NSWC/WOL/TR 76-161 



2.3 Physical 



The physical effects of underwater explosions include the 

 following: shock waves, cratering, noise, disturbance of the bottom 

 leading to the suspension of bottom materials, and the possible 

 deposit of metal fragments on the bottom. 



Cratering is not of concern unless explosions are near or on 

 the bottom. Craters can be measured with a tape by personnel wading 

 in shallow water, or by probing from a small boat in water up to 

 three meters deep. Deeper water generally requires the services 

 of divers if crater measurements are needed, though a depth-finder 

 can be used in some cases. 



However, crater monitoring is probably not needed on a routine 

 basis because the size can be predicted with sufficient accuracy, 1 

 and tests are normally done over relatively barren bottoms. 



Shock waves are generated in water and in air, and the water 

 shock is usually measured as part of the test procedure. The major 

 environmental effect of the underwater shock is the killing of fish. 

 The shock wave in air becomes a sound wave as it travels away from 

 the test site, and it can produce noise at a considerable distance. 1 

 There is no need to monitor this noise unless relatively large 

 charges are fired at relatively shallow depths. Inexpensive 

 commercial devices are available for this purpose. 



The amount of suspended solids in the surface pool can be 

 monitored by using the same water samples collected for the analysis 

 of dissolved chemical products. The solids are mostly particles 

 of sedimentary materials which eventually settle out. However, 

 explosion products such as carbon and aluminum oxide may be present. 

 Methods for the analysis of solid products or for unreacted 

 explosives are described by Lai. 10 The weight of suspended solids 

 can be determined by filtering and weighing and, in some cases, 

 identification and size measurement can be done with an optical 

 microscope. This may be difficult because the suspended particles 

 tend to agglomerate when they are filtered. 



III. EXPERIMENTAL PROGRAM - MAY 1976 



3. 1 Introduction 



A limited series of explosion trials was conducted during the 

 first week of May 1976 to test various monitoring techniques under 

 a variety of conditions and to determine the time required. Only 

 the equipment on hand at the time was utilized - no special purchases 

 were made. No data were obtained on shock wave parameters, in 

 order to enable the experimental personnel to devote full time 

 to environmental monitoring. The tests were conducted in the 

 Patuxent River in the vicinity of the Naval Surface Weapons Center 

 Facility at Solomons, Maryland. 



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