In their desire to provide ballistic protection, some range planners have designed highly specialized structures that become unusable for any other purpose at a future date. This may not necessarily be of great importance in a municipal range, however, it does impact a public or commercial range building. Meggitt specifically designs shields and guards to contain misdirected shots within the range and maintain ballistic integrity. Range planners should avoid heavy earthen berms and overly thick concrete walls and ceilings in their building design.
Walls: Range walls should be of poured concrete or concrete block filled with cement or grout,not gravel. This type of construction provides maximum noise attenuation and ballistic security.Blocks filled with sand are not recommended as any crack or penetration of the block will causeleakage onto the range floor. For additional ballistic protection, steel plating can be applied tothe side walls downrange.
Flooring: The most suitable type of flooring for the range is a smooth, non-absorptive hardened
concrete floor from the firing line to the bullet trap. The floor will take a lot of low shots so a
smooth floor results in less erratic ricochets. The firing line and the area behind it are typically
covered with vinyl or rubber flooring.
Due to environmental considerations, floor drains require filtering systems to collect range contaminates. These systems are typically expensive so the vast majority of range planners today exclude floor drains and sloped floors from their design.
Ceiling: A slab or precast ceiling is most suitable because it normally requires minimal baffles and guards. Guards are still required for lighting, plumbing, conduit, ducts, or protuberances in the ceiling downrange. Therefore, when using a slab or precast ceiling, the range designer should attempt to route pipes, conduit, etc., on the outside of the range and enter into the range only at the points absolutely required.
For other types of ceilings, a series of angled air-space baffles or redirective guards suspended at various locations are usually required. The exact placement is determined by ceiling height, range length, and if any shooting activity will be conducted beyond the primary firing line. Meggitt provides these suggested placements and load weight computations to the range planner as a part of the drawing package.
Dividing the Range: Dividing the range into bays should be considered if the range will exceed ten shooting points. Generally, a ten-point range will function more efficiently if divided into two bays of five points each, a twelve-point range into two bays of six points, etc. By dividing the range into bays, several advantages can be realized. Among the most significant are:
A solid, or a minimum 8-inch fully grouted block wall is recommended for separating the bays. The type of shooting activities planned for the range will dictate the thickness. The separating. wall should be continuous from the front to the rear wall of the range and extend from the floor to ceiling. This is required for range safety, noise reduction, and ventilation integrity. Doors between adjoining ranges may be required to meet fire regulations so the range planner should verify this with the local fire department.
Spectator area walls separate the firing line from the ready room or lobby area. Bulletproof glass must be specified for the viewing area that is capable of stopping the largest caliber round that will be shot on the range.
Range Ventilation: An adequate ventilation system accounts for a substantial amount of the cost for interior equipment for a range. Federal and state health standards must be recognized and adhered to when specifying the range ventilation system. Interestingly, the major concern of regulators isn’t as much for the patrons of the range as it is for the employee or range master who will be spending so much time in the shooting environment. Find out what the regulations are and build to conform. Advice here is to plan for state-of-the-art ventilation equipment rather than risk being forced later to upgrade or totally retrofit an inadequate system at considerable expense.
The Occupational Safety and Health Administration (OSHA) regulation 1910.1025 sets the Permissible Exposure to Lead (PEL) at 0.05 milligrams per cubic meter of air. This standard is based on an eight-hour time weighted average. The National Institute of Occupational Safety and Health (NIOSH) recommends the ventilation system should provide an air flow of a minimum of 50 FPM past the shooter toward the bullet trap, with exhaust points located downrange.
Other ways to mitigate the lead problem include the use of Reclining GranTrap™ rubber bullet trap designed to prevent bullet fragmentation, thus reducing airborne lead dust. Also, by specifying the type of ammunition that may be used in the range, things such as barium pollutants from primers and lead from bullets can be eliminated.
Range Lighting: Two types of illumination are required in the range; general and target lighting. General illumination is normally provided by fluorescent fixtures and target lighting consists of incandescent reflector-type lamps.
Typically two swivel fixtures are provided at each target stop. The wattage is dependent upon the length of throw but usually 150 watt lamps will provide the desired 100 mfc at the target face. The lights are placed in a protected area in the ceiling in banks across the range. All lights for each target stop, (i.e., 21-foot line target stop) are on one bank and controlled by a dimmer switch to provide variable light conditions for law enforcement training.
