Asset Management Approach for replacing small meters

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Asset Management Economic Analysis for Small
Meter Replacement Eric Brainich Asset
Manager Portland Water Bureau May 2008
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Small meter in Portland

• Portland Water Bureau small meters
• Replacement cost 13 million
• Annual income measured by small meters
• 23 million for water
• 56 million for sewer

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Methodology

• 5/8 meters
• Estimate meter degradation curve
• Calculate unrecorded water revenue loss as meter
  accuracy declines during life of meter
• Cost of replacing meter
• Minimize life-cycle cost of meters

4
Estimating meter degradation

• Factors to consider in estimating degradation
• Make/model of meter
• Model A Model B
• Consumption (vs. age) of meter
• 500 / 1000 / 1500 / 2000 / 2500 / 3000 ccf
• Test flow rates
• Low 0.25/0.5/1.0 gpm
• Medium 3 gpm
• High 10 gpm
• Weighted flow rates
• Low 15
• Medium 75
• High 10

5
Estimating meter degradation

• Random sample of 441
• 5/8 meters (222 of Model A
• and 219 of Model B)
• Minimum 30 samples for
• each model and
• consumption category
• Plotted on GIS to provide qualitative check to
  ensure randomness of sample data

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Portland Water BureauMeter Shop
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Meter Test Results
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Meter Test Results
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Economic Analysis Least Cost Life Cycle
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Economic Analysis Least Cost Life Cycle
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Economic Analysis Least Cost Life Cycle
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Economic Analysis Least Cost Life Cycle
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Economic Analysis Least Cost Life Cycle
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Economic sensitivity analysis
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AWWA meter guidelines1

• Removal from service based on accuracy and meter
  type.
• Recommends using sample test data to identify
  groups of meters with accuracy problems to ensure
  money used to exchange meters is spent on the
  poorest performing meters.
• 1/ Taken from M6 Manual

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Conclusions Recommendations

• Least-cost life-cycle analysis used to justify
  replacement timing (ensures cost of program not
  more than revenue loss or rate increase needed
  to cover unrecorded water usage)
• Random sample of meters
• Weighted flow rates depend upon local consumption
  patterns