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Stop Butt Construction and Maintenance THIN GUIDE

Stop Butt Construction and Maintenance. Forfurtherinformationcontact Title MrMarkImber ... If the stop butt is deeply scooped up to 1 m may have to be

SBCM

Stop Butt Construction
and Maintenance

THIN GUIDE

for Environmental Officers

February 2005

Stop Butt Construction
and Maintenance

THIN GUIDE

for Environmental Officers
Prepared by Environmental Resources Management Australia

For further information contact

Mr Mark Imber
Assistant Director Environmental Stewardship
Environment, Heritage and Risk Branch
Department of Defence
T 02 6266 8058
E [email protected]

This work is copyright. Apart from any use permitted under the Copyright Act 1968, no
part may be reproduced without prior written permission from the Department of
Defence.

Title

Stop Butt Construction and Maintenance, Thin Guide for Environmental Officers

Introduction

Department of Defence sites are valuable assets and environmental resources
and are at risk of environmental damage as a result of intensive training activities
or intrusive works. Therefore the Department of Defence has developed
guidelines relating to Stop Butt Construction and Maintenance in order to raise
the awareness of potential issues relating to these features.
The purpose of the document is to provide Environmental Officers, Planning
Officers, CMC Staff, Range Inspectors and Range Staff with relevant guidance
with respect to potential air, soil and water contamination associated with Stop
Butt Construction and Maintenance at man-made (constructed) stop butts. This
document will include details relating to:
+ Key and potential issues;
+ Potential contaminants with respect to site usage;
+ Legal requirements; and
+ Environmental best practise management.
The benefits of sound environmental management practise at any site include the
following:
+ Protection of the environment, natural resources and wildlife;
+ Improved community relations;
+ Improved aesthetics of the range/good business practise;
+ Resource re-utilisation through recovery/recycling lead; and
+ Reduced public scrutiny.
This document supplements the thin guide relating to stop butts.

03

Definitions

There are a number of different types of bullet containment systems at rifle or
pistol ranges. The following definitions provide some explanation of the most
common types of bullet containment systems:

Stop butt: An earth mound or concrete/masonry wall constructed to reduce or
eliminate the ricochet danger area of a firing range. The stop butt may
incorporate or be used in conjunction with a bullet catcher. They are generally
located directly behind the targets and are between 5 and 7 metres high with a
recommended slope as steep as possible. In some instances, stop butts may be
naturally occurring hillsides. The uppermost layer of the stop butt (to a depth of
up to 0.5 m) exposed to the shooting activity is free of large rocks and other
debris. These materials tend to increase ricochet and bullet fragmentation,
which will in turn make lead reclamation activities more difficult.

Bullet Catcher: An absorbent bank, layer or construction specifically designed or
intended to trap and collect projectiles fired on a range to prevent ricochet,
splashback or secondary projectiles. A bullet catcher does not reduce the range
danger area but may be a face layer of a stop butt to prevent splashback.

Ricochet: A largely intact projectile which leaves the range fairway after impact
with the range floor, earthworks or infrastructure. Ricochets may or may not be
ballistically stable and can propagate from hard or yielding surfaces at angles of
incidence less than 30 degrees.

Splashback: The spray of projectile components resulting from a projectile
impacting a hard surface at greater than 30 degrees. Splashback may be
deflected at high angles to the original line of fire and may also be projected
limited distances towards the firing line.

Secondary Projectile: A projectile dislodged from the range floor, stop butt or
bullet catcher. Secondary projectiles are usually but not always previously fired
projectiles resting near the surface of the bullet catcher. Secondary projectiles
may be launched short distances in any direction and may have a high vertical
trajectory.

Pellet absorption layer: an outer layer of material placed in a stop butt that is
designed to absorb pellets within a firing range.

