Underground Utility Marking Tape buried properly above utility lines is used to alert excavation personnel of the presence of underground utility installations before dig in damage occurs. Underground Warning Tapes are available in non-detectable polyethylene styles or metallic tape that can be located with an industrial grade non-ferrous metal detector. APWA color coded, easy to see and identify tapes are designed for high visibility, impervious to alkalies, acids and other soil components for long term burial underground. Detectable tape is commonly used on buried plastic pipe lines and non-detectable tape is used on buried metal pipe lines.