How the waste has been handled at the generator site, usually at a central accumulation area, can have a significant impact on the cost of the off-site disposal operation. This usually depends on the method of preparation of the waste for disposal. Collecting containers of waste in a Lab Pack is usually much more expensive for ultimate disposal than is commingling of compatible wastes, partly because a 55-gallon Lab Pack only holds about 16 gallons of waste. However, factors other than economics may control those decisions. When small amounts of different wastes are generated, a situation typical of many academic laboratories, commingling compatible wastes may not be practical. The Lab Pack approach is usually chosen. On the other hand, waste solvents can often be combined advantageously, even in small operations.
On-site storage time limits also must be considered. For those generators that are governed by the 90-day limit, yet are relatively small operations, it is difficult to accumulate sufficient materials to make commingling a favorable option.
Safety can often be the determining factor. Using Lab Packs is quite simple. As described above, small containers of compatible waste materials are placed in a larger container, usually a 55-gallon drum, along with appropriate packing materials, as they are collected. When a drum is filled, it is sealed and ready for shipping. An inventory list of the contents of a Lab Pack is required for shipping and is usually requested by the TSDF.
In contrast, commingling requires opening of containers and transferring their contents from the smaller laboratory containers to a larger drum. Here the potential risk for workers is much greater. Furthermore, the containers should be rinsed before they are considered nonhazardous, and the rinsate must be treated as a hazardous waste. Drums of commingled waste usually require only a general hazard classification identification, although some TSDFs require an analysis or listing of contents.
Because the long-term liability for the waste remains with the generator, it is imperative that the generator be thoroughly familiar with the experience and record of the transporter and TSDF. Economic factors alone should not govern choices, for the long-term consequences can be significant. The generator must obtain assurance, in terms of documentation, permits, records, insurance and liability coverage, and regulatory compliance history, that the chosen service provider is reliable.
There is often an advantage, particularly for smaller facilities, to contracting for all of the hazardous waste disposal operations. These include the packing and appropriate labeling of waste for off-site transportation and disposal, preparation of the shipping manifest, and arranging for the transporter and disposal facility. Again, the liability remains with the generator, and so the choice of such a contractor is critical.
In some states, Minnesota and Montana, for example, arrangements have been developed with local regulators to allow a large laboratory waste generator to handle the waste from very small laboratories such as those at small colleges and public schools. This plan results in informed assistance and cost savings for the smaller units. In Wisconsin, a statewide commercial contract that can be accessed by all state educational systems has been arranged. There is usually significant advantage to working with local and state agencies to develop acceptable plans for disposal methods that are environmentally and economically favorable for both large and small generators.
Multihazardous waste is waste that contains any combination of chemical, radioactive, or biological hazards. The combinations of these hazards are illustrated in Figure 7.2. Although many of the principles discussed for chemically hazardous waste earlier in this