04

Key and potential issues

Prior to construction, consideration of the possible sites for a stop butt is essential
to prevent or minimise potential environmental impacts. There are a number of
factors that need to be considered, prior to commencement of construction
including:
+ Precipitation;
+ Frequency and type of use and number of rounds expected to be fired;
+ De-leading requirements;
+ Soil characteristics;
+ Dissolved contaminants in groundwater/surface water;
+ Groundwater & surface water;
+ Stormwater runoff and erosion;
+ Topography;
+ Vegetation;
+ Animal habits;

05

+ Air borne particulate lead; and

+ De-leading requirements.

Consideration of the volume of rounds to be fired should also be taken into
consideration for airborne particulate lead.

Precipitation

When lead is exposed to air and water, it may oxidise and form one of several
compounds. Mobility of lead is far greater once oxidised. The greater the annual
rainfall the greater the likelihood of oxidation of lead.

Consideration of the mobility of antimony, arsenic, nickel and heavy metal
impurities from steel sheet such as chromium and copper should be taken into
account. The minimisation of the volumes of leached material is discussed in
“Construction and Design”.

Frequency and type of use

Knowing the likely frequency and type of use of a range will determine the size
and specific characteristics, including the size and the depth of the pellet
absorption layer.

Soil characteristics

When lead is exposed to air and water, it may oxidise and form one of several
compounds. The compounds created and their rate of migration is greatly
influenced by soil characteristics such as pH and soil types. Knowing the soil
characteristics of an existing site is a key component to effective management.
Lead reacts more readily and may become more mobile under acidic (pH <6) or
highly alkaline (pH>8) conditions, eventually breaking down and contaminating
underlying soil. In moderately alkaline soils (pH 7-8.5), the lead precipitated out
of solution binds to the soil. This binding effect prevents the lead from migrating
to the subsurface.

The migration rate of specific lead compounds is affected by the physical
characteristics of the soil. Heavy clays will prevent the lead compound from
moving quickly through the subsurface. In addition any free lead ions become
attached to clay particles with this bond preventing migration. If locally available
soil is not suitable it is recommended that appropriate soil be imported for the
construction of the stop butt.

06

It should be noted that in many cases, the Range Construction guidelines
recommend the use of sand in the bullet catcher/stop butt. This may in turn
influence migration of lead within the stop butt.

Dissolved contaminants in groundwater/surface water

Lead in general is insoluble in water. However, lead may become soluble with
increasing acidity (decreasing pH). Lowering of pH can result from acidic soils or
rainwater. When acidic water comes in contact with lead impacted soil, the lead
can be dissolved into the water and transported to a nearby surface waterway or
groundwater system. If sufficient lead is mobilised, environmental receptors may
be affected and risk to human health could occur if receptor waters are used for
drinking purposes.

It should be noted that although lead is much more soluble with increasing
acidity, highly alkaline conditions can similarly increase the mobility of lead. It is
therefore suggested that a pH range for both soils and water between 6.5 and 8.5
be maintained where possible (National Shooting Sports Foundation (NSSF),
1997). It is recommended that stop butts should not be constructed on sites
where highly acidic/alkaline conditions are known to exist.

Groundwater and surface water

Depth to the water table is one of the critical parameters in the assessment of
dissolved lead migration. The closer the water table is to the ground surface the

07

higher the risk that lead leaching from the soil will impact the groundwater
quality. As a guide, in fine grained soils such as clay and silt with depths to
groundwater greater than 3m, lead impacts on groundwater are unlikely. Where
sandy soils exist the impacts from lead on groundwater are highly likely.

Stormwater runoff and erosion

Stormwater runoff has the potential to erode and transport lead-impacted soil, or
to a lesser extent, projectiles from within the confines of the stop butts. A
number of factors can influence the potential transport of contaminants from the
range including rainfall intensity, ground slope, soil type and obstructions such as
vegetation and fabricated structures.

08

Topography

The position in the landscape in relation to catchment areas can significantly
affect the impact of a range on the environment. Minimising the potential
through flow of surface water can significantly minimise the transportation of
lead off site. Flooding and heavy rains can enable transportation of lead/metal
projectiles across and beyond the site boundary. Areas subject to these events
are more susceptible to erosion irrespective of the soils structure and capacity to
store water. Other than soil type the other major factor in water erosion of a site
is its slope, the greater the slope the greater the erosion potential and the ability
to move at a higher velocity and carry sediment and projectiles.

