How to Read an Excavation Estimate and Compare Two Bids Honestly

A site work estimate is not really a price. It is a description of a job, with a number attached. When two bids differ by twenty thousand dollars, the interesting question is almost never who is cheaper. It is what each one thinks the job is.

Learning to read these documents takes about fifteen minutes and it is the highest return fifteen minutes in your whole project.

Scope is the part that matters

Start with what the estimate says will be done, not what it costs. A usable site work scope names the operations: clearing and grubbing, stripping organics, excavation, imported fill placed and compacted in lifts, the driveway section, trenching, final grade, drainage, erosion control.

If a bid says site work as a single line with one number, you cannot evaluate it and neither can anyone else. That is not a bid, it is a hope. Ask for it broken out.

Lump sum and unit price, and when each protects you

Lump sum means one price for a defined scope. It is clean, it is easy to compare, and it works well when conditions are genuinely known.

Unit price means a rate per unit: dollars per cubic yard of excavation, per ton of gravel, per hour of machine time. You pay for what is actually done.

In site work, the honest answer is usually a mix. The predictable parts go lump sum. The parts that depend on what the ground turns out to be, especially excavation depth and imported material volume, work better as unit prices with an estimated quantity shown.

Here is why that protects you. If organics turn out to be four feet deep instead of one, a lump sum contractor has to either eat it or come back with a change order written under pressure, and you have no reference for whether the new number is fair. With a unit price agreed in advance, the rate is already settled and only the quantity changes. You can check the math.

The quantities decide your final number

For the material heavy items, look for a quantity next to the price. So many cubic yards of excavation. So many tons of gravel. So many square feet stripped.

Then sanity check them against each other. If one contractor plans four hundred yards of import and another plans nine hundred for the same driveway and pad, they are not disagreeing about price. They are disagreeing about how thick the section needs to be or how deep the organics run, and that is a question worth asking both of them directly. Their answers will tell you a lot about who actually walked the site.

Allowances

An allowance is a placeholder for something not yet fully defined, carried at an assumed number. Allowances are legitimate and often necessary. They are also where budgets quietly slip, because an allowance is a guess wearing a price tag.

For each one, ask what happens if the real number comes in higher, and what the assumption behind it was. An allowance with a stated basis is a plan. An allowance with no basis is a coin flip you are funding.

Exclusions are the most important section

Most people skip straight past exclusions. It is the section that determines whether you have a complete picture.

Common exclusions in site work include rock excavation, dewatering, disposal of stumps and debris off site, engineering and permit fees, importing topsoil, and anything unforeseen below grade. None of those are unreasonable to exclude. All of them cost money if they turn out to be needed.

When you compare bids, put the exclusions side by side first. A cheaper bid that excludes stump disposal and a more expensive bid that includes it may well be the same job at the same price, and the ranking flips once you add the missing work back in.

Comparing two bids that are not the same job

Build a simple table. List every operation either bid mentions. Fill in each contractor's price, or note excluded. Add the missing scope to whichever bid lacks it, using the other bid's number as a stand in.

Two things happen almost every time. Bids that looked far apart move much closer together. And the remaining gap becomes explainable, usually by the gravel section thickness or the assumed depth of organics, which are exactly the two things you want to be discussing.

Questions worth asking before you sign

• Did you walk the site, and what did you find when you dug.
• What depth of organics are you assuming, and what happens if it is deeper.
• What thickness is the gravel section, and is it compacted in lifts.
• Is drainage included, specifically ditching and culverts.
• What is excluded that you would expect to come up on this lot.
• What is the payment schedule, and what does the deposit cover.

On that last one: a modest deposit to mobilize is normal. Paying for the whole job in advance is not, and neither is a deposit that covers most of the contract before a machine arrives.

MNA Construction writes estimates that list the scope, the quantities, and the exclusions, because an estimate you can actually check is the foundation of a job that does not turn into an argument. If you have a bid in hand and want a second read on it, or want an estimate for excavation and site work in Southcentral Alaska, get in touch.