Method and means for improved erosion control

Means for improved erosion control comprising a concrete module having a base, two upwardly extending sidewalls, an upwardly extending rearwall, a wave-disrupting ramp extending between the side walls from the base to the rear wall, and holes to aid in lifting and placement of the module and to link adjacent modules where a plurality are used to build a breakwall. A method for controlling erosion due to wave action comprising at least one module, and preferably fastening together a plurality of modules with flexible means thereby causing interference with wave action while permitting the individual modules to conform to wave action and bottom conformation.

BACKGROUND OF THE INVENTION 
This patent is a continuation-in-part of U.S. pat. application Ser. No. 
870,155, filed June 3, 1986. Now abandoned. 
1. Field of the Invention. 
The present invention is in the field of hydraulic and earth engineering; 
more specifically, this invention is in the field of improved wave 
dissipation and erosion control. 
2. Description of the Prior Art. 
In the field of erosion control and specifically in the area of protecting 
or restoring beaches where wave action tends to move sand onto and away 
from any given area over a period of time, many methods have been utilized 
in attempts to maintain an existing beach or to restore one which has been 
washed away. The methods vary in their cost and their effectiveness. For 
instance, a moderately effective but extremely expensive erosion-control 
means is the building of a wall or jetty or riprap slightly upstream or in 
the direction receiving the general wave action. The resulting wave action 
then breaks on the wall or jetty, which causes turbulence in the wave 
pattern and causes the flow of water to diminish in the desired beach 
area. With the interruption of water flow, suspended particulate material, 
generally sand, drops to the bottom and in a relatively short time forms a 
beach which is predominantly upstream and, to a lesser extent, downstream 
from the wall. The beach will be uneven due to the larger quantity of sand 
buildup on the upstream side of the jetty. 
As noted above, the jetty construction is very expensive and requires heavy 
equipment for the emplacement of the rock. Further, the rock must be 
massive and hard; sandstone or shale, for instance, would be unsuitable. 
Therefore, in addition to the heavy equipment, a suitable source of rock 
must be available within an economic distance. 
Where the economics of a source of massive rock do not permit its use, 
large wire baskets containing smaller rocks have been used. While this 
method is less costly to install because heavy equipment is not required, 
the wire tends to corrode and erode with time and the movement of the rock 
within the basket causes mechanical failure of the basket. Further, 
flotsam impelled into the basket by storm turbulence can bend and break 
the baskets. As a result, the rocks become dislodged which leads to a 
diminution of the effectiveness of this type of erosion control. 
In an attempt to meet the problems described above, various methods have 
been tried. Campbell, in U.S. Pat. No. 3,875,850, describes a massive 
modular erosion-control device formed of concrete. The design of the 
module causes an impinging wave to break and drop the suspended sand. 
Morren, in U.S. Pat. No. 3,953,976, shows a wall formed of modules 
hingedly affixed at their ends. Rankin, in U.S. Pat. No. 4,297,052, shows 
a number of units installed and fastened rigidly together, no provision 
being made for relative movement among the units used. He teaches that 
under some circumstances, it is necessary to add sandbags to help retain 
sand and gravel from lake wave action. 
In some devices employed for the protection of beach area, the weight of 
the device, combined with fairly constant low-amplitude motion induced by 
wave or current, causes the device in effect to burrow, or settle, into 
the floor beneath the body of water. Over time, the device can practically 
cease functioning as a wave-disrupting mechanism, requiring replacement of 
the device or more effort in placing new devices. This severely limits the 
effectiveness of such devices for protection of a beach. 
None of the devices of references cited or the existing art have protected 
beaches and stopped erosion with the same economy and efficiency as the 
present invention. 
SUMMARY OF THE INVENTION 
Therefore, it is the object of the present invention to provide a new and 
improved water erosion control device. 
Another object of the present invention is to provide an erosion control 
module which dissipates wave energy and retains sand along lake shores. 
A further object of the present invention is to provide erosion control 
modules attached together by cables to form a continuous break wall which 
can conform to irregular shoreline contours and prevent cracking of the 
modules due to wave induced stresses. 
A still further object of the present invention is to provide a portable 
erosion control module which can be manufactured and transported to the 
erosion site. 
Another object of the present invention is to provide an erosion control 
module which is capable of dissipating wave energy while not sinking into 
the lake bottom on which it is installed. 
A further object of the present invention is to provide an erosion control 
module which prevents scouring of sand from beneath the module by wave 
action.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention provides improved control of water erosion and 
includes a concrete module having a base, two upwardly extending side 
walls, an upwardly extending rearwall, a wave-disrupting ramp extending 
between the side walls from the base to the rear walls and holes to aid in 
lifting and placement of the module and to linking adjacent modules where 
a plurality are used to build a breakwall. The method of the present 
invention includes setting the module on the floor of a body of water 
while the open end oriented to receive waves and current flow and 
connecting the modules together with cables to form a breakwall shaped as 
necessary to conform to a shoreline. 