Vegetation

Vegetation absorbs rainwater, thereby reducing the time that the lead is in
contact with water. Vegetation also minimises surface water runoff, preventing
the metals from migrating off-site.

Vegetation cover or fabricated erosion control measures can effectively reduce
the level of soil erosion and therefore limit the transport of lead pellets.
Vegetation cover can limit soil erosion by reducing flow velocities or wind and
water, increasing infiltration and reducing the impact of heavy rainfall on the soil
surface. Fabricated control measures limit soil erosion in a similar fashion to
vegetation however they are more easily constructed and have the benefit of
being effective immediately, without having to wait for growth. Consideration
should be given to soil type and climate, which can dramatically affect the type
and survival of vegetation.

Shallow-rooted grasses don't have much impact on soil moisture content, or the
absorption of rainwater. Another point to note is that if the stopbutt has been in
use for some time, and the level of residual lead is high (ie not the fragments
which cause ricochet, but the fines which are not screened out), then grasses may
not grow. In this instance fabricated control measures such as the planting of
lead tolerant species and the placement of imported fill material may be
appropriate as is the placement of geosynthetic materials.

Animal habitats

In order to prevent lead contaminating the food chain of any animals,
consideration should be given to any surrounding habitats when selecting a site.
The planners also need to consider if the construction of the stop butt itself will
result in the destruction of habitat (be it flora or fauna). There is also a need to
consider if some particular habitats are more susceptible than others (eg wetlands
and waterways).

09

Airborne Particulate Lead

Small particles of lead may become airborne due to wind action, foot traffic or
maintenance activities, which disturb contaminated soils. Airborne particles
smaller than 10 microns can be inhaled, and fine particles less than 250
microns in diameter can be incidentally ingested. The location of neighbouring
residences and reduced air movement due to the presence of structures should
be considered when selecting a site.

In summary the main environmental concerns associated with stop butts relate
to increased lead mobility within the range environment. This lead can be
transported as airborne particulate lead stormwater runoff and erosion and
dissolved lead in groundwater or surface water.

Deleading of range stop butts

There are two basic requirements for deleading:

1. Secondary Projectile hazard mitigation (Ballistic Deleading); and

2. Environmental Lead hazard mitigation (Environmental Deleading).

The purpose and methodology associated with both ballistic and
environmental deleading are detailed in the table below.

Methodologies associated with deleading of range stop butts

Type Purpose Method Endstate

Ballistic Remove Remove surface layer. Sieve to remove Larger projectile
deleading potential projectile components
secondary removed.
projectiles Replace sieved soil on bullet catchers. Contamination in
Projectiles sold as scrap metal. bullet catcher
acceptable.

Environmental Remove lead Remove bullet catcher treat to stabilise Contaminated

deleading contaminated lead and dispose of through hazardous soil removed.

bullet catcher waste contractor. Leachate hazard

soil mitigated in

Bullet catcher replaced with new medium term.

material.

Ballistic deleading

The minimum requirement for ballistic deleading it to remove the top 150 mm of
soil from the face of the stop butt sieve it and return it to the face. This removes

10

Puckapunyal Military Area - Photo courtesy of Emilie Warner

11

the potential secondary projectiles and slightly reduces the potential for lead
leachate. Face material is usually removed by scraping with a backhoe or larger
digging arm. If the stop butt is deeply scooped up to 1 m may have to be
removed between scoops to reinstate a straight face. Prior to replacement of
the face layer the stop butt core is to be benched or scored horizontally to
provide a keying layer between the core and face.

Construction and design

Once a prospective site has been chosen, assuming the selection criteria above
has been taken into consideration, some control measures may need to be
implemented to prevent or minimise impact.

