The existing combined sewerage system in this ancient town did not
meet the current requirements of EU directives for overflow discharge.
Southern Water have instructed Black Veitch-Costain JC to construct
a deep collector sewer which will provide sufficient storage to
reduce overflow events to only the severest conditions. The sewer
will be constructed 12m deep and up to 1.5m in diameter by pipe
jacking between 6 shafts, with further works by directional drilling.
Soil Instruments' sister company, ITM Ltd, have been awarded the
contract to provide services to monitor settlement as a consequence
of these works. The instruments for the initial phase of monitoring
instrumentation have been installed at three of the shaft locations
and works for the tunnels will follow shortly.
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
were 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 loggers are key to the success of
this contract. These consist of radio tiltmeters and crackmeters
with no cabling requirements, ideal for sensitive and inaccessible
locations such as these. 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 is transmitted to a computer
running I-Site software in the ITM-Soil offices at Uckfield.
One of Lewes' many listed buildings
A further development of this contract has been the use of Net-Site
software. Instead of a computer on site running analysis software,
the client has opted for Net-Site, which 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, without 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
will be alerted by SMS text message and email.
Close-up of a radio crackmeter
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