In the UK, at the last Periodic Review, the Business Plans of the water utilities included costs for alleviating flooding of properties from sewers. The unit costs of these schemes varied widely, the highest being six times more expensive than the lowest.
To ensure utilities use cost-effective solutions to alleviate sewer flooding the UK economic regulator, Office for Water Services (Ofwat) wanted to provide a greater understanding of these schemes and the costs involved. Such and Salinger Partnership (SSP) and WRc are undertaking the research to develop a classification system used to identify expected scheme costs on the basis of the flooding cause and solution type. The matrix will provide simplified cost functions for the most significant types of scheme, developed along the lines of the industry TR61 cost estimating database.
Ofwat will use the results of this project to structure and assess utility submissions on sewer flooding at the next Periodic Review.