Bob Dylan was quite right in the sixties, though not perhaps in the way he intended, when he said ‘a hard rain’s a-gonna fall’. Now 40 years on we see it happening before our eyes – the intensity of rainfall is undoubtedly increasing right across the country as is the frequency of storms.
The resulting deluges of stormwater have stretched our drainage and sewerage infrastructure to breaking point – the stinking floods of 2007 and the huge discharges of raw sewage from overwhelmed combined foul and stormwater sewers into the Thames and other rivers have been a national disgrace. The Concrete Pipeline Systems Association is seriously concerned about the national position and has made a call to action with a range of proposed measures:
1. We think that the national storm and sewerage distribution network should be thoroughly surveyed and a national infrastructure investment programme undertaken; an initial sample survey should be carried out to look at the relative performance of different pipeline materials. We are particularly concerned that the relatively recent use of plastic flexible pipes in larger diameters may be compromising the capacity of our drainage network to take more intensive rainfall.
2. With the Government planning a major increase to over 250,000 new houses each year it is essential that sewerage system pipeline and treatment capacity be increased by a minimum of 50% on all new schemes to allow for this housing growth.
3. Capacity of all new and refurbished storm drainage systems in the UK to be at least doubled by a 50% increase in diameter from now on to allow for the higher intensity of rainfall and the need to remove run-off water much more quickly and efficiently.
4. Local Authorities, Highways Agency and other asset owners to re-focus attention on gulley emptying and the clearing and improvement of run-off bottlenecks. There is a lot of anecdotal evidence that gulley emptying and runoff maintenance have been overlooked with very damaging results to flooded households and undermined road surfaces. We hope that proper surveys will be undertaken and a reinvestment programme undertaken.
5. Durability of new pipeline systems to be set at a minimum of 100 years. It is quite wrong that less durable pipelines are installed without taking into account whole life performance. It is not just about the pipeline itself – the savings in bedding material can be very significant both in cost and in conserving virgin aggregates.
6. Combined sewers carrying storm water and sanitary sewage to be separated as far as possible with combined sewer overflows minimised as far as possible and eliminated completely in coastal and other highly sensitive areas.
The new Chairman of the CPSA is Andy Goring of Milton Precast who feels passionately about the issues identified by the Association. “The major incidents of flooding during 2007 coupled with the dreadful pollution incidents from overflowing sewage are a wake-up call to the infrastructure community. Together we must alert the public and the politicians that a better drainage and sewerage network is vital to support public health standards, housing and commercial growth, as well as to deal with the higher, more concentrated rates of rainfall and runoff that we will experience from now on. Ownership of the problem may be diffuse but the Government has a clear role to bring all stakeholders together to solve it.
“Although last year the problem was drought, it is clear that in this era of climate change there will be extremes at both ends of the spectrum. Whilst the problems of hosepipe bans and empty reservoirs from last year may be easily forgotten, we should act to see that the under spending on flood defence and drainage infrastructure does not go the same way. We hope our six point plan will help to set the agenda.”
Martin Clarke is Secretary for the Concrete Pipeline Systems Association and chief executive of trade group British Precast.
