Energised Is Not Commissioned. Only One of Those Dates Was in the Contract.

A plant we had built was switched on in the second week of one month and was treating sewage properly in the second week of the month after that. Both of those are true statements, and only one of them was a date anybody had written down. The contract had a figure for the plant, a figure for the civil works, a delivery period and a handover date. It had nothing at all about the weeks between the day the machines first ran and the day the water leaving the plant could pass a test.

Those weeks belong to somebody. If the contract does not say who, they end up belonging to whoever is standing on site when the first lab sheet comes back, which is usually us, and sometimes the client, and occasionally nobody, which is the worst of the three.

I have written before about a plant that was three weeks old and failed its first compliance test. That piece is the field story — what we smelled, what the cone read, what we did. This one is the commercial half of the same problem: what we now put in a contract so that the story does not have to be told again.

Energised is not commissioned, and they are different dates

A plant is energised when the panel is live, the pumps run on their level switches, the air is on and water moves through the chambers in the order the drawing says. That is a day's work to confirm and it is genuinely finished. Most people in the building treat it as the plant being done, because it looks done. The tanks are full, something is humming, and the water coming off the end is clear enough to be unconvincing.

A plant is commissioned when the biology inside it can do the job the permit asks for, repeatably, at the flow and strength the building is actually producing. That is not a day's work and it is not under anybody's control in the way a pipe connection is. You are growing something.

The gap between those two dates is where almost every argument about a new plant comes from, and the reason it is an argument rather than a schedule item is that the two populations in the tank do not grow at the same speed. The organisms that remove BOD come back in hours to days. The ones that convert ammonia take a day or two just to double their numbers, and on a new plant starting from nothing they need weeks. So the first lab sheet off a young plant has a signature you can almost predict: BOD respectable, solids respectable, ammonia high. Under DAO 2016-08 as amended by DAO 2021-19 the ammonia limit is 4 mg/L as NH3-N for a Class C receiving water and 3 mg/L for Class B — numbers a plant that has been running for ten days has no realistic way of meeting, however well it was built. The full table is on our DENR discharge standards page if you want to check your own class.

The sample date is a technical decision that gets made as an administrative one

On the job that taught us this, the first compliance sample had been scheduled two weeks after energising. Not for any treatment reason — it was set to suit the occupancy paperwork, because a certificate was waiting on a lab result and somebody picked the earliest date that fitted the filing. The result of that test was decided the moment the date was chosen, before anybody took a bottle to the outfall.

Nothing mechanical was wrong with the plant. The smell was thin rather than foul, and the cone reading was well under the working range we expect — there was barely any biomass in there to read. That is not a plant failing. That is a plant that has not started yet, being asked to prove something it cannot yet prove.

So the first thing that now goes in writing is this: the compliance sampling date is proposed by us, in the contract, as a consequence of the commissioning period, and if the client's paperwork needs a date earlier than that, we say so before signing rather than after the result. It is a small clause and it has saved more trouble than any other sentence we have added in two years.

What we actually do in those weeks

On that plant we seeded the tank with return sludge from another plant of ours that was running well. Then we did the thing that sounds wrong and is not: we ran the plant deliberately small. The building was at about a fifth of its design occupancy, so there was a fraction of the organic load the drawing had been sized for, and a starving tank holds nothing — you cannot grow a population on a load that is not there. One train only, flow held back through the equalisation tank, no sludge wasted at all, and the chemical dosing left alone instead of turned up to chase a number. We watched alkalinity, because nitrification consumes it and a plant that runs out of buffer stalls just as the thing you were waiting for starts to happen.

It came right in week five, with nothing about the plant changed. No extra equipment, no drum of bacteria, no second opinion on the design. What it needed was time and somebody reading the plant rather than reading the specification.

That is the part of this work I rate highest, and I rate it higher than the arithmetic. Knowing what to do next from what the results are doing, from what the tank smells like on the day — that is worth more than the calculations, and more than the equipment list. The calculations used to be the hard part. They are not any more; with the tools available now they are close to a commodity, and anyone can check ours — I have invited clients to do exactly that. Specifying the right machines is harder, and we treat that as a design problem in its own right. Commissioning is harder still.

We once paid somebody else for this, and we paid them happily

I will put our own money where that claim is. On a project we had contracted at around ₱2.4 million, we brought in another consultant and paid him ₱200,000 — roughly eight per cent of the contract — because we were having trouble with our commissioning stage. We were the buyer, not the seller, and I have never regretted it. It is the only honest market price for wastewater consultancy anywhere in my records, and the thing being bought was not a drawing or a machine. It was judgement during the weeks nobody had priced.

