Unexploded Ordnance (UXO)
Millions of acres of property in the United States contain unexploded ordnance (UXO), most of which is a result of weapons system testing and troop training activities conducted by the Department of Defense (DoD). This property includes active military, formerly used defense (FUD), and base realignment and closure (BRAC) sites. The risks posed by property containing UXO could be great depending on the types and amount of UXO present and how the property is or may be used.
OVERVIEW OF UXO
Department of Defense defines "explosive ordnance" as any munition, weapon delivery system, or ordnance item that contains explosives, propellants, and chemical agents. UXO consists of these same items after they (1) are armed or otherwise prepared for action, (2) are launched, placed, fired, or released in a way that they cause hazards, and (3) remain unexploded either through malfunction or design. A person's ability to recognize a UXO is the first and most important step in reducing the risk posed by a UXO hazard. This section presents information on the most common types of UXO and how it may be found in the field.
Types of UXO
In the past century, all shapes, sizes, and types of explosive ordnance have been used in the U.S. for weapons system testing and troop training activities.
Ordnance is color-coded during manufacturing for identification purposes. However, color markings cannot be relied upon to identify UXO markings can be altered or removed by weather or exposure to the environment. Instead, other features should be used to identify UXO. The following sections describe the basic features and characteristics associated with each general type of UXO. Additional information can be found in Unexploded Ordnance (UXO) Procedures (U.S. Army 1994).
Small Arms Munitions
Small arms munitions contain projectiles that are 0.5 inches or less in caliber and no longer than approximately 4 inches. They are fired from various sizes of weapons, such as pistols, carbines, rifles, automatic rifles, shotguns, and machine guns. Generally, the shell casings of small arms munitions are made from brass or steel. Although the hazards associated with these UXO are much less than for other munitions, unexploded small arms munitions may explode if thrown into a fire or struck with a sharp object such as a nail. Figure 1 illustrates various small arms munitions.
Hand Grenades
Hand grenades are small explosive- or chemical-type munitions that are designed to be thrown at short range. Various classes of grenades may be encountered as UXO, including fragmentation, smoke, and illumination grenades. All grenades have three main parts: a body, a fuze with a pull ring and safety clip assembly, and a filler. Figure 2 shows typical grenades.
Fragmentation grenades are the most common type of grenade used. They have a metal or plastic body filled with an explosive material. When the filler explodes, the body of the grenade or a metal fragmentation sleeve breaks into small, lethal, high velocity fragments. These grenades use a burning delay fuze that functions 3 to 5 seconds after the safety lever is released. Other grenades may be made of metal, plastic, cardboard, or rubber and may contain explosives, white phosphorus, chemical agents, or illumination flares, depending on their intended use. Most use a burning delay fuze that functions 3 to 5 seconds after the safety lever is released, but some are activated instantly when the lever is released (smoke grenades).
Rockets
A rocket uses gas pressure from rapidly burning material (propellant) to transport a payload (warhead) to a desired location. Rockets can range from 11/2 to more than 15 inches in diameter, and they can vary from 1 foot to over 9 feet in length. All rockets consist of a warhead section, a motor section, and a fuze. They are unguided after launch and are stabilized during flight by canted nozzles at the base of the motor or fins attached to the motor. Figure 3 shows the typical components of a rocket.
The warhead section of the rocket is the portion that produces the intended effect; it can be filled with explosives, toxic chemicals, white phosphorus, submunitions, riot-control agent, or illumination flares. Fuzes may be located in the nose of the rocket or internally between the warhead and motor. The fuzing on rockets can be impact, time-delay, or proximity fuzing. Impact fuzes function when they hit the target. Delay fuzes contain an element that delays explosion for a fixed time after impact. Proximity fuzes are intended to function when the rockets reach a predetermined distance from the target. Caution: Do not approach--proximity fuzing may activate, causing the rocket warhead to explode. Also, fired rockets may still contain residual propellant that could ignite and burn violently.
Guided Missiles
Guided missiles are similar to rockets (see Figure 4) however; they are guided to their target by various systems. Some are wired-guided, and others are guided by internal or external radar or video. Guided missiles are usually stabilized by fins controlled by internal electronics. Internal proximity fuzes are used in guided missiles, which makes approaching them extremely dangerous. Also, fired guided missiles may still contain residual propellant that could ignite and burn violently.
Projectiles
Projectiles can range from approximately1 inch to 16 inches in diameter and from 2 inches to 4 feet in length. Projectile fuzes can be located in the nose or in the base. Like rockets, projectiles may be stabilized during flight by fins or bands fixed around the circumference of the projectile.
