Planning Policy and Building Regulations

Arguably, energy efficiency and carbon reduction have had a higher profile on the sustainable agenda in recent years. But – prompted by major surface water flooding events (e.g. in the Summer of 2007) and the impact of Climate Change –  policymakers have increasingly turned their attentions to the need to control the quantity and quality of water. Based on the foundation of strategies such as Future Water in the UK, and European Water Framework  Directive, regulations and guidance are making increasing demands on the building industry.

Legislation and Sustainable Drainage

Legislation is increasingly targeting the better management of both the quantity and quality of stormwater, in particular through the Flood and Water Management Act 2010 and the Water Framework Directive and its derivatives.

Current regulations and guidance already place expectations on developers to design drainage systems in line with Sustainable Drainage Systems (SUDS) criteria. The current objectives of the Environment Agency, who have a statutory power to object to planning applications, are to restore the site to its pre-development runoff potential or better.

The use of SUDS to attenuate surface water discharge excess is widely acknowledged and adopted and will soon become compulsory for new developments. However, retrofitting SUDS solutions into our existing built environment is still a subject for considerable development and a matter of ongoing debate.

Planning Strategies

The introduction of the National Planning Policy Framework (NPPF) in March 2012 superseded existing Planning Policy Statements including PPS25: Development and Flood Risk, which was the principal planning advice on flood
risk in England, alongside policy statements in Wales (Technical Advice Note 15) and Scotland (Planning Advice Note 61).

The NPPF is complemented by Technical Guidance and this includes additional guidance to local planning authorities on flood risk.  The key elements of PPS25 have been retained, including Sequential and Exception Tests, Flood Risk Assessment (FRA), climate change and managing residual flood risk.  The Technical Guidance is intended to be an interim measure until a wider review of planning policy guidance can be undertaken.

There remains a strong emphasis on sustainable development for planning, design and construction.  However, it should be noted that the current Technical Guidance does not cover sustainable drainage (SuDS) implementation or drainage design.


Essential Advice

The EA offers an advisory service to planners, to assist them in complying with the Regional Spatial Strategies and Local Development Documents and avoid adding to sources of flood risk. The EA is also the statutory body consulted by the Local Planning Authority as part of the planning approval process following its advice should be a key component in reducing the cost and increasing the speed of achieving approvals.

The EA identifies sustainable drainage systems (A Guide for Developers) as a preferred option. The EA points out that early incorporation of SUDS into the site evaluation stage, even before detailed design, could save time and cost during the development. Additionally, protection of the local environment from pollution and flooding during the build must be demonstrated.

Building Design

Approved Document Part H of the Building Regulations 2000 governs the measures that must be taken to design appropriate drainage systems to manage  surface water flow from a building or impermeable surface.

Part H requires developers to consider a hierarchy of solutions for disposal of rainwater and encourages developers to adopt a SUDS approach. Part H sets out an order of preference for discharge of surface water with the highest priority being given to an infiltration system such as a soakaway or infiltration trench. However, it must be established that such an approach would be both feasible and sustainable, can be adopted and properly maintained and would not need to any other environmental problems (such as pollution risk to groundwater). The second preference would be for a system which discharges to a watercourse, and thirdly, if the first two options are not technically feasible, an outfall to a sewer.

Sewer Rights

Of specific interest to building development has been the definition or interpretation of the term sewer (Water industry Act 1991), as this affects the adoption and long term responsibility for the structure which accepts surface water discharge. In Scotland this has been codified (Sewers for Scotland, and Water Environment and Water Services (Scotland) Act (2003)), while the issue is currently  less clear cut elsewhere in the UK.

However, the automatic right of a developer to connect to a utilities-owned surface water sewer is also under close scrutiny. This right needs to be addressed on a development by development basis at the moment. However this will change with the implementation of the Flood and Water Management Act and the introduction of compulsory national standards for SUDS.

SUDS – the Pragmatic Approach

Maximising return on investment through efficient use of space is a matter of critical importance for developers, especially in challenging economic conditions. Developers need to maintain a pragmatic approach in the design, selection and application of SUDS techniques, whilst acting in accordance with regulations.

The use of open attenuation ponds and swales by themselves may provide an aesthetic enhancement and satisfy ecologists, but the amount of valuable land given up could make the build economically unsustainable. In addition, other site constraints, such as adjacent infrastructure or contaminated land on greenfield sites, may make open water features untenable.

Engineering Nature’s Way

By definition, SUDS solutions mimic the natural flow of water through a catchment. Best practice solutions are often achieved through engineering a combination of ‘natural’ features and proprietary systems which operate seamlessly together.   In many cases the proprietary system can enable or enhance a ‘natural’ feature to provide the ecological benefits of SUDS feature (e.g. a pond or swale) where this would not otherwise be possible.