Use of waste clay in the construction of slurry lagoons or water storage reservoirs: RPS 91
Updated 13 October 2026
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This publication is available at https://www.gov.uk/government/publications/use-of-waste-clay-in-the-construction-of-slurry-lagoons-or-water-storage-reservoirs-rps-91/use-of-clay-in-slurry-lagoons-or-irrigation-reservoirs-rps-91
This regulatory position statement (RPS) does not change your legal requirement to have an environmental permit where one is required.
However, the Environment Agency will not normally take enforcement action against you if you do not comply with this legal requirement provided that:
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your activity meets the description set out in this RPS
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you comply with the conditions set out in this RPS
In addition your activity must not cause (or be likely to cause) pollution of the environment or harm to human health, and must not:
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cause a risk to water, air, soil, plants or animals
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cause a nuisance through noise or odours
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adversely affect the countryside or places of special interest
Activity this RPS applies to
This RPS relates to the use of waste clay (waste code 17 05 04) in the construction of slurry lagoons or water storage reservoirs.
Conditions you must comply with
You must:
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construct slurry lagoons in line with the Water Resources (Control of Pollution) (Silage, Slurry and Agricultural Fuel Oil) (England) Regulations 2010 regulation 4 and schedule 2 – read guidance on storing silage, slurry and agricultural fuel oil
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ensure the water storage reservoir meets, where relevant, the requirements and standards of the Reservoirs Act 1975 as ammended and the Flood and Water Management Act 2010
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ensure both the clay and the construction are certified fit for purpose by a suitably qualified engineer
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keep records for 3 years to show that you have complied with this RPS and make these records available to the Environment Agency on request
You must not:
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use more than 6,000 tonnes of waste clay per construction
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use this RPS in conjunction with waste exemption: U1 use of waste in construction.
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use waste clay that has come from construction and excavation sites affected by contamination or waste clay that contains hazardous substances
Things to note
This RPS relates to an activity that the Environment Agency considers is potentially suitable to be an exemption under the Environmental Permitting (England and Wales) Regulations 2016. A change is law would be required for this.
When you must check back
The Environment Agency will review this RPS by 14 October 2027.
The Environment Agency can withdraw or amend this regulatory position before the review date if they consider it necessary. This includes where the activity that this RPS relates to has not changed.
You will need to check back from time to time, including at and before the review date, to see if this RPS still applies.
This RPS remains in force until it is removed from GOV.UK or is otherwise identified as having been withdrawn.
You can subscribe to email updates about this RPS. These will tell you if the RPS has changed and when it has been withdrawn. Use the ‘Get emails about this page’ feature on the RPS publication page.
If you cannot comply with this RPS
If you operate under this RPS but can no longer comply with it, you must:
- stop the activity to which this RPS relates
- tell the Environment Agency immediately by contacting enquiries@environment-agency.gov.uk with RPS 91 in the subject.
Contact the Environment Agency
If you have any questions about this RPS email enquiries@environment-agency.gov.uk with RPS 91 in the subject.