Differentiate hydrant flushing from system flushing in distribution maintenance.

Differentiate hydrant flushing from system flushing in distribution maintenance.

• A. Hydrant flushing is used only for cleaning hydrants; system flushing cleans the entire treatment plant.
• B. Hydrant flushing changes chlorine residuals; system flushing does not affect residuals.
• C. Hydrant flushing is performed monthly; system flushing is performed weekly.
• D. Hydrant flushing targets local zones and dead-ends; system flushing is a broader approach to clean the distribution network and verify residuals.

Answer: (D)