Pinpointing Exfiltration in Large Diameter Pressurized Wastewater Pipelines with the Sahara Tethered System

Building on the success of the Sahara Leak Location system in potable water mains, a new service is now being finalized for use in rising mains and other pressurized wastewater pipelines to pinpoint exfiltration. Failure of wastewater forcemains cause an environmental hazard as well as extreme operational difficulties while the forcemain is being repaired. Previous research has shown that pipes at greatest risk of failure have often been leaking for some time, but unfortunately, to date there has been no technology available to undertake an effective force main inspection in a live operating condition without excavation. As with the water main leak detection system, the intention is for surveys to be carried out with the pipe remaining in service and provide real time information on the exact location of leaks of any size of plastic, fiberglass, iron, concrete, steel, ductile iron, cast iron or clay pipes. It has become apparent that water utilities would prefer any device put inside their live pipelines to be tethered so that the device can be controlled and removed. This preference is echoed with wastewater system operators who realize the serious potential problems associated with lost equipment in an operating pressurized system. This paper discusses some of the important operational issues to consider when using an intrusive tethered survey tool in wastewater pipelines and some of the challenges overcome during the development and adaptation of the Sahara system. Field trials conducted by WRc that have shown that the Sahara leak location system can be successfully deployed and operated in wastewater piping systems are presented.