Distinguishing between ‘embedded’ and ‘secondary’ mitigation measures

EIMA Article

In accordance with Part 5, Regulation 18 and Schedule 3, an Environmental Statement (ES) should include the following, “a description of any features of the proposed development, or measures envisaged in order to avoid, prevent or reduce and, if possible, offset likely significant adverse effects on the environment.” These measures are generally regarded as ‘mitigation measures’.

Mitigation measures can take many forms and the degree to which a measure is considered ‘embedded’ (or ‘primary’) or ‘secondary’ is often a debatable point. AM-P take the view that an ‘embedded’ mitigation measure is one that has been incorporated into the design of a particular development to prevent, reduce or offset any significant adverse effects, while a ‘secondary’ mitigation measure is one that prevents, reduces or offsets any remaining significant adverse effects of the proposed development. To try and provide further clarification, it is AM-P’s view that an ‘embedded’ mitigation is measure is one that is ‘standard’ and ‘guaranteed’ to be delivered as part of proposals. Whereas a ‘secondary’ mitigation measure is one that is more ‘bespoke’ to the proposed development and that is required to mitigate adverse significant effects over and above the ‘standard’ approach. To give a practical example, in noise and vibration terms, British Standard BS 5228: Parts 1 and 2 should be adopted as the basic code of practice for the management of construction noise and vibration on a site. Based upon guidance provided in BS 5228 and applied as appropriate through the Construction Environmental Management Plan (CEMP), various measures include: 1) appropriate operational hours; 2) acoustic covers for plants and compressors; and 3) locating noisy plant and equipment as far away as reasonably possible from sensitive receptors. These examples are considered ‘embedded’ mitigation measures in order to minimise noise and vibration from the construction activities. Therefore, when initially assessing the significant effects of construction noise, these measures are considered ‘part of’ proposed development. However, after an initial assessment, should further mitigation measures be required, such as significant noise barriers or screening (over and above the ‘standard’ requirements), these would be considered ‘secondary’ measures. The residual effects of the proposed development would then be assessed with these further ‘secondary’ mitigation measures in place.

It is therefore important that the distinction between ‘embedded’ and ‘secondary’ measures is explained and set out clearly in the ES. This is usually best undertaken within in each individual chapter of the ES, where specific aspects and measures relating to the proposed development are set out.

AM-P considers that this distinction is particularly important when assessing and explaining the residual effects of proposed development. The ES should clearly assess the effects of proposed development ‘without’ any mitigation measures in place. It should be clear to the reader if ‘embedded’ mitigation measures are actually included at this point. If potential adverse effects have been identified with ‘embedded’ mitigation in place, the ES should then set out what further ‘secondary’ mitigation measures have been incorporated into proposed development. It should be clear from the ES why (or in response to what) ‘secondary’ mitigation measures have been included in proposed development.

It is AM-P’s view that setting out the distinction between ‘embedded’ and ‘secondary’ mitigation measures clearly demonstrates the design evolution of proposed development to the reader and also importantly demonstrates how proposals have sought to “design-out” potential adverse effects.

Prepared by Mr Ian Butcher, Associate Director, Andrew Martin – Planning – March 2022