ana Department of Environmental Management 1001 waste code and is to be disposed of accordingly, at an approved treatment, storage, and disposal facility (TSDF).
Two considerations dictate how used carbon is handled on-site:
Is the carbon contaminated with agent?
How much agent is present on the carbon?
The current practice when a filter tray containing exposed carbon is removed from operation is to first bag the tray in two plastic bags and then place the double-bagged tray in a 95-gallon polyethylene drum (see Figure 2-9), which is stored for future disposal. This practice avoids unnecessarily exposing personnel to agent as would be the case if the carbon were to be removed from the filter trays prior to packaging for storage and disposal. While this approach minimizes any chance of exposure to agent during packaging, it makes it difficult to characterize the amount of agent that might be present on the used carbon. Recall from Table 2-1 that each MDB HVAC filter unit typically consists of six banks and each bank consists of 48 filter trays. Each filter tray is specified to contain 48.3 lb of carbon.
Only the used activated carbon from the PFS is handled in bulk form; i.e., the used carbon is not contained in filter trays. The used carbon from PFS filters is emptied as a loose solid into plastic bags, and the bags are placed in polyethylene drums for storage and disposal. The PFS filter beds are arranged in two horizontal zones in series in the process vent gas stream with ACAMS monitoring between the zones. In some facilities, combustion gas flowing to Zone 1 is not monitored for agent because it is expected to be free of agent during normal plant operation based on tests performed when the facility was licensed for operation. While the PFS carbon is not expected to be exposed to agent, each disposal facility has installed a DAAMS monitor downstream of Zone 1. The sampling tubes in this monitor are regularly removed and analyzed in the laboratory.
Finding 2-1. At some chemical agent disposal facilities, no depot area air monitoring system monitor has been installed in front of Zone 1 of the pollution abatement system filtration system.
Recommendation 2-1. If the activated carbon in a pollution abatement system filtration system unit at a chemical agent disposal facility is ever to be changed out, consideration should be given to installing a depot area air monitoring system (DAAMS) upstream of Zone 1 (the first carbon bed) of the pollution abatement system filtration system if none exists now. The addition of this DAAMS unit would document the absence of agent in the gas stream flowing to the carbon in Zone 1, even though no agent is expected to be released as a result of incineration and subsequent scrubbing of the incineration flue gases.
While current management philosophy dictates handling the used carbon as contaminated material, most of the used carbon will be unexposed even at the end of agent disposal operations, barring an airborne release on-site. Furthermore, standard operating procedures may preclude the exposure of filters in air streams that contain agent. Four key factors that reduce the agent loading on the MDB HVAC filter are these:
Keeping agent vapor levels low in Level A (the most contaminated) process areas by periodic decontamination with caustic to clean up spills and leaks.
Providing ACAMS and DAAMS monitoring between zones. A vestibule is provided to change