Noise Abatement: There are two primary noise considerations in a shooting range; lowering the sound level within the range and preventing the transmission of noise outside of the range. Acoustical applications are of some benefit to lowering the noise level. The walls from twelve feet forward of the firing line to the back wall should be covered with acoustical material. In addition, the horizontal ceiling above the firing line and the front surface of downrange baffles should also be treated. The most widely used material for this application is Class 1 acoustical foam. Check with your local fire department for class requirements.
The walls, ceiling, and floor surfaces within twenty feet of the bullet trap receive most misdirected shots and should not receive acoustical treatment due to the high frequency of repair that would be required. Any surface downrange of the firing line that does receive acoustical material should have an air-space between the hard and soft surfaces, even if it’s just the thickness of furring strips.
Doors leading into the firing range are great offenders of noise transmission. For best sound attenuation, two solid-core doors should be installed at right angles to each other to create an air-lock at the range entrance.
One of the benefits of installing an environmental rubber bullet trap is the elimination of noise associated with bullet impact and deceleration on steel bullet traps. This is particularly important when the range shares a common wall with other occupants of the building.
Ballistic Security: Air-space baffles, steel guards, and redirective guards are used to protect protrusions in the range, minimize ricochet threats, and close off the paths that may allow shots to escape. Each device has its own particular function in a range.
An air-space baffle is composed of a wood or rubber facing, separated from a steel sheet by a wooden or rubber frame. By separating the surfaces, a misdirected shot will penetrate the front wood or rubber surface and traverse the air space. The round strikes the steel sheet backing and loses its velocity so it is less likely to return to the open space of the range. The area extending from the firing line to twelve feet downrange is one of the most critical areas in a range where a misdirected shot can compromise shooter’s safety. Utilizing an air-space ceiling system reduces the risk of injury or damage from a vertically directed shot by stopping the path of the round and trapping it in an air-space panel.
The air-space panels are suspended horizontally from the ceiling. Typically these panels start at the firing line and extend twelve feet downrange. On occasion, coverage is required behind the firing line and beyond the 12-foot expanse downrange. After installation, acoustical material may be applied to the exposed panel surface to assist in noise abatement. A series of air-space baffles are often required to protect the ceiling, lights fixtures and pipes located further downrange. The baffles are suspended from the ceiling at a described angle to the floor in intervals determined by ceiling height, range length, and shooting activity. The last row(s) of baffles, immediately in front of the bullet trap, take the greatest number ofhigh shots. Rubber air-space guards should be specified for these baffles in range facilities using rubber bullet traps and redirective steel guards for ranges with steel bullet traps.
Steel guards are often used in place of air-space baffles on flat, slab or precast ceilings. The angled steel guards protect downrange protrusions such as light fixtures, conduit, and ducts from impact and deflect bullets in the direction of the trap.
If shooters will be allowed to advance downrange beyond the primary firing line, Combat Walls should be considered for the side-walls of the range. Using the proven design of air-space baffles, a misdirected round impacting the Combat Wall will be safely contained or redirected towards the bullet trap.
Determining the type of range to build and specifying the equipment is a function of the planned type of shooting activity that will take place. Indoor range designs are generally of four types; private, commercial, military service, and law enforcement/security training. In many instances, commercial ranges have dual purposes. Normally a range larger than five positions will be equipped to accommodate law enforcement training in one bay and public shooting in the other. The following describes the basic types of ranges and discusses in detail the various items of equipment, including the optional items that can greatly extend the overall usefulness of the range.
Private: Included in this category are crime labs, research and test facilities, home ranges, and other low volume applications. The equipment consists of a rubber granular bullet trap and a manually operated or electrically driven guide wire target retrieval system.
Military Service: Advocated for National Guard armories, reserve training centers, and ROTC schools, these ranges are normally 50 feet in length. The firing line and ready area are not separate areas. The equipment consists of a rubber granular bullet trap, shooting stalls to separate the shooters, and a manually operated guide wire target retrieval system.
