Flood Risk Assessment, Wandsworth, London
Sep 5, 2013

RAB Consultants has recently updated a flood risk assessment for the site of the former Putney Hospital, Wandsworth.  The planned development will see most of the site redeveloped as a school and a block of residential flats.  Because the site is situated in the Environment Agency’s Flood Zone 3 at risk of flooding from the tidal River Thames a full assessment of the risk to the developments final occupants was required.

We originally produced the report in February 2012 in accordance with PPS25. However, the introduction of the National Planning Policy Framework in March 2012 superseded PPS25 and meant that the report needed to be amended to up to date government guidance. Consultation with the Environment Agency revealed that the data provided in 2011 for the original report was also now out of date and consequently we had to update this as well.

The assessment involved the following:

* A site visit to assess flood risk at the site;
* Assessment of collected Environment Agency data;
* Preparation of a flood risk assessment report in accordance with the National Planning Policy Framework;
* Preparation of a Sequential Test and Exception Test in accordance with the National Planning Policy Framework;
* Desk based assessment of suitable mitigation measures to offset any risk of flooding.

The report concluded that the flood defences along the stretch of the River Thames closest to the site offered sufficient protection for even the most extreme floods modelled by the Environment Agency now and would continue to do so in the future if defences are raised in line with the TE2100 Plan. Because the site was also shown to not be at risk of flooding from all other sources including surface water and drainage infrastructure, it was concluded that the development is appropriate for the flood risk.

RAB operations in London and South East England are headed up by Ray Pickering; a Chartered Engineer with 20 years of experience leading people, projects and programmes in the public and private sectors, across all aspects of flood and coastal risk management.

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