The survey process begins with a work plan that outlines the scope of work, project schedule, levels of service vs. risk allocation and desired delivery method.
Non-destructive surface geophysical methods are then leveraged to determine the presence of subsurface utilities and to mark their horizontal position on the ground surface. Vacuum excavation techniques are employed to expose and record the precise horizontal and vertical position of the assets. This information is then typically presented in CAD format or a GIS-compatible map.
A conflict matrix is also created to evaluate and compare collected utility information with project plans, identify conflicts and propose solutions. The concept of SUE is gaining popularity worldwide as a framework to mitigate costs associated with project redesign and construction delays and to avoid risk and liability that can result from damaged underground utilities.
Five levels of detail can be provided:
- Desktop studies to combine all existing information relating to the utilities, reviewing this information and identifying key objectives and methods to move forward with the project.
- Combine desktop study with existing surface features associated with buried and surface utilities, such as hydrants, stop taps, sub-stations and pylons.
- Onsite utility survey using the very best remote sensing and geophysical survey instruments available on the market. The information is surveyed on site and added to a topographic survey. Results from the desktop study will be used on site and in the processing post survey to compile a comprehensive record of the site surveyed.
- Highest level of accuracy that combines the results of the desktop study, site survey with actual exposure of the services to confirm number, depth, material and identification. Trench section reports are compiled identifying each service, its location and depth. In addition to the services the ground makeup will be identified showing depths of each material excavated. This service will typically be done using vacuum excavation or hand digging to prevent any damage to the services.