He Asked Us to Take the Concrete Out of the Quote. Now We Price It Three Ways.
A client read our quotation, got to the civil works line, and asked us to take it out. He had a contractor already — the same one who had built his warehouse extension, a man he trusted and had paid on time for years. Could we just supply the equipment and let his own people pour the tanks?
Ten years ago I would have said no, because the answer that protects us is always no. What we do now is quote the concrete three ways on every job, with the price and the exposure of each one written down, and let the owner decide which one he is buying. We build it. He builds it. Or his contractor builds it and we supervise for a stated fee. On a new sewage treatment plant the concrete is usually the largest single line in the quotation and almost always the long pole on the schedule, so this is not a footnote. It is the decision that moves the most money in the whole contract.
Here is what each of the three routes actually contains, and where we have watched the savings in route two and three arrive and where we have watched them disappear.
Route one: we build it
We design the tanks, we build the tanks, we install the plant, we commission it, and there is one company to call when the water does not come out right. On the blocked layouts we now draw as standard — shared cross walls, chambers poured as one monolith rather than six separate boxes — our own rate has been running at around ₱14,000 per cubic metre of tank capacity on a 3,000 psi mix. On one project that came to about ₱1.2 million for a 70,000-litre three-chamber tank with a 4,000 psi top slab. Those are contract figures from jobs we actually sent out, not a rate card: excavation depth, water table, access for a mixer truck and whether the tank is a free-standing structure or wedged against an existing building all move it, and your site will not be our site.
What the owner buys at that rate is not concrete. It is the fact that nobody can hand the problem sideways. If a penetration comes out 150 mm off and the return line will not fall, that is ours to break out and recast at our cost. If the tank weeps at a joint, that is ours. If the plant misses its discharge parameters during the first compliance test, nobody gets to say the civil works was somebody else's scope. We have been on jobs where the design was ours, the tanks were not, and the argument about whose fault the carry-over was ran longer than the fix would have taken.
Route two: the client builds it
This is the route the client in the opening asked for, and it is legitimate. An owner with a standing contractor, a site the contractor already knows and a project manager who will actually stand over the pour can build a water-retaining tank for less than we can, because he is not paying anybody's margin on top of his own. The one figure we have from a client's own contractor doing tanks to our drawing was around ₱10,500 per cubic metre of capacity — roughly a quarter under our rate, on that job, on that site, with that contractor. Again: one job, not a market rate.
What he gets from us in that case is a drawing set and a specification, and we are deliberately narrow about what goes on it. The contractor gets the what: dimensions, wall and slab thicknesses, the 3,000 psi mix, reinforcement, the waterstop and kicker detail at every construction joint, the position and diameter of every penetration and cast-in item, and the acceptance test. We keep the how — pour sequence, lift heights, where we stop and check — on an internal sheet. That is not gamesmanship about trade secrets so much as scope hygiene: the moment we start telling another man's crew how to organise their pour, we have quietly taken on their workmanship without being paid for it or being on site to see it.
The acceptance test is the part of that drawing set I care most about, because it is the only line that cannot be argued about later. Fill the tank, mark the level, come back in 24 hours. A drop of more than about 1/500 of the water depth and the tank has not passed, whatever it looks like. We write it as a witnessed hold point with a date, before anything is backfilled and before a single piece of equipment is set. A tank that fails that test while it is still open and visible is a bad morning. The same tank discovered after the slab is on, the pipework is in and the plant is running is a different kind of event entirely.
Route three: his contractor builds it, we supervise for a stated fee
Most owners who ask for route two actually want route three once they see both written down, and this is the one we now expect to be chosen. The client's contractor does the work at the client's price. We issue the drawings and specification, we attend at the points where a mistake becomes expensive rather than cheap — setting out, reinforcement before the first pour, penetrations before the wall goes up, the fill-and-mark test — and we charge a stated supervision fee for it. Stated, in the quotation, as a number, so nobody discovers it later.
The reason this route usually wins is that the expensive civil mistakes on a treatment plant are not structural. A contractor who builds warehouses will give you a perfectly sound tank. What he will not know, because there is no reason he should, is that the draw-off has to leave the clarifier below the water surface rather than over a weir, that the sludge line needs a fall the whole way, that two chambers sharing a wall cannot both be poured to the same top level if one of them is meant to overflow into the other, or which of the fifteen holes in that drawing are the three that cannot move. Those are process decisions that happen to be made in concrete, and they are cheap to get right on the morning of the pour and expensive at any point afterwards.
One honest caveat on this route: supervision is not inspection of everything. We say so in writing. We are not certifying his structural design, his scaffolding or his safety, and we are not on site for every hour. What we are doing is standing between his workmanship and our process drawing at the handful of moments where those two things meet.
What does not move to the client's side in any of the three
The three routes cover who pours the concrete. They do not touch our own scope, and we have learned to say that explicitly, because an owner reading a slimmer civil line sometimes reasonably assumes other things came off with it.
