On the last day of his trade mission, Governor Rick Snyder of Michigan, USA, visited KWR to hear more about possible solutions to the drinking water problems in the city of Flint. Since last year, the city has been experiencing lead release in the pipe network. Principal scientist Jan Vreeburg advocated the ‘self-cleaning water pipe network’ as a more reliable and less expensive alternative for the existing network.
The core of the lead problem in Flint is the change in water quality which has caused the lead solubility of the water to increase significantly. The Flint water company changed last year from drinking water from Detroit to local river water. Jan Vreeburg: “The short-term solution to this problem is reversal to the original situation regarding both source and treatment. In the long term, however, the complete network has to be replaced.”
Analysis of the Flint pipe network shows the diameter of the pipes to be (much) too large for the actual water demand. Vreeburg: “This results in accumulation and resuspension of deposits leading to discoloured water. Public opinion associates this discolouration closely with the lead problem. However, problems with discoloured water are much more generic and occur in all over-dimensioned networks containing deposits which may resuspend. This is a challenge that is dealt with actively in the Netherlands, just like the lead pipes problem.”
Less expensive and more reliable
Governor Snyder showed great interest in the new concept of ‘self-cleaning networks’, which is now considered as the solution for existing pipe networks in the Netherlands. The design and implementation of the self-cleaning network is radically different, with a minimum number of valves, for example. The most important condition is that a velocity high enough to remove the material causing discolouration is reached every day. “For the situation in Flint,” Vreeburg continues, “this leads to a less expensive and more reliable network, because it is 50% shorter and has up to 90% fewer valves. The costs of such a network are 40 to 50% lower compared to a conventional network. Combined with an adequate treatment of the drinking water (preventing the lead in the pipe network from dissolving) this will restore consumer trust and confidence in the drinking water: better water quality and lower costs.”
KWR CEO Wim van Vierssen offered Governor Snyder the option to investigate the possibilities for a pilot project in Flint to introduce this new principle in the USA and to demonstrate the effects and benefits of the new approach. Michigan State University professor Joan Rose confirms that the situation in Flint (ageing infrastructure with water quality issues) is representative of many urban areas in the US.
Rose: “I believe that there is an urgent need to invest in water technologies to aid in water diagnostics and innovative water treatment systems to address water chemistry and biological stability. I do not believe that what happened in Flint is a stand-alone incident. This is an occasion where we must take the lessons learned, all the efforts to monitor and model and provide this information to cities around the US and the world. It is not enough to just fix the pipes, what will make the difference is to provide the pathway forward for all the novel and innovative technology that can move Flint to a City of the Future.”
The principle of the self-cleaning network is already being applied by all Dutch water companies. So far, an estimated 7,000 to 10,000 km of this kind of network have been realised, with all the associated benefits. Several companies (WML, Brabant Water and PWN) are redesigning their complete network. The result of this will be used as a blueprint for rehabilitation projects, like WML in Limburg.