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TitleMonitoring the effect of telluric currents on water mains
AuthorWeston, G; Samson, C; Boteler, D H; Trichtchenko, L; Raymond, D
SourceProceedings of ASTRO 2008; 2008 p. 1-8; 1 CD-ROM
Alt SeriesEarth Sciences Sector, Contribution Series 20100359
MeetingASTRO 2008; Montreal; CA; April 29 - May 1, 2008
MediaCD-ROM; digital
File formatpdf
Subjectsgeophysics; telluric surveys; telluric field; telluric interpretations; magnetospheric currents; solar variations; pipelines
Illustrationsdiagrams; aerial photographs; graphs; plots
ProgramTargeted Hazard Assessments in Northern Canada, Public Safety Geoscience
AbstractTelluric currents on a 1-km long cathodically-protected water main section in Ottawa were monitored between May and November, 2007. Data-loggers attached to 9 test posts along the water main recorded a repeated variation in pipe-to-soil potential, which correlated to diurnal variations in the geomagnetic field. Analysis of the data in the spectral domain revealed two dominant peaks at periods of 24 and 12 hours. To investigate spatial variations along the water main, the data recorded at each test post were plotted against a reference test post. An overall decrease in relative amplitude and DC offset was observed from west to east, as distance from the current source of the cathodic-protection system increases. While telluric current induction was evident during the study, the resulting PSP variations too small to compromise the cathodic-protection system. Periods of more active geomagnetic disturbances, however, could still remove the water main from the safe PSP ranges of -0.85 V to -1.35 V, making it more susceptible to corrosion.