Phosphates on the Somerset Levels and Moors Ramsar Site
Following a recent Judgement (known as Dutch N), Natural England have advised the Somerset Authorities that, in light of the unfavourable condition of the Somerset Levels and Moors Ramsar Site due to high levels of phosphates, any application that would result in additional phosphate loading in the catchment should be subject to a Habitats Regulations Assessment (HRA) and if necessary, mitigation measures
The types of development affected include:
- New residential units - including tourist accommodation, gypsy sites /pitches
- New commercial floorspace including extensions to existing, change of use from one business to another where there is an increase in employees and/or to a use that would impact on wastewater
- Agricultural Development - additional barns, slurry stores etc. where it is likely to lead to an increase in herd size
- Prior Notifications of agricultural development where, as a result of the development, the herd size may increase. Also, prior notifications for change of use of office to dwellings and agricultural buildings to dwellings
- Anaerobic Digesters
- Tourism attractions which provide additional over-night accommodation (e.g. hotels, holiday lets campsites etc.)
Additional phosphate loading generally arises from the discharges from sewage treatments works and private package treatment works/sewage tanks, with agricultural development and anaerobic digesters also giving rise to specific issues. Increased loading can also arise as a result of surface water run-off from the changed use of land.
Within Sedgemoor the main Wessex Water sewage treatment works do not discharge into the RAMSAR catchment area, and any development to be connected to mains sewage is unlikely to contribute to increased phosphate loading from sewage outflows, although the underlying change of use of land may result in an increase due to the change in nature of the surface water runoff. Any proposal for mains connected development within the catchment area should be supported with confirmation of a connection to the mains system as well as details of the receiving sewage treatment works together with an assessment of the surface water runoff.
For development using a private treatment works an assessment of the additional phosphates loading will be required. Interim guidelines for small scale development using package treatment works has been produced. This may enable the LPA to conclude that there will be no likely significant effect and some smaller developments may be able to proceed without the need for detailed assessment of the phosphate loading.
For all relevant development that cannot comply with this advice, or that connects to a treatment works that discharges to the RAMSAR catchment and where there is a change of use of land that results in an increased phosphate loading due the surface water run-off, a detailed assessment of the phosphate loading will be required. This will enable appropriate mitigation to be proposed and a HRA to be carried out. If this concludes that there would be no likely significant effect on the RAMSAR site planning permission could be granted subject to measures to ensure that the agreed mitigation is carried out and maintained thereafter.
A phosphates calculator has been created to enable the additional phosphate loading to be calculated. This is available as an online Phosphate Calculator.
The calculator should be completed and provided in support of any relevant development within the catchment zone to enable the phosphate loading to be assessed. We are working to produce detailed guidance on suitable mitigation strategies across Somerset. In the meanwhile developers should seek ecological advice from their advisors and where possible address any mitigation within the application site.
Further detailed advice is available from Somerset Ecology Services and you can also contact Sedgemoor District Council about specific site proposals using our Pre-Planning Application Advice or, for general inquiries Development Management.