The process design stays ours in all three. So do the internals of the clarifier, which on any underground tank we now build to a single standard: rectangular, poured with the other chambers, a mass-concrete hopper falling inwards to a central sump whose floor is the structural slab, nothing cast below the foundation line, an inlet stilling baffle, a submerged outlet draw-off through the cross wall about 200 mm below top water level, and a submersible pump in the sump. No weir plate and no scum board, because once the cover slab is on, levelling a weir or skimming a board means confined-space entry and that is not a thing you ask a building maintenance man to do. Those internals priced at about ₱60,000 on the job where we settled the standard. We do not hand that list to a contractor as a suggestion.
Establishing the receiving water and its DENR classification stays ours too, in every route, and at our cost. It decides the treatment target before a single dimension is drawn — the class of the water you discharge to is what makes ammonia the parameter that decides whether the plant passes — and it is regulatory engineering, not builder's work. It has never belonged on a client's action list, and the same goes for the parameters your industry is actually held to and the flow you declared on the permit.
Where the saving is real and where it evaporates
The arithmetic on route two is straightforward and I will not pretend it is not attractive. On a 70 m³ tank the gap between our rate and the one client-contractor figure we have is a few hundred thousand pesos. That is a real number and an owner is entitled to go after it.
What eats it, when it gets eaten, is re-work and time. Breaking out and recasting a wrong penetration in a finished wall is a day of hacking, a patch that will always be the weak point of that wall, and a pipe run redesigned around it. A tank that fails the fill-and-mark test after backfill means excavating again to find the joint. And a civil programme that runs four weeks over pushes the equipment installation, the commissioning and the first compliance sampling out with it, which on a building waiting for an occupancy permit is usually the most expensive part of the whole business, though it never appears in anybody's civil quotation. Route three exists precisely because it buys most of route two's saving while putting somebody on site at the four moments where those things are decided.
The other thing worth saying plainly: the cheapest civil quotation is often cheap because it has left something out. We have read quotations with no waterstop line, no kicker, no acceptance test and a slab thickness that could only work if the tank were never full. That is not a competitive price. It is a different, smaller scope wearing the same name. If you are comparing ours against another, compare the specifications side by side before the totals — and if you want the equipment side of the same comparison, the cheaper quotation is frequently not the cheaper plant.
What we ask of our own civil quotations
There is a rule we now apply to ourselves before a civil works quotation leaves this office: it has to show how we intend to build the tank, not only what the tank will cost. Sequence, joints, where the waterstop goes, what gets tested and when. If we cannot put that on paper for a tank, we do not understand that tank well enough to price it.
That habit came out of getting it wrong on our own drawings first — the design is where the money on a plant is actually decided, and the civil drawing is the last place a design error is still cheap. It also makes the three routes possible at all. You cannot offer an owner a straight choice between building it yourself, us building it, and us supervising yours, unless the method is written down clearly enough that all three of you are talking about the same tank. Ours is also always drawn against more than one wastewater strength so the chamber volumes in front of the contractor are not resting on a single unexamined assumption, and any treated-water storage the reuse plan needs is in the drawing before the slab goes on rather than broken into afterwards.
If you want to see what the civil and equipment split looks like for your own volume before talking to anybody, our price estimator and the design generator will both give you a shape to work with, and our wastewater services page sets out what we actually do on the plant side. The projects we have finished are there too, and most of them are within an hour or two of Cordova.
What travels and what does not
These three routes work for us in Cebu, with our own fabrication network, our own rates and contractors we can reach the same day. Somewhere with a shortage of competent concrete crews, route two may not exist in practice. On a small plant — say the 5 m³/day end of the range — the whole civil line can be small enough that splitting responsibility to save on it is not worth the seam it creates, and there an above-ground tank with no excavation at all often reads better than any of the three. On a retrofit into a running plant the constraint is usually access and keeping the existing tanks in service, not the concrete rate. And the ₱14,000 and ₱10,500 figures are Cebu numbers from specific jobs; quoting them back at a contractor in another province will not make them true there.
The part I would carry anywhere is the shape of it rather than the prices. An owner who is told what each route costs and what each route exposes him to makes a better decision than one handed a single bundled figure, and he makes it before the concrete is poured instead of during the argument afterwards. We put the assumptions and the risks of all three in writing before the contract is signed, including the ones that are not flattering to us, because the client has a right to see them while he can still act on them. That much has worked for us over and over again — and where a route is genuinely the owner's business decision rather than an engineering one, it is not our place to choose it for him.
If you are weighing up how to get the tanks built for a plant you are planning, or you already have a contractor's civil quotation in front of you and want a second pair of eyes on the specification, book a free 15-minute consultation and we will go through it with you. If it is an existing plant that is giving you trouble rather than a new build, our operation and maintenance support is the better starting point, and a proposal or an ocular visit can be arranged from there.