Standard S250-20 – Mapping of underground utility infrastructure

Best Practices for Increasing Awareness of Underground Infrastructures

A considerable number of underground infrastructures has been installed over the years without having their location and dimensions accurately noted. The lack of information on these existing infrastructures, particularly within urban networks, makes the current situation problematic for all stakeholders, both within the planning and designing field as well as in the construction industry.

This document establishes which best practices should be used to access information regarding the accurate location and current state of underground infrastructures. Problems related to lack of information, unknown basic data as well as which approach is needed to acquire information according to the type of work to be carried out are defined in this document. Information stored in a geomatics database can easily be accessed and shared, and is therefore recommended to all network owners.

Implementation of these practices will gradually improve knowledge of existing networks, limit the risks associated with excavation work and ultimately benefit the whole community.


The standard’s implementation increases the accuracy and reliability of the location and mapping of underground infrastructures, and also improves record maintenance. This standard applies to planned underground infrastructures (public and private utilities), as well as existing, abandoned and out-of-service infrastructures, or reserved structures for future use.

During the preliminary design phase of a project, the designer collects all relevant information. The most recent plans for existing underground infrastructures, either abandoned or out-of-service, final surveys or plans are included in the collected information.

During the design stage, subsurface utility engineering (SUE) is used to locate, identify, and define any existing underground infrastructure found within a given project. SUE is applied in a structured manner in accordance with the practices and quality levels specified in the ASCE 38-02 Standard Guideline for the Collection and Depiction of Existing Subsurface Utility Data.

Source: CSA Group and Best Practices Guide

Buy standard CSA S250-20

What is SUE? (french)

Standard ASCE 38-02