Site Work, Excavation, and Earthwork
Core concepts
Earthwork questions test whether you understand soil behavior, compaction, and water. Key terms: bank (in-place), loose (excavated), and compacted volume, tied together by shrinkage and swell factors. A cubic yard in the ground does not equal a cubic yard in a truck or in a fill lift. Optimum moisture content and maximum dry density come from a Proctor test; compaction is verified by nuclear gauge or sand cone.
Also know cut and fill balance, borrow vs. waste, subgrade preparation, proof rolling, and slope stability. Erosion and sediment control (silt fence, stabilized construction entrance, temporary seeding) is a frequent code item, along with call-before-you-dig utility locating.
Traps to watch
- Confusing swell (volume increase when excavated) with shrinkage (volume decrease when compacted).
- Assuming native soil is suitable fill - expansive clays and organic soils usually are not.
- Forgetting that compaction spec is a percentage of maximum dry density, not a fixed number.
- Overlooking that trench spoil and dewatering discharge have separate handling rules.
Rule of thumb
Convert everything to bank cubic yards before comparing bid quantities. If a plan gives compacted fill volume and the soil has 15% shrinkage, divide by 0.85 to get the bank volume you must excavate and pay for.
Worked example
1,000 compacted CY of fill needed; shrinkage 15%. Bank volume = 1,000 ÷ 0.85 ≈ 1,176 BCY. If swell on hauling is 25%, loose haul volume ≈ 1,176 × 1.25 ≈ 1,470 LCY.