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Sitework & Earthworkaka: digaka: cutaka: trenchingaka: bulk excavation

Excavation

In Plain English

Digging into the ground to remove soil and rock — to install foundations, pipes, or prepare a site for construction.

Definition

The process of mechanically removing earth, rock, or other materials from a site to achieve a required depth, shape, or profile for foundations, utilities, grading, or other purposes. OSHA regulates excavation safety with requirements for sloping, shoring, or trench boxes based on soil classification and depth. Excavations deeper than 5 feet require protective systems.

Why It Matters in Bidding

Excavation is one of the highest-risk and most quantity-sensitive items in a bid because unit volumes are large and unit costs swing with soil type, haul distance, and protective-system requirements. Unforeseen rock or groundwater can blow the earthwork budget, so estimators tie their numbers tightly to the geotechnical report and the contract's differing-site-conditions language.

Example

An estimator takes off 3,200 cubic yards of mass excavation from the grading plan, prices it against the geotech boring logs showing no rock above subgrade, and adds a trench-box line item for utility runs deeper than 5 feet.

Related Terms

EarthworkShoringDewateringSubgrade

Frequently Asked Questions

Estimators calculate cut and fill volumes in cubic yards from grading plans or earthwork software, then adjust for swell and compaction to size haul-off or import. They separate mass excavation, structural excavation, and trenching because each has different production rates, equipment, and protective-system costs that affect the unit price.
Soil classification, presence of rock or groundwater, haul distance to a disposal or borrow site, depth-driven shoring or trench-box requirements, and access constraints all move the unit cost. The geotechnical report is the estimator's primary risk document, since unanticipated rock or dewatering can sharply increase production cost.
They base quantities on the geotech borings, note assumptions clearly, and rely on the contract's differing-site-conditions clause for recovery if actual ground differs materially. Where the report is thin, an estimator may carry a contingency or unit price for rock and dewatering rather than burying that risk in a lump sum.

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