Commercial: The equipment for a commercial range must be rugged, simple to use, and suitable for a wide variety of shooting activities. Equipment typically specified includes a granular rubber bullet trap, electrically driven guide wire target retrieval system, and shooting stalls. If there are plans to conduct law enforcement or security training in the range, the range designer must give consideration to equipping one bay with equipment designed for that application (see description below).
Law Enforcement: The range equipment selected for use by law enforcement or security agencies must be flexible to allow precision firearms training, simple mandatory re-qualification, and advanced reactive exercises. In addition, considerations must be made for tactical training situations that often require the shooter to advance downrange and engage multiple targets. A granular rubber bullet trap and combat walls are ideal for this application because they provide a safer range environment for close and cross range shooting. The target retrieval system must provide turning targets and be capable of being controlled individually by the shooter and from a central range control station. Another target system feature that is desirable is an on-board target light to allow training under variable light conditions. Shooting stalls with barricades and acoustical blast shields are typically specified for law enforcement ranges.
A properly designed indoor firing range ventilation system introduces adequate airflow into the range to ensure that lead contaminated air is quickly removed from the shooter’s breathing zone. Dependent upon the range's geographic location and code requirements, supply air is tempered to provide comfort to the shooter during firing.
The American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE) and the National Institute of Occupational Safety and Health (NIOSH) recommend that a minimum of 50 fpm (feet per minute) be supplied at the firing line with 75 fpm being optimum, that downrange air flow conveyance through the range be at least 35 fpm, and that the ventilation exhaust capacity should exceed supply capacity by at least 10%. Air distribution at the supply diffuser/airwall is also a very critical consideration; a laminar wall of air needs to be provided evenly at the firing line.
A common rule for estimating ventilation system requirements is to use a cross section area of
the range; the width multiplied by the height of the range at the firing line, multiplied by the
velocity required at the firing line in feet per minute (fpm).
To determine ventilation supply and exhaust capacities, utilize the following formula:
find: a x b x c = cfm
where: a = width of range
b = height of range at the firing line
c = velocity at the firing line in feet per minute (50 fpm is minimum with 75 fpm as optimum)
cfm = cubic feet per minute required on the supply side
Once the supply capacity in cfm is determined, utilize the following equation to determine the exhaust capacity.
find: cfm x 1.1 = ec
where: cfm = cubic feet per minute required on the supply side
ec = exhaust capacity in cubic feet per minute
The reason exhaust capacity needs to exceed supply capacity is you want to create a negative pressure in the range proper. In another words, air tends to want to enter the range from adjacent areas. Negative pressure serves two purposes. First, it provides the pull to move contaminated air from the firing line down range and out through the exhaust ducting, and secondly, it does not allow contaminated air to escape into other adjacent areas.
A new exhaust system should come complete with HEPA filtration. Currently, there is a standard for lead emissions outlined in the Clean Air Act of 10 tons per year from a stationary point source. Some states have lowered this level down to ½ a ton per year. In most cases, a range would not exceed the federal level at any given point, however, those ranges who do not filter their air will have to clean up the lead deposits found outside the building at some point. Utilizing HEPA filtration prevents this exterior contamination. It is pay me now or pay me later. The more prudent thing to do is to incorporate HEPA filtration into the exhaust system.
Design of the diffusing system is also critical. The most widely used and successful method of diffusing air behind the firing line is through an airwall. An airwall is basically a perforated plenum, floor to ceiling, spanning the backwall the entire width of the range. Supply air should be fed evenly into the plenum at the ceiling. The duct-work diffusers into the airwall should be evenly balanced. The airwall is typically 12 to 16 inches in depth and perforations should be ¼ inch in diameter centered every 1 inch. The distance from this airwall to the firing line should be at least 10 feet, optimally 15 feet. The reason this is critical is that air is turbulent and needs time to stabilize. Depicted below in Figure 1 is an example of an airwall section. Improper air distribution, even with adequate velocities, can lead to shooter overexposure. Air distribution is often overlooked in the design of the system. This one factor is the most critical part of the total system design.
