The station group had been running since 1987. Nobody could say how much water it actually moved — only that the fields at the tail of the network stopped getting any by late July.
The baseline nobody had
Before design we metered the whole line for six weeks: flow at every station, pressure along the main canal, and water level at four points that had never been instrumented. That measurement is the only reason the savings figure in this piece can be audited — it is a difference between two measured seasons, not a difference between a measurement and a promise.
The survey found something the drawings did not show. Two of the twelve stations were operating almost entirely outside their efficiency envelope, burning roughly a third more energy per cubic metre than the rest of the group. Both had been rewound at least once, and neither impeller matched the curve on the nameplate.
If you cannot measure the network before the works, you are not engineering a rehabilitation — you are guessing at one.
What the test measured
Acceptance was a duty-point test at each station, witnessed by the client’s engineer and signed on the spot: flow, head and absorbed power against the values in the hydraulic model. Three figures, one sheet per station, no interpretation required.
| Parameter | Model | Measured |
|---|---|---|
| Combined flow | 3 200 m³/h | 3 245 m³/h |
| Head at duty point | 42 m | 41.6 m |
| Absorbed power | 1 180 kW | 1 164 kW |
| Conveyance loss | 20.0 % | 20.3 % |
Two things we would change
Telemetry before civil works
The radio survey should happen in the first month, not after the stations are built. Two nodes needed a repeater we had not budgeted for, and the mast went up after the concrete had cured.
A spare pump on site, not in the contract
Lead time on a replacement unit is four months. Holding one on site from day one costs less than the season it protects.
What the client operates now
Twelve stations on one dispatch screen, with a daily water balance per station and an alarm list their own operators clear. The four-week training programme finished in September 2024; since then the network has run a full season with no unplanned stoppage, and the report that says so came out of their system, not ours.
