CGA Best Practices
The Common Ground Alliance (CGA) Best Practices are the U.S. industry's consensus playbook for preventing damage to underground utilities—covering the full lifecycle from an 811 locate request, to facility marking, to safe excavation and jobsite close-out. They're not law, but are widely referenced by owners, contractors, and state programs; many project specs adopt them verbatim.
Purpose: Damage Prevention • Scope: Complete Utility Lifecycle • Status: Industry Consensus Standard • Coverage: 160+ Best Practices
What They Cover (Utility-Relevant Highlights)
811/One-Call Process & Roles
Define roles for excavators, facility owners, locators, designers, and 811 centers—so everyone follows the same steps before digging.
Excavators
- • Submit locate requests
- • Mark excavation areas
- • Wait for clearance
- • Follow safe dig practices
Facility Owners
- • Respond to locate requests
- • Provide accurate markings
- • Maintain facility records
- • Support damage investigations
Locators
- • Mark utilities accurately
- • Use proper equipment
- • Document limitations
- • Provide timely responses
Positive Response
Owners/locators must confirm—via marks and/or an electronic message—that they have addressed the ticket before excavation starts.
Response Requirements
Physical Marking
- • Spray paint markings
- • Flags or stakes
- • Temporary marking tape
- • Electronic markers where applicable
Electronic Response
- • Clear/No conflict messages
- • Facility marked notifications
- • Scope limitations documented
- • Contact information provided
Excavation Delineation ("White-Lining")
How excavators should mark proposed work areas before requesting locates.
White-Lining Requirements
- • Use white paint or flags
- • Mark excavation boundaries clearly
- • Include depth information
- • Show direction of boring/trenching
- • Mark before submitting locate request
Benefits
- • Improves locate accuracy
- • Reduces unnecessary markings
- • Clarifies work scope
- • Enhances communication
- • Supports damage prevention
Uniform Color Code (APWA/ANSI Z535.1)
Standard colors for electric, gas, communications, water, sewer, etc., to avoid confusion in the field.
Electric Power Lines, Cables, Conduit, and Lighting Cables
Gas, Oil, Steam, Petroleum, or Gaseous Materials
Communications, Alarm or Signal Lines, Cables, or Conduit
Potable Water
Reclaimed Water, Irrigation, and Slurry Lines
Sewers and Drain Lines
Temporary Survey Markings
Proposed Excavation Limits
Tolerance Zone Practices
How to work safely near marks within the legally defined tolerance zone (distance varies by state)—typically requiring careful/"soft" excavation methods.
Critical Safety Zone
The tolerance zone extends a specified distance (typically 18-24 inches) on either side of marked utilities. Special precautions are required within this zone.
Required Practices
- • Hand digging or pneumatic tools
- • No mechanical excavation
- • Visual inspection before digging
- • Immediate stop if utilities encountered
- • Proper support of exposed utilities
State Variations
- • Distance varies by state law
- • Some states specify by utility type
- • Check local regulations
- • May require notification procedures
- • Penalties for violations vary
How to Use Them on a Project
Write Into Project Specifications
Write them into your specs as the baseline for locating, marking, white-lining, tolerance-zone work, and positive response.
Specification Areas
- • Utility location and marking procedures
- • Excavation safety requirements
- • White-lining and delineation standards
- • Positive response verification
- • Tolerance zone compliance
Audit for Compliance
Before digging, verify you've received a positive response from each notified owner/operator.
Compliance Checklist
- • All utility owners contacted
- • Positive responses received
- • Markings present and verified
- • White-lining completed
- • Documentation current and complete
Train Field Crews
Use the Appendix B visuals (white-lining and color code) for consistent jobsite markings.
Training Topics
- • Color code recognition and meaning
- • Proper white-lining techniques
- • Tolerance zone safety procedures
- • Emergency response protocols
- • Documentation requirements
Working in Canada?
Canadian Common Ground Alliance (CCGA) Best Practices
Use the Canadian Common Ground Alliance (CCGA) Best Practices—they harmonize with CGA and are the Canadian reference many owners require (current Version 5.0, Mar 2024).
Key Differences & Harmonization
Similarities
- • Same color coding system
- • Similar locate request processes
- • Aligned safety practices
- • Common excavation standards
Canadian Specifics
- • Provincial regulatory alignment
- • Canadian legal framework
- • Metric measurements
- • Regional best practices
Benefits of Following CGA Best Practices
Damage Prevention
Significantly reduces utility strikes and associated costs, delays, and safety incidents.
Legal Protection
Demonstrates due diligence and industry standard compliance in case of incidents.
Industry Standardization
Creates consistent practices across all project stakeholders and geographic regions.
Cost Savings
Prevents expensive utility relocations, service interruptions, and emergency repairs.
Industry Recognition
CGA Best Practices are widely referenced by owners, contractors, and state programs. Many project specifications adopt them verbatim as the industry standard for damage prevention.
Need Help Implementing CGA Best Practices?
Contact us to learn how our Visual Ground Disturbance System can help you implement and maintain compliance with CGA Best Practices throughout your projects.