The construction of an engineered stop butt is the first step in implementing an
integrated management program for the stop butts. A program would include
the following:

+ Control and containment of lead bullets and bullet fragments;

+ Prevention of migration of lead through the soil profile and to surface water
bodies;

+ Removal and recycling of the lead from the range; and

+ Documentation of activities and keeping records.

Types of bullet catchers

A variety of bullet catchers have been used by the ADO over the years these
being:

+ Earth/Sand Bullet Catchers: A relatively simple use of topsoil or sand layer
over a clay core sloped at or near to the angle of repose.

+ Improved Earth Sand Bullet Catchers: Earth or sand bullet catchers improved
with added low density material to reduce the probability of secondary
projectiles. Added materials include straw bales and sawdust and have been
used where very short range firing (<10 m) is required.

+ Particulate Rubber Bullet Catchers: These bullet catchers use shredded
rubber derived from recycled tyres or conveyor belting either loose in a
containment box with a sacrificial containment membrane or fixed in a
polyurethane foam matrix. The key perceived advantage that projectiles are

12

broken up by impact reducing contamination will probably be spurious for the
intentionally fragile 5.56 mm Ball round. Particulate rubber bullet catchers
have serious fire hazard issues and are expensive to install.

+ Steel Plate Bullet Catchers: These bullet catchers are primarily used for indoor
ranges and use angled or vertical hardened steel plates to stop projectiles
normally destroying them in the process. Vertical steel plate catchers use some
form of penetrable anti splash material to prevent projectile components
hitting the firer. Anti splash materials used within the ADO have included
Cotton waste, Stramet, Conveyor belting and Linatex Rubber. All steel plate
bullet catchers produce substantial amounts of fine lead dust which is spread
over the surrounding area. No steel plate bullet catcher produced to date is
fully suitable for firing of 5.56 mm Ball ammunition. Some plate and curtain
bullet catchers have safety issues when engaged at low angles of incidence.

+ Rubber Lamelle Bullet Catchers: These Bullet catchers consist of multiple
layered curtains of rubber conveyor belting with the number of layers required
dependent on the ammunition to be stopped. 7-8 layers of conveyor belting
hung at 12 mm spacings is sufficient to stop 5.56 mm and 9 mm ammunition
but is subject to considerable wear if used for high volume of firing
applications.

+ Shock Absorbing Concrete (SACON): SACON is an aerated concrete product
which can be used to build free standing structures and will absorb projectile
strike without backsplash and with a far lower ricochet angle. It is still
undergoing trials but show considerable promise for a variety of range
applications.

Bullet catcher and stopbutt construction

Three main forms of stopbutts and bullet catchers are constructed for the ADO
these being:

+ Earth/Sand Bullet Catcher over Clay Core stop butt;

+ Improved Earth Sand Bullet Catcher over Clay Core Stop butt; and,

+ Earth/Sand Bullet Catcher over Concrete Wall stop butt.

These are illustrated over the page.

13

Each layer of the core and the face compacted by
Sheepsfoot Roller to create a compacted intermixed binding
key between the two components.

Clay core raised layer by layer
Earth facing raised layer by layer concurrently
Earth/sand bullet catcher over clay core stop butt

Sand over straw bale improved bullet catcher

Clay core
Earth facing
Sand
Straw bale
Improved earth/sand bullet catcher over clay core stop butt

14

Concrete stopbutt wall

Earth/sand bullet catcher

Clay core to reduce cost

Timber retaining wall

Earth/sand bullet catcher over concrete wall stop
Stop butt projectile build up characteristics
The repeated impact of projectiles into a bullet catcher or stop butt has two main
effects on the nature of the stop butt being displacement of the bullet catcher
material from the most regular points of impact (called “Scooping”) and the
concentration of projectiles which eventually forms a secondary projectile
hazard.
Scooping is the displacement of earth/sand from the face of the stop butt as dust
clods or mud spatter. Over time scooping can become quite deep especially on
classification ranges where fixed targets and narrow lines of fire concentrate fire
onto small portions of the stop butt. The key effect of scooping is to complicate
the removal of the surface layer during deleading by increasing the depth of
excavation needed.
Concentration of Projectiles. It was once considered that all projectiles fired into
a stop butt penetrated deeply and once enough rounds had been fired coalesced
into a solid hard mass which would cause projectiles to ricochet or splash back. It
is now known that most projectiles lodge in the top 150 mm of the bullet catcher
and are often disturbed by subsequent projectiles. Projectiles may be
concentrated further by being washed into erosion channels which form along
the centre line of the bullet scoops.