Any person who frequents, uses, or maintains a range may be exposed to lead by merely being at the range. The Occupational Safety & Health Administration (OSHA) has set standards for exposure to airborne concentration of lead and has established maximum concentrations for lead in the blood stream. Likewise, the Environmental Protection Agency (EPA) has established national primary and secondary ambient air quality standards for lead. Overexposure to lead is poisonous and can cause serious health effects. To protect people from exposure to lead in indoor ranges, owners and operators need to evaluate and determine typical exposures to lead during the various unique activities that occur in the range itself. Having this exposure information will allow range owners and operators to determine if people are being adequately protected. It also serves to assist in identifying administrative and engineering controls and work practices that will assist in reducing exposure back to safe levels.
This bulletin serves to provide background information on lead and its effects on the body as it pertains to poisoning through overexposure and its impact on indoor firing ranges.
Pure lead (Pb) is a heavy metal at room temperature and pressure and is a basic chemical element. It can combine with various other substances to form numerous lead compounds. Exposure to lead occurs in several different occupational categories in indoor ranges including users, rangemasters, trainers, maintenance personnel, and others who may use or frequent an indoor firing range. Exposure to lead in indoor and outdoor firing ranges is primarily caused by airborne lead. Airborne lead is produced during firing from various sources including lead styphnate in the primer, melting of the bullet base by hot gases, shavings produced as the bullet leaves the casing and travels through the barrel, and bullet fragmentation at the backstop.
The Occupational Safety and Health Administration has established a permissible exposure limit (PEL) of 50 micrograms of lead per cubic meter of air (50 μg/m3), averaged over an 8-hour workday. Furthermore, OSHA has established an action level of 30 micrograms of lead per cubic meter of air (30 μg/m3). The action level triggers several ancillary provisions of the OSHA standards such as exposure monitoring, medical surveillance and training. When absorbed into your body in certain doses, lead is a toxic substance. The object of the OSHA lead regulations is to prevent absorption of harmful quantities of lead. Lead can be absorbed into your body by inhalation (breathing) and ingestion (eating). Lead cannot be absorbed through your skin.
When lead is scattered in the air as a dust, fume, or mist, it can be inhaled and absorbed through your lungs and upper respiratory tract. Inhalation of airborne lead is generally the most significant source of occupational lead absorption. Lead can also be absorbed through your digestive system if lead gets into your mouth and is swallowed. If range personnel handle food, cigarettes, chewing tobacco, or make-up, which may have lead in them, or handle them with hands contaminated with lead, this will contribute to ingestion.
A significant portion of the lead that is ingested gets into the blood stream. Once in the blood stream, lead is circulated throughout the body and stored in various organs and body tissues. Some of this lead is quickly filtered out of the body and excreted, but some remains in the blood and other tissues. As exposure to lead continues, the amount stored in the body will increase if you are absorbing more lead than the body is excreting. Even though people may not be aware of any immediate symptoms of disease, this lead stored in your tissues can be slowly causing irreversible damage, first to individual cells, then to your organs and whole body systems.
Long-term overexposure to lead may result in severe damage to the blood-forming, nervous, urinary and reproductive systems. Some common symptoms of chronic overexposure include loss of appetite, metallic taste in the mouth, anxiety, constipation, nausea, pallor, excessive tiredness, weakness, insomnia, headache, nervous irritability, muscle and joint pain or soreness, fine tremors, numbness, dizziness, hyperactivity and colic. In lead colic there may be severe abdominal pain. Damage to the central nervous system in general and the brain (encephalopathy-acute exposure) in particular is one of the most severe forms of lead poisoning and is a result primarily of large acute exposures to lead.
The most severe and often fatal form of encephalopathy may be preceded by vomiting, a feeling of dullness progressing to drowsiness and stupor, poor memory, restlessness, irritability, tremor, and convulsions. It may arise suddenly with the onset of seizures, followed by coma and death. There is a tendency for muscular weakness to develop at the same time. This weakness may progress to paralysis often observed as a characteristic "wrist drop" or "foot drop" and is a manifestation of a disease to the nervous system called peripheral neuropathy.
Chronic overexposure to lead also results in kidney disease with few, if any, symptoms appearing until extensive and most likely permanent kidney damage has occurred. Routine laboratory tests reveal the presence of this kidney disease only after about two-thirds of kidney function is lost. When overt symptoms of urinary dysfunction arise, it is often too late to correct or prevent worsening conditions and progression to kidney dialysis or death is possible. Chronic overexposure to lead impairs the reproductive systems of both men and women. Overexposure to lead may result in decreased sex drive, impotence and sterility in men.
