Water & Wastewater Treatment Magazine
Issue link: https://fhpublishing.uberflip.com/i/705933
In the know Digging deeper: property-level flood protection 28 | august 2016 | WWt | www.wwtonline.co.uk form of water resistant doors and windows, water-tight air bricks, and water proofing of the fabric of the building to minimise water ingress through walls, up through floors and drainage points within the building (oen termed secondary flow pathways). The deployment of PLP as the fourth stage of this catchment wide approach can therefore enable far larger numbers of properties to be confidently taken out of flood risk than was previously possible. Passive Property Level Flood Protection The best measures offering the greatest benefit to property owners – domestic and business alike – are those where the owner has to do noth- ing other than close the door of the property to keep the water out. Where flood barriers and guards have to be physically taken out of storage and in- stalled, there is a greater risk of failure particularly if the property owner is not present at the time of the flood. Latest developments in fully passive PLP allow water resistant windows and doors to be able to withstand relatively high external water levels, whilst still being aesthetically pleasing with as many choices of styles and finishes available as for ordinary door and window products. Sealing of the fabric of a building can be achieved quite easily and a typical flood mitigation 'make over' can take as little as two days and cost on average £5,000 per property. The result is that the property owner experiences minimal disruption, and has peace of mind when the work is completed. Applying PLP to water company sewerage operations Whilst the Environment Agency and Tier 1 Local Authorities have statu- tory duties to reduce flood risk from rivers, water courses and highways, water companies are responsible for protecting properties from flooding from their sewerage systems, the cur- tilages of buildings and in some cases from highway run off where the water flows from the road onto the property. However, due to the complex interac- tive nature of flooding mechanisms, the water company oen has to put measures in place that provide protection from all causes of flooding, even where these are not their direct responsibility – simply because not to do so would leave the property owner at risk of flooding even if improve- ments to their sewer systems have been put in place. In the end, the customer does not recognise these complexities, and if he sees that the water company has failed to resolve the flooding a complaint will result leading to a higher SIM score. Consequently, scheme costs can easily exceed the indexed average cost per property, leading to delay in achieving a solution and leaving the property owner at risk. The average budget cost to eliminate internal property flooding is circa £60,000 per property, compared with £5,000 applying PLP measures. PLP therefore offers an affordable solution for flood mitigation and reducing overall solution costs. In AMP6, water company performance is measured through Outcome Delivery Incentives (ODI) and performance commitments. Most water companies have an ODI performance commitment linked to reducing internal flooding of properties. The associated flooding index provides an assessment of actual performance with respect to reducing sewer flooding whilst providing a direct measure of customer experience. The water companies are therefore incentivized to reduce property flooding whilst achieving high customer satisfaction at least cost. Typically in AMP6 a large water company will have rewards of £50M and penalties of £100M linked to flooding, so there is a real incentive to perform well. Because PLP is targeted at specific properties, rather than on a wider scale such as installation of large sewers and manholes, fewer customers are affected by the work, and there is a real opportunity to delight the customer whilst the PLP is being implemented, as well as enhancing the appearance of the property with bespoke doors and windows that are attractive whilst providing a high level of flood mitigation. The outcome is a householder that is confident that their property will not flood, that had a good experience of the installation process, and at a cost that allows significant cost efficiencies to be made whilst delivering considerable benefit and achieving the ODI performance commitments. In Summary PLP offers water companies an op- portunity to reduce flood mitigation solution cost through a balanced catchment management approach that includes targeted property level protection balanced with associated smaller scale hydraulic improvements to the sewer network. At the same time a higher degree of customer sat- isfaction is possible leading to a lower SIM score, positive ODI outcomes and significant cost savings. This innovative approach can help transform a water company's AMP6 sewerage operations and enable a significantly higher level of customer performance than has been the case in previous AMPs. Multiple small modifications can be used to implement PLP (Photo: Whitehouse)