Drainage before pad, topsoil before fill, compaction before you cover it. The sequence that keeps site prep from being done twice.
Site preparation done in the wrong order does not fail immediately. It fails after the concrete is poured.
The sequence below is not clever. It is the order in which each step depends on the one before it, and nearly every site prep problem we are called to fix is a step taken out of turn.
1. Establish where water goes
Walk the site in the rain if you can. If not, read the ground: scour lines, silt deposits, the places that stay green in August.
Every later decision — pad elevation, road alignment, where fill can go — is downstream of this. Once you have moved earth, you have destroyed the evidence of what the drainage was doing.
2. Install perimeter erosion control
Silt fence, construction entrance, inlet protection — before disturbance, not after. Beyond being what the stormwater permit requires, it is cheaper than chasing sediment off roads and out of ditches.
3. Strip and stockpile topsoil
Burying topsoil under fill destroys it twice: you lose the material, and you introduce compressible organics into your fill. Strip it, stockpile it separately, and seed the pile if it will sit through a season.
4. Install drainage structures
Culverts, storm pipe, French drains, swales — before the pad.
The most commonly deferred step, because drainage is invisible in the finished product and the pad is what the client is waiting for. Retrofitting it means excavating the pad you just paid for.
5. Cut and fill
Balance the earth on site. Hauling is usually the largest avoidable cost in site prep, and both import and export are priced per load. Raise it with your engineer while the plan is still a draft — a pad elevation moved eighteen inches can balance a site, and it is nearly free to change on paper.
6. Place fill in lifts and compact each one
Layers, each compacted before the next arrives. Dumping to depth and rolling the top gives you a surface that tests fine over a mass that was never compacted, and it settles unevenly once the structure is on it.
Moisture governs everything: too dry will not bind, too wet will not compact regardless of passes. This is why West Virginia schedules slip in spring — saturated clay cannot be brought to spec, and pushing on produces subgrade that fails testing and has to be removed.
7. Test compaction properly
Third-party density testing at the engineer's intervals, results kept on file. On commercial work the inspector will ask, and the difference between a smooth inspection and a two-week delay is usually whether the documentation exists.
8. Final grade, verify, document
Finish grade shot against the benchmark and checked against plan, as-built elevations recorded, and photographs of what went into the ground before it was covered. That last one costs nothing at the time and is worth a great deal the first time someone asks what is under the slab.
The failures we get called to fix
- Drainage retrofitted after the pad — the expensive way to do a cheap step.
- Topsoil buried in the fill — organics compress, the pad settles unevenly.
- Fill placed too thick — compacted at the surface only.
- Compacted wet — passed a visual check, failed under load.
- No documentation — the work may have been fine, but nobody can show it.
All five are a step taken before the one it depended on. The pressure to start the pad before the drainage is in is always well-intentioned, and it is the single most reliable predictor of a site that has to be partly rebuilt.