Forewarned is Forearmed - New Techniques for Sewer Rising Main Inspection
There were over 800 rising mains failures in England and Wales in 2006/7. Rising mains failures always cause loss of service and can result in pollution of receiving waters or sewer flooding, particularly in larger mains where it is not possible to use tankers to divert the flow. These mains are therefore some of the most critical parts of the sewer system. Wholesale replacement or reactive repair is more expensive than planned maintenance but the lack of suitable inspection tools makes cost effective planning and repair extremely difficult.
A collaborative project (CP371) involving 6 water companies has finished its first phase. This identified and tested 6 inspection techniques that appear to offer significant benefits in the detection and location of actual or potential structural fault before total failure occurs. Although the principle behind each of the techniques is well understood, the project has combined the inspection technique with new deployment methods to enable inspection of rising mains.
A second phase of the project is just starting, this will involve field trials of the techniques to establish the practicalities, costs and results obtainable when surveying real rising mains with each of the techniques. WRc will coordinate the trials and record and assess the results before producing a selection matrix for participants to aid planning of cost effective surveys and repairs in the future. New participants are welcome to join the project to share in the benefits.