Water loss from pipelines impacts ecological and infrastructure integrity. MLOG is the first proactive permanent tool for continuous assessment of pipeline integrity. An enterprise solution, MLOG enables water utilities to prevent water loss and manage pipeline integrity in a sustainable and affordable manner.
Water distribution systems in the U.S. typically draw water from surface or underground sources. Water is treated and pumped into a network of transmission, distribution, and service pipes. This buried infrastructure is documented by Geographic Information Systems (GIS). Pipelines are currently maintained by excavation and infrequent acoustic surveys – little changed in 150 years. The U.S. Environmental Protection Agency estimates that up to $200 billion will be required by 2025 to maintain and rehabilitate the aging pipeline infrastructure. The MLOG system addresses a pressing need for monitoring pipeline integrity automatically, 365 days a year.
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Summary

The MLOG water leak detection system is a complete solution for recovering lost water and monitoring pipeline integrity. Benefits include optimizing operating resources and long term reduction of the financial and other costs of developing water resources.

The ZCorr water leak detection system is a new, systematic approach to water pipeline inspection and examination. ZCorr digital water leak correlating loggers offer significant advantages over listening loggers by detecting and pinpointing multiple water leaks in a zone overnight. ZCorr′s technical advances make efficient water leak surveying viable for water utilities.
ZCorr is a software-driven approach that allows a water distribution system leak survey to be efficiently directed from the office, integrating water leak detection data, distribution system maps, and database tools to: 1. Plan the water leak survey and print deployment orders; 2. Pinpoint water leaks and print repair reports; 3. Track water leak survey progress and performance.
Water leaks correlating loggers such as ZCORR offer significant advantages over listening loggers: 1. A single overnight water leak correlation study of 3 recordings almost completely eliminate any false positive detection of water leak noise; 2.A listening logger can only register water leak noise that is close to or louder than background vibration levels. In contrast, the ZCORR water leak correlation process is capable of detecting and pinpointing water leak noise that is unaudible and over a hundred times quieter than background noise; 3.The ZCORR water leak correlation process simultaneously detects and pinpoints multiple water leaks between any 2 loggers.
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Summary

The ZCORR water leak detection and correlating system is operationally viable for most water utilities with over 2,000 service connections. It has superior performance and is cost-effective compared to other water leak survey and detection methods.

With losses from water distribution systems varying from 10% to 60% (dependant upon geography, measurement method and politics) it is widely recognized that these losses are not sustainable. This paper identifies the important role of the water leak noise correlator for modern water leak location in water pipes. It sets out the major innovations and advantages of DigiCorr, compared to the older technologies in other water leak noise correlators.
DigiCorr uses a system of Automatic Leak Frequency Analysis (ALFA) to detect and pinpoint water leak sounds with no user intervention. It is able to collect water leak sound energy from many different frequencies – not just a single frequency band - and to discriminate among multiple sources of water leak sounds. ALFA tracks the spectral patterns of water leak sound over time to ‘tune in’ to the water leak sound even when other noise dominates the recording. Once ALFA has registered the characteristics of the water leak sound, the results of the correlation process will be significantly less susceptible to disruption by ambient noise, such as traffic, or changing flow noise due to usage variations. A key aspect of ALFA is that this tracking and characterization of leak sounds is performed uniquely and optimized in every recording.
With ALFA an accurate registration and pinpointing of each water leak sound occurs automatically with every recording. This includes multiple water leak sounds within a correlation span and water leak sounds that would have been lost in analog FM radio transmission). When no water leak is present no correlation occurs. It is not necessary to re-record with many different filter settings to ensure that ‘no water leak’ is truly present.
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This paper describes a new method of surveying water distribution systems for water leaks based on digital correlation. Digital correlation allows computerized analysis and storage of acoustic data recorded during a survey. Water leaks are detected and pinpointed without the need for skilled interpretation of the recordings in the field. The general objective is to develop a water leak detection and surveying method that maximizes recovery of lost water, increases time-efficiency, and is fully accessible to small utilities and non-expert users.
Water leak noise digital correlation offers several advantages over conventional water leak surveying methods. The correlator can pinpoint water leak sounds with a single measurement performed over significant distances. Water leak sounds below the threshold of human hearing can be readily detected. Loud water leaks are accurately pinpointed. Advanced signal processing can distinguish between true water leak sounds and other sounds, such as traffic and wind, that may obscure water leak noise.
The analysis of correlation data can be made very flexible with the capability of storing tens of thousands of recordings before a comprehensive analysis is performed. The digital correlation survey therefore effectively includes a comprehensive listening survey as a subset of its capabilities. Analysis and interpretation of water leak noise correlations can be performed in the field, in the utility′s office, or by a specialist. Automatic analysis capabilities allow all recordings to be analyzed together. This permits a higher level of interpretation, such as the ability to compare nearby sites for confirmation of suspected water leaks.
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Conclusion

Two surveys have been presented, using a new digital correlation method. The two distribution systems present an interesting contrast: Mt. Vernon is an older, urban system with typical water losses (presurvey UFW was 18%); Chicopee is a newer suburban system (pre-survey UFW was 9%). There were 32 leaks found in Mt. Vernon versus 4 in Chicopee. Post-survey, both systems had similar estimated residual water leakage of less than 4% of total water pumped. These preliminary results suggest that digital correlation is capable of controlling water leakage in a cost-effective manner.