Traditional construction practices often have a heavy environmental toll including high energy consumption, carbon emissions, and habitat destruction.

While it is widely acknowledged that the world faces unprecedented challenges in protecting the environment related to climate change and resource depletion, other environmental stressors and the value of rare and unique habitats are becoming more apparent. As more aspects of the environment prove to be under stress, adopting sustainability solutions, including the principle of Nutrient Neutrality in construction and civil engineering, becomes increasingly imperative.

In March 2022, Natural England (on behalf of the Government) wrote to the Local Planning Authority and County Council Chief Executives and Heads of Planning, as well as several other local and national governmental bodies. They outlined new requirements for the approval of new development, designed to ensure that some of the most important wildlife sites in England do not experience any further adverse effects caused by nutrients entering the environment in the construction of new development.

While this advice focuses on development that includes new overnight accommodation, which is predominantly new housing, the ruling by the Court of Justice of the EU (known as the Dutch Case), also prompted the Government to introduce other measures. The new measures aim to reduce the amount of nutrients entering the environment, leading to deterioration in the condition of designated environmental sites.

What is Nutrient Neutrality?
Nutrient Neutrality is the term used to describe the scenario where the nutrient output (which is measured in total phosphorous and total nitrogen) of a development has been limited to the level that existed prior to development. This is achieved by introducing measures to capture nutrients on-site or by offsetting by reducing the level of nutrients discharged from other sources.

The excess of nutrients affecting designated environmental sites is caused by several factors, including planned and unplanned release of treated and untreated sewage from the existing population and agricultural run-off. It also comprises the construction of new housing development and its contribution through the change in land use and the influx of new population.

Additional population from new residential development increases the volume of phosphorus and nitrogen passing through sewage treatment works. These nutrients, while required for any ecosystem to survive, in excess can encourage the disproportionate growth of algae and other microorganisms (i.e. algal blooms). This is a process known as eutrophication that leads to the reduction in available oxygen which can be devastating for sensitive aquatic species and ecosystems.

Norfolk and Nutrient Neutrality
Many ecologically valuable sites and species in England are identified and designated under a European Directive known as the Habitats Directive. Subsequently, these and the areas that support them, are designated under various UK regulations as Special Areas of Conservation (SAC).

Norfolk contains many SACs; some of which are chosen based on their aquatic habitats, such as those found in the Broads and the River Wensum (a chalk-fed oolite river channel). Local Planning Authorities cannot approve developments incorporating new overnight accommodation within these SACs if the development would increase the amount of nutrients entering the SAC.

In Norfolk, a consortium of local authorities has formed a company called Norfolk Environmental Credits to help developments achieve Nutrient Neutrality using credits. Developers may have the option to purchase credits generated from these types of solutions to offset the impact of their development or to implement some of these solutions themselves.

Other options for offsetting nutrient production include replacing heavily polluting septic tanks with less polluting treatment options, introducing water-saving measures into new and existing accommodation and enhancing water recycling infrastructure such as sewage treatment works.

Whichever option is used, the mitigation must result in no net increase in nutrients entering the environment for the lifetime of the development. They must be robustly evidenced and secured before a decision notice being issued by the Local Planning Authority.

A consortium of Norfolk Local Planning Authorities and Anglia Water has formed a not-for-profit company producing nutrient credits called Norfolk Environmental Credits Ltd (NEC). They have already completed a mitigation project involving the removal of livestock from some areas of land at Markshall Farm, next to the A47 south of Norwich. This project has allowed a significant number of housing projects to move forward. In addition, the Nutrient Mitigation Fund – Norfolk was recently launched, which offers £200,000 grants and is backed by a fund of £9.3M to help potential new entrants to the credit market develop solutions.

Our Experience
Many of our clients have faced their projects being delayed due to the introduction of the requirement to demonstrate Nutrient Neutrality.

Our team of experienced civil engineers at Rossi Long Consulting regularly works with developers to help them address the significant challenges arising from the introduction of the new measure. We can provide clients with either the evidence base required to obtain nutrient credits and allow their projects to proceed or with engineered solutions where credits are not viable.

By exploring innovative solutions with other stakeholders and regulatory bodies, we are also able to assist clients who are seeking an alternative resolution where neither of these are an option.

To continue to expand our expertise in this new and rapidly evolving field, we work closely with Local Planning Authorities, Water Companies, Natural England, the Environment Agency, Norfolk Environmental Credits and various other stakeholders. The knowledge and experience we have gained over the last two years since Natural England advised of the requirement to achieve Nutrient Neutrality, and the relationships we have built with key stakeholders, makes us ideally placed to assist clients with finding the right Nutrient Neutrality solution.