Department of Defense underwater ranges may be required to remove unexploded and fuzed munitions from the seafloor. Explosive charges for blow-in-place (BIP) render safe procedures are often considered the preferred option for removal of unexploded ordnance (UXO) as compared to physical removal and disposal. However, underwater BIP operations in support of cleanup projects have the potential to damage adjacent habitat as well as to adversely impact species such as fish, sea turtles, and marine mammals. Covering technologies such as geotextile bags filled with sediment or sand may provide additional or synergistic mitigation with or without the use of bubble curtains.

The objective of this SERDP Exploratory Development (SEED) project is to develop proof-of-concept data for the mitigation of underwater blasts using covering technology.

A two-phased approach will be employed, one in the laboratory and one in a small-scale field effort. Laboratory evaluations will be carried out in a large metal tank. The substrate will be varied to simulate two types potentially encountered during BIP operations, specifically sand and hard substrate (e.g., slabrock/coral). The small-scale field testing will be conducted in a lake near the shore in an area that is approximately 3 meters deep. An appropriate covering technology, compliant with the laboratory optimization and scaling, will be utilized for purposes of mitigation. Field tests will use explosive charges with electric blasting caps.

This project aims to identify additional techniques to mitigate underwater explosions in order to reduce nearfield explosive blast damage to habitats and biota as well as far-field acoustic impacts on marine species. Covering technology has the potential to mitigate against shrapnel and blast; whereas, bubble curtains do not. It also has the potential to greatly reduce underwater explosion pressures during BIP operations to clear unexploded munitions in the shallow marine environment.