15

Ammunition factors. 7.62 mm and 9 mm projectiles usually remain intact after
impact but 5.56 mm is designed to break up into multiple components under any
impact parameters under 400 m. This projectile breakup substantially reduces
the secondary projectile problem but also increases the lead contamination
issues.

Control by design

Contouring of the stop butt

The likelihood of erosion can also be minimised by the shaping of the stop butt.
The slope of the surfaces has a direct effect on the velocity and therefore upon the
erosive potential. Optimally the stop butt should be constructed so that there is a
maximum angle of 45 degrees on the front, which is perpendicular to the
shooters, plus or minus 2 degrees. The top of the stop butt should be
approximately 4-5 m wide and the back slope should be around 18 degrees to
minimise erosion potential. The entire berm should be vegetated, with larger
more mature vegetation on the back slope. The slope of the back slope is
influenced by the type of ammunition, and the length of the range.

Flow retardation structures

The incorporation of flow retardation structures can limit soil erosion on site and
limit the transport of lead contamination. Examples include contour banks and

16

diversion banks on sloping land, traps within drainage lines to catch lead particles
and silts, energy dissipaters within drainage lines, windbreaks along site
boundaries and vegetation to stabilise soils and increase infiltration. The use of
flow retardation structures will be site specific and dependent on whether or not
erosion and the offsite transport of lead is an issue. In order to prevent gullies
forming at the base of the stop butt vegetated stormwater channels should be
constructed. Vegetation in these channels controls erosion in the channel,
reducing the velocity of the water and filtering out sediment which may contain
lead. Stormwater channels may also be stabilised through the construction of
concrete spoon drains or through the layering of geotextile materials such as
treemax.

These channels should flow towards a constructed wetland/detention basin, the
size of which is determined by annual precipitation and the size of the catchment.
These channels must be maintained to ensure flow during flood. Material
removed from the channels can be placed back onto the stop butt or tested if it is
to be taken off site.

Surface water flow

The purpose of the constructed wetland/detention basin is to allow residual
sediment to settle out before the run-off is released. Constructed wetlands are
generally made up of two components including a relatively deep upstream pond
with littoral microphytes and a downstream wetland with extensive microphyte
vegetation. In general, constructed wetlands service to capture sediments and
pollutants adsorbed to these particles before they reach local aquatic areas (NSW
EPA 1997). The adoption of constructed wetland systems can be complex and
therefore site specific if their construction is permitted. The addition of vegetation
makes the basins a likely habitat for wildlife, however this should be discouraged
through practices such as the construction of fencing that may isolate habitat
from active areas of the site.

Prevention of migration through soil

The pH of a soil is also very important, soils with pH's less that 6.5 or greater than
8.5 increase the solubility of lead. Once soluble the porous nature of some soils
does little to reduce the vertical migration in to the ground water. Where slightly
acidic soils are an issue on site, measures can be taken to increase the soil pH thus
reducing the potential mobility of lead. Such measures include incorporating
high alkaline materials such as lime, gypsum and dolomite within the soil.
Application of these materials will effectively raise the pH of soils, reducing
dissolved lead concentrations.

17

These materials could be spread across the surface in either powder or coarsely
crushed form using agricultural equipment. Fine or powdered materials can
control acid quickly, however they do not last long. Conversely, application in
larger particles will result in a slower reaction but they will last longer (NSSF,
1997).

Levels of application will be site specific and should be determined by an
appropriate person who can advise on application rates. The application of the
minerals may result in highly alkaline conditions that can similarly mobilise lead.

