Water Management Planning Guidance for Construction Projects

The Flood and Water Management Act (FWMA) in 2010 provides clarification of accountabilities for local authorities to take a lead role. Storm and rainwaters provide risk and opportunity within the built environment, risk of surface waters creating channels within the built environment and resulting in flooding and opportunity that if attenuated from roofs provide reasonable resource. Planners and designers will account for the flood risk for the building, but teams planning the construction process need to consider the risk and impact for a construction site.

Consideration of surface water management and flooding should cover the following:

1. Are local water courses identified on the site plan?
2. Are the routes to water course identified?
3. Have areas of potential erosion and sediment transport been identified?
4. Is there a plan to mitigate potential erosion impacts?

Erosion and Silt/Sediment Control planning

Erosion and sediment control planning will be increasingly important for large projects with Water Framework Directive and ecological status measures in mind, and also with increasingly erratic weather patterns caused by climate change.

Projects where sediment/silt runoff could be a problem should consider the development of an erosion and sediment control plan which can include, but not be limited to, the following information:

• Property boundaries
• General soil description
• Existing and final contours - including location of cut and fill banks
• Existing and final overland flow drainage paths
• Limits of clearing or disturbed areas where applicable e.g. on large properties
• Location of vegetated buffer strips
• Stabilised entry/exit point (rumble pad)
• Location of soil and sand stockpiles
• Location of all proposed temporary drainage control measures
• Location of all proposed erosion control measures (alternatively, use notes to describe locations) including installation sequence and maintenance requirements
• Permanent site stabilisation measures.

A statement of whom is responsible for establishing and maintaining all erosion and sediment measures.

Land Drainage

Contractors may operate on or adjacent to banksides of main rivers or riparian owned watercourses. In this case, a flood defence consent will be required. In either case, notify and work with the national environmental regulator, Local Authority, and in certain parts of the country, the Inland Drainage Board. Each has specific designated duties to protect river channels and ensure flows are free to effectively drain an area and protect the community from flooding.

http://www.ada.org.uk/idbs.html

Flood and Water Management

The areas of FWMA 2010 most relevant to contractors and construction sites are: use of Sustainable Drainage systems (SuDS), process of surface water drainage approvals & adoptions, connection to public sewer and associated provisions, designation of third party flood management assets and note of the powers for water companies to control non-essential uses of water.

Sustainable Drainage systems (SuDS)

SuDS is a technique that manages surface water and groundwater sustainably. If planned and designed, it is an extremely effective approach. Site managers should ensure that SuDs are protected from construction activity.