Manhole Diameter
(feet)
|
Wall Thickness
(inches)
| |
---|---|---|
4
|
5
| |
5
|
6
| |
6
|
7
| |
6 1/2
|
7 1/2
| |
7
|
8
|
All sections shall be cast solid, without lifting holes. Flat-top
slabs shall be a minimum of eight inches thick and shall be capable
of supporting an H-20 loading.
|
Manhole Depth
(feet)
|
Manhole Diameter
(feet)
|
Time to Drop 1 inch Hg
(10 inches to 9 inches)
| |
---|---|---|---|
10 or less
|
4
|
120 seconds
| |
10 to 15
|
4
|
150 seconds
| |
15 to 25
|
4
|
180 seconds
|
For five-foot diameter manholes, add 30 seconds to the time
above.
| |
For six-foot diameter manholes, add 60 seconds to the time above.
|