Mortars
Mortars range from approximately 1 inch to 11 inches in diameter and can be filled with explosives, toxic chemicals, white phosphorus, or illumination flares. Mortars generally have thinner metal casing than projectiles, but use the same types of fuzing and stabilization. Figure 6 shows various types of mortars.
Projected Grenades
The most commonly used projected grenade is the 40 millimeter (40mm) grenade. This grenade is also among the most commonly found UXO items. The 40mm grenade is about the same size and shape as a chicken egg, as shown in Figure 7. It contains high explosives and uses a variety of fuzes, including some of the most sensitive internal impact fuzing systems. Because of their relatively small size, 40mm grenades are easily concealed by vegetation. They are extremely dangerous and can explode if moved or handled.
Rifle Grenades
Rifle grenades look like mortars and range from about 9 to 17 inches in length. They may be filled with high explosives, white phosphorus, riot-control agent, illumination flares, or chemicals that produce colored screening smoke. Rifle grenades are fired from standard infantry rifles. They have an opening at the far end of a tube near the fin assembly that allows the rifle grenade to be placed on the barrel of a rifle. Rifle grenades rely on impact fuzing, which is located on the nose or internally behind the warhead. Figure 8 shows various types of rifle grenades.
Submunitions
Submunitions include bomblets, grenades, and mines filled with explosives or chemical agents. They may be antipersonnel, antimateriel, antitank, dual-purpose, incendiary, or chemical submunitions. Submunitions are typically spread over a large area by dispensers, missiles, rockets, or projectiles. Each of these delivery systems disperses the submunitions while still in flight, scattering the submunitions over an area. Submunitions are activated in a variety of ways, depending on their intended use. Some are activated by pressure, impact, or movement or disturbance. Others are activated in flight or when they come near metallic objects. Some submunitions contain a self-destruct fuze as a backup. The self-destruct time can vary from a couple of hours to several days. Warning: Submunitions are extremely hazardous because even very slight disturbances can cause them to explode. Some types of submunitions require stabilization to hit the target straight on. Stabilization can be provided through an arming ribbon, parachute, or fin assembly. Figure 9 shows a variety of submunitions.
Bombs
Bombs range in weight from 1 to 3,000 pounds and in length from 3 to 10 feet. Generally, all bombs have the same components--a metal container, a fuze, and a stabilizing device (see Figure 10). The metal container, or bomb body, holds the explosive or chemical filler and may consist of one piece or multiple pieces. Bombs use either mechanical or electrical fuzes, typically located in the nose or tail section, either internally or externally. Mechanical fuzes are generally armed by some type of arming vane. The arming vane operates like a propeller to line up all the fuze parts and thus arm the fuze. The fuzes may be configured as impact, proximity, or delay fuzes. Bombs are stabilized during flight by fin or parachute assemblies attached to the rear section of the bomb. These assemblies often detach from the bomb after impact.
Encountering UXO
UXO is found in the environment in many different ways depending in part on the specific type of ordnance, when and where it was deployed, how it was deployed, and activities that may have taken place at the location since deployment. For example, UXO can be at the ground surface, can be partially buried, or can be fully buried. In fact, UXO may be found at depths in excess of 30 feet below the ground surface. Ordnance stabilized by parachute may be completely buried, but the parachute may appear at the surface. UXO may also be found fully intact or in parts or fragments. All UXO, whether intact or in parts, presents a potential hazard and should be treated as such. In addition, the UXO casing may have deteriorated depending on the type of material used, the length of time since deployment, and the elements to which it was exposed. UXO that has deteriorated presents a particular hazard because it may contain chemical agents that could become exposed. UXO may be encountered as an isolated munition or as one of many in a given area. The density and type of UXO in an area depends on the intensity and proximity of troop training and weapons testing activities, the degree of UXO cleanup already conducted, and the types of ordnance used. For example, UXO such as dispensers, missiles, rockets, or projectiles may still contain submunitions, or those submunitions may have been scattered across a large area. If any UXO is found, one should assume that other UXO are in the area.
UXO, whether present in an area by design or by accident, poses the risk of injury or death to anyone in the vicinity. To lessen the danger of UXO hazards and to help prevent placing others at future risk, certain precautions and steps should be taken by anyone who encounters UXO.
"IF YOU DID NOT DROP IT, DO NOT PICK IT UP!"
UXO SAFETY WARNINGS
When you see UXO, stop. Do not move closer.
Never transmit radio frequencies (walkie-talkies, citizens' band radios).
Never attempt to remove anything near a UXO.
Never attempt to touch, move, or disturb a UXO.
Clearly mark the UXO area.
Avoid any area where UXO is located.