In the present invention, the module, singly or in combination with others, 
is set offshore to protect existing shorelines and structures, and to 
build a substantial beach. As a wave strikes the unit, both the spray and 
some of the flowing water pass up the ramp over the rear wall and through 
the holes in the side walls and rear walls to deposit sand in the quiet 
zone behind the module. The design of the module causes wave action from 
any direction to be dissipated--a result not obtained with other designs. 
Stated alternatively, while the performance of the module is best when its 
open end is oriented toward the direction from which the water flows, the 
module has proven effective in all aspects of installation and its 
protective effect is substantially independent of wave direction. 
As shown in attached FIGS. 1, 2 and 3, the erosion control module, 
generally indicated with the reference numeral 10, has a base 11, upwardly 
extending and rearwardly converging left and right side walls 12 and 13, 
rear wall 14, and ramp 15 extending from the base to a central location on 
rear wall 14. First hole 16 and second holes 17 in rear wall 14 permit a 
portion of water flowing into the space defined by base 11, side walls 12 
and 13, and rear wall 14 to pass through the module. 
This feature reduces the net force exerted on the module by wave or current 
action, and contributes to a longer life of a breakwall than would be the 
case without the holes. 
Base 11 provides a large surface area over which to distribute the weight 
of the module thereby reducing the bearing pressure of the module on the 
bottom of the body of water and preventing settling of the module as has 
occurred with other erosion control devices. The portions of the base 10 
which extend outside the side walls 12 and 13 increase the bearing area of 
the base and contribute to stability of the module as sand builds up over 
these portions of the base. 
The side walls 12 and 13 converge toward the back of the module to reduce 
the instantaneous build up of pressure on the module thereby reducing 
overturning forces applied to the module by the wave action. 
Ramp 15 assists in directing a wave, entering the module, to flow 
vertically up the back wall 14 and into the air over the module which 
dissipates the wave energy as most of the water falls back into the 
module. The water falling back into the module is directed by the ramp 15 
and base 11 horizontally back out the front of the module which causes a 
build up of sand forming a ledge of sand in front of the module. This sand 
ledge protects the module from the scouring of sand from beneath the front 
edge of the base which makes the module more stable than any other 
previous erosion control device which is not anchored to the lake bottom. 
The reaction from the water being diverted vertically from the module 10 
tends to hold the module against the lake, ocean or river floor beneath 
the body of water, rendering it even more stable and effective. 
Holes 16 and 17, along with third holes 18, fourth holes 19 and fifth holes 
20, each provide a dual purpose. Holes 16 and 20 are located in rear wall 
11 and side walls 12 and 13 on a line passing through the center of mass 
of the module. Holes 17 are located in rear wall 11, above the center of 
mass, and holes 19 are located in arms 12 and 13 below the center of mass. 
The holes thus located are useful in handling the module for emplacement 
with holes 20 permitting general handling by means of a wire sling and the 
other holes affording control over yaw, pitch and roll as required. 
After the module has been placed where desired and the handling slings 
removed, the various holes, particularly 18, serve to permit the modules 
to be fastened together as required as well as allowing water to pass 
through and thus decreasing the net force exerted on the resulting 
structure, while providing a continuous breakwall where desired. 
The mass of the module and its construction of reinforced concrete provides 
resistance to the force of the water. Those skilled in the art will 
further realize that the holes in the modules are useful in fastening one 
or a plurality of modules to the floor of the body of water in which the 
modules are emplaced, as a further or alternative means of preventing 
movement of the modules. This feature is especially utilitarian to prevent 
movement due to ice masses in installations in the Great Lakes. 
The perspective view of FIG. 1 shows a plurality of the modules of the 
present invention fastened together by fastening means 21 to form a 
breakwall. In such an arrangement, any of the holes can be used with 
fasteners to attach adjacent modules together in the manner shown with the 
fastening 21 through holes 18. Those skilled in the art will realize that 
this permits modules 10 to be fastened in a wide variety of configurations 
to accomodate either a desired shore or beach conformation or to take 
advantage of a particular underwater bottom configuration. 
Further, while FIG. 1 shows the modules with their arms 12 and13 juxtaposed 
toward the flow of the water, the modules can be staggered or assembled in 
a configuration most suitable for the bottom conditions and current flow. 
In the method of this invention, the modules 10 are placed individually, if 
the shoreline or beach requirements so permit and if the wave action or 
current is relatively gentle, or fastened together to form a continuous 
breakwall as shown in FIG. 1, if the current or wave action is severe. 
