Proportionate flow chart.
Therefore the actual
invert at the lower manhole is the
elevation of the invert of the upper
multiplying the velocity ratio by the
manhole less the product of the slope
multiplied by the length of the sewer
example, the full flow velocity was
found to be 3.2 feet per second and
elevations of the upper manhole will
the velocity ratio 1.045.
be known for each section except the
the actual velocity will be (3.2 x
The invert at the first
1.045) = 3.34 feet per second.
manhole will usually be made as close
to the ground level as possible while
10 feet per second.
If lampholes are
still maintaining adequate cover.
to be used, then the velocity must be
17. SAMPLE DESIGN PROBLEM
at least 3 feet per second.
elevations can be determined once the
slope is known.
The elevation of the
For use with sample design (issued as separate item).