Lead can alter the structure of sperm cells raising the risk of birth defects. There is evidence of miscarriage and stillbirth in women whose husbands were exposed to lead or who were exposed to lead themselves. Lead exposure also may result in decreased fertility and abnormal menstrual cycles in women. The course of pregnancy may be adversely affected by exposure to lead since lead crosses the placental barrier and poses risks to developing fetuses. Children born of parents either one of whom were exposed to excess lead levels are more likely to have birth defects, mental retardation, behavioural disorders or die during the first year of childhood. Overexposure to lead also disrupts the blood-forming system resulting in decreased hemoglobin (the substance in the blood that carries oxygen to the cells) and ultimately anemia. Anemia is characterized by weakness, pallor and fatigability as a result of decreased oxygen carrying capacity in the blood.
Health Protection Goals For Ranges
Prevention of adverse health effects for most indoor firing range users, maintenance personnel, and others who frequent the range from exposure to lead throughout a working lifetime, requires that the person's blood lead level (BLL, also expressed as PbB) be maintained at or below forty micrograms per deciliter of whole blood (40 ug/dl). The blood levels of range users, maintenance personnel and others who frequent the range (both male and female) who intend to have children should be maintained below 30 ug/dl to minimize adverse reproductive health effects to the parents and to the developing fetus. Some studies suggest that BLLs below twenty-five micrograms per deciliter (25 ug/dl) are necessary to avoid adverse health effects.
The measurement of blood lead levels (BLL) is the most useful indicator of the amount of lead being absorbed by the body. Blood lead levels are most often reported in units of milligrams (mg) or micrograms (ug) of lead (1 mg=1000 ug) per 100 grams (100g), 100 milliliters (100 ml) or deciliter (dl) of blood.
These three units are essentially the same. Sometime BLLs are expressed in the form of mg percent or ug percent. This is a shorthand notation for 100g, 100 ml, or dl. (References to BLL measurements in this document are expressed in the form of ug/dl.) BLL measurements show the amount of lead circulating in the blood stream, but do not give any information about the amount of lead stored in the various body tissues.
BLL measurements merely show current absorption of lead, not the affect that lead is having on your body or the affects that past lead exposure may have already caused. Past research into lead-related diseases, however, has focused heavily on associations between BLLs and various diseases. As a result, your BLL is an important indicator of the likelihood that a person will gradually acquire a lead-related health impairment or disease.
Once blood lead levels climb above 40 ug/dl, the risk of disease increases. There is a wide variability of individual response to lead, thus it is difficult to say that a particular BLL in a given person will cause a particular affect. Studies have associated fatal encephalopathy with BLLs well below 80 ug/dl. The BLL is a crucial indicator of the risks to a person's health, but one other factor is also extremely important. This factor is the length of time the person has had elevated BLLs. The longer a person has an elevated BLL, the greater the risk that large quantities of lead are being stored in the organs and tissues (body burden).
The greater the overall body burden, the greater the chances of substantial permanent damage. The best way to prevent all forms of lead-related impairments and diseases -- both short term and long term -- is to maintain your BLL at least below 40 ug/dl.
Employers have the prime responsibility to assure that the provisions of the OSHA regulations are compliedwith both by the company and by individuals. Personnel who frequent ranges, however, also have a responsibility to assist their employer in complying with the regulations. Range users, maintenance personnel and others who frequent ranges can play a key role in protecting their own health by learning about the lead hazards and their control, learning what the regulations require, following the regulations where it governs a person's own actions, and seeing that employers comply with provisions governing his or her actions.
Emissions of lead into the environment can be detrimental to both human health and to the environment in general when those emissions exceed natural background levels prevalent in the area as well as when they exceed levels established by the Environmental Protection Agency (EPA). The EPA regulates ambient air quality and disposal for inorganic lead.
