From audit to approved: the water project

It starts with an observation. In February, three year 10 students at Marrook College notice the oval sprinklers running at midday during a heatwave, mist drifting off in the wind while everyone shelters inside. The easy move is a complaint. Instead, remembering the first rule of framing, they decide to measure before proposing anything.

They set a boundary: the irrigation system for the oval and front gardens, and nothing else. With the groundskeeper's permission they photograph the irrigation water meter every morning before school for two weeks. The numbers are bigger than anyone guessed: the system uses about 210,000 litres a week in summer, and the timer logs show close to half of it is sprayed between 10am and 3pm, when evaporation is at its worst. Their problem sentence writes itself: Marrook College irrigates with about 210,000 litres a week in summer, and nearly half of it is applied during the hottest hours of the day, when much of it evaporates before reaching the roots.

Then they design the smallest response that would still matter. Not a new irrigation system, not synthetic turf: three changes. Move all watering to between 5am and 7am. Fit a rain sensor so the system skips watering after rain instead of running regardless. Trial it for one term, reading the meter weekly. They cost it honestly: the rain sensor is $185 from an irrigation supplier, a local electrician quotes $140 to fit it, and reprogramming the timers costs one hour of the groundskeeper's time. Total: $325 and a few hours.

The premortem surfaces the biggest risk early: the groundskeeper. When they show him the plan, he raises two fair concerns. Watering at 5am means nobody is around to spot a broken sprinkler head flooding a garden bed, and he does not want a system he cannot override on genuinely scorching weeks. Rather than arguing, they treat both as design input. The plan gains a monthly five minute midday test run of each zone so heads can be checked visually, and the groundskeeper keeps full manual override. He goes from the likely objector to the project's most useful ally.

Now the pitch. They know their audience: the principal will scan for cost, risk and the ask, and the business manager will want the payback. So they write one page, and only one page. It reads like this:

• Problem: Marrook College irrigates with about 210,000 litres a week in summer, and nearly half is sprayed between 10am and 3pm, when much of it evaporates before it can help the grass.
• Response: shift all watering to 5am to 7am, fit a rain sensor so the system skips watering after rain, and run a monthly midday test of each zone so sprinkler heads are still checked. The groundskeeper keeps full manual override.
• Cost: $325 once ($185 sensor, $140 fitting) plus about one hour of staff time a month. Expected water savings repay the cost within the first term at current water charges.
• Measurement: we photograph the meter weekly and compare against our two week summer baseline of 210,000 litres, reporting the results at the end of the trial.
• Ask: approval for a term long trial of these settings, starting the first week of next term, with a one page results report to you at the end.

The principal approves it within a week. The two objections she raises in the meeting, what if the oval browns off, and whose job is the monitoring, are already answered in the page: the trial can be reversed in an afternoon, and the students own the weekly meter readings with the groundskeeper as backup. Having the answers ready, they later agree, did more for their credibility than the sensor did.

The first Monday of the trial sets the pattern for the term. One of the three photographs the irrigation meter before school, notes the reading against the previous week, and drops the figure into a shared sheet the group keeps. It takes about two minutes. That two minutes, repeated every week, is the whole of the measurement plan working exactly as it was designed, and it is the reason that when the principal asks in the middle of term how it is going, they can answer with a number instead of an impression.

The trial runs for a full term. The weekly meter photos tell a clean story: usage averages about 140,000 litres a week, roughly a third below the baseline, with the biggest single weeks of savings coming when the rain sensor skipped watering after storms. The oval stays green, because early morning water actually reaches the roots. Their end of term report is, naturally, one page. The principal makes the settings permanent, the business manager quietly notes the savings in the facilities budget, and the groundskeeper now shows the meter to year 7 geography classes. Total cost: $325. The students' next proposal, they have noticed, will be much easier to get approved. Second projects always are.