Purpose of Bench-Scale Tests

Bench-scale testing is conducted to establish the short-term construction costs, long-term maintenance costs, and long-term success of a solidification/stabilization project. The effect of these factors on project success is summarized below:

• Construction Costs: Reagent costs for solidification/stabilization projects typically account for at least 12 to 15% of the total project costs. When the costs for mixing, placing, compacting, and testing the treated material are included, the bench-scale tests deal with aspects of the project that account for about 30 to 40% of the total construction costs (with the remainder being site preparation, construction of liners and caps, etc.). Hence, minimizing reagent costs through bench-scale testing can greatly benefit the project budget.
   
• Maintenance Costs: If leachate migrates from the cell, it can impact adjacent groundwater, potentially causing additional remedial action and costs. The potential for leachate development can be evaluated through bench-scale tests.
   
• Long-Term Success: Proper waste treatment provides long-term environmental protection and alleviates some of the long-term maintenance, monitoring, and liability costs. Although leachate migration can be greatly reduced by placing waste in a cell with a low-permeability liner and a sloped cap, even the U.S. Environmental Protection Agency (1989) acknowledges that these features cannot guarantee that water or leachate will not enter or exit the disposal cell. Furthermore, liners tend to degrade over time through desiccation, settlement, burrowing rodents, seismically-induced liquefaction, etc. If the liners fail and the waste is poorly stabilized, then the environmental protection goals of the project may not be realized despite considerable expense and effort. However, if the waste is thoroughly and properly stabilized, then the impact of liner failures can be negated.  The degree of solidification/stabilization can be evaluated through bench-scale tests.

Reference

U.S. Environmental Protection Agency. 1989. Requirements for Hazardous Waste Landfill Design, Construction, and Closure. Center for Environmental Research Information, Office of Research and Development. Cincinnati, Ohio.