PROTECTION DES PONCEAUX DE DRAINAGE CONTRE LES CASTORS

BEAVER GUARD FOR DRAINAGE CULVERT

Abrégé anglais

"BEAVER GUARD FOR DRAINAGE CULVERT"
ABSTRACT OF THE DISCLOSURE
A guard is provided for placement over the upstream opening
of a culvert, to bar beavers from entering the culvert and to provide a
useful means for dislodging the dam wall which the beavers will build
against the guard.
The guard comprises a flexible grid consisting of longitudinally
extending, spaced apart steel chains, to which are welded a plurality of
transversely extending , spaced apart, rigid steel rods. The width of
the grid is sufficient to extend across the culvert opening and bear
against the culvert side wall; the length of the grid is sufficient so
that it extends along the ground surface in front of the culvert opening,
so as to be positioned beneath the beaver dam wall. Means are provided
at the upper end of the grid, for securing it to the culvert or roadway,
so that the grid remains hung over the opening. A long chain extends
from the lower end of the grid, which chain is always available to be
grasped and which may be attached to a vehicle on the roadway. This
provides a means for rolling up the grid and bringing its load of ac-
cumulated debris onto the roadway for disposal.

Revendications

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A beaver guard for placement over the upstream opening
of a drainage culvert extending across a roadway or other structure,
comprising:
a plurality of vertically spaced apart, generally horizontal,
substantially rigid rods;
at least two elongate, flexible members extending transversely
of the rods and being connected thereto to form a cohesive,flexible
grid;
the width of said grid being sufficient so that it extends
across the opening and bears against the culvert wall, the length of said
grid being sufficient so that it extends some distance along the ground in
front of the opening;
said grid having means attached to its upper end for secure-
ment to the culvert or the roadway or other structure, so that the grid
may be positioned to extend across the opening as required;
said grid having an elongate, flexible second member attached
to its lower end, said second member being of sufficient length so that,
in use, its free end is accessible to be pulled on to roll up the grid
to loosen and remove debris accumulated thereon.
2. A beaver guard for placement over the upstream opening
of a drainage culvert extending across a roadway, comprising:
a plurality of vertically spaced apart, generally horizontal,
steel rods;
a plurality of lengths of steel chain extending transversely
of the rods and being welded thereto to form a cohesive, flexible grid;
- 6 -

the width of said grid being sufficient so that is extends
across the opening and bears against the culvert wall, the length of said
grid being sufficient so that it extends some distance along the ground
in front of the opening;
the spacing of the rods being sufficiently narrow so as to
prevent the passage therebetween of a full grown beaver;
said grid having means at its upper end for securement to the
culvert or the roadway, so that the grid may be positioned to extend
across the opening as required;
said grid having a length of steel chain attached to its lower
end, said chain being of sufficient length so that, in use, its free
end is accessible to be pulled on from the roadway, to roll up the grid
to loosen and remove debris accumulated thereon.
- 7 -

Description

I 3
1 BACKGROUND OF THE INVENTION
2 Field of the Invention
3 The present invention relates to a guard for placement at the
4 upstream opening of a drainage culvértj to bar beaversifrom entering the
culvert and to provide a means for dislodging the dam which the beavers
6 will build at the opening.
7 Prior Art
7 Of the sixteen orders of placental mammals, the most plentiful
8 species are the order 'rodentia'. It is to this order that the amphibious
9 beaver (Family: Costarred) belongs.
The beaver dam is probably the first construction undertaken
11 by a beaver colony. The dam, composed of sticks, stones, roots and
12 earth, is commenced by the laying of sticks and branches in a parallel
3 upwardly extending arrangement along a narrow point of the riparian bed.
4 Stones, roots and earth are plastered onto this parallel branch frame-
work to form a first layer. The dam is constructed by the gradual build
16 up, layer by layer of a series of such solid-filled branch frameworks.
17 Uprooted culverts are rapidly dammed by beavers in this manner,
18 necessitating the use of costly excavation equipment and many man-hours
19 of labor to unplug the culvert. Further, merely maintaining unprotected
culverts in a clear condition is a laborious and expensive task.
21 Various attempts to discourage dam building within culverts,
22 exemplary of which are the use of bright, moving streamers or the like,
23 have not proved successful.
24 Conventional culvert guards are available and comprise,
in essence, a rigid wire screen secured over the culvert end. While such
26 protectors effectively prevent dam building within the culvert, they fail,
27 however, to deter the beavers From building the dam upon the screen face.
28 Such a dam must be subsequently removed in the manner previously referred
29 to.

