Hydraulic and earth engineering – Subterranean waste disposal – containment – or treatment – With treatment of waste
Reexamination Certificate
2002-01-29
2004-02-10
Swann, J. J. (Department: 3677)
Hydraulic and earth engineering
Subterranean waste disposal, containment, or treatment
With treatment of waste
C405S129450, C588S256000, C588S253000, C423S089000
Reexamination Certificate
active
06688811
ABSTRACT:
BACKGROUND OF INVENTION
The leaching of lead into the environment has been a major concern of health officials and water supply professionals for many years. In addition to concern over direct leaching of lead into ground waters and surface waters, regulators and professionals have also been concerned with indirect leaching of lead from unlined landfills which generate acidic leaching conditions due to decay of organic matter and thus high levels of lead leaching potential. In response to the concern of lead leaching from both water and landfill leachate borne conditions, the USEPA under direction from Congress, prepared regulations for testing, managing, and disposing of lead bearing wastes. The regulations under the Resource Conservation and Recovery Act (RCRA) and Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA—a.k.a. Superfund) are extensive, complex, and have great impact on industry and practices involving heavy metals including lead. Under RCRA, lead bearing wastes may be considered hazardous if failing the Toxicity Characteristic Leaching Procedure (TCLP) at 5.0 ppm, and thus required to be disposed of at a hazardous waste landfill or treatment, storage and disposal facility (TSDF). These options are very expensive, normally $200.00 per waste ton. Under CERCLA, regulators can control or require treatment of lead wastes at almost any level as the states have flexibility in setting cleanup standards. Consequently, producing Pb bearing waste can be very expensive. Similar regulatory and remedial cost conditions exist in Japan, Switzerland, and other countries. To date, range soils have been subject only to CERCLA action which requires stabilization or disposal of the soils at closed range sites. The soil commonly fails TCLP criteria of 5.0 ppm and is thus a characteristic hazardous waste. The current methods used to manage these lead contaminated soils are reactive, i.e., they treat the lead after the soil becomes contaminated and, consequently, after the hazard exists. The chemicals used to treat lead bearing soils include phosphates, silicates, cements, and sulfides. The methods are, however, reactive in design except for U.S. Pat. No. 5,722,928 issued to Forrester which provides a method for stabilizing leachable lead by adding phosphate and complexing agent to the lead bearing material or waste prior to generating waste. Existing stabilization technology for shooting ranges teach methods of stabilization regardless of the range usage and thus apply readily soluble chemicals in all areas subject to lead exposure.
SUMMARY OF THE INVENTION
This invention relates to the stabilization of lead projectiles used in shotguns, handguns, rifles, and other projectile methods during impact of the projectile onto the collection soils, such that un-stabilized lead is not exposed to the open environment and/or range soil. The stabilization method involves applying impact-released phosphates, magnesium oxides, activated carbon, phosphates with complexing agents such as calcium, iron, chloride and aluminum, precipitants and combinations thereof to the range soils such that these stabilization agents will cause lead to convert to less soluble lead minerals upon contact in the range berm or soils which capture lead projectiles. The method reduces the leaching of lead from the surface of rifle, handgun and shotgun bullets and other lead projectiles. The method also includes contacting the lead projectiles with at least one stabilizing agent such that lead projectiles have reduced Pb leaching potential prior to exposure to the environment or projectile collecting traps. Optimally, the lead projectile is contacted with at least one stabilizing agent during entry into the soil mixed with the stabilizing agent. Lead projectiles stabilized by the methods described herein comprise a lead stabilizing agent incorporated during impact upon the surface of the projectile in an amount effective in reducing leaching of lead from the projectile, such as under natural or induced leaching conditions (e.g., TCLP, Japanese leaching test, California Waste Extraction Test).
This invention has the advantage of reducing the leachability of lead immediately upon first generation as a contaminant in the soil or material berm as well as into the environment with use of open area projectile use. This allows the soil berm and other lead projectile soils/materials to remain below TCLP levels and thus exempt from RCRA hazardous waste regulation. This immediate in-situ stabilization also assures control of Pb leaching and reduction of ecological and human exposure risks by creation of immediate upon-contact water insoluble lead compounds such as pyromorphite, lead phosphates, and stable compounds with silicates, hydroxides, hydroxyapatite Pb minerals, all of which have significantly less mobility and toxicity than the projectile lead form as elemental or lead oxides. The invention provides a means to control Pb solubility both under TCLP testing for hazardous waste classification as well as Pb bioavailability in the open environment.
The impact released lead stabilizing agent addition to the berm or range soils does not modify the soil density, appearance, fugitivity, particle size distribution, compactability or workability, and thus provides assurance that the projectile capture berm and soils will remain effective.
DETAILED DESCRIPTION OF THE INVENTION
Stabilization is herein defined as reducing the leaching of lead from projectiles and projectile contact areas including open environment, beds, traps, berms, stops or barriers used in the management or control of lead projectiles at rifle, handgun, shotgun, or military ordinance ranges where such projectiles are used for target practice or competition. The reduction of leaching is determined by performing a suitable or regulatory required leaching test on the material or waste.
The lead, in the projectiles to be fired or already fired into the soil, can be in elemental form and/or cationic form. The most common form of lead is elemental in the form of projectile slugs or fine particles of slug left on soil surfaces. The soil subjected to projectile exposure can contain as high as 100,000 ppm compositional lead and 1500 ppm TCLP leachable lead. Leachable lead in lead projectile exposed soils is commonly from 50 to 500 ppm TCLP, 200 ppm California Soluble Threshold Limit Concentration (STLC) and between 0.5 and 5.0 ppm total soluble and 1.0 micron suspended colloidal lead by water column and water extraction tests.
Leach test conditions, as defined herein, include the conditions to which a material or soil is subjected during dilute acetic acid leaching (TCLP), buffered citric acid leaching (STLC), distilled water or carbonated water leaching (Japanese and Swiss and SW-924). Suitable acetic acid leach tests include the USEPA SW-846 Manual described Toxicity Characteristic Leaching Procedure (TCLP) and Extraction Procedure Toxicity Test (EP Tox) now used in Canada. Briefly, in a TCLP test, 100 grams of waste are tumbled with 2000 ml of dilute and buffered acetic acid for 18 hours. The extract solution is made up from 5.7 ml of glacial acetic acid and 64.3 ml of 1.0 normal sodium hydroxide up to 1000 ml dilution with reagent water.
Suitable water leach tests include the Japanese leach test which tumbles 50 grams of composited soil sample in 500 ml of water held at pH 5.8 to 6.3, followed by centrifuge and 0.45 micron filtration prior to analyses. Another suitable distilled water CO
2
saturated method is the Swiss protocol using 100 grams of cemented waste at 1 cm
3
in two (2) sequential water baths of 2000 ml. The concentration of heavy metals and salts are measured for each bath and averaged together before comparison to the Swiss criteria.
Suitable citric acid leach tests include the California Waste Extraction Test (WET), which is described in Title 22, Section 66700, “Environmental Health” of the California Health & Safety Code. Briefly, in a WET test, 50 grams of waste are tumbled in a 1000 ml tumbler with 500 grams of sodium citrat
Hamilton Brook Smith & Reynolds P.C.
Mitchell Katherine
Swann J. J.
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