Robust sensing suite for measuring temporal dynamics of surface temperature in sewers

© 2018, The Author(s). Sewerage systems are paramount underground infrastructure assets for any nation. In most cities, they are old and have been exposed to significant microbial induced corrosion. It is a serious global problem as they pose threats to public health and economic repercussions to water utilities. For managing sewer assets efficaciously, it is vital to predict the rate of corrosion. Predictive models of sewer corrosion incorporate concrete surface temperature measurements as an observation. However, currently, it has not been fully utilized due to unavailability of a proven sensor. This study reports the feasibility of infrared radiometer for measuring the surface temperature dynamics in the aggressive sewer conditions. The infrared sensor was comprehensively evaluated in the laboratory at different environmental conditions. Then, the sensor suite was deployed in a Sydney based sewer for three months to perform continuous measurements of surface temperature variations. The field study revealed the suitability of the developed sensor suite for non-contact surface temperature measurements in hostile sewer conditions. Further, the accuracy of the sensor measurements was improved by calibrating the sensor with emissivity coefficient of the sewer concrete. Overall, this study will ameliorate the present sewer corrosion monitoring capabilities by providing new data to models predicting sewer corrosion

High Precision GPS Aided In-pipe Distance Calibration For Satellite Image-based Pipeline Mapping

Asset management and pipe condition assessment (CA) activities in the water industry usually require locating buried pipes accurately to minimise inspection and maintenance costs. A typical challenge in practice is locating an anomaly detected by an in-pipe inspection tool from aboveground in order to dig up a pipe for replacement. Accumulated in-pipe errors over longer distances in particular can easily lead to selecting the wrong pipe section for further investigation or exhumation. In fact, some in-pipe CA providers suggest utility personnel dig up a number of sections of pipe around the suggested location so as to ensure finding the target section. In this paper we propose a mechanism to accurately correlate a 3D pipeline profile built from GPS surveying results of aboveground pipeline features with in-pipe chainage distances, so as to establish an accurate link between above-ground GPS coordinates and inpipe distance measurements. This approach naturally characterises and corrects for some of the most prominent in-pipe chainage measurement errors that can lead to uncertainties about the reported location of a buried pipeline from above-ground. The detailed pipeline information can then be projected onto satellite imagery as an accurate easy-to-understand reference for efficient decision making

Predictive Analytics Toolkit for H2S Estimation and Sewer Corrosion

This paper presents a predictive analytics toolkit, which is based on the emerging spatiotemporal data analysis techniques, for the estimation of hydrogen sulphide (H2S) gas distribution and prediction of sewer concrete corrosion level. The toolkit is an easy-to-use desktop application with a user-friendly interface for querying and producing output results on GIS. The inputs to the toolkit are the sewer network geometry, monitored factors, and hydraulic information; the outputs of the toolkit are spatiotemporal estimates of H2S gas concentration and concrete corrosion levels on the entire sewer network with uncertainties of the predictions. The toolkit is also able to integrate experts’ domain knowledge or existing physical model’s results as prior knowledge into the analytics model. The final outcomes of the toolkit can be used to prioritise high risk areas, recommend chemical dosing locations, and suggest deployment of sensors. A simulation of H2S and corrosion level prediction on a subsystem of the sewer network in the greater Sydney area is reported to demonstrate the capability of the toolki

Free chlorine analysers: a user's selection guide

Selecting new instrumentation for integration into water quality monitoring programs is fraught with uncertainties and potential pitfalls. An evaluation methodology for assisting water managers and operators to make the correct choice of an online free chlorine (FC) analyser based on key performance parameters is presented. Eight amperometric and one colorimetric online FC monitors were evaluated against 15 metrological parameters (response, delay, rise and fall times, linearity, limit of quantification, day-to-day repeatability, the effect of interferences, etc.) according to the procedure outlined in the two standards: ISO Standards 8466-1 (1990) and 15839 (2003). The test results were compared with the analysers' technical characteristics supplied by their manufacturers. In general, colorimetric systems performed better than amperometric systems, with the latter experiencing significant interference from the pH of water which was not adjusted during tests. All analysers performed within manufacturers' claimed limits for some metrological parameters, whereas for other parameters their performance was not adequate. It is strongly encouraged to perform evaluation tests under conditions similar to those in the field before purchasing a monitor.A. Badalyan, M. Holmes, C.W.K. Chow and D. Vitanagehttp://www.scopus.com/record/display.url?eid=2-s2.0-77954531083&origin=resultslist&sort=plf-f&src=s&st1=Free+chlorine+analysers%3a+a+user%27s+selection+guide&sid=1D336FA726D1207C7091B4896A8F1B3B.mw4ft95QGjz1tIFG9A1uw%3a20&sot=b&sdt=b&sl=64&s=TITLE-ABS-KEY%28Free+chlorine+analysers%3a+a+user%27s+selection+guide%29&relpos=0&relpos=0&searchTerm=TITLE-ABS-KEY%28Free+chlorine+analysers%3A+a+user%5C%27s+selection+guide%2

On-line free-chlorine/total-chlorine monitors' evaluation - a step towards a correct choice of residual disinfectant monitor

A number of commercially available on-line disinfection residual analysers were evaluated using a test rig under laboratory conditions. The methodology used for this trial was based on the following two standards: ISO Standard 15839 (2003), “Water Quality – On-line sensors/analysing equipment for water – Specifications and performance tests” and ISO 8466-1 (1990), and “Water Quality – Calibration and evaluation of analytical methods and estimation of performance characteristics. Part 1: Statistical evaluation of the linear calibration function”. The assessment of each analyser involved the determination of a set of performance characteristics including response delay, rise and fall times, linearity, limit of quantification and day–to-day repeatability. The effects of likely interferences were also covered. Results obtained from this trial for two total chlorine monitors were compared with the technical specifications as supplied by their respective manufacturers. This study concludes that persons responsible for instrument procurement should be cautious when relying only on manufacturers' technical specification claims. A more informed selection can be made by undertaking an evaluation study similar to the one described in this paper, as this will confirm the performance of a monitor under particular operating conditions. In general, residual disinfectant monitors utilising the colorimetric measurement method showed better performance than those employing amperometric/polarographic methods.Alexander Badalyan, Joachim Buff, Mike Holmes, Christopher W. K. Chow and Dammika Vitanag

Innovative Data-driven “along-the-pipe” Condition Assessment for Critical Water Mains

Recent research findings on remaining life prediction for older Cast Iron critical water mains suggest increasing reliability by calculating stress concentration factors from the corrosion patch geometries expected to be present in the asset, not just extreme pitting as is generally carried out within the industry. This study proposes an innovative data-driven “along-the-pipe” framework able to utilise local inspection results further by capturing data correlations present in the remaining wall thickness measurement. This knowledge can in turn be utilised to produce estimates for “along-the-pipe” patch geometry predictions, hence remaining life. Results from inspections in a real pipeline in the Sydney Water network are compared to conventional Extreme Value Analysis (EVA) to validate the improvements of the proposed strategy