OSHA Trenching & Excavation Standards
29 CFR 1926 Subpart P — the federal standard for all open excavations. Public domain. Applies to every trench over 5 feet deep (and shallower trenches if hazardous conditions exist).
Legal requirement: Any excavation deeper than 5 feet requires a protective system (sloping, benching, shoring, or shielding). Any excavation deeper than 20 feet requires a PE-designed system. This is federal law, not a suggestion.
Soil Classification (OSHA Appendix A)
| Soil Type | Description | Test Method | Unconfined Strength |
|---|---|---|---|
| Type A | Cohesive, stable. Stiff clay, hardpan, caliche. No fissuring, no prior disturbance, no water seepage. | Thumb penetration: <0.25"; Pocket penetrometer: ≥1.5 tsf | ≥ 1.5 tsf |
| Type B | Cohesive or granular. Angular gravel, silty clay, previously disturbed Type A, fissured soils, dry rock not hard enough for Type A. | Thumb penetration: 0.25"–1"; Penetrometer: 0.5–1.5 tsf | 0.5 – 1.5 tsf |
| Type C | Cohesive <0.5 tsf, granular (sand, gravel), submerged soil, soil subject to water, layered systems sloping into excavation. | Thumb penetration: >1"; crumbles easily. Water present. | < 0.5 tsf |
Required Sloping Angles (OSHA Appendix B)
| Soil Type | Max Slope | H:V Ratio | Setback per foot of depth |
|---|---|---|---|
| Type A | 53° | 3/4 : 1 | 0.75 ft each side |
| Type B | 45° | 1 : 1 | 1.0 ft each side |
| Type C | 34° | 1.5 : 1 | 1.5 ft each side |
| Stable Rock | 90° | Vertical | 0 |
Competent Person Daily Checklist
✓ Soil type classified before workers enter
✓ Utilities located and protected (811 called ≥ 3 days prior)
✓ Surface encumbrances removed or supported
✓ Spoil placed minimum 2 ft from trench edge
✓ Protective system (slope / bench / shield / shore) in place
✓ Access and egress within 25 LF of all workers
✓ Water accumulation evaluated — dewatering if needed
✓ Atmospheric testing if depth >4 ft (confined space risk)
✓ Adjacent structures evaluated for stability
✓ Inspection after rain, freeze-thaw, or any hazard change
Trench Shield (Box) Requirements
- Permitted in all soil types as an alternative to sloping or shoring
- Must extend ≥ 18 inches above top of unstable soil, or within 2 ft of surface in stable soil
- Workers must not be in the shield during movement or repositioning
- Must be designed by a PE or meet manufacturer tabulated data
- Spoil minimum 2 ft from trench edge regardless of shield use
- Maximum 2 ft of unprotected trench in front of and behind the shield
Key Regulations
1926.650 — Scope and definitions ↗
1926.651 — Specific excavation requirements ↗
1926.652 — Requirements for protective systems ↗
OSHA Trenching eTool ↗
OSHA 2226 — Trenching and Excavation Safety (Public Domain PDF) ↗
Use our OSHA calculator → The Trench Safety Calculator walks through protective system requirements by soil type, depth, and method.
OSHA PPE Requirements — Construction
29 CFR 1926 Subpart E — Personal Protective Equipment requirements for construction sites. Applies to all contractors on federal projects and most state equivalents.
| PPE Item | When Required | Standard | Notes |
|---|---|---|---|
| Hard hat | All areas where head injury risk from falling objects, bumping, electrical | 1926.100 / ANSI Z89.1 | Class E for electrical work. Replace after impact. |
| Safety glasses / goggles | Grinding, chipping, drilling, concrete work, chemical exposure | 1926.102 / ANSI Z87.1 | Side shields required for flying debris |
| High-visibility vest | Work near moving vehicles or equipment (MUTCD / ANSI 107) | MUTCD / 23 CFR 634 | Class 2 min near traffic; Class 3 on highway right-of-way |
| Steel-toe boots | Heavy equipment operation, material handling | 1926.96 / ASTM F2413 | EH-rated for electrical hazards |
| Gloves | Handling sharp materials, chemicals, concrete, hot surfaces | 1926.28 (general duty) | Cut-resistant for pipe handling; chemical-resistant for solvents |
| Hearing protection | Noise ≥ 85 dBA TWA (jackhammers, compactors, excavators) | 1926.52 / 1910.95 | Earplugs: ~33 NRR. Earmuffs: ~25–30 NRR |
| Fall protection | Leading edges, excavations, elevated platforms ≥ 6 ft | 1926.502 | Harness + lanyard OR guardrail + safety net system |
| Respiratory protection | Silica dust, confined spaces, spray-applied coatings | 1926.1153 / 1910.134 | Silica PEL: 50 μg/m³ TWA. N95 minimum for silica. |
Silica Rule (1926.1153): Effective 2017. Employers must have a written exposure control plan, limit worker exposure to 50 μg/m³ (action level: 25 μg/m³), and provide medical surveillance. Applies to grinding, cutting, or drilling concrete, stone, or mortar.
