Future proofing for flood risk

It is now widely acc-epted that climate change will increase flood risk over the coming century. Gov-ernment policy with respect to all types of development in flood risk areas changed in December 2006 with the issue of planning policy statement 25 (PPS25) Development and flood risk.

A host of guidance is available, including Development and flood risk: a practice guide companion to PPS25 – living draft and the Environment Agency’s standing advice.

Current guidance recommends allowance for around 900mm of sea level rise, combined with increased storm frequency and intensity, and 20% increase in flows in watercourses. It aims to ensure that the planning process takes full account of the impacts of flood risk. Specific measures include:

• to ensure flood risk is taken into account at all stages in the planning process
• to avoid inappropriate development in areas at risk of flooding
• to direct development away from high risk areas
• to ensure new developments take climate change into account and do not increase flood risk elsewhere.

Planning authorities should ensure that sites at little or no risk of flooding are developed in preference to areas at higher risk. The ‘sequential test’ refers to the application of this approach in determining land uses that are compatible with the level of flood risk at each allocated development site within a planning area.

Development should be directed to flood zone 1 (low probability) wherever possible, and then sequentially to flood zones 2 (medium probability) and 3 (high probability), and to the areas of least flood risk within zones 2 and 3. The most vulnerable uses should be directed towards the lowest risk areas.

So, how does this relate to the waste sector? Legislation expects that waste and mineral planning authorities will develop their policies and plans with due regard to regional spatial strategies, regional flood risk appraisals and any available strategic flood risk assessments (SFRAs).

However, since the policy is relatively new, most wastes and minerals plans do not yet reflect this, and sites for waste management, mineral extraction and processing have not been allocated by applying the sequential approach.

In a different class

Site uses are classified at different levels of vulnerability. Specific waste-related uses are classified as follows:

• highly vulnerable: installations requiring a hazardous substances consent
• more vulnerable: landfill and hazardous waste management
• less vulnerable: waste treatment (except above), minerals working and processing
• water compatible: sand and gravel extraction.

PPS25 confirms that a risk-based sequential test should be applied at all stages of planning. For sites not allocated by this method, and for windfall sites, it will be the responsibility of the developer to convince the planning authority and Environment Agency of their suitability for the intended use under the planning policy statement.

Useful indicators

The EA’s web-based flood map and standing advice provide a useful indication of the likely flood risk issues at a site, and the SFRA – if available – may provide further information. However, this information is based on coarse level mapping and does not currently allow for climate change. Therefore, it should not be relied upon completely, particularly for sites close to flood zone boundaries.

To manage the developer’s risk appropriately, it is advisable to undertake some investigation before committing to a site, including some elements of the sequential test and flood risk assessment (FRA), to identify all the likely constraints and any potentially fatal or expensive issues.

More detailed assessment and the production of a FRA and sequential test evidence would then be undertaken in parallel with the development of the planning submission and licensing/permitting process.

If timed correctly, this will advise the site design. It will be advantageous to engage with the Environment Agency and planning authority throughout this process to ensure their ‘buy in’ and to obtain the best out-turn for the developer.

Phil Hunter is from Leyden Kirby Associates