The EPA under the authority of the Clean Air Act (42 U.S.C. 7409, 7501) has established national primary and secondary ambient air quality standards for lead. This standard is 1.5 micrograms per cubic meter (ug/m3), maximum arithmetic mean averaged over a calendar quarter. This standard is primarily aimed at ensuring that ambient air in the geographic area adjacent to and in the proximity to a lead emission source is not in excess of 1.5 ug/m3.
The standard was originally directed at large industrial lead smelting operations, and other operations involving the mining, production, and smelting of lead and lead compounds. Emissions of lead from firing range ventilation systems eventually enter the ambient air in the geographic area adjacent to and in the proximity to a ventilation system exhaust. If these emissions are less than 1.5 ug/m3 at the emission source of the ventilation system, then it is not possible to exceed the ambient air quality standard as a result of the lead emitted from the indoor firing range via the ventilation system. In any instance, most ranges should be equipped with high efficiency filtration systems.
Range owners and operators can insure they are adequately meeting these standards by conducting tests that establish source emission airborne lead levels and/or ambient air lead levels. These tests will determine if the ventilation filtration system is adequately filtering, which in turn, identifies the extent in which the environment is being protected.
Lead bullets generated during firing are typically trapped and collected at the base of a bullet trap. This spent lead if handled and packaged properly is exempt from the requirements under the Resource, Conservation, and Recovery Act (RCRA-EPA 40 CFR 261). Not all lead dust and lead waste streams can be recycled. An example would be a ventilation filter. With these materials, special testing is required to determine if the wastes are hazardous as defined by current EPA regulations. The EPA specifies that the Toxic Characteristic Leaching Procedure (TCLP-EPA SW-846) be used to classify by-product lead wastes to determine if they are hazardous under current regulatory definitions. Under current federal law, a TCLP test result of 5 mg/l or greater will classify the material as hazardous under RCRA.
Exposure to lead in indoor firing ranges can be minimized and controlled through awareness, proper ventilation, medical surveillance, administrative controls, and work practices and procedures. Critical to controlling this manageable problem requires that owners and operators understand lead and its impact on range operations. Verifying existing range conditions is the first step to take to identify the impact of lead in the range. This includes ventilation evaluation and airborne lead testing during range use and operations, a review of existing maintenance practices and procedures, and a review of general range procedures. From this effort, range modifications, medical surveillance programs, work practices and general range operations procedures can be modified, developed and instituted to minimize exposure to lead.
The Airborne Lead Hazard
Exposure to lead dust and fumes at the firing range can present a potential health risk to shooters, firearms instructors and other range employees. Protecting the health of range employees and shooters, while minimizing environmental contamination from lead exposures, is an important element in the safety plan for firing ranges.
How does lead affect the body? Adults can be exposed to lead by breathing in lead dust or fumes from shooting or work activities, by eating, drinking or smoking in work areas, or by handling contaminated objects - and accidentally swallowing lead dust. Workers and shooters in many firing ranges have so much lead in their bodies that they are slowly being poisoned. The symptoms may hardly be noticeable at first. But over time, lead can damage the brain, blood, nerves, kidneys and reproductive organs. This damage can cause serious disability: memory loss, extreme tiredness, emotional problems, even kidney failure, coma or death.
Young children are especially affected by lead. Lead dust can collect on clothes during the day. When those clothes are worn home, the lead can contaminate shooters’ and workers' cars and homes, thereby exposing young children to lead-contaminated dust.
What are the signs of lead poisoning? There are many symptoms or signs that suggest a problem with lead, but they can also be symptoms of other illnesses. It is also possible to have lead poisoning without noticing any symptoms. If you work around lead you should regularly see your doctor, whether or not you are experiencing the following symptoms:
Early Signs and Symptoms
Later Signs and Symptoms
Airborne lead dust is a concern in outdoor ranges and can contaminate the surrounding environment. Lead dust exposure to employees or shooters can occur. Lead contamination in an outdoor environment can occur through water runoff and from wind carrying the lead offsite. The process of removing spent bullets, or the face of a berm, can generate large quantities of lead dust.
Bullet traps or steel backstops, similar to those constructed in indoor ranges, can be used instead of earthen backstops. Although the initial cost may be high, the spent bullets can be recovered and sold without soil removal. The trap holds the bullets and fragments, minimizing the amount of lead pollution in the soil.