With almost a year still to go until new sustainable drainage laws come into effect, there is still plenty for the industry to do to prepare now. Jo Stimpson reports.
More than a year has elapsed since the Flood & Water Management Act was passed last April, outlining new sustainable drainage duties that require every new development to include sustainable drainage systems (Suds), and which must be approved by a Suds approving body (SAB) before construction begins.
However, the latest estimates from industry insiders suggest that SABs will not begin their work until around April 2012 because the new system cannot get up and running until the new national standards for Suds are approved.
Although originally due last year, consultation on the standards is now not expected to begin until this autumn, meaning the final document is unlikely to be published this side of the New Year.
Progress on starting new duties
Progress on starting the new duties is slow, but the delays at least give the industry more time to get to grips with the changes. The need for every new development to have Suds will be “a challenge for people who haven’t done it before,” says Hydro stormwater director Alex Stephenson. “But that shouldn’t be a problem if they get up to speed.”
Smaller firms might struggle to ensure that they have a Suds specialist on their staff, he says. “The smaller the practice, the harder it’s going to be. There will be some companies that will struggle and some that will see the opportunity and employ more people.” A lack of in-house Suds expertise could also affect a company’s attractiveness to clients, he says.
“If you go back 10 to 18 years Suds was a bit of an oddball topic. But now it’s going mainstream and you’re already seeing firms advertising their Suds expertise.”
Small consultants could suffer because the requirement to have Suds approval ahead of construction could mean devoting precious time and resources to detailed drainage design at an early stage, with no guarantee that the design will be approved. “People might have to spend more money and carry out more work at the early stage,” he says. “[Small firms] might be concerned about doing days and days of detailed design work to find out that a scheme doesn’t work or has to be started again.”
Contractors should also think
Contractors should also think about their Suds knowledge, to ensure they can construct the systems effectively, says Arup associate director David Schofield. For example, he says: “A good way for infiltration drainage to fail is that a contractor doesn’t realise that by using heavy plant on that area during construction he is compacting the ground.”
Larger firms, however, are already likely to have plenty of expertise in-house, says Stephenson. In fact, consultants well versed in Suds could even find a new workstream arising from the regulations. SABs do not have to assess proposed schemes themselves, but have the option to employ engineering consultants for that work − if their budgets allow.
But many local authorities − who are currently understood to be responsible for setting up SABs − will be looking to boost their in-house Suds skills. “Funding desperately needs to be addressed,” says Schofield. “We need to source that expertise.”
Department for Environment
The Department for Environment, Food and Rural Affairs’ (Defra) assertion that the transfer of ownership of private sewers to water companies will free up local authority funding to deal with Suds is misguided because councils currently spend very little in this area anyway, he says. “I’ve heard Defra say that, and they’re wrong to do so. [That] will not provide the funding stream that’s needed. Not even close.”
But MWH executive technical director David Balmforth points out that SABs will be entitled to charge for their services, and that could be a way of raising funds to employ drainage experts. “I think that the funding mechanism is there to provide that expertise. And there’s plenty of expertise in the other stakeholders for them to tap into,” he says. “The Environment Agency and water companies have a vested interest in supporting an appropriate set of decisions.”
Relevant figures in local authorities should begin building up those relationships with stakeholders now, he says, so that they are not starting from scratch next year when their duties begin. Engineers should look to good Suds examples in other countries such as the United States, which Schofield says is “streets ahead” on surface water management.
Portland, Oregon, in particular has made “massive changes in the urban environment from introducing sustainable drainage”, he says, with nearly 50,000 properties in the city now disconnected from the surface water drainage network.
Public enthusiasm for the schemes
Public enthusiasm for the schemes has even led to residents erecting signs proclaiming “I’ve disconnected”, and there is a local cycling tour of notable drainage sites. UK water companies including Yorkshire Water are now working with Portland authorities to learn from their drainage solutions and public engagement.
Another source of Suds expertise is the British Geological Survey (BGS), which is working to raise awareness of the potential negative effects of infiltration-based Suds on ground conditions. BGS contaminant hydrogeologist Rachel Dearden recommends that engineers look at three crucial factors when considering an infiltration scheme.
Firstly, the system could cause groundwater flooding if the unsaturated ground above the water table into which surface water will drain- known as the unsaturated zone − is not thick enough.
Unsaturated zone thickness
“Guidance suggests that an unsaturated zone thickness of at least 1m is necessary between the base of a soakaway and the groundwater,” she says. Secondly, the infiltration of water to deposits of soluble rocks could change the ground properties and lead to instability that might threaten neighbouring structures.
“Ground instability resulting from changes in drainage, or addition of water to the ground, has been observed to cause ground collapse on a number of occasions,” she says.
Finally, the passing of contaminants from surface water to groundwater should be minimised either by passive treatment prior to infiltration, or by attenuation in the unsaturated zone, to avoid the possibility of contaminating water sources.
Water sources could be threatened
Schofield agrees: “If we’re not very careful we could threaten some of our water sources. That’s not scaremongering; that’s a possibility that could happen.”
But the most important thing in Suds design is tailoring every system to its particular development, to avoid ineffective or unattractive Suds. “We mustn’t believe that one size fits all,” says Schofield. “It’s important to go back to the toolbox and select the correct solution.”
Stephenson also advises that products for use in Suds be carefully and shrewdly selected. “All of a sudden the world and his wife have got a Suds product. There’s a danger of things not being done properly,” he says.
“Companies have come up with cheaper products that have collapsed and been failures.” Members of the British Water Suds Focus Group have suggested creating an independent standard for Suds products, he says − but no official discussions have yet happened.
Above all, Schofield says, the biggest challenge to Suds success will be whether the government sets up the SAB system and the national standards in a way that encourages the best Suds practices. “We seem to have made it difficult for ourselves. There are probably too many stakeholders,” he says.
“What we’re doing isn’t rocket science − the challenge is administrative rather than the technology.” Balmforth says the skills and technology already exist, and the Netherlands has proven that Suds can be done well despite a complex system of water stakeholders − but British attitudes towards Suds will have to change. “You need to have the realisation that you need to do [drainage] well,” he says.
Ultimately, the incoming Suds requirements for new developments will be a test case, and success here could lead to the growth of Suds retrofitting for existing developments − which is seriously needed to deal with flood risk, says Balmforth.
However, he says early deliverables should be the focus now. “This is a vitally important first step. There’s no point in looking at the finish line and tripping over the first hurdle.”