Preferably, the modules are fastened with bases 11 juxtaposed adjacent the 
beach, and side walls 12 and 13 directed generally toward the oncoming 
wave or current action. As noted hereinabove, it is within the spirit and 
scope of this invention to fasten the modules together in interlocking 
fashion if conditions require that configuration and with side walls 12 or 
13 toward the predominant wave action. 
Fastening means 21, shown in FIG. 1, is a flexible means, preferably one 
which is resistant to corrosion caused by water and air. Wire rope, 
preferably stainless steel, or a high-strength polymeric material such as; 
e.g., poly)phenylene terephthalamide) fiber, woven or braided glass fiber, 
or other corrosion-resistant flexible material, is chosen for fastening 
the modules. By the use of flexible fastening, as already noted, the 
modules 10 can be arranged in other than a straight-line breakwall, 
providing an ability to sculpture the desired beach or to conform to an 
existing shoreline or lake or river bottom. Further, where the wave action 
is vigorous, such as may be encountered with ocean waves or storms on the 
Great Lakes, a wave strong enough to cause relative movement between 
adjacent modules will not fracture the breakwall itself or shear the 
fastening between the modules, which could be the case if the modules were 
fastened rigidly. 
Also in consideration of the utility of the modules on the Great Lakes, the 
action of the masses on a breakwall constructed in accordance with the 
present invention generally will not shear the flexible fastening between 
modules, even though the action of the ice may be enough to move the 
entire wall. In this case, the wall could be moved a small distance by an 
unusual mass of ice driven by a strong current or wind action, but the 
likelihood of separation of the modules is minimal. 
A further advantage of the present method inheres in the flexible 
fastening. In the event that a fastening between modules is broken through 
any combination of circumstances, it is unnecessary to secure realignment 
of the modules to fasten them together again. In this case, a single 
worker with or without breathing apparatus could thread a new cable 
through adjacent holes 18 and tighten it as necessary without moving the 
modules, having a crane brought in, or building a cofferdam around the 
site. 
Those skilled in the art will realize that ramp 15 can be flat, as depicted 
in the drawings, a series of discrete steps, or curved. The surface of 
ramp 15 can start asymptotically with the base rising through an ascending 
angle until meeting rear wall 20 asymptotically at its surface, such as 
paraboloid or hyperboloid. The choice of ramp surface characteristic is a 
function of the nature of the current encountered and the shoreline to be 
protected. 
While not shown in the drawings, those skilled in the art will realize that 
under some extreme circumstances, such as on the Great Lakes, where ice 
movement can disrupt movable devices, the modules can be fastened into the 
floor of the body of water. This can be effected in any number of ways 
such as drilling into base rock and employing rock anchors, and using 
cement in a natural or prepared hole. 
The alternative embodiment of the present invention shown in FIGS. 4, 5 and 
6 includes the module 10' with base 11' and rearwardly converging left and 
right sidewalls 12' and 13' having outwardly diverging portions 22 and 23 
which, with rear wall 14', form a pocket to contain rocks 24. The rocks, 
preferably 20 to 30 inches in diameter, are contained in this pocket by a 
grate 25 across the front of the pocket and a grate 26 over the top of the 
pocket which prevents wave action from moving the rocks. The purpose of 
the rocks in this embodiment is to help dissipate the wave energy and 
reduce the amount of spray created by the module. 
Grates 25 and 26 are formed by cutting rectangular openings 27 in sheet 
metal configured to slide beneath guide way 28 and 29 formed in the 
module. Holes, similarly located as those in module 10, can be formed for 
lifting and attaching adjacent modules. Other devices for lifting and 
attaching modules, such as depressions or hooks, can be used in this 
invention. In this alternative embodiment, the side walls 12' and 13' have 
sloping front edges 12" and 13" which reduce the overturning moment on the 
module caused by the pressure of water striking these edges. Preferably, 
front edges 12" and 13" form a 67.5.degree. angle with the base 11. 
Rock can be installed in the preferred embodiment of the invention to 
accomplish the same results. 
An addition alternative embodiment of this invention would be to eliminate 
the rear wall 14 and ramp 15, as shown in FIGS. 1, 2 and 3, and have side 
walls 12 and 13 converge together toward the rear of the base. This 
configuration will perform efficiently; however, it has been found to wear 
rapidly. 
From the foregoing detailed description, it will be evident that there are 
a number of changes, adaptations and modifications of the present 
invention which come within the province of those skilled in the art. 
However, it is intended that all such variations, not departing from the 
spirit of the invention, be considered as within the scope thereof as 
limited solely by the appended claims.