Manhole classification by depth: A manhole is considered “shallow” when its depth (from cover to invert) lies approximately within which range?

Introduction / Context:
Manholes provide access for inspection, maintenance, and ventilation of sewers. They are commonly classified as shallow, normal, or deep based on depth, which guides structural detailing and safety measures.

Given Data / Assumptions:

• Depth measured from finished cover level to sewer invert.
• Conventional municipal practice for classification.

Concept / Approach:
Shallow manholes serve near-surface sewers and small changes in direction or grade. Typical reference ranges place shallow manholes around 0.7 m to 0.9 m depth, normal up to about 1.5 m, and deep beyond that, subject to local codes.

Step-by-Step Solution:
Review common classification bands used in standard texts.Select the range that corresponds to “shallow.”Confirm that other ranges represent normal or deep manholes.

Verification / Alternative check:
Design handbooks and examination references repeatedly cite 0.7–0.9 m as the depth range for shallow manholes in conventional practice.

Why Other Options Are Wrong:
0.4–0.7 m: too small for standard shallow manholes; often used for inspection chambers.0.9–1.5 m: more typical of normal manholes.

Common Pitfalls:

• Confusing small inspection chambers with manholes capable of entry.
• Ignoring site-specific safety requirements that may redefine categories.

Final Answer:
0.7 m to 0.9 m