Personnel must have successfully completed the Salvage/Construction Demolition Course and be assigned the proper blasting Navy Enlisted Classification (NEC) 5375. Personnel must complete the Explosives Handling Personnel Qualification and Certification Program at the local command in accordance with OPNAVINST 8023.2.
An Underwater Explosives Operation Plan must be prepared before a blasting operation can be conducted. The plan is prepared after a detailed site survey has been done. The plan should contain:
• Description of what is to be done.
• Site specific information:
- Local restrictions
- Charts (depth/profile)
- Bottom materials (samples)
- Tidal information
- Current conditions
- Weather expected
- Wave conditions
- Water temperature
- Ice conditions
- Thickness and character of overburden
• Location/frequency of ship/submarine traffic.
• Description/location of underwater structures, cables, ranges, and pipelines.
• Description of affected adjacent land structures.
• List of permits/authorizations required.
• Environmental concerns:
- Marine life
- Park/Recreational areas
- Natural oil/gas seepage
• Debris management.
NAVSEA SW061 -AA-MMA-010 provides discussion items to consider when planning underwater blasting operations. Consideration must be given to adjacent and nearby structures, ships, and facilities, both on land and on or under the water.
Ideally, the energy released from the explosives should all be directed at doing the specific job. However, a large amount of energy will be released into the environment and must be taken into consideration to prevent damage to local facilities and ships. Consider the following when planning the blasting operation:
• Released energy tends to follow the path of least resistance.
• Released energy concerns are: air shock waves, water shock waves, and ground motion.
- All can rattle and break windows.
- Ground motion and water shock waves can severely damage ships, underwater structures, and buildings.
• Charges detonated inside structures and buildings can reduce air/water shock waves but increase ground waves.
One underwater explosive technique that is effective in containing the shock wave is bubble screening, sometimes called the "air curtain." This simple technique of creating a "wall of air" around the blast will reflect the shock wave back in the direction it came from. The air screen pattern is constructed using standard 2-inch galvanized piping that can be assembled in any geometric shape. A standard air hose fitting is attached at each end. The pipe is then perforated at regular intervals with holes not larger than 1/4 inch in diameter. The assembled pipe is lowered and positioned around the blast area. When a large volume air compressor (250 scfm or greater) is used to pump air into the pipe, the air escapes through the perforations and rises through the water column to create an " air curtain."
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