Mobility of lead in soil is reduced if pH is kept between less that 6.5 or greater
than 8.5 and can be further reduced if clay particles or organic matter content
is greater. Testing of clay and organic matter content should be undertaken.
The required levels will vary between ranges. Shrinking and swelling clays such
as montmorillonite and bentonite are two clays typically used to increase clay
content, however care should be taken to ensure effective mixing.
Insufficiently mixed clays have a tendency to slump during wet weather.

The use of a clay layer beneath a constructed stop butt, much the same as used
beneath solid waste landfills to prevent vertical migration of contaminants has
been discussed but not evaluated by the U.S. Department of the Army.
Concerns have been raised regarding the eventual exceedance of any lead
absorbing capacity leading to migration through this layer. Problems may also
develop when the water on top of the clay layer eventually saturates and allows
horizontal movement. In highly porous areas the use of a clay layer may be the
only solution to reduce vertical migration of contamination. In addition, a
synthetic liner may be used at the base of the stop butt to serve a similar
purpose and prevent any vertical migration of lead into the soil and
groundwater.

Ricochet

During the construction of a stop butt, the positioning of any objects that have
the potential to cause ricochet must also be considered. Items likely to cause
ricochet include brackets, baffles and bolt heads. The Range Construction
Manual specifies the use of sand and/or straw bales in the stop butt
immediately behind the target. This reduces ricochet and extends the life of
the stop butt. The use of straw however can affect leachability as it
decomposes. Further, the straw can interfere with the deleading process, by
interfering with the screens used to sieve the stop butt material.

18

Recycling

The regular physical removal of the lead shot from the stop butt is an extremely
effective way of reducing the risk of migration of lead into the environment. The
removal of lead shot also reduces risk to human health and safety. Consideration
of this during design and construction can not only make undertaking this task
less arduous but also more effective. Consideration needs to be given to the
process which will be undertaken to remove the appropriate depth of the stop
butt absorption layer, and the machinery and space required.

Information provided by Defence indicated that normally de-leading of stop butts
occurs after approximately 80 000 rounds. The stop butt facings are dry sieved
and where possible the recovered lead is recycled. The remainder of the
materials, are where possible reinstated into the stop butts. Consideration
should be given to the pH, type of soil and the concentration of lead and heavy
metals proposed to be used in any replacement materials incorporated into this
facing.

During the refacing of the stop butts, consideration should also be given to the
temporary storage of lead contaminated materials in order to minimise leaching
to adjacent areas. This may include stockpiling of impacted material on an
impermeable layer (eg. concrete, bitumen, HDPE liner) and the usage of silt

19

barriers to minimise migration. Alternatively soil can be placed directly into lined
waste ships, In general, the shorter the distance the material has to be
transported for stockpiling, the better.

Documentation of activities

A site management plan is important for each individual shooting range as it
identifies the key site specific management issues associated with that site. If a
range has an existing site management plan, checks should be made to ensure
that the plan covers the relevant issues relating to projectiles outlined in these
guidelines and any appropriate changes should be made accordingly.

In addition, the Regional Environmental Officer (REO) needs to ensure that a
contaminated site is included on the Defence Contaminated Sites Register
located on DEMS. It is also the responsibility of the consultants to advise the REO
of any activities (remediation or investigations) that are performed on the site, so
that data may also be entered on the Register.

Potential contaminants with respect to site
usage

When lead ammunition contacts with soil, it may corrode. The lead oxidises to
form corrosion products, which precipitate onto soil particles and as a layer
around the pellets. The corrosion products are able to dissolve into the soil water
(soil solution) and the soil soaks up (fixes) some of the lead. The corrosion process
is effectively dissolving the pellets into the soil.

New lead pellets consist of over 90% lead, 1-7% antimony, < 2% arsenic and
<0.5% nickel. As a result, these metals are considered to be the potential
contaminants of concern associated with stop butts.

Steel shot corrodes faster than lead and the ammunition contains substantial
heavy metal impurities including chromium and copper, which also have the
potential to be released to the environment through corrosion.

