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Sitework & Earthworkaka: engineered fillaka: structural fillaka: borrow

Fill Material

In Plain English

Dirt or other material brought in to raise the ground level or fill in holes.

Definition

Soil, rock, or engineered material placed in an excavation or on a site to raise grades, provide structural support, or improve soil conditions. Fill must be suitable for its intended use — free of organic matter, excessive fines, and deleterious materials — and placed and compacted according to specifications. Engineered fill (controlled compacted fill) is tested to verify density.

Why It Matters in Bidding

Fill is a high-volume earthwork cost where small unit changes compound across thousands of cubic yards, so estimators must distinguish suitable on-site cut from imported borrow and engineered fill priced with testing and compaction. Misjudging fill suitability or quantity is a leading source of earthwork overruns and disputed change orders when unsuitable material must be exported and replaced.

Example

After reviewing the geotech report, a sitework estimator prices imported structural fill under the building pad because the cut soils are too organic, and adds compaction testing to the unit cost.

Related Terms

BackfillImport MaterialCompactionSubgrade

Frequently Asked Questions

On-site fill is priced for moving and compacting material already present, while imported fill adds purchase, haul, and placement costs per cubic yard. The geotech report and cut-fill balance determine the split, so estimators quantify borrow needs early because trucking imported material can dominate an earthwork bid.
Engineered or controlled fill is placed in specified lifts and compacted to a tested density to support structures. The added survey, moisture conditioning, and compaction testing raise its unit cost over general fill, so estimators price it separately wherever the specs call for it beneath foundations or slabs.
If on-site soils contain organics or excess fines, they cannot be reused as structural fill and must be exported and replaced with borrow. That swing can blow an earthwork budget, so estimators rely on the geotech report and add qualifications about assumed soil conditions to protect against undisclosed unsuitable material.

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