Lead Contamination in Soil at Outdoor Firing Ranges

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
* Lead Pollution in Outdoor Firing Ranges (PDF)
* National Association of Shooting Ranges Library

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:
* metal speciation
* soil chemistry
* water chemistry
* bullet composition and condition
For more information about lead mobility, please refer to the full term paper and the following link: Lead Mobility at Shooting Ranges.


EPA Region VIII recently developed draft guidelines for remediation of outdoor firing rangesTheir approach proceeds in several steps:
  1. Sift munitions fragments from the soil. The fragments can be recycled and doing so makes them exempt from hazardous waste reporting and management requirements.
  2. 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.
  3. Analyze the soil in layers to determine the extent of the contamination. Layers that do not exceed the limit need no further action.
  4. 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:
* Soil Treatments to Limit Lead Mobility - PDF
* Innovative Technologies for Addressing Heavy Metals in Soils and Sediments
* Phosphate Induced Metal Stabilization


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:

* Phytoremediation Using Brassica
* Flower Power: Plants Recruited to Clean Up Toxins
* Edenspace Phytoremediates Ft. Dix Firing Range; Site Goals Met
* Environmental Science and Technology articles - access full articles through NJIT on-line library

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:

* U.S. Military "Green Bullet"
* U.S. Army to Use "Green" Ammo

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:

* EPA: Best Management Practices for Lead at Outdoor Shooting Ranges
* Environmental Aspects of Construction and Management of Outdoor Shooting Ranges
* Range Design and Planning

Posted 11/24/01 by Robin Izzo Scott
URL: http://www.princeton.edu/~rmizzo/firingrange.htm