811 / Blue Stakes — Call Before You Dig
811 is the national "call before you dig" number. Blue Stakes of Utah administers the program for Utah. Required by law before any excavation. Not optional.
Utah law (Utah Code 54-8a): Every excavator must notify Blue Stakes at least 3 business days (72 hours) before digging. Failure to notify can result in fines and full liability for damage to underground facilities.
The 5 Steps to Safer Digging
1
Call or click 811 at least 3 business days before digging. Provide exact location, type of work, and dig depth. Online: bluestakes.org
2
Wait the full time. Facility operators have 3 business days to locate and mark utilities. Don't dig early — even if you think you know where lines are.
3
Confirm all markings. Check Electronic Positive Response (EPR) to see which utilities responded. If a utility hasn't responded, submit a No Response Notice before digging.
4
Respect the marks. Protect markings throughout excavation. Re-notify if marks are destroyed before work is complete or if work extends beyond 20 days.
5
Hand dig within the tolerance zone. 24 inches on either side of any marking. No power equipment in the tolerance zone until utilities are hand-exposed and confirmed.
Utility Marking Color Codes (APWA Standard)
RedElectric power, lighting, cables, conduit
OrangeCommunication, alarm, fiber optic, signal lines
YellowGas, oil, steam, petroleum, gaseous materials
GreenSewer, storm drain, drain tile
BluePotable water
PurpleReclaimed water, irrigation, slurry lines
PinkTemporary survey markings
WhiteProposed excavation area (your markings)
What Blue Stakes Does NOT Cover
- Private service lines (from meter to building) — these are the property owner's responsibility
- Abandoned lines — may still be present and energized
- Non-member utilities — some small utilities may not be registered
- Accuracy within the tolerance zone — 24" either side of marks is your responsibility to hand dig
Confined Space Entry — Construction
29 CFR 1926.1200–1213 — Confined spaces in construction. Covers manholes, vaults, tanks, excavations deeper than 4 ft with limited access. One of the most dangerous activities in underground utility work.
Fatality risk: More than 60% of confined space fatalities are would-be rescuers. Never enter a confined space to rescue a downed worker without proper equipment and training. Call 911 first.
Permit-Required Confined Space (PRCS) Criteria
A space is permit-required if it has one or more of:
- Hazardous atmosphere (or potential for one) — oxygen-deficient (<19.5%), oxygen-enriched (>23.5%), flammable >10% LEL, toxic at or above PEL
- Material that could engulf an entrant (water, soil, grain)
- Internal configuration that could trap or asphyxiate
- Any other recognized serious safety or health hazard
Atmospheric Testing Order (Always in this sequence)
1
Oxygen content — must be 19.5%–23.5% before entry
2
Flammable gases/vapors — must be <10% LEL
3
Toxic contaminants — CO, H₂S, etc. below PEL (CO <25 ppm, H₂S <1 ppm for 8-hr TWA)
Common Confined Spaces in Underground Utility Work
| Space | Primary Hazards | Notes |
|---|---|---|
| Manholes | Oxygen deficiency, H₂S, methane, engulfment | Always treat as PRCS until tested. Sewer gas is heavier than air — pools at bottom. |
| Valve vaults | Oxygen deficiency, gas leaks | Test all corners. Purge if O₂ low. |
| Trenches >4 ft | Cave-in, oxygen deficiency (near gas lines) | Atmospheric monitoring required if risk of gas infiltration. |
| Wet wells / lift stations | H₂S, methane, oxygen deficiency, electrocution | Highest H₂S risk. Immediately dangerous to life at 100 ppm. |
| Storage tanks | Flammable vapors, toxic residue, O₂ deficiency | Hot work permit required. Inert atmosphere possible. |
Best Construction YouTube Channels
The best free education in construction is on YouTube. These are the channels worth following — field knowledge, equipment, business, and industry news.