It may be appropriate to mitigate the impact of these heavy metals through the
application of lime or similar products to restrict the mobilisation of metals to the
environment.

20

Legal requirements

There is currently no legislation available relating specifically to the installation,
construction or contamination at shooting ranges.

With regard to issues relating to the contamination of soil reference should be
made to the NEPC (1999) National Environment Protection (Assessment of Site
Contamination) Measure.

With regard to issues relating to the contamination of groundwater reference
should be made to the ANZECC (2000) Guidelines for Fresh and Marine Waters.

Construction and operation of a rifle range comes under the Environmental
Protection and Biodiversity Conservation Act 1999 EPBC, 1999. The EPBC Act
provides that an existing rifle range does not require approval under the Act if it is
a lawful continuation of a use of land that was occurring before 16 July 2000. An
enlargement, expansion or intensification of use is defined not to be a
continuation of use, therefore the EPBC might apply in either of these
circumstances.

The following steps must be followed when applying for the construction and/or
operation of a STP;

+ Defence proposing to construct or operate a rifle range must refer to the
Commonwealth Environment Minister in accordance with the requirements of
the EPBC;

21

+ The construction and operation of a rifle range will require assessment of the
impacts that it has, will have, or is likely to have on the relevant matters of
national environmental significance; and

+ After the assessment process for the rifle range has been completed, the
Commonwealth Environment Minister must decide whether or not to grant
the construction and/or operation of the rifle range licence.

Best practice management

Outdoor Shooting Ranges

General Range Maintenance

Best practice methods for general maintenance of shooting ranges should be
applied. It should be noted that there is currently no available Australian best
practise management documentation with respect to Stop Butts/Rifle Ranges so
reference has been made in this document to US experiences.

Activities such as the maintenance of impact berms and mowing of sparsely
vegetated areas within the range can lead to the generation of lead contaminated
dust. The light spraying of water over areas exhibiting a potential for dust
creation and the attachment of water applicators to machinery will reduce dust
generation. Undertaking these activities at times of low wind velocities will also
assist in the suppression of dust.

Employees or range users undertaking such activities where exposure to lead
contaminated dust may result should be adequately protected. As well as the use
of water applicators, machinery (excavators and bull dozers) should be equipped
with air conditioned cabins that have an effective air filtering system fitted to the
air intake.

The growing of vegetation or use of covers over stockpiles may also assist in the
suppression of lead contaminated dust. The incorporation of paved roads and
parking areas as well as speed restrictions near the range can minimise dust
generation. Similarly, foot traffic should be kept to paved areas (NSSF, 1997).

Indoor shooting ranges

Projectile traps

A wide variety of projectile traps and impact berms may be applied to indoor
shooting ranges. Projectile traps are designed to decelerate the bullet and collect

22

the resulting fragments. Some traps have also been designed to minimise
airborne lead dust generated when bullets strike the traps (Pro-Act, 1998).
Examples of munition traps are summarised below:

Upward deflecting backstops

An upward deflecting backstop is an angled metal impact plate that deflects the
projectile particles upward into a swirl chamber. The projectile particles then fall
into a tray at the base of the trap and are collected.

Rubber projectile traps

A rubber projectile trap consists of multiple strips hung from a frame and oriented
edgewise to the line of fire. The benefit of using rubber strips is they are able to
adsorb the energy of the lead pellet, leaving in tact and eliminating the problem
of airborne lead dust. The munitions then fall to the base of the trap for
collection. This trap requires periodic maintenance to replace the rubber strips.
The frequency is dependent on the amount of activity at the shooting range.

Granulated projectile traps

A granulated projectile trap consists of a steel box with a rubber front. The box
contains recycled granulated rubber material that can adsorb the impact of the
munition passing through the rubber thus keeping the pellets intact. Once again,
periodic maintenance is required to repair the rubber front.

