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Advice to Natural England

Enquiry

• From: Natural England
• Date advice given: 13 June 2012
• Enquiry type: Email

R17[2] ? 9 . ?Best Case? flight activity?

During previous stages of the examination I understand that there was some concern as to whether the ?best case? flight activity has been applied in the calculation of disturbance and displacement instead of the worst case as required. The Statement of Common Ground appears to indicate agreement that the calculation is robust.

Could the Inspector please clarify what is meant by ?Best case? flight activity as we haven?t been able to find any reference to this in the statement of common ground or HRA. We want to be sure we are responding correctly to the question

Advice given

This question originated prior to the finalisation of the SoCG between NE and Vattenfall. From the SoCG it is noted that the density model (referred to as the 3rd model in the SoCG) has been agreed and the outputs (when applied to the JNCC baseline giving a different result to the 1.4%) accepted as the most robust prediction of displacement.

Just to explain the background though: the phrase 'best case' in the context of this question is referring to the difference between the values calculated under the different models used, with a 0.5% displacement output from the proportionate model (a 'best case' scenario) and 1.4% from the density model (the worst case scenario). From the submitted HRA report it was not clear which model was accepted as the most suitable and which figure for displacement was being taken forward as the most robust prediction.

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