Heavy Civil & Underground Utility
Heavy Construction Academy
Equipment operation, site management, and heavy civil fundamentals. One of the most educational channels in the space. Covers excavators, graders, scrapers, and more.
Equipment · Operations
Premier Underground Construction
Real underground utility construction work — pipe installation, trench work, water and sewer. Authentic field footage from an active contractor.
Underground · Pipe · Field work
Stanley "Dirt Monkey" Genadek
Excavation, landscaping, and field operations from a hands-on contractor. Great for understanding production rates, equipment selection, and running a crew.
Excavation · Equipment · Business
Trimble Civil Construction
Machine control, GPS grade technology, and field layout for heavy civil. If you're using or evaluating machine control systems, start here.
Technology · Machine control · Grade
Business & Leadership
BuildWitt
Aaron Witt's channel on workforce development, culture, and the future of heavy civil. Excellent for PMs, supers, and anyone building a construction company.
Leadership · Culture · Workforce
Construction Leading Edge
Business systems, project management, and leadership for construction company owners. Practical and no-fluff.
PM · Business · Systems
Matt Risinger — Build Show
Deep dives on building science, materials, and methods. More residential/commercial but excellent for anyone who values understanding WHY things are built the way they are.
Building science · Materials · Methods
The Constructer
Civil engineering concepts, structural design, and construction methods explained clearly. Good for field engineers and PMs wanting to understand the engineering behind the work.
Civil engineering · Structures · Education
Equipment & Field Operations
Caterpillar
Equipment operation, maintenance, and machine innovation straight from Cat. Good for operator training reference and keeping up with new machine technology.
Equipment · Maintenance · Technology
Komatsu
Smart Construction, machine control, and equipment operation. Particularly strong on autonomous and semi-autonomous equipment — the future of heavy civil.
Equipment · Autonomous · Smart construction
Case Construction Equipment
Backhoe, excavator, and compact equipment operation and maintenance. Useful for training operators and understanding equipment specs.
Equipment · Operation · Training
Missing a channel? Open a GitHub issue and suggest it. We want this list to be community-maintained.
News, AI in Construction & Industry Updates
Where to stay current on what's happening in construction and how AI is changing it. No paywalls where possible.
Daily / Weekly News
Construction Dive
The best free daily construction news. Covers industry, technology, labor, policy, and major project awards. Free newsletter — subscribe and actually read it.
Daily news · Free · Industry
Engineering News-Record (ENR)
The industry paper of record. ENR Top 400, Top 100 Design Firms, regional lists. Some content behind paywall but headlines and rankings are accessible.
Industry rankings · Paywalled · Authoritative
Construction Executive
Business-focused construction news — finance, risk, technology, workforce. Aimed at owners and executives but useful for anyone wanting to understand the business side.
Business · Finance · Leadership
Construction Business Owner
Field operations, estimating, project management, and running a construction company. Practical articles for contractors at all levels.
Operations · Estimating · Business
AI in Construction
Construction Industry AI
The best dedicated source for AI in construction. Monthly roundups, tool reviews, and guides on how contractors are actually using AI. Some content is paid but free tier is solid.
AI · Contech · Tools
Construction Dive — Technology
The tech section of Construction Dive covers AI, robotics, drones, BIM, and software. Heavy coverage in 2025 — best free option for AI-in-construction news.
AI · Robotics · BIM · Free
openmud ← you're here
Open-source AI tools for heavy civil. The only free, open-source construction AI project built by contractors for contractors. Contribute, fork, use it.
Open source · Free · Heavy civil
Podcasts
The Civil Engineering Podcast
Anthony Fasano interviews civil engineers and contractors on career, projects, and industry trends. Good for field engineers wanting to grow.
Civil engineering · Career · Industry
The Dirt World Podcast (BuildWitt)
Aaron Witt interviews contractors, equipment operators, and industry leaders. One of the best pods for understanding the culture and future of heavy civil.
Culture · Leadership · Heavy civil
Construction Leading Edge Podcast
Systems, project management, and business operations for construction companies. Matt Verderamo interviews contractors building better companies.
