Assessment of detection limits of fiber-optic distributed temperature sensing for detection of illicit connections

Distributed temperature sensing (DTS) with fiber-optic cables is a powerful tool to detect illicit connections in storm sewer systems. High-frequency temperature measurements along the in-sewer cable create a detailed representation of temperature anomalies due to illicit discharges. The detection limits of the monitoring equipment itself are well-known, but there is little information available on detection limits for the discovery of illicit connections, as in mixing of sewers, and attenuation also plays an important role. This paper describes the results of full-scale experiments aiming to quantify the detection limits for illicit connections under various sewer conditions. Based on the results, a new monitoring set-up for (partially) filled sewer conduits has been proposed.

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Fibre-optic distributed temperature sensing in combined sewer systems

Water Science & Technology ◽

10.2166/wst.2009.467 ◽

2009 ◽

Vol 60 (5) ◽

pp. 1127-1134 ◽

Cited By ~ 14

Author(s):

R. P. S. Schilperoort ◽

F. H. L. R. Clemens

Keyword(s):

Temperature Sensing ◽

Fibre Optic ◽

Distributed Temperature Sensing ◽

Sewer System ◽

Sewer Systems ◽

Combined Sewer ◽

Combined Sewer System ◽

Fibre Optic Cable ◽

Set Up ◽

Single Instrument

This paper introduces the application of fibre-optic distributed temperature sensing (DTS) in combined sewer systems. The DTS-technique uses a fibre-optic cable that is inserted into a combined sewer system in combination with a laser instrument that performs measurements and logs the data. The DTS-technique allows monitoring in-sewer temperatures with dense spatial and temporal resolutions. The installation of a fibre-optic cable in a combined sewer system has proven feasible. The use of a single instrument in an easy accessible and safe location that can simultaneously monitor up to several hundreds of monitoring locations makes the DTS set-up easy in use and nearly free of maintenance. Temperature data from a one-week monitoring campaign in an 1,850 m combined sewer system shows the level of detail with which in-sewer processes that affect wastewater temperatures can be studied. Individual discharges from house-connections can be tracked in time and space. With a dedicated cable configuration the confluence of wastewater flows can be observed with a potential to derive the relative contributions of contributary flows to a total flow. Also, the inflow and in-sewer propagation of stormwater can be monitored.

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Monitoring the performance of a storm water separating manifold with distributed temperature sensing

Water Science & Technology ◽

10.2166/wst.2012.152 ◽

2012 ◽

Vol 66 (1) ◽

pp. 145-150 ◽

Cited By ~ 7

Author(s):

J. G. Langeveld ◽

C. de Haan ◽

M. Klootwijk ◽

R. P. S. Schilperoort

Keyword(s):

Fiber Optic ◽

Cost Effective ◽

Temperature Sensing ◽

Storm Water ◽

Effective Solution ◽

Distributed Temperature Sensing ◽

Sewer System ◽

Sewer Systems ◽

Monitoring Technique ◽

Impervious Areas

Storm water separating manifolds in house connections have been introduced as a cost effective solution to disconnect impervious areas from combined sewers. Such manifolds have been applied by the municipality of Breda, the Netherlands. In order to investigate the performance of the manifolds, a monitoring technique (distributed temperature sensing or DTS) using fiber optic cables has been applied in the sewer system of Breda. This paper describes the application of DTS as a research tool in sewer systems. DTS proves to be a powerful tool to monitor the performance of (parts of) a sewer system in time and space. The research project showed that DTS is capable of monitoring the performance of house connections and identifying locations of inflow of both sewage and storm runoff. The research results show that the performance of storm water separating manifolds varies over time, thus making them unreliable.

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Processing of DTS monitoring results: automated detection of illicit connections

Water Practice & Technology ◽

10.2166/wpt.2013.037 ◽

2013 ◽

Vol 8 (3-4) ◽

pp. 375-381 ◽

Cited By ~ 3

Author(s):

Mats Vosse ◽

Rémy Schilperoort ◽

Cornelis de Haan ◽

Jaap Nienhuis ◽

Marcel Tirion ◽

...

Keyword(s):

High Resolution ◽

High Frequency ◽

Field Measurements ◽

Automated Detection ◽

Temperature Sensing ◽

Fibre Optic ◽

Distributed Temperature Sensing ◽

Noise Levels ◽

Temperature Changes ◽

Sewer Systems

Fibre-optic Distributed Temperature Sensing (DTS) is a widely used technique. The technique measures temperature with a high resolution and high frequency along cables with lengths up to kilometers. This paper focuses on the application of DTS in sewer systems with the aim of locating illicit connections, and especially on an automated way to analyze the large amount of data. The automated procedure scans the data for sudden temperature changes that are not caused by rainfall. These changes are marked as possible illicit connections when temperature changes are significantly larger than noise levels in the measurements. By adding artificial spills to field measurements it is concluded that the procedure works for the defined spills. Also when applied to field measurements it is concluded that the automated procedure produces good results.

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Thermodynamics of a fast-moving Greenlandic outlet glacier revealed by fiber-optic distributed temperature sensing

Science Advances ◽

10.1126/sciadv.abe7136 ◽

2021 ◽

Vol 7 (20) ◽

pp. eabe7136

Author(s):

Robert Law ◽

Poul Christoffersen ◽

Bryn Hubbard ◽

Samuel H. Doyle ◽

Thomas R. Chudley ◽

...

Keyword(s):

Fiber Optic ◽

Basal Layer ◽

Temperature Sensing ◽

Distributed Temperature Sensing ◽

Catchment Scale ◽

Outlet Glacier ◽

Coarse Spatial Resolution ◽

High Vertical Resolution ◽

Fast Motion ◽

Strain Heating

Measurements of ice temperature provide crucial constraints on ice viscosity and the thermodynamic processes occurring within a glacier. However, such measurements are presently limited by a small number of relatively coarse-spatial-resolution borehole records, especially for ice sheets. Here, we advance our understanding of glacier thermodynamics with an exceptionally high-vertical-resolution (~0.65 m), distributed-fiber-optic temperature-sensing profile from a 1043-m borehole drilled to the base of Sermeq Kujalleq (Store Glacier), Greenland. We report substantial but isolated strain heating within interglacial-phase ice at 208 to 242 m depth together with strongly heterogeneous ice deformation in glacial-phase ice below 889 m. We also observe a high-strain interface between glacial- and interglacial-phase ice and a 73-m-thick temperate basal layer, interpreted as locally formed and important for the glacier’s fast motion. These findings demonstrate notable spatial heterogeneity, both vertically and at the catchment scale, in the conditions facilitating the fast motion of marine-terminating glaciers in Greenland.

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