MIL-HDBK-1005/16
designed utility trench. For buried lines, apply general sewer
pipe selection guidelines.
Table 7
Special Pier Structures and Appurtenances
Structure or
Appurtenance
Where to Use
Details
Requirements
See Figure 4
In-line
At junctions and
cleanout
changes of direction
and when required
according to spacing
shown in details
under regular
manhole below
See NAVFAC
Regular
Terminally on all
Lower invert
Guide Spec
manhole
lines; at all
through manhole
NFGS-02530,
junctions and
a distance equal
Sanitary
changes of direc-
to expected loss
Sewage
tion; at changes in
of head in
invert elevation or
manhole, plus
slope. Otherwise,
0.8 times any
according to spac-
change in sewer
ing shown below:
size. For
junction man-
Pipe
holes, check
Size
Max
which upstream
(in. Spacing
invert is
[mm]) (ft [m])
critical in
determining
18(450)
400(120)
outlet invert.
or less
Raise top of
18-48
500(150)
manhole above
(450-1200)
possible
flooding level.
48(1200)
600(180)
and greater
See NAVFAC
For difference
Drop manhole
When difference
less than 2 ft
between inlet and
Guide Spec
NFGS-02530
(0.6 m),
outlet inverts
increase
exceed 2 ft (0.6 m)
upstream sewer
slope to
eliminate drop.
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