Validation requirements
How to secure phosphate mitigation
Planning applications which require phosphate mitigation must secure this via a condition and/or a Section 106 legal agreement. The below section provides further information regarding this. There may be some situations in which the method of securing mitigation could be different from that set out below – if you have any queries please contact the Phosphate team: phosphates@somerset.gov.uk.
Types of Phosphate Mitigation
Third-party Phosphate Credits (P-Credits) – with an overarching legal agreement with Somerset Council
Pre-commencement Condition:
- Submission of a Reservation Notice prior to grant of planning permission (via either delegated authority of following a positive resolution at committee). The Reservation Notice demonstrates the developer has paid a deposit to secure sufficient Phosphate Credits. Somerset Council then imposes a planning condition on the permission, requiring submission of an Allocation Certificate prior to commencement of development.
Somerset Council Phosphate Credits (P-Credits)
- Section 106 Agreement
Septic Tank/PTP upgrades (Serving 1 dwelling)
- On-site: Condition (Compliance)
- Off-site: Section 106 Agreement
Septic Tank/PTP upgrades (Serving multiple dwellings)
- On-site: Section 106 Agreement
- Off-site: Section 106 Agreement
Orchard Planting or Woodland Planting
- On-site: Condition (Compliance)
- Small-scale on-site orchard or woodland planting where it relates to a single dwelling, and the Officer is satisfied that the site is such that the proposed orchard or woodland would not become separated from the proposed or existing dwelling.
- On-site: Section 106 Agreement
- Required for proposed developments for multiple dwellings
- Off-site: Section 106 Agreement
Wetland Creation
- On-site: Section 106 Agreement
- Off-site: Section 106 Agreement
Sustainable Drainage Systems (SuDS)
Section 106 Agreement
- Required for monitoring and maintenance of the Sustainable Drainage Systems in perpetuity (80-120 years).
Please note: In some cases, Sustainable Drainage Systems design is secured via condition (for example for flood risk). However, design details of Sustainable Drainage Systems being used as phosphate mitigation must be reviewed, confirmed and secured prior to the determination of the application. An exception to this is for Outline applications, for which design details for Sustainable Drainage Systems with a phosphate reduction rate of 50% or lower can be secured via condition to be provided at Reserved Matters stage. Please see the SuDS NNAMS Guidance for applicants for further details.
Multiple mitigation types
Each mitigation type is secured as above
- Multiple mitigations which require a Section 106 Agreement can be captured into one single Section 106 Agreement. Mitigation which can be secured via planning condition in accordance with the above, should be. It is not necessary to also include within the Section 106 Agreement.
Templates and guidance
The following documents have been created by Somerset Council to assist applicants in the preparation of planning applications subject to phosphate neutrality, and to assist in the consideration of possible phosphate mitigation solutions.
The templates and guidance should help applicants with preparing Nutrient Neutrality Assessment and Mitigation Statements (NNAMS), shadow Habitat Regulations Assessments (sHRA) as well as providing additional guidance on nutrient neutrality opportunities:
General Guidance
- Nutrient Neutrality in Somerset – Guidance for Applicants
- Interim Guidelines on Small Scale Thresholds: Quick Guide and Background Information (October 2023)
- Package Treatment Plants and Septic Tanks Advice Note September 2022 (September 2022)
Nutrient Neutrality Assessment and Mitigation Strategy (NNAMS) Guidance
- Nutrient Neutrality in Somerset Guidance for Applicants – Package Treatment Plants (PTPs) and Septic Tanks
- Nutrient Neutrality Assessment and Mitigation Strategy Guidance for Applicants – Third-Party Credits
- Nutrient Neutrality Assessment and Mitigation Strategy Guidance for Applicants – Sustainable urban Drainage Systems (SuDS)
Templates
From September 2025, Somerset Council will no longer be accepting shortform HRAs. Instead, please use the Somerset Council Habitats Regulation Assessment Template above or a suitable alternative.
Useful information
Stakeholder engagement:
Somerset Council Planning Service – Update to Agents (October 2024)
- Somerset Council Planning Service – Update to Agents (March 2024)
- Somerset Council Planning Service – Update to Agents (December 2023)
- Somerset Council Planning Service – Update to Agents (July 2023)
- Somerset Agent’s Forum Meeting (March 2023)
- Former Somerset West and Taunton Council Agents Forum Meeting (July 2022)
- Wessex Water: Phosphorus and Development in Somerset Presentation (June 2021)
- Former Somerset West and Taunton Council Agents Forum Meeting (December 2020)
Somerset Solutions Report (March 2022)
The former Councils appointed consultants to provide technical support and develop mitigation solutions. Information regarding this can be found on the below link.