NBC Conditions and the Battlefield
Operations involving weapons of mass destruction must be dealt with as any other battlefield condition, such as cold, night, desert, and so forth. Unit leaders must consider NBC in assessing their mission essential task list (METL). Employment of NBC recon assets to negate or offset enemy employment of NBC weapons is a critical component of warfighting preparation and operations.
The purpose of NBC reconnaissance is to detect and identify NBC contamination. With equipment currently in the field, we can only detect and identify chemical and radiological contamination.
It is much easier to detect radiological contamination than it is to detect chemical contamination. Radiological contamination is normally found over large areas. The behavior of radiological contamination is more easily predicted. Chemical contamination, however, is typically limited to small areas of terrain. Chemical agents are influenced by a number of environmental conditions that make it difficult to predict their behavior. Biological contamination is the most difficult to detect and predict.
The primary environmental factors that affect the ability to detect chemical agents for NBC recon purposes are the surface and soil type, contamination footprint, concentration, and meteorological conditions.
Contamination hazards depend on ground conditions encountered on the battlefield. The surface and soil type will affect how readily the chemical agent is absorbed into the soil. The type of surface also affects the persistency of chemical agents. Even though the actual battlefield is a combination of conditions, looking at four general conditions separately will give an indication of what to expect.
Sand--Any surface that has a large amount of sand (such as a beach). This generally, has good drainage. When chemical agents are applied to this surface, they tend to be drawn into the subsurface, lowering the quantity of contamination available for liquid detection.
Soil--Any surface that contains quantities of clay and loam. Depending on the relative amount of each soil component, chemical agents react differently. Generally, some percentage of the agent is absorbed into the subsurface (until saturation).
Grass--Any surface covered with a layer of grass, from a few centimeters to half a meter in height. A portion of the chemical agent remains on the grass, while the rest is absorbed into the underlying soil. The chemical agent on the grass is available for liquid detection.
Mud--Any surface saturated with water resulting in muddy conditions. The amount of persistent agent that can be absorbed by wet soil is inversely related to the water content of the soil (such as the more water, the less chemical agent absorbed). Under this condition, chemical agents will remain on the surface longer. This increases the probability of detection.
The more absorbent the soil, the less liquid remains on the surface. This decreases the probability of detection by detector paper (M8 and M9). For the M93 NBC recon system (NBCRS) (Fox), the smoother and harder the surface is, the higher the probability of detection. When NBCRS is detecting on rough surfaces, the sampling wheel tends to bounce, decreasing the probability of detection. On soft or porous surfaces, the ability of NBCRS to detect contamination can be improved by stopping to lower the probe near the surface. The heated probe will cause absorbed chemical agent to vaporize. The vaporized agent can then be analyzed by the NBCRS.
Planners and executers of NBC recon operations must understand that chemical attacks will not cover extensive areas with liquid contamination. Depending on the type of munition and delivery system, contaminated areas may be relatively small in comparison to the operational area. The contamination footprint is the actual dimensions of the liquid hazard area formed by the detonation of chemical weapons.
Chemical munitions are typically fuzed to burst over the target, to get the best spread of agent on the target. When a munition detonates at ground level, it deposits most of the agent in the shell crater, minimizing the contaminated area. When munitions burst above the target, wind speed and direction directly influence the spread of the agent. As a munition bursts, the heavier droplets fall faster, and the, smaller ones drift downwind. The most heavily contaminated area is near the attack area. The chemical agent radiates in a bell shape in the direction of the wind. This creates the contamination footprint. Figures 1-1 to 1-4 show typical contamination footprints for persistent chemical agents delivered by artillery, multiple rockets, missiles, and aircraft bombs. A unit conducting NBC recon has a higher probability of detecting contamination when traveling crosswind to the footprint.
The higher the concentration of the agent, the higher the probability of detection. The M93 NBCRS can detect extremely low concentration levels about .001 miligrams per cubic meter (mg/m3). CAM and M256 detectors are not as sensitive. The concentration of agent on the ground depends on the type of agent, time since delivery, and the delivery method.
Meteorological conditions influence the persistency of liquid contamination. Such contamination is detected in two ways: as a vapor as it evaporates, or by physical contact. As wind speed and temperature increase, evaporation of liquid contamination increases. This means there is more vapor present to detect, thus increasing the probability of detection. The evaporation rate of chemical agent can be predicted using tables in FM 3-6.
Potential enemy forces have the capability of employing weapons of mass destruction against US forces. Nuclear weapons are used to maintain the momentum of advance during the offense and to seize the initiative from the attacker in the defense. Enemy nuclear weapons will be targeted against troop concentrations; nuclear delivery means; airfields; air defense systems; command, control, and communications centers; logistical facilities; port, and to create obstacles.
Biological agents produce either immediate or delayed casualties. These weapons can be used against military or civilian targets. Biological attacks can range from attacks against a specific target or can cover vast areas of terrain. Detection and identification of biological agents are extremely difficult. FM 3-3 provides additional information on biological attacks.
Chemical weapons are used to restrict our mobility to maneuver and concentrate forces, to contaminate combat support and combat service support systems, to cause immediate and delayed casualties, and to force an increase in protective measures. Persistent chemical agents are typically used against deeper targets or those areas not expected to be immediately occupied. Persistent agents will be used against reinforcements, deep targets, and units along the flanks of attacking enemy forces to produce casualties, create a decontamination burden, and restrict mobility. Enemy forces in the defense can be expected to employ persistent agents against attacking forces.
Chemical agents also are used to produce casualties (immediate or delayed). The threat's primary delivery systems will either be artillery or rocket. When the delivery means is via artillery, the persistent chemical agents are a mixture of droplets, micro-particles, and vapors. Chemical agent droplets are readily detectable, while micro-particle contamination is not as detectable, using standard NBC detection equipment. Dissemination via rocket will result in gross contamination, leaving small puddles of chemical agent in addition to droplets and micro-particles. Detection is easier when rockets are used; however, the areas of contamination are significantly larger.
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