Download - Sewer Infiltration Monitoring
Sewer Infiltration Monitoring
David Walters BEng CEng MCIWEM
Principal Research EngineerInnovation
SWIG Sensing in Water 201524th September 2015
Sewer Infiltration MonitoringBackground
Widespread seasonal problem for many water companies
‘Unaccounted for Water’ typically caused by groundwaterentering the sewer through aged / defective pipework
Can result in internal & external flooding and pollution
Increased energy costs and wear at Sewage Pumping Stations
Increased vehicle / tanker movements(24/7 in some catchments)
Unhappy customers & stakeholders MP’s, LA’s, EA etc.
Sewer Infiltration MonitoringBackground
Thames Water experienced wide scale infiltration eventsduring the winter of 2012/13 and 2013/14
Ongoing commitment to undertake investigations andinvestment in catchments at greatest risk
Investigations include flow monitoring, catchment &groundwater modelling, PS analysis etc.
Existing site investigation techniques – lift & look surveys,CCTV surveys, impermeable area surveys, stoppering etc.
Innovation considered alternative investigation techniques,both linked to temperature monitoring
Sewer Infiltration MonitoringDTS
Distributed Temperature Sensing (DTS)
Fibre-optic cable installed in a sewer with laser light pulsedalong the length
Temperature measurement recorded at 2m intervals everyminute.
Temperature differences identify inflows to sewer
Service provided Royal HaskoningDHV with site contractor
manhole manhole
sewer pipe
laser/computerinstrument
fiber-opticcable
container
external power supply
manhole manhole
sewer pipe
laser/computerinstrument
fiber-opticcable battery pack
Sewer Infiltration MonitoringDTS Investigations
Hambleden1674m cable
Monitoring Started 8th October 2014
Monitoring Ended 11th November 2014
Cuxham1151m cable
Monitoring Started 16th December 2014
Monitoring Ended 16th February 2015
Sewer Infiltration MonitoringDTS – Hambleden Cable Installation
Sewer Infiltration MonitoringDTS – Hambleden Cable Installation
Sewer Infiltration MonitoringDTS Example of Results
Sewer Infiltration MonitoringDTS Example of Results
Sewer Infiltration MonitoringDTS Example of Results
Sewer Infiltration MonitoringDTS Example of Results
Sewer Infiltration MonitoringDTS – Pump run times
Sewer Infiltration MonitoringDTS Results
Trial demonstrated the potential of the system andprovided lots of data
Timing of deployment critical to capture infiltrationevent
Deployment required just prior to an eventBut, this is the unknown..
Technique also required jetting & CCTV
Some operational problems – ragging
Costly
Sewer Infiltration MonitoringTemperature Loggers
Temperature measurement is used to optimise sewagetreatment processes
Considered option to identify infiltration into seweragenetworks?
Reduced temperature could indicate infiltration
Low cost equipment – around £100 per loggerSealed units – wireless data reader
Trial undertaken within a catchment with previoushistory of infiltration: Fencott & Murcott
Trial started September 2013
SLI51-KIT - USB-5Temperature Data Loggers
Sewer Infiltration MonitoringTemperature Loggers
Comparable recordings from each logger
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05/02/2015 07/02/2015 09/02/2015 11/02/2015
Deg
rees
C
Date
Temperature Logger Comparison Test
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2
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5
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5
Sewer Infiltration MonitoringTemperature Loggers
Sewer Infiltration MonitoringTemperature Loggers
Sewer Infiltration MonitoringTemperature Loggers
Sewer Infiltration MonitoringTemperature Loggers
Very good diurnal pattern recorded
Sewer Infiltration MonitoringTemperature Loggers
Merton
Sewer Infiltration MonitoringTemperature Loggers
All sites - seasonal pattern over nearly 2 years
Sewer Infiltration MonitoringTemperature Loggers
Infiltration Event Captured 2013 – 2014
Sewer Infiltration MonitoringTemperature Loggers
Event with rainfall
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4
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5
Sewer Infiltration MonitoringTemperature Loggers
Sewer Infiltration MonitoringTemperature Loggers
Pump run times
Sewer Infiltration MonitoringTemperature Loggers
Pump run times
Sewer Infiltration MonitoringTemperature Loggers
Other catchments – Ramsdell
Sewer Infiltration MonitoringSummary
Temperature loggers have provided good results todate
Durable hardware – survived in the sewers
Potential to use in the network to target sources ofinfiltration or unaccounted for water
Cost effective tool for long term measurement ofcatchment performance
No confined space access needed
Trial ongoing and rolled out to further catchments