Biodiversity Supplementary Planning Document
(3) Chapter 5: Mitigation hierarchy
The design of all development proposals should reflect the findings and recommendations in the ecological surveys carried out for the site and incorporate measurable biodiversity net gain of at least 10%. The mitigation hierarchy should also be applied. The mitigation hierarchy is a widely used tool that guides users towards limiting harm to features of biodiversity value through avoiding harm, minimizing and mitigating harm and, as a last resort, compensating or offsetting harm.
The first step is avoid – harm to features of biodiversity value should be avoided. The Council has a supply of deliverable housing sites with allocations in the adopted Local Plan and a 5 year housing land supply. Development on sites that are not allocated in the Local Plan and likely to harm features of biodiversity value should be avoided by locating development on an alternative site. Another way of avoiding harm is to consider an alternative layout which will avoid harm to features of biodiversity value. It could be as simple as retaining trees and hedgerows on site. Avoiding harm is often the easiest and cheapest way of reducing harm and can make it easier to achieve a minimum of 10% biodiversity net gain.
If harm cannot be avoided, any harm should be minimized and mitigation measures incorporated into the design of the development proposal. A mitigation strategy should be prepared and submitted with the planning application which includes details of how the mitigation measures will be managed and maintained for a period of at least 30 years.
As a last resort, if despite mitigation there would still be harm, compensation measures should be incorporated into the design of the development. The applicant will need to demonstrate how these measures will be managed and maintained for a period of at least 30 years. Compensation measures should provide alternative habitat of higher quality and a greater area to the habitat lost. This is the exception and must be fully justified.
Where habitat will be lost or damaged, habitat creation should take place before the existing habitat is lost or damaged to help maximise habitat coverage. This will be especially important in situations where the habitat supports species that are particularly sensitive to temporal effects. For example, ground dwelling bees having one generation per year will not be able to persist in areas devoid of suitable habitat while awaiting restoration post loss.
The approach to following the mitigation hierarchy should be informed by up-to-date survey and assessment of the ecological value of the habitats and species likely to be affected, aligned to best practice standards as set out in BS42020:2013 Biodiversity – Code of practice for planning and development. This standard identifies the ecological data required and considerations for its assessment, and its use in the design of mitigation measures.
Where a development proposal cannot satisfy the requirements of the mitigation hierarchy, development will not be supported in accordance with Policy ENV1 (Environment) Part C, criteria (ii) and Part C (i)-(iii) of the Colchester Local Plan, which states:
"For all proposals, development will only be supported where it: (ii) Where there is reason to suspect the presence of a protected species (and impact to), or Species/Habitats of Principal Importance, applications should be accompanied by an ecological survey assessing their presence and, if present, the proposal must be sensitive to, and make provision for their needs and demonstrate the mitigation hierarchy has been followed." [Part C, criteria (ii)]
"Proposals for development that would cause significant direct or indirect adverse harm to nationally designated sites or other designated areas, protected species, Habitats and Species of Principle Importance, will not be permitted unless:
(i) They cannot be located on alternative sites that would cause less harm; and
(ii) The benefits of the development clearly outweigh the impacts on the features of the site and the wider network of natural habitats; and
(iii) Satisfactory biodiversity net gain, mitigation, or as a last resort, compensation measures are provided.
The Local Planning Authority will take a precautionary approach where insufficient information is provided about avoidance, mitigation and compensation measures and secure mitigation and compensation through planning conditions/obligations where necessary." [Part C (i)-(iii)]