~ll2'33l(~6;3
1 Perception of the need for a guard having rapid and inexpensive
2 clean-up capability, and a knowledge of beaver behavioral patterns have
3 been combined to provide the present device which while simple in concept,
4 is effective in use.
SUMMARY OF TOE INVENTION
6 In accordance with the present invention, there is provided a7 guard for placement over the upstream opening of a culvert. This guard
8 comprises a flexible grid which assumes a generally L-shaped configuration
g when in use. Preferably the grid comprises transverse spaced apart steel
rods welded to a pair of spaced apart, longitudinally extending steel
chains. The upwardly extending section of the grid, which covers the
12 opening, functions to bar the beavers from entering the culvert to build
the dam, and provides a base framework or lattice against which the
beavers will construct the dam wall. The foot section of the grid ox-
tends upstream some distance along the ground surface and provides a
16 movable substrate on which the dam wall will stand. The upstream end
of the grid foot section has an elongate member or tail attached thereto
18 such as a length of steel chain, which can be pulled on, to partially
19 roll up the grid, thereby dislodging the mass supported by it. The backed-
up water will then swiftly wash the packed earth out of the dislodged
21 wall, leaving a light, mainly wooden assemblage which can relatively
22 easily be rolled onto the roadway by continuing to pull on the tail chain.23 The guard is characterized by a number of advantages and
24 characteristics, namely:
(1) it does not normally interfere with the flow of water
26 through the culvert
27 (2) it is characterized by load-bearing capability so that it
28 can be used to dislodge and manipulate the dam mass
29 supported by it, to start the water flowing, which water
then does most of the work in removing heavy components,
31 particularly the earth, that assist in making up the dam,

slob
1 (3) the tail chain is readily accessible and a.car.or.truck
2 can be tied onito.itj to provide the pull needed to first
3 dislodge the.dam:.and then draw the grid onto the roadway
4 to recover the residue material;
(4) the grid is operative to-keep the beaver out of the
6 culvert;
7 (5) the beaver will start their construction immediately
8 against the grid, sup that the dam Hall ends up being
9 positioned on the foot section; and
(6) because the guard can be very quickly cleaned, it is
11 feasible to use a frequent maintenance schedule, to avoid
12 permitting the beaver to build up the dam wall to a point
13 where it becomes difficult and time-consuming to break it
14 down.
DESCRIPTION OF THE DRAWINGS
16 Figure 1 is Kaplan view of the guard; and
17 Figure 2 is a perspective view of the guard in place over a
18 culvert opening.
19 DESCRIPTION OF.THE~PREFERRED EMBODIMENT
The guard 1 comprises a flexible grid 2 formed by welding
21 a plurality of transversely extending, spaced apart, steel rods 3 to a
22 pair of spaced apart, longitudinally extending steel chains 4.
23 The rods 3 are spaced apart about 4", to prevent a full-sized
24 beaver from squeezing there between.

1.231~b~3
l The chains 4 are~brought-~ogether at their upper ends and
2 joined to form a loop 5. This loop 5 may be secured to the culvert 6
3 by hanging it over the bent back upper lip 7 of the culvert. The
4 loop 5 therefore provides means, attached to the upper end of the grid
2, for Sacramento to the culvert or the roadway or the structure through
6 which the culvert extends, so that the grid may be positioned to extend
7 across the culvert opening I as required.
8 The chains 4 are also brought together at their lower ends
9 and a long tail chain 9 secured thereto.
The grid 2 is sufficiently wide, for example about 4" wider
if than the diameter of the culvert, so that it will extend across the full
12 diameter of the culvert opening 8 and bear against the side edges of the
3 culvert 6. The length of the grid 2 is sufficient so that it will extend
4 along the ground surface lo in front of the culvert opening 8, perhaps three
feet, to provide a foot section if which will underlie the dam (not shown.
16 In use! the grid's upper section 12 extends across the culvert
7 opening. The transverse rods 3 prevent the beavers from entering the
18 culvert 6 and building their dam therein. The beavers when barred in
19 this manner, normally use the grid upper section 12 as the dam wall frame
and build against it. The grid foot section if thus underlies the dam.
21 When the dam is to be removed, the long tail chain 9, whose end is left
22 accessible on the bank of the stream, is attached to a vehicle on the
23 roadway. The vehicle can then be backed up and rocked to roll up the grid
24 2 to a limited extent. This loosens the dam mass and the backed up water
seeps through. In short order, the flow becomes a turbulent stream and
26 the heavy earth in the dam is washed away, leaving a relatively light
27 assemblage of branches and the like. The vehicle can then be backed
28 up further to roll this debris onto the roadway.
29 The scope of the invention is defined by the following claims.
- 5 -