Technologies for Assessing the Condition of Water Mains · – DIPRA 10-Point (AWWA C105) ... tools...
Transcript of Technologies for Assessing the Condition of Water Mains · – DIPRA 10-Point (AWWA C105) ... tools...
Technologies for Assessing the Condition of Water Mains NC AWWA Spring Conference 2014 Matt Shultz, PE - HDR
Condition Assessment
• Determining and documenting the physical state of infrastructure at a point in time
• Identify improvements to extend asset life • Prioritizing improvements
Aging Infrastructure is the driver for Condition Assessment and Renewal
Reference: AWWA, Buried No Longer: Confronting America’s Water Infrastructure Challenge, 2012
Water Main Failures Can Cause Problems
Photo: Bill O’Leary, Washington Post
….and have Consequences
Photo: Al Seib, LA Times
Three Components of Condition Assessment Determine Success and Usefulness
Assessment Technologies…there are a lot of them
Source: EPA, 2012 Condition Assessment Technologies for Water Transmission and Distribution Systems
Ductile and Cast Iron Pipe…aging is a problem
Aging can occur from: • Internal corrosion • External corrosion • Fatigue Failure Methods: • Pits or rust holes • Bursts (longitudinal) • Breaks (circumferential) • Leaks at joints or service taps
Pitting Corrosion
General Corrosion
Aging is a problem…but not always the answer
The Evolution of Iron Pipe is Dominated by Reduction in Wall Thickness
1928 Class D CI
1.58” 1952
Class 150 CI 1.22” 1957
Class 27 CI 0.94”
1957 Class 22 CI
0.87” 1965 Class 3 DI
0.58” 1976
Class 50 DI 0.43”
1991 Class 150 DI
0.38”
EXAMPLE FOR MINIMUM WALL 36-INCH IRON PIPE
External Corrosion…corrosive soils
Soil and Water Analysis • Resistivity, pH, Sulfate, Chloride, Redox Potential, Etc.
– DIPRA 10-Point (AWWA C105) • Linear Polarisation Resistance
External Corrosion… stray currents
ANODEGROUND BED
+
CATHODICALLY PROTECTEDSECTION OF PIPELINE A
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POSITIVE DC CURRENT FLOW PIPELINE A
PIPELINE B
RECTIFIER
ACCELERATED CORROSIONON PIPELINE A
Overhead Power Transit Systems
Other Utilities
Ductile and Cast Iron – Assessment Technologies
Electromagnetic: Remote Field Eddy Current • PICA’s See Snake • Provides end to end 360-deg evaluation • Accurate determines pit size, depth, and location • Provides general corrosion loss • 2” to 36” pipes, tools match pipe size • Free swimming or tethered • Waterline can remain in service • Can navigate through bends
Design - PCCP Standards Changed Over Time …and not always for the better
Assessment Technology - PCCP Water Mains
Acoustic Events/Wire Breaks Leading up to SDCWA Failure
Asbestos Cement Pipe
Deterioration can occur from: • Soft Water Corrosion • Acidic Corrosion (low pH water) • Sulfate Corrosion • H2S Corrosion Failure Methods: • Bursts (longitudinal) • Breaks (circumferential)
AC Pipe: Acoustic Velocity Thickness
A comparison by Sweetwater Water Authority (CA) was promising
Technologies for Assessing the Condition of Water Mains NC AWWA Spring Conference 2014 Matt Shultz, PE - HDR