Construction or structural platform

A construction or structural platform is an engineered base for an overlying construction feature, for example a:

• large or small building
• car park
• retaining wall
• storage tank
• road or pavement

The base will be less than 1 metre (m) thick on average. A platform can vary from just a few square metres to tens of thousands of square metres.

The platform will be covered by a building or low permeability surface. This surface must remain intact and have low permeability over the lifetime of the structure.

Building a construction platform may include compacting IBAA in a trench or other void, providing the total average depth of IBAA does not exceed 1m.

Sub-base for road, cycleways and footpaths

The sub-base (or sub-base with capping layer) is the layer placed over the subgrade that acts as a foundation layer for the base and surface course. It must have a thickness of less than 0.7m.

The surface course must be of low permeability and durable so that it remains intact and of low permeability over the lifetime of the structure. You must build this with adequate falls to prevent standing water.

Pipe bedding

Pipe bedding is material laid in the bottom of a trench that has been excavated for drainage pipes or other pipelines. It lets you lay pipes accurately to specific levels, and it transfers overburden or traffic stresses evenly around the pipe.

The pipe sits on and is surrounded with the pipe bedding and is not a drainage medium. Pipe bedding must be less than 0.3m thick in a trench less than 2m wide.

Combinations of construction activities

A combination of the types of construction activities described above will often take place on the same development. For example, you could lay pipe bedding and sub-base in a trench which then forms part of a construction platform or road sub-base. Where this occurs you must still meet the criteria specified in this RPS (for example, maximum width or thickness) for each individual construction component.

Temporary construction features

Temporary construction features of the kinds described earlier must still meet all of the criteria and limits set out in the RPS.