The Challenge

A recent landmark ruling in the European Court of Justice known as the Dutch Nitrogen Case ruled that where an internationally important site (i.e. SACs, SPAs and Ramsar Sites) is failing to achieve condition due to elevated nutrient (phosphorus and nitrogen) concentrations then planning permission cannot be legally granted until a development can be proven to be nutrient neutral. This has resulted in greater scrutiny of planning applications that are likely to increase nutrient loads to internationally important sites. Natural England and Natural Resources Wales have both recently published guidance on the implications of the ruling and advice on achieving nutrient neutrality. 

Royal HaskoningDHV are currently working with local authorities within Somerset to overcome their problem with elevated levels of phosphates within the Somerset Levels and Moors Ramsar. The work includes the development of a phosphorus budget calculator and an accompanying GIS based heat map. 

Phosphorus budget calculator

The phosphorus budget calculator provides a rapid, quantifiable assessment of phosphate loading from a development. The calculator incorporates regional specific inputs and best-available scientific data and has been endorsed by Natural England and received high praise following review. The calculator goes significantly beyond previous guidance published on developing phosphorus calculators as it estimates the area needed for mitigation. The calculator can be used to quantify the loading from a development connected to mains sewage treatments works as well as on-site treatment plants. 

The calculator can be found on the websites of the relevant local authorities in Somerset.

GIS heat mapping

The heat mapping tool is a GIS based viewer that provides a high-level assessment of land that is suitable for conversion to mitigation sites for offsetting excess phosphorus from developments. The tool considers environmental data to develop criteria by which to assess the suitability of land parcels to provide short and long-term nutrient management solutions, including wetland creation. 

Strategic advice

Wetland creation is often the most effective way of removing phosphorus from watercourses.  We are currently assisting Somerset West and Taunton Council to identify potential mitigation sites and assess their suitability for wetland creation on these sites.

Our Services

Royal HaskoningDHV have a multidisciplinary and experienced team of freshwater habitat specialists, hydrologists, ecologists and GIS experts that can offer their technical expertise on issues relating to phosphorus neutrality. Our key services include:

  • Development of the phosphorus budget calculator following a small number of new inputs required to calibrate the model for a new region
  • Creating a heat-mapping tool for assessing mitigation sites
  • Screening of mitigation sites and feasibility assessments for wetland creation
  • Advice on wetland design and creation
  • Assistance in strategy work and developing a policy for Local Plans
  • Assistance with producing a supplementary planning document (SPD)

Contact us

Ian Dennis

Technical Director, Catchment Management

Haywards Heath, UK

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