Best Practices Version 20.0

Search or Filter

Search Best Practices

Filter by Industry Icons

Table of Contents

Submit a Best Practice Proposal

Download a Copy

Purchase a Book

Access Best Practices Toolkit

4.23 Trouble Locate (Unlocatable) Resolution Protocol98/

Practice Statement:

The operator has a trouble locate resolution protocol that emphasizes the timely and accurate completion of the trouble locate request with communication between the parties and documentation of actions taken.

Practice Description:

The practice is intended to be applied in cases where upon initial arrival at the location, the tolerance zone for an existing facility cannot be established with confidence consistent with the operator's compliant mark out criteria.

In this scenario the locate entity/operator:

  • Applies any initial locate protocols available to them that may result in establishing the tolerance zone and placing markings to avoid unnecessary escalation.
  • After exhausting initial trouble locate protocols, and prior to the required marking date, escalates the trouble locate internally for advanced/enhanced resolution measures, i.e., vacuum truck, line tracer, ground penetrationg radar (GPR), in-line 3D gyro mapping technology, etc.
  • Attempts to make direct contact with the excavator (cell phone, text, email) and documents the method and message.  If a specific interim positive response code is available or comments can be placed in the 811 center system, share why the locate cannot be completed, along with contance information.
  • Designates the trouble locate area consistent with their procedures and uses paint, flags or other methods that distinguish the specific trouble area from the locatable areas.
  • Prioritizes the completion of the trouble locate and maintains communication with the excavator until resolved.  In this communication, the operator should warn of any unique or elevated risk associated with the unlocatable facility (high pressure gas, high voltage electric, high-density fiber, etc.).
  • Operator makes the appropriate records/mapping corrections, and when feasible takes action to make the facility locatable moving forward (tracer wire, electronic marker system/marker balls, etc.).
  • Completes the appropriate positive response in jurisdictions that provide that option.

This practice does not relieve an owner/operator/ responding to a valid 811 center notification, from complying with existing statutory language regarding the notification and response time, but rather provides supplemental tools to reduce damage potential and maintain excavator productivity.


Enhances communication and documentation between the parties, keeps the excavator working in non-trouble areas when applicable, improves operator's facility records, and reduces damages to at-risk facilities that could otherwise cause a delay.


  • Existing practice by Southwest Gas operating in Arizona, California, and Nevada; UGI Utilities, Inc., operating in Pennsylvania and Maryland; NiSource operating in Indiana.

Submit a Best Practice Proposal

Download a Copy

Purchase a Book

Access Best Practices Toolkit

Damage Prevention in Your State

Explore damage prevention information, local contacts and rules for safe digging in North America.

Find Your State

CGA Toolkits

CGA has created a suite of toolkits designed to help members generate public awareness about the importance of damage prevention.

Explore Resources