Notice

TA5 1UD, NNB Generation Company (HPC) Limited: environmental permit variation (change) application advertisement – EPR/JP3122GM/V013

Published 28 October 2025

Applies to England

Details of the application

The Environment Agency has received an application to vary (change) an environmental permit under the Environmental Permitting (England and Wales) Regulations 2016 from NNB Generation Company (HPC) Limited. The proposed variation may have significant negative effects on humans or the environment.

Application number

EPR/JP3122GM/V013

Regulated facility type

Water management zones and effluent treatment units serving the Hinkley Point C (HPC) construction site

Application type

Variation

Regulated facility address

Hinkley Point C Construction Site
Hinkley Point C power station
Wick Moor Drove
Near Bridgwater
Somerset
TA5 1UD

National grid reference discharge points

Existing discharge points permitted via outlet 1 at national grid reference (NGR) ST 20375 46165 and outlet 12 at NGR ST 19315 46475

Receiving environment

Severn Estuary

Effluent types

Newly proposed and existing permitted discharges of trade effluent consisting of

• Addition of trade effluent under the existing permitted water discharge activity (WDA) references A(i), A(ii) and A(iii) generated from testing of the site’s fire hydrant system via outlet 1
• Trade effluents generated from cold commissioning activities from the existing permitted WDA reference I and the addition of newly proposed WDA references J(i) and J(ii) via outlet 12. These WDAs include effluents generated from activities such as flushing, hydro-testing and byproducts from demineralised water production from the demineralised water plant and commissioning effluent treatment plant (CETP). HPC’s variation application intends to segregate existing permitted effluents from WDA reference I as the newly proposed WDA references J(i) and J(ii). This is required by HPC to ensure that the whole capacity of the discharge through WDA reference I is utilised for the effluent containing hydrazine and ammonia, which will be treated by the CETP prior to its discharge via outlet 12.

Brief description of the proposed variation (change)

1) Permit an amendment to the existing description of water discharge activity (WDA) references A(i), A(ii) and A(iii) for the additional discharge via the construction surface water network of ammoniated firewater leaked during the fire hydrant pressure and flow testing of the site’s fire hydrant network.

2) Permit the addition of a new WDA as reference J(i) and J(ii). This is required to allow for the discharge of effluents generated as part of cold commissioning activities, including

• WDA reference J(i): This effluent is generated from the flushing and hydrotesting associated with cold commissioning activities potentially containing ethanolamine and trisodium phosphate. This WDA will not contain ammonia and/or hydrazine.
• WDA reference J(ii): This effluent is generated from the site’s demineralised water plant.

3) Permit a change of the discharge pattern from an originally planned batched discharge to a continuous discharge for the existing permitted WDA reference I, and newly proposed WDA references J(i), and J(ii). HPC state this change is required to increase operational flexibility and to efficiently utilise the commissioning effluent treatment plant (CETP) following its detailed design outcomes. The originally planned batched discharge by HPC was based on the then proposed operation of the CETP in batch-mode (not a batched discharge linked to the state of the tide).

HPC have stated that the concentrations and impact on the Severn Estuary of key potential pollutants in the effluents generated under WDA references I, J(i) and J(ii) were assessed in previous variation applications that were determined and granted for this permit on 25 March 2022 (for variation application V009) and 22 September 2025 (for variation application V012). There are no other proposed changes to the remaining permitted WDAs as part of this permit variation application (V013). For ease of reference these are WDA references B, C, E1, E2, F and H.

Volumes

• Under WDA references A(i), A(ii) and A(iii): An additional discharge volume of up to 10 cubic metres per day (m³/day) of ammoniated firewater to enter the surface drainage network to allow for the testing of fire hydrants on site for discharge via outlet 1.
• Under WDA reference J(i): A maximum discharge volume of up to 1,500m³/day of wastewater effluent associated with the flushing and hydrotesting of systems not containing ammonia and/or hydrazine for discharge via outlet 12.
• Under WDA reference J(ii): A maximum discharge volume of up to 1,500m³/day of wastewater effluent (concentrated potable water and chemicals used within the demineralised water plant) from the production of demineralised water for discharge via outlet 12.

How to view the variation application

The variation application can be viewed online: https://consult.environment-agency.gov.uk/psc/ta5-1ud-nnb-generation-company-hpc-limited-v013

Please contact us via e-mail at psc-waterquality@environment-agency.gov.uk or contact us on 03708 506 506 to arrange to see the variation application documents if you are unable to access Citizen Space.

How to view and comment on the variation application

If you have any comments on the variation application send these by 23:59 on 30 November 2025.

You can comment:

Online: https://consult.environment-agency.gov.uk/psc/ta5-1ud-nnb-generation-company-hpc-limited-v013

Via email: psc-waterquality@environment-agency.gov.uk

For advice about how to make a representation or if you are unable to make a representation via our e-consultation tool (Citizen Space) or e-mail please call 03708 506 506.

The Environment Agency will normally put any comments it receives on the public register. This includes your name but not your personal contact details. Please tell us if you do not want your response to be public.

The privacy notice for permit applicants/operators can be viewed at https://www.gov.uk/guidance/environmental-permits-privacy-notice

Find out more about our regulation of the HPC site via our GOV.uk page at the link below:

https://www.gov.uk/guidance/hinkley-point-nuclear-regulation