as metals) or in solution or slurry forms (such as salts). There may be varying quantities of organic materials present, ranging from simple agent chemical decomposition products to sewage-treatment-like sludges generated by biological processes. As a practical matter, solutions or slurries must be dried to reduce their volume for landfill disposal, with the extracted water discharged as a vapor or liquid stream.
The U.S. Army has conducted extensive health and safety tests and has established technical specifications on the maximum allowable concentrations of residual agent in various processed material streams, dependent upon the type of agent, the type of processing stream, and their subsequent disposition. The maximum allowable air concentrations have been defined and are relatively easily monitored in essentially homogeneous gaseous streams. Relevant air emission and exposure standards (the latter set by the Surgeon General' s Office) for agent are shown in Table 3-1, along with corresponding lethal doses. The standards have not been set for aqueous streams discharged from agent disposal operations. Drinking water standards might suffice, but it is possible that much higher standards will be established.
The monitoring of solids or mixtures of solids and liquids is much more difficult since they are not homogeneous and may involve agent-solid material interactions that hide the agent until subsequent activities result in its release. Thus, two additional decontamination parameters, 3X and 5X, have been developed.
A waste is deemed to be 3X material if an air sample taken over contained material at room temperature is below Army agent standards, when the most sensitive, currently available monitoring equipment is used. This level has been determined to be safe for unprotected handling by plant personnel, and 3X material can be shipped under Army control. However, since agent could still reside in the cracks and interstices of the solids or even in unopened areas (such as underneath a bolt), these materials cannot be released off-site unless sent to a controlled facility such as another Army chemical agent destruction facility or a licensed hazardous waste landfill. In order to be unconditionally released, or delisted, the solid must be submitted to a high-temperature treatment of 1000º F or greater for at least 15 minutes (5X material), which provides the needed assurance that residual agent will be destroyed.
No single, established technology is capable by itself of producing waste materials that meet both treaty and hazardous waste disposal criteria. For example, incineration requires a downstream pollution abatement system such as scrubbers to capture the acid gases and to dry the products for discharge as salts. Neutralization could require subsequent treatment for conversion of detoxification products to products that meet treaty irreversibility criteria.