The passive components of a containment system listed in Fig. 1 are those that do not require a continuous input of energy. Typical examples of passive components include drain tile collection system, barrier walls, caps, and liners. Passive components require input of energy to maintain their operational mechanisms. Passive components can be further divided into three major subsystems.
1. Hydraulic barrier wall,
2. Top seals (cap, covers), and
3. Bottom seals (liners).