ANS:C - 0.7 to 0.9 m

A manhole depth between 0.7 to 0.9 meters generally falls within the classification of a medium-depth manhole. Here's an explanation of this classification:

1. Medium-Depth Manhole: Manholes within the depth range of 0.7 to 0.9 meters are considered medium-depth manholes. They are designed to provide access to underground utility lines, sewer systems, or other infrastructure components that require periodic inspection, maintenance, or repair.
2. Characteristics: Medium-depth manholes typically have a circular or rectangular shape with dimensions suitable for workers to enter and perform necessary tasks safely. They may have ladder rungs or steps for access and are often equipped with covers or lids to prevent unauthorized entry and to protect against environmental elements.
3. Applications: Medium-depth manholes are commonly used in urban and suburban areas where underground utilities are present but are not excessively deep. They may be found along roadsides, sidewalks, or in utility corridors where access to underground infrastructure is necessary for maintenance and repair purposes.
4. Construction and Maintenance: Constructing and maintaining medium-depth manholes requires careful planning and adherence to safety standards to ensure the integrity of the structure and the safety of workers. Regular inspection and maintenance are essential to identify and address any issues that may arise over time.