Excavation & Sitework Reference Charts

ABOUT THESE CHARTS

These charts cover the numbers excavation and utility contractors check before anyone enters a trench: the OSHA maximum allowable slopes by soil type with their actual angles, the Type A/B/C classification tests and disqualifiers, the benching configurations (and the soil that can never be benched), when a protective system is required and the design options 1926.652 allows, the trench box rules, the shoring table frameworks, the 20-foot engineer line, the day-to-day 1926.651 rules — egress, spoils, inspections, atmosphere — the 811 process with the APWA marking colors, and working around water.

Nearly everything here is federal law — 29 CFR 1926 Subpart P — and directly life-safety: trench collapses kill around two dozen workers a year, almost all in unprotected trenches. Two authorities outrank every table on these pages: state OSHA plans, which can be stricter than the federal text, and the competent person, in whom the standard vests soil classification and protective-system decisions on site. These are working references for that person — not a substitute for the standard, the tabulated data, or the site call.

The earthwork-math side covers the estimating numbers: swell and shrink factors by material with the bank-loose-compacted conversions, material weights per cubic yard, the volume formulas, cut-and-fill balancing, dump truck capacities and why weight governs before volume, bucket ratings and fill factors, topsoil stripping, the fill classifications, and soil moisture with the Proctor basics.

Soil is not a catalog product: soil-dependent values on these pages are ranges with stated typicals — swell, weight, and moisture genuinely vary by site — and the geotech report always governs. When the answer needs computing instead of looking up — quantities, slopes at depth — the estimating side of NORDIX does that math.