Site Work, Excavation, and Foundations
Moving dirt profitably
Sitework estimating turns on volume change. Soil in its natural state is bank volume; once excavated it swells into loose volume; once compacted it shrinks below bank. Haul counts use loose cubic yards, payment often uses bank or compacted cubic yards. Structural fill is placed in lifts and compacted to a specified percentage of maximum dry density (commonly 95 percent of Standard Proctor) near the wet or dry optimum, verified by field density tests.
Excavation safety - the most testable material here
Under OSHA 1926 Subpart P: a protective system is required at 5 feet; a competent person inspects daily and after rain; spoils and equipment stay at least 2 feet back from the edge; a ladder or ramp is required within 25 feet of lateral travel in a trench 4 feet or deeper; and access/egress plus atmospheric testing apply where hazards exist. Maximum allowable slopes by soil type: Type A ¾:1, Type B 1:1, Type C 1½:1. Call 811 before digging.
Foundations
Shallow foundations (spread footings, mat) rely on bearing capacity of competent soil and must bear below frost depth and on undisturbed or engineered fill. Deep foundations (driven piles, drilled shafts, piers) transfer load past unsuitable soil. Dewatering, erosion and sediment controls (silt fence, stabilized entrance), and utility coordination belong in the site plan, not the afterthought.
Trap
A question describes a 6-foot trench with vertical walls and no protective system and offers 'Type A soil' as an excuse - soil classification alone does not eliminate the 5-foot trigger.
Rule of thumb
Five feet for protection, four feet for egress, 25 feet of lateral travel, two feet of spoil setback: memorize the four numbers.