Removable Grating for Culverts.
As an alternative, drainage structures may be constructed of
multiple pipes, each pipe having a diameter of 10 inches (254 mm) or less,
joined to each other and to the drainage crossing. An economical solution to
secure metal drainage structures is to weld short (approximately 6-inch
(152.4-mm) long) multiple pipes, with diameters less than 10 inches (254 mm),
in the "in-flow" end of the drainage culvert as shown in Figure 5.
ditches or swales, the designer must assure that the intruders are prevented
from passing under the fence. Where water flow is minor and generally not a
problem, the main fence may be carried across a ditch or swale with additional
fence added below. The fence added below must be attached every 2 inches
(50.8 mm) along the intersection of the two fence sections and either attached
to a series of ground stakes secured to the sides and bottom of the ditch, or
embedded in a concrete sill in the ditch or swale (see Figures 6 and 7).
Where heavier flows of water are anticipated, a cross-hatched
screen type arrangement must be provided below the fence using vertical and
horizontal bars similar to those described in the above paragraph. The flow
capacity must first be analyzed to determine the size grillwork that will
accommodate the maximum amount of water that may be experienced. Rainy
seasons and possible debris that can be carried by the flow must be taken into
In any case, not more than 9 inches (228.6 mm) will be allowed
between either vertical or horizontal bars, and bars will be welded at each
intersection (Figure 8).