A method and apparatus are disclosed for preventing excavation damage to buried infrastructure. A plurality of excavation-sensing modules is buried near the buried infrastructure. The modules protect buried infrastructure by emitting dense clouds of highly visible gas when the modules are activated by
impact with excavation equipment. In most cases the visible gas will be brightly
colored and it may also have a strong
odor and may produce a loud sound when the module is activated. The dense clouds of highly visible gas, the optional
odor and loud sound alert construction crews or other workers that their excavation is nearing a protected underground structure. Once installed, no maintenance or
active monitoring is required. In a preferred embodiment of the excavation-sensing module, the dense cloud of highly visible gas is produced by ignition of a
smoke grenade within the module. In the preferred embodiment, the
smoke grenade is ignited by the interaction of the
excavator striking and breaking the buried module. Also in the preferred embodiment, the
excavator will normally pull the ignited
smoke grenade out of the buried module and to the surface increasing the
visibility of the gas. Also in the preferred embodiment, a more reliable design for ignition of the smoke grenade is disclosed.