What Else Is Down There?

Our infrastructure above and below ground changes daily. As-built records for utilities are unreliable, lost, or damaged, making it more challenging to determine their location underground. There also could be other facilities, objects, and structures, etc., underground, which are critical to identify to be successful. How do we know what else is below ground? The ASCE 38-02 and newly published 38-22 Standard Guideline for Investigating and Documenting Existing Utilities provide many techniques for finding underground utilities. But what about the other objects, including structures or private utilities, that could affect a project? These can include abandoned utilities, vaults, underground tanks, and septic systems. These may not show up on any records or have any above ground features to facilitate identifying them. This paper will discuss different types of equipment and techniques that can be used to help determine what else may be underground. These include electromagnetic methods (pipe and cable locators, radio frequency identification, terrain conductivity metal detectors, ground penetrating radar, and infrared), elastic wave (acoustic), magnetic, and the use of metadata.