Business · Systems · PM
Podcasts
The best podcasts for heavy civil, construction business, and industry news. See the full list in the News & AI Updates section.
Standards & Codes Reference
Key standards for underground utility and heavy civil construction. Know which ones apply to your work.
| Standard | What it covers | Who publishes | Applies to |
|---|---|---|---|
| 29 CFR 1926 Subpart P | Excavation and trenching safety | OSHA | All construction excavations |
| 29 CFR 1926 Subpart E | Personal Protective Equipment | OSHA | All construction workers |
| 29 CFR 1926.1200 | Confined spaces in construction | OSHA | Manholes, vaults, tanks |
| AWWA C900 | PVC pressure pipe for water distribution | AWWA | Waterline, 4"–60" |
| AWWA C151 | Ductile iron pipe specifications | AWWA | Waterline, DIP |
| AWWA C200 | Steel water pipe specifications | AWWA | Large diameter steel pipe |
| ASTM D3034 | PVC sewer pipe (SDR 35) | ASTM | Gravity sewer, storm |
| ASTM D3035 | HDPE pipe for pressure applications | ASTM | Force mains, directional drill |
| ASTM C76 | Reinforced concrete pipe | ASTM | Storm drain, culverts |
| ASCE MOP 36 | Design and construction of sanitary sewers | ASCE | Sewer system design |
| MUTCD | Manual on Uniform Traffic Control Devices | FHWA | All work zone traffic control |
| APWA Color Code | Underground utility marking colors | APWA | All utility locates |
| CGA Best Practices | Damage prevention for underground utilities | Common Ground Alliance | All excavators |
Open-Source Construction Tools
A curated directory of open-source tools for construction, civil engineering, and estimating. All free to use, fork, and contribute to.
openmud ⭐
AI chat, 18 calculators, Python tools for estimating, hydraulics, trench takeoff, OSHA safety, bid math, and unit conversion. MIT license. This is the project you're on.
Python · JavaScript · MIT · Heavy civil
TrueCost
AI-powered construction estimation engine using 7 specialized agents to analyze CAD plans and generate risk-adjusted cost estimates with Monte Carlo simulation.
Python · AI · Estimation · CAD analysis
Awatif
Web-based parametric structural engineering platform with FEM analysis and meshing. MIT license. Good for structural design calculations embedded in web tools.
JavaScript · FEM · Structural · MIT
Camber
Open-source Dynamo package for Autodesk Civil 3D. Extends Civil 3D functionality for heavy civil workflows. Good for firms using Civil 3D wanting automation.
C# · Civil 3D · Dynamo · AutoCAD
BuildWise
AI-powered construction cost estimation with real-time calculations, material/labor optimization, and dashboards. React + Firebase + Gemini API.
React · Firebase · AI · Estimation
Ara 3D Connect
Open-source tracking, reviewing, and versioning for BIM data built on Git. Version-control your BIM models the way developers version-control code.
BIM · Version control · .NET
Know an open-source construction tool that should be here? Open a GitHub issue and we'll add it.
Public Construction Datasets
Free, publicly available data sources for construction research, pricing, and analysis.
BLS Occupational Employment Statistics
Federal wage data by occupation and region. The best source for construction labor rates by trade, region, and union/non-union status. Updated annually.
Labor rates · Federal data · Free
BLS Producer Price Index — Construction
Material price indices for construction materials: concrete, steel, pipe, lumber. The authoritative source for tracking material cost inflation over time.
Material costs · Inflation · Free
WA State L&I Prevailing Wages
Washington State prevailing wage rates by trade and county. If you bid public works in WA, these are the rates. Updated quarterly.
Labor · Prevailing wage · Washington
Utah Prevailing Wage Rates
Utah Labor Commission prevailing wage rates for public works projects by county and trade. Required for public contracts in Utah.
Labor · Prevailing wage · Utah
Census Bureau — Value of Construction Put in Place
Monthly construction spending data by sector: residential, commercial, infrastructure, utilities. The macro view of where construction money is flowing.
Market data · Spending · Monthly
eCFR — 29 CFR Part 1926 (OSHA Construction)
The complete OSHA construction standard in searchable, linkable format. Public domain. The primary source for all OSHA compliance questions.
