Alabama Wastewater Collection Grade 1C Practice Test 2026 – Complete Exam Prep

The situation that likely causes the most wear on pump impellers is the presence of grit in wastewater. Grit, which includes sand, silt, and other abrasive particles, can be quite damaging to the surfaces of pump impellers. When these abrasive materials flow through the pump, they can create erosion on the impeller blades, leading to reduced efficiency, increased vibration, and ultimately, failures over time.

The impellers are typically designed to handle liquid flows, and the addition of solid particles, especially those that are sharp or angular, significantly increases the wear and tear on these components. This wear can result in costly maintenance and downtime, as impellers may need to be repaired or replaced more frequently when grit is present in the system.

The other situations listed, while they can impact pump operation, do not typically contribute to mechanical wear in the same direct manner as grit does. For instance, velocity head and feet of head are more related to hydraulic conditions rather than physical abrasiveness, and running the pump dry, while harmful, usually leads to overheating or cavitation, not wear from abrasive substances.