Excavation sloping (simple slope, 20 ft or less)
Used on the ASP, CSP and CHST. The worked example below is computed by code and checked against the source.
Horizontal run = depth × H:V ratio
Type A 3/4:1, Type B 1:1, Type C 1½:1
Maximum allowable slopes from Subpart P, Appendix B, for excavations 20 ft deep or less.
Worked example
A 12 ft deep trench in Type C soil.
12 ft × 1.5 = 18 ft of horizontal setback on each side
Where it appears on the exam
ASP: ASP11 Domain 1, Mathematical Calculations
Blueprint: ASP11 Domain 1, task 4: slope angle and depth ratio for trenching and excavation
Practice: Excavation and Trenching
CSP: CSP11 Domain 1, Advanced Application of Safety Principles
Blueprint: CSP11 Domain 1, task 3: common workplace hazards (excavation)
Practice: Excavation and Working Over Water
CHST: CHST5 Domain 1, Hazard and Risk Identification and Control
Blueprint: CHST5 Domain 1, knowledge 3: excavations
Practice: Construction Safety Math: Noise and Excavation Slopes, Excavations and Trenching
Source
The formula comes from
29 CFR 1926 Subpart P, Appendix B (Figure B-1)(opens ecfr.gov in a new tab)“All simple slope excavation 20 feet or less in depth shall have a maximum allowable slope of 3/4 :1. ... All simple slope excavations 20 feet or less in depth shall have a maximum allowable slope of 1:1. ... All simple slope excavations 20 feet or less in depth shall have a maximum allowable slope of 1 1/2 :1.”
Questions
- What is the formula for excavation sloping (simple slope, 20 ft or less)?
- Horizontal run = depth × H:V ratio; Type A 3/4:1, Type B 1:1, Type C 1½:1. Maximum allowable slopes from Subpart P, Appendix B, for excavations 20 ft deep or less.
- Will this formula be given on the BCSP exam?
- BCSP says the formula is included in the question whenever one is needed, unless the question is testing whether you know the formula. You can't bring a formula sheet into the exam, so learn what each formula does and when to use it.
BCSP on formulas at the exam
BCSP, What to Expect When Sitting for a BCSP Exam (item 7)(opens bcsp.org in a new tab)“For any question requiring a mathematical formula, the formula will be included within the exam question (unless the question is specifically testing your knowledge of a formula). You will not be provided or permitted to bring a formula sheet.”
Related
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- Sling tension from the load angle factor
- Personal fall arrest distances
- Secondary containment capacity
- ASP formula sheet
- CSP formula sheet
- CHST formula sheet
Checked 2026-10-16. Spot a problem? Email hello@passcited.com.