Water projectile trap

A water projectile trap consists of a funnel leading into a decelerating chamber
containing a small amount of water. The pellets enter the deceleration chamber,
deflect into the water and rotate around until they stop. The water in the
chamber reduces the likelihood of fragmentation and airborne lead dust. The
munitions then fall into a collection tray at the bottom of the trap for easy
removal.

Ventilation Apparatuses

Dust generated from the firing of lead projectiles and their impact with munitions
traps may be classified as air pollution and can result in a human health risk to
both users and workers at the range.

Incorporation of an exhaust ventilation system equipped with a High Efficiency
Particulate Air (HEPA) filter should effectively remove dust. Filters should be
regularly checked to ensure optimum operating conditions.

23

Even with ventilation systems in place, lead contaminated dust may collect within
indoor shooting ranges. Good housekeeping procedures should ensure dust
levels are kept at a minimum. Cleaning dust should incorporate the use of wet
suction sweepers or specialised vacuums equipped with a HEPA filter.

People exposed to lead dust (primarily range workers/contractors) should be
equipped with approved respirators. Assurances should be made that the
respirator fits properly, is sufficient for the level of exposure, is regularly
maintained and the user is adequately trained for its use. Information on
protection against dust hazards, including ventilation systems, is available from
your local Workcover authority.

Site management

During the design and construct phase of stop butts consideration should also be
given to the implementation of a monitoring program to ensure the possibility of
releases is minimised. This should include but not be restricted to:

+ Regular inspection for soil erosion and the implementation of erosion
measures as appropriate;

+ Ongoing mowing of range;

+ The regular checking of silt fencing and the removal of built up silts from
stormwater channels and drains;

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+ Monitoring of surface water and groundwater quality;

+ Ongoing range maintenance to prevent ricochets. This includes deleading and
replacing stop butts as appropriate; and

+ Implementation of community education program that deals with issues
relating to environmental, safety and wildlife issues.

Reference with respect to site management should be also be made to the
Combined Arms Training Centre Range Construction Manual.

References

ANZECC (1992) Australian and New Zealand Guidelines for the Assessment
and Management of Contaminated Sites. Australian and New Zealand
Environment and Conservation Council and National Health Council, January
1992.

Brady, N.C. (1990) The Nature and Properties of Soils. Tenth Edition.
Macmillan Publishing Company, New York.

Department of Defence, Combined Aims Training Centre Range Construction
Pamphlet.

ITRC, 2003, Characterisation and Remediation of Soils at Closed Small
Arms Firing Ranges.

National Shooting Sports Foundation (NSSF), 1997 Environmental Aspects of
Construction and Management of Outdoor Shooting Ranges. NSSF, 11
Mile Road, Newtown, CT 06470-2359.

NSW Department of Housing (1998) Managing Urban Stormwater: Soils &
Construction. NSW Department of Housing, Housing Production Division.

NSW EPA (1997) Managing Urban Stormwater: Treatment Techniques.
NSW EPA, Chatswood, NSW.

Pro-Act (1995) PRO-ACT Fact sheet on Lead Contamination in Soil at Small
Arms Firing Ranges.

Pro-Act (1998) Lead Contamination in Soils at Military Small Arms Firing
Ranges.

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Partridge, R. (date unknown) Technical Track: Indoor Range Design. Design
Criteria for Indoor Bullet Traps. Fourth National Shooting Range Symposium.
US. Army, Environmental Center's Range Team XXI Team & the US Army Training
Support Center (1998) Prevention of Lead Migration and Erosion from Small
Arms Ranges.
US National Institute of Building Sciences (NIBS) (2004) Whole Building Design
Guide Firing Range. Washington D.C.
US EPA (2001) Best Management Practices for Lead at Outdoor Shooting
Ranges.
NRA. (1996) Baffles, Berms and Backstops. By David Luke, Range Technical
Team Advisor NRA.
US EPA, Region 2 Waste, Best Management Practices for Lead at Outdoor
Shooting Ranges.

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Stop Butt Construction
and Maintenance

THIN GUIDE

for Environmental Officers
Prepared by Environmental Resources Management Australia


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