This website was created
by Robin Izzo Scott in support of a term
paper for Environmental Sciences 610, Environmental Chemistry.
The
Issue
The main concern with lead in outdoor firing ranges
is the fate and transport of heavy metals from bullets and bullet fragments
accumulating in soil.Of these metals,
lead is the predominant contaminant.Lead
is considered the top environmental threat to children’s health.The
following sites offer information about the impact environmental lead pollution:
The U.S. military alone has cleaned up more than
700 fire ranges across the country over the past several years.There
are currently 1813 commercial outdoor firing ranges registered with the
National
Shooting Sports Foundation.According
to estimates by the Environmental Working Group, outdoor firing ranges
put more lead into the environment than any other industry in the U.S.,
with the exception of metals mining and manufacturing.Civilians,
the Department of Defense, the Department of Energy and law enforcement
agencies combined use tens of billions of rounds of ammunition each year,
translating to hundred of tons of lead per day.
The following website offer additional information about lead pollution at firing ranges:
PRO-ACT Fact Sheet on Lead Contamination in Soil at Small Arms Firing Ranges
The
Outdoor Firing Range
A typical outdoor firing range is comprised of a
series of targets in front of an impact berm.The
targets may be made of paper, wood or metal and the impact berm may be
equipped with bullet traps.The bullet
will likely move through the target and will strike the impact berm, penetrating,
fragmenting, agglomerating, smearing or richocheting.
Lead
Bullets
Lead has been the material of choice because of
its low cost, easy availability, versatility and excellent performance.Many
bullets are jacketed with copper making them more environmentally sensitive
in wet soils due to the galvanic corrosion potential. Some bullets
will remain intact, particularly bullets from skeet shooting and pistols.
Bullets from rifles are more likely to break apart, exposing more lead
to the soil and providing a larger surface area.
Galvanic corrosion occurs when two metals with significantly
different electromotive forces come together in the presence of an electrolyte,
such as water. The following websites offer more information:
Lead
Mobility
Once the lead bullets and debris settle on the soil,
a number of factors will determine the extent of the actual hazard it might
pose.The more easily the lead moves
through the soil, the more of an impact it will have.The
total soil concentration of lead alone has little or no bearing on lead
mobility or bioavailability.In order
become mobile, it must dissociate into pore water and migrate via mass
transport. Solubilization of lead depends on a number of factors
including:
For more information about lead mobility, please
refer to the full term paper and
the following link: Lead
Mobility at Shooting Ranges.
Remediation
EPA Region VIII recently developed draft guidelines
for remediation of outdoor firing ranges. Their
approach proceeds in several steps:
- Sift munitions fragments from the soil. The fragments can be recycled and doing so makes them exempt from hazardous waste reporting and management requirements.
- Sample and analyze the remaining soil to determine if the leachable level is at or above the EPA limit of 5 mg/L. If it does not exceed the limits, the soil can be disposed or reused or left in place with no further action needed. If it exceeds the limit, proceed. When analyzing the soil, it is important to choose the right test methods.
- Analyze the soil in layers to determine the extent of the contamination. Layers that do not exceed the limit need no further action.
- Treat or dispose of the soil. There are numerous options, including placement in a hazardous waste landfill, onsite stabilization and solidification and soil washing.
There are many options for treating the soil.
The full term paper explains a few of these methods in more detail.
The following references may be useful in selecting a treatment method:
Phytoremediation
Using plants to extract lead from soils is an emerging
technology.Researchers have found
that certain plants accumulate and tolerate very high concentrations of
certain heavy metals in their shoots.These
“hyperaccumulators” theoretically should be able to reduce lead levels
in contaminated soil to an acceptable level. Indian Mustard, corn
and pea plants have all shown promise for phytoremediation. Soil
treatment with chelating agents appear to enhance the lead absorbing ability
of the plants.
The following website offer more information about phytoremediation:
Pollution
Prevention
There are a number of methodologies for reducing
lead pollution from outdoor firing ranges, including environmentally lead-free
bullets, better bullet trapping, and pretreatment of soil.
Green
Bullets
Probably the most promising pollution prevention
strategy for both indoor and outdoor firing ranges is the development of
the “green bullet”.Rather than lead,
this new bullet is a slug made from tungsten and tin (Figure 9).Tungsten
is an environmentally non-toxic metal with a higher density than lead.
The material can easily be pressed into shape to replace many small caliber
bullets.
The following web sites offer more information about Green Bullets:
Building
a Better Firing Range
At
the time that most existing firing ranges were built, designers did not
consider the impact of lead on the environment. Newer designs incorporate
technologies to reduce lead pollution and other negative environmental
factors, such as noise.
A few references for renovating or building new firing ranges are available at:
Posted 11/24/01 by Robin Izzo Scott
URL: http://www.princeton.edu/~rmizzo/firingrange.htm