Testing and Performance Criteria for Stabilized/Solidified Waste Forms - Stabilization and Solidification of Hazardous, Radioactive, and Mixed Wastes - page 306

TABLE 11.8
Key Properties and Performance Indicators of S/S Waste Forms 15

Level Key Property Performance Indicator Expression

1 Contaminant Concentration Contaminant Concentration mg/kg

Initial Leachate Concentration Initial Leachate Concentration mg/L of Leachate

Availability for Leaching Amount of Contaminant

Available for Leaching

mg/kg

Equilibrium-Based Assessment
(over a range of pH values and
liquid-to-solid ratios)

Equilibrium-Based Assessment
(over a range of pH values and
liquid-to-solid ratios)

mg/L of Leachate

2 Mass Transfer Assessment Contaminant Mobility Leachability Index

Physical Property Hydraulic Conductivity m/s

Compressive Strength MPa

Durability Freezing/Thawing Cycles % mass loss

Wetting/Drying Cycles % mass loss

Biodegradability [pass/fail]

S/S materials for co-disposal with municipal garbage where they have failed to
satisfy the other three scenarios, provided it is within the acceptable limits of the
landfill. However, it should be mentioned that with the new regulations being set up
(described in Section 11.5.2), the above landfill scenarios might no longer be viable.

11.6.3.2 Evaluation Approach

In order to decide the utilization and disposal scenarios for S/S waste forms, several
key properties of S/S wastes related to their potential environmental impact in
utilization and disposal scenarios should be evaluated, as shown in the second column
of Table 11.8. One or several performance indicators are used to characterize each
key property as listed in the third column of Table 11.8. A performance indicator is
a direct experimental result that is used as a measure of a key property. The perfor-
mance indicators can be divided into two levels of containment: Level 1: containment
by chemical immobilization, and Level 2: containment by physical entrapment.
A flowchart of the procedure used to evaluate an S/S waste against this protocol
is shown in Figure 11.2. First, the waste is subjected to Level 1 testing. The results
are then compared against the Level 1 criteria for unrestricted utilization (denoted
as “A” in Figure 11.2). If the waste passes the criteria, it is acceptable for unrestricted
utilization. If it fails, the Level 1 results are compared with the Level 1 criteria for
controlled utilization (“B”). If the waste passes these criteria, it is acceptable for
controlled utilization. If it fails, either the Level l results are compared with the Level
1 criteria to determine if the waste is acceptable for disposal in a segregated landfill
(“C”), or Level 2 testing is conducted to determine if the waste is acceptable for
controlled utilization based on Level 2 criteria. This decision procedure can be
repeated as indicated in Figure 11.2 to determine the suitability of the waste form
for the remaining disposal scenarios. If the waste form fails both the Levels 1 and 2