That figure is one job, not a rate card, and I am not offering it as what consultancy costs. What it tells you is where the value sits in a plant, measured by what we were willing to pay for it ourselves rather than by what we put on a quotation.

What the commissioning period looks like as a contract item

Everything above now shows up as clauses rather than as goodwill. Our side of it:

Commissioning completes on a result, not on a date — a compliance sample within limits at the discharge point, taken by a third-party laboratory. A calendar date for commissioning is a promise about biology, and we are not in a position to make one.

We hold our position on billing: we do not invoice the commissioning milestone until the plant has passed. That is our position, not an industry standard, and I am not going to pretend otherwise — plenty of reputable suppliers bill on energising and are entitled to. But it is the cleanest way we have found to make sure the weeks belong to somebody, because they obviously belong to us.

The occupancy ramp goes in as a stated assumption, with a number in it. A plant commissioned into a building at a fifth of occupancy behaves differently from one commissioned into a full building, and the client knows his own ramp far better than we do. This is the same practice as showing more than one influent strength rather than one confident column: write the assumption down where it can be argued with, and the argument happens before the concrete instead of after the lab sheet.

Seed sludge is named — where it is coming from, and that it is coming at all. Starting a plant from nothing is weeks slower than starting it from a bucket of established biomass, and we would rather commit to supplying the bucket than discover on the day that there is no running plant to borrow from.

And the client's side gets written down too, as a short list of genuinely his items rather than ours: continuous power through the period, the influent line actually connected and carrying real sewage rather than clean water, and his operator available on site for handover while something is happening worth watching. Operators move on, so training during commissioning is worth more than training at handover, and a lot more than a manual on a shelf. What does not go on his list is anything that is our engineering — establishing the receiving water and its DENR classification is our work and our cost, as is everything else on the regulatory side, and we have taken the same line on the civil works routes.

Half of commissioning is decided back at the drawing

A plant can be designed to be easy to start or hard to start, and that choice is made months earlier by somebody who will not be standing there in week three.

FBBR-style fixed-film media is the clearest example. It starts slower than a purely suspended-growth plant, because a film has to establish on the media before it does much, and then it holds on through everything that would otherwise wash a population out — a load that disappears for a fortnight, a bad week on the clarifier, a blower that stops for three days. On a building whose occupancy is going to climb over a year, that trade is worth taking almost every time.

Equalisation volume is the other one. Holding flow back is the first move available during commissioning and the first move available in a crisis, and it is only available if somebody bought the concrete for it. It is also the one tank clients most often ask to shrink.

Then the small decisions that decide whether the plant survives its first new operator: one duty machine and one standby rather than a row of small ones, air pumps rather than blowers on a small plant so that nobody switches the aeration off at night during the exact weeks the nitrifiers are trying to establish, a cone instead of an instrument so the daily reading cannot go out of calibration, and a plant you can smell. Every one of those is a commissioning decision wearing the clothes of an equipment choice.

Underneath all of it, the plant has to have been designed properly in the first place, because a young plant and a badly designed plant hand you the same first lab sheet, and telling them apart is the whole job. If what you have is the second one, no commissioning period fixes it — that is a different piece of work altogether.

Where this does not transfer

Cebu is warm all year, and that helps more than anything else in this piece. The same plant starting in a cold climate takes longer, and the ammonia end of it takes longer again. A plant going into a fully occupied building starts faster than one going into a tower that fills over eighteen months. A retrofit onto an existing sewer, where there is already an established population somewhere in the system to borrow from, is a different and much kinder proposition than a new build on a bare site.

And our billing position is ours. It suits a company that designs, builds and then has to live with the plant afterwards; it would not suit everybody, and if you are reading a contract that bills commissioning on energising, that is not by itself a reason to walk away. The thing worth insisting on is narrower than that: that the document says what commissioning means, who schedules the test that proves it, and what happens if the building is not yet producing the sewage the plant was drawn for. Those are questions to ask before signing, not after.

If you are putting a plant out to tender and want to see how the numbers move, the STP price estimator and the design generator will both give you a starting basis in a few minutes, and the parameters by industry page will tell you which limits your sector is actually held to. Our own work is on the completed projects page, and what we do on wastewater and around Cebu is set out there. If a plant you already own is in the middle of this, operations and maintenance support is the right door.

If you would rather just talk it through, book a free 15-minute consultation and bring the contract.