low angle side slopes which shall not obscure observation from a 4-foot (1.2-
m) high line of sight above grade of roadway.
Signs. Perimeter security fences for restricted areas will be
posted with signs. See OPNAVINST 5530.14B. Signs will be posted on security
fences at no less than 200-foot (60.9-m) intervals along the entire perimeter.
If the perimeter is the exterior wall of a building or structure, it will be
posted at the point of ingress. Where a language other than English is
prevalent, warning signs will be posted in both languages.
For nuclear sites, signs will be provided as prescribed in
paragraph 3-701, Warning Signs, of OPNAVINST C8126.1. When military working
dogs will be used with security forces, appropriate warning signs will be
provided as prescribed in Appendix A of OPNAVINST C8126.1.
Drainage Culverts and Utility Openings. Special protective
measures must be designed for culverts, storm drains, sewers, air intakes,
exhaust tunnels, and utility openings, that:
Pass through cleared areas.
Traverse under or through security fences.
Have a cross-section area of 96 square inches (61,939 square
mm) or greater, with the smallest dimension being more than 6 inches (152.4
Such openings and barrier penetrations will be protected by
securely fastened grills, locked manhole covers, or other equivalent means
that prevent entry or provide security penetration resistance of approximately
10 seconds. When grills are fabricated for this purpose, they may be made by
cross-hatching 3/8-inch (9.5-mm) steel bars 9 inches (228.6 mm) on center.
The bars will be welded at their intersections. Grills used for culverts will
always be placed outside the secure area. For steel pipe, the grill ends will
be welded to the pipe as shown in Figure 2. For concrete pipe, the grill ends
will be welded to a steel rim that fits snugly over the concrete pipe. The
rim and grillwork will be fastened over the concrete pipe and bolted or pinned
to the rim of the concrete pipe as shown in Figure 3. As an alternative, the
grill ends can be embedded in a concrete headwall that encapsulates the
concrete pipe. Care must be taken during design to assure that bars and
grills across culverts, sewers, storm drains, etc., are not susceptible to
clogging. This must be considered early during the security fence planning
phase. Culverts, storm drains, and sewers must be designed with a debris
catcher to permit either rapid clearing or removal of grating for cleaning
when required. If the inlet is outside the fence line, the debris catcher and
grating will be incorporated into the same structure. If the outlet is
outside the fence line, the debris catcher will be on the inlet side inside
the fence line and the grating on the outlet side. A solution is shown in