22.4 Asset Management, Energy Optimization & Water Loss Control

22.4 Asset Management, Energy Optimization & Water Loss Control

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Asset Management

Asset management answers five questions:

1. What do I own? — the asset inventory
2. Where is it and what condition is it in? — location and condition assessment
3. What is its remaining useful life? — residual life estimation
4. What is the cost to repair versus replace? — economic analysis
5. What is my best long-term funding strategy? — the financial plan

Criticality

$\text{Criticality} = \text{Likelihood of Failure} \times \text{Consequence of Failure}$

[!IMPORTANT] Criticality is not the same as failure frequency. A pump that fails twice a year but has a redundant standby and takes an hour to swap is low criticality. A 36-inch transmission main that has never failed but has no parallel path and would take a week to repair is high criticality. Maintenance and capital resources should follow criticality, which frequently means spending more attention on assets that have never given trouble.

Condition assessment methods include visual inspection, CCTV for sewers, leak detection and C-factor testing for water mains, vibration and thermographic analysis for equipment, coating and cathodic protection surveys for tanks, and break history analysis.

Remaining useful life blends age against expected service life with observed condition and performance. Typical expected lives: cast iron main 75 to 100 years, PVC main 70 to 100 years, ductile iron 50 to 100 years, pumps 15 to 25 years, mechanical equipment 15 to 20 years, instrumentation 10 to 15 years, and SCADA hardware 10 to 15 years.

Level of service is what the asset management plan is protecting: pressure, reliability, water quality, response time, and compliance. Defining it explicitly is what converts asset management from a maintenance exercise into a business decision.

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Water Loss Control

The AWWA Water Audit Method replaced the older "percent unaccounted-for water" approach with a standard water balance.

The Water Balance

[!IMPORTANT] Apparent and real losses require completely different responses, which is why the distinction matters. Apparent losses are paper losses — the water reached a customer but was not correctly measured or billed — and they are addressed by meter testing and replacement, billing system audits, and theft detection. Real losses are water physically escaping and are addressed by leak detection, pressure management, and infrastructure renewal. Apparent losses are usually worth more per gallon, because they are valued at the retail rate, while real losses are valued at the cost of production.

Why Percent Is a Bad Metric

[!WARNING] "Percent unaccounted-for water" is discouraged as a performance metric because it moves with consumption rather than with utility performance. A system whose losses are unchanged will report a higher loss percentage in a wet year when customers irrigate less, and a lower percentage in a hot dry year — the opposite of what a performance metric should do. AWWA recommends volume-based indicators instead.

Performance Indicators

ILI is the most useful comparative figure. Unavoidable annual real losses is the technically achievable minimum for a system of that size, pressure, and connection density. An ILI of 1.0 means the system is at the practical minimum; an ILI of 8 means real losses are eight times the achievable minimum and there is substantial recoverable water.

Controlling Real Losses

The four recognized components of intervention:

1. Pressure management — reducing excess pressure reduces leakage rate at every existing leak and reduces new break frequency. This is often the fastest and cheapest intervention available.
2. Active leakage control — finding unreported leaks rather than waiting for them to surface: acoustic leak surveys, correlators, leak noise loggers, and district metered areas with night-flow analysis.
3. Speed and quality of repairs — the volume lost is the leak rate multiplied by the time to repair, so awareness and response time are half the equation.
4. Infrastructure renewal — replacing the mains that leak chronically.

District metered areas (DMAs) isolate a portion of the system with a single metered inlet and analyze minimum night flow, typically between 2 and 4 a.m. when legitimate consumption is at its lowest. Whatever is flowing at that hour beyond a small legitimate allowance is leakage, and a rising night flow in a DMA identifies a new leak within days rather than months.

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Energy Optimization

Energy is typically the largest controllable operating cost after personnel.

Opportunities

[!IMPORTANT] Understand your electric rate before optimizing. Many utility accounts carry a demand charge based on the highest 15-minute demand in the billing period, and that charge can rival the energy charge. Starting two large pumps simultaneously can set a demand peak that is billed for the entire month, so staggered starts, soft starts, and using storage to shift pumping to off-peak hours can reduce a bill substantially without reducing a single kilowatt-hour of actual consumption.

Energy audits benchmark consumption per million gallons treated or per pound of BOD removed, establishing where the energy actually goes and which measures will repay their cost.