Maintenance Hole Design Calculator
Maintenance hole depth, internal geometry and indicative concrete volume.
Inputs
Results
Maintenance hole depth
3.40m
Ground level less invert level · external diameter 1.50 m
Dimensional and indicative quantity information only. Excludes benching, cone, cover slab, step irons and pipe penetrations. No structural design check is performed.
Calculation details
Engineering equations
Depth = ground level − invert level
D_o = D_i + 2t
V_wall = (π / 4)(D_o² − D_i²) · (depth − t_b)
V_base = (π / 4) · D_o² · t_b
Variables
- D_i
- Internal diameter (m)
- D_o
- External diameter (m)
- t
- Wall thickness (m)
- t_b
- Base thickness (m)
- Depth
- Ground level less invert level (m)
- V_wall
- Indicative wall concrete volume (m³)
- V_base
- Indicative base concrete volume (m³)
Assumptions
- Indicative concrete volume only.
- Excludes benching, cone, cover slab, step irons and pipe penetrations.
- Internal geometry is a plain vertical cylinder.
- Dimensional and quantity information only; no structural design check is performed.
Worked example
Ground level 25.00 m, invert level 21.60 m, D_i = 1200 mm, wall 150 mm, base 200 mm
Depth = 3.40 m, D_o = 1.50 m
Wall volume = 2.04 m³, base volume = 0.35 m³
Indicative concrete volume = 2.39 m³
Results are preliminary engineering estimates based on the stated assumptions. Confirm inputs, assumptions and requirements against the applicable standards and authority requirements before use in design or construction.