Passive alarm to prevent buried infrastructure damage

A self-contained excavation-sensing module capable of being emplaced in the soil near an existing buried structure comprising:

• a hollow, tubular housing,
• a smoke grenade with a pull-type igniter affixed within and at one end of said housing, and
• a trigger that will activate said smoke grenade when the the module is disturbed by an external force;
• wherein said tubular housing has one or more circumferential scores which weaken said tubular housing such that said tubular housing will easily break upon application of external shear, tensile, or torsional force;
• and,
• wherein said trigger comprises a wire with one end of said wire affixed to the other end of said tubular housing and the other end of said wire connected to the pull-type igniter of said smoke grenade such that when said tubular housing is broken said wire will pull on said pull type igniter and ignite said smoke grenade.

A self-contained excavation-sensing module capable of being emplaced in the soil near a buried structure comprising:

• a. a housing,
• b. a friable diaphragm dividing said housing into at least a first and a second compartment,
• c. at least one striker bar mounted within each compartment,
• d. a first chemical compound being contained within said first compartment,
• e. a second chemical compound being contained within said second compartment,
• said first and second chemical compounds being selected such that, when mixed together, they generate a dense cloud of colored, odorous gas,
• said striker bars being mounted within said housing such that impact on the housing by excavation equipment which is strong enough to rupture said housing will cause the striker bars to rupture said diaphragm,
• whereby a dense cloud of colored, odorous gas will be formed upon mixing of the first and second chemical and released.

A self-contained excavation-sensing module capable of being emplaced in the soil near a buried structure comprising:

• a first, outer housing,
• a second, inner housing mounted within said first, outer housing,
• a first quantity of a compressed, colored, odorous gas stored in the space between said first and second housings,
• said gas being stored at a first pressure,
• a second quantity of said compressed gas stored within said second, inner housing at a pressure higher than said first pressure,
• a whistle incorporated in the second, inner housing in communication with both said housings,
• a friable diaphragm mounted within said whistle,
• and wherein rupture of said first housing by excavation equipment will release the first quantity of compressed, colored, odorous gas and cause said friable diaphragm to rupture releasing the second quantity of compressed gas through said whistle, generating a loud sound while releasing a dense cloud of colored, odorous gas.

A method of protecting a buried infrastructure against excavation damage comprising the steps of:

• providing one or more self-contained excavation-sensing modules comprising:
• a housing,
• one or more gas generators contained within said housing,
• said one or more gas generators being capable of generating a visible gas, and
• one or more triggers that will initiate the one or more gas generations when the device is disturbed by external forces;
• burying one or more of said self-contained excavation sensing modules near said buried infrastructure such that said one or more self-contained excavation sensing modules will release a visible gas upon being disturbed by excavation equipment.