Lewes Combined Sewer Outfall
The pre-existing combined sewerage system in the ancient town of Lewes did not meet EU directives for overflow discharge. Southern Water instructed Black Veitch-Costain JV to construct a deep collector sewer which will provide sufficient storage to reduce overflow events to only the severest conditions. The sewer was constructed 12m deep and up to 1.5m in diameter by pipe jacking between 6 shafts, with further works by directional drilling. itmsoil was awarded the contract to provide services to monitor settlement as a consequence of these works.
The route of the new system takes it close to the High Street at the bottom of a natural escarpment, where many old and listed properties are densely packed. With the project spread over much of the town and with detached individual private properties to be monitored, a conventional hardwired system would not have been practical, so the newly introduced wireless monitoring systems was key to the success of this contract.
These systems consist of radio tiltmeters and crackmeters which don’t require cabling and are ideal for sensitive and inaccessible locations such as in this situation. They communicate every few minutes with a radio logger sited nearby. This is automatically interrogated 24hrs a day via a GSM modem and the data was transmitted to a computer running I-Site software at itmsoil’s headquarters in Sussex.
For data management, ARGUS Monitoring Software was used. ARGUS displays monitoring data by means of a password - protected web page. The data is transmitted to the web site at regular intervals allowing data to be instantly accessed by any member of the contract team. This approach removes the need for the client to have either a dedicated computer or engineer viewing the data. In the event that preset limits are exceeded, nominated personnel are alerted by SMS text message and email.
- Radio crackmeters
- Radio tiltmeters
- Manual survey
- ARGUS Monitoring Software