OSHA · Public domain · Searchable
Soil Classification Reference
Field identification methods and engineering properties of common soil types encountered in underground utility work.
| Soil Type | Description | Field Test | Swell Factor | Shrink Factor | Bearing (PSF) |
|---|---|---|---|---|---|
| Sand (clean) | Loose to dense granular, no cohesion, drains freely | Falls apart in hand when dry. No ribbon forms when wet. | 10–15% | 5–10% | 1,500–3,000 |
| Gravel | Coarse granular, excellent drainage, stable when compacted | Individual particles visible. No plasticity. | 10–20% | 5–10% | 3,000–6,000 |
| Silty clay | Medium cohesion, moderate plasticity, slow drainage | Ribbon 1–2" before breaking. Thumb penetration 0.5"–1". | 20–30% | 10–15% | 1,000–2,000 |
| Stiff clay | High cohesion, low permeability, stable excavation walls | Ribbon 2"+ before breaking. Thumb barely penetrates. Penetrometer ≥1.5 tsf. | 25–35% | 15–20% | 2,000–4,000 |
| Soft clay | Low strength, high plasticity, unstable in excavation | Thumb penetrates easily. Oozes when squeezed. | 30–40% | 20–25% | 500–1,000 |
| Rock (soft) | Shale, limestone, weak sandstone. Can be ripped. | Scratches with knife. Breaks with hammer blow. | 25–40% | 0% | 10,000–50,000 |
| Rock (hard) | Granite, basalt, hard sandstone. Requires blasting or rock saw. | Cannot scratch with knife. Rings when struck. | 30–50% | 0% | 50,000+ |
Swell factor: volume increase when excavated (BCY → LCY). Shrink factor: volume decrease when compacted (BCY → CCY). Always verify with actual soil testing for design.
Utility Marking Color Codes
APWA Uniform Color Code for underground utility markings. The national standard used by all 811 programs.
RedElectric power lines, cables, conduit, lighting cables
OrangeTelecommunication, alarm/signal lines, cable TV, fiber optic
YellowGas/oil distribution, steam, petroleum, gaseous materials
GreenSewers, drain lines, culverts
BluePotable water, irrigation, slurry lines
PurpleReclaimed water, irrigation, slurry lines (non-potable)
PinkTemporary survey markings, unknown/unidentified
WhiteProposed excavation limits (you mark your dig area in white)
GrayTemporary dewatering/pumping lines
Source: APWA Uniform Color Code. Used by all 811 One-Call programs nationwide. Marks are typically flags, paint, or stakes. Respect all marks — even if you know where a line is.
Pipe Specifications Quick Reference
Common pipe materials, their typical applications, pressure ratings, and standards. Use the full pipe reference table in the Calculators for OD, wall thickness, and weight.
| Material | Typical Use | Size Range | Joint Type | Standard | Notes |
|---|---|---|---|---|---|
| PVC C900 | Water distribution, pressure pipe | 4"–60" | Push-on gasket | AWWA C900 | DR18 = 165 PSI, DR14 = 200 PSI. Most common water pipe. |
| PVC SDR 35 | Gravity sewer, storm drain | 4"–15" | Push-on gasket | ASTM D3034 | Gravity only. Not for pressure. Flexible ring-tight joints. |
| HDPE (DR11) | Force mains, directional drill, gas | ½"–63" | Butt fusion, electrofusion | ASTM D3035 | 200 PSI. Fully restrained joint. Excellent for DD crossings. |
| HDPE (DR17) | Low-pressure water, reclaimed water | ½"–63" | Butt fusion | ASTM D3035 | 100 PSI. Lighter wall, lower cost. |
| Ductile Iron (DIP) | Water, sewer under pressure, harsh soils | 3"–64" | Push-on or mechanical | AWWA C151 | Restrained joints (TR Flex, Megalug) required at fittings and long runs. |
| RCP (Class III) | Storm drain, culverts | 12"–144" | Bell and spigot, O-ring | ASTM C76 | Gravity only. Class I–V by wall strength. Class III most common. |
| Steel | Water transmission, large diameter | 4"–252" | Welded, flanged, mechanical | AWWA C200 | Requires interior/exterior coating. Good for large diameter, high pressure. |
| VCP (Vitrified Clay) | Sanitary sewer (existing systems) | 4"–42" | Push-on, compression | ASTM C700 | Chemically inert, common in older sewer systems. Brittle. |
Construction Glossary
Common terms in heavy civil and underground utility construction. From field slang to engineering terminology.