WO2020146586A1 - Erosion control and turf reinforcement mat - Google Patents

Abstract

An erosion control and turf reinforcement mat includes an upper layer having an underside and a plurality of clusters of upwardly extending, cantilevered blades and defining a plurality of growth gaps dispersed between the clusters; a middle layer comprising a sheet defining a plurality of through holes and connected to the underside of said upper layer; and a lower layer comprising a geotextile fabric mat connected to the underside of said middle layer.

Description

EROSION CONTROL AND TURF REINFORCEMENT MAT

Field of the Invention

The present invention relates to environmental control devices, and more particularly, to erosion control and turf reinforcement mats.

Background of the Invention

Erosion control products are applied to slopes, berms, earthen dams/levees, shorelines, culvert outlets, pipe outfalls and other high flow channels to protect from the highly erosive forces of flowing water before, during and after vegetation establishment.

Temporary products, referred to as erosion control blankets (ECBs) are typically made of natural materials, which are bio- and photo-degradable. Typical of such materials include straw, coconut, and wood excelsior fiber. For more severe applications such as high flow drainage channels, more permanent products and materials include synthetic turf reinforcement mats (TRMs). Currently available ECBs and TRMs consist of organic and/or synthetic fibers and filaments, oriented in a generally parallel fashion to the mat structure and corresponding soil contour, which are held in place by nettings or meshes, or which may be extruded or woven into the mat structure. Also, for more severe applications such as high flow drainage channels, erosion protection products may comprise large rock riprap, tied concrete block mats and other“hard armor” linings.

Currently available TRMs and ECBs do not provide the immediate aesthetic appeal or protection of natural grass. The generally parallel orientation of the fibers or filaments within these blankets and mats forms a generally planar top and bottom surface with spaced apertures to allow for vegetation growth through the mat structure. The planar top surfaces of these materials do little to reduce the force of water flowing over the mat and penetrating the mat through its apertures, which makes the mat prone to uplift away from the soil surface during flow events and results in significant soil erosion beneath the mat structure. Moreover, the planar bottom surfaces of these materials do nothing to help adhere the mat to the soil surface to prevent such uplift in flow, or to impede flow velocity and soil/seed movement beneath the mat. Efforts to improve these mats have included adding more fibers and reducing the size and/or number of apertures within the mat structure, but decreasing size and/or number of apertures and increasing the horizontally oriented fibers, which are perpendicular to budding vegetation growth beneath the mat, then impedes vegetation growth and emergence through the mat.

The following United States Patents are representative of such erosion control blankets and synthetic turf reinforcement mats:

Patent No./

Publication No. Inventor Title

9,587,364 Ayers et al. Synthetic Ground Cover System with

Impermeable Backing and Binding Infill for Erosion Control

9,315,961 Lancaster Self- Anchoring Turf Reinforcement Mat and

Reusable Sediment Filtration Mat

9,163,375 Ayers et al. Synthetic Ground Cover System with Binding

Infill for Erosion Control

8,651,770 Lancaster Erosion Control Ballast and Soil Confinement Mat

7,655,584 Biran et al. Highly Porous Self-Cohered Web Materials

7,001,554 Bohannon, Jr. Synthetic Fiber Filled Erosion Control Blanket

6,729,807 Spittle Integral Loft Polymer Grid and Fiber Web Matrix

Turf Reinforcement Mats

5,849,645 Lancaster Reinforced Composite Matting 5,651,641 Stephens et al. Geosynthetics

5,616,399 Theisen Geotextile Fabric Woven in a Waffle or

Honeycomb Weave Pattern and Having a

Cuspated Profile After Heating

5,326,192 Freed Methods for Improving Appearance and

Performance Characteristics of Turf Surfaces

4,177,312 Rasen et al. Matting Article

4,002,034 Mühring et al. Matting for the Prevention of Hydraulic Erosion 3,517,514 Visser Soil Protection Mats

US2012/ Wang Three-Dimensional Netted Vegetation Blanket 0282042 Al with Upright Loops

While the hard armor erosion protection products provide better immediate erosion resistance (than TRMs, at least until TRMs become vegetated), they are more costly, are more labor-intensive to install, require heavy equipment to transport and install and don’t typically promote vegetation growth. Conversely, conventional TRMs are cheaper, easier to install and can allow vegetation growth, but they provide very poor erosion resistance upon installation and until vegetation is established.

What is needed is an erosion control and turf reinforcement mat that provides improved erosion control both immediately upon installation and after establishment of vegetation.

Summary of the Invention

Generally speaking, an erosion control and turf reinforcement mat is provided that comprises a monolithic mat structure with a multitude of perpendicularly and/or diagonally oriented, cantilevered and relatively rigid blades extending from the top surface of the mat and a lightweight filtration fabric on the bottom surface of said mat.

In one embodiment, an erosion control and turf reinforcement mat includes an upper layer having an underside and a plurality of clusters of upwardly extending, cantilevered blades and defining a plurality of growth gaps dispersed between the clusters; a middle layer comprising a sheet defining a plurality of through holes and molded with or bonded to the underside of said upper layer; and a lower layer comprising a geotextile fabric mat bonded to the underside of said middle layer.

It is an object of the present invention to provide an improved erosion control and turf reinforcement mat for use on slopes, berms, earthen dams/levees, shorelines, culvert outlets, pipe outfalls and other high flow channels.

Other objects and advantages will become apparent from the following description of the preferred embodiment.

Brief Description of the Drawings

Fig. 1 is a side, elevational view of an erosion control and turf reinforcement mat

10 in accordance with the present invention.

Fig. 2 is an exploded and side cross-sectional view of the erosion control and turf reinforcement mat 10 of Fig. 1.

Fig. 2a is an enlarged view of a cluster 15 of blades 14 of the upper layer 11 of Fig.

2.

Fig. 3 is a cross-sectional view of a portion of the upper layer 11 of the erosion control and turf reinforcement mat 10 of Fig. 2, taken along the lines 3—3 and viewed in the direction of the arrows.

Fig. 3a is an enlarged view of a section of the upper layer 11 of Fig. 3.

Fig. 3b is a side, elevational view of a blade deflection test procedure of 10 blades

14 mounted in a row.

Fig. 3c is a cross-sectional view of a portion of the upper layer 11 of the erosion control and turf reinforcement mat 10 of Fig. 3 in accordance with another embodiment of the invention.

Fig. 4 is a cross-sectional view of a blade 14 of the upper layer 11 of Fig. 7, taken along the lines 4—4 and viewed in the direction of the arrows.

Fig. 5 is a cross-sectional view of the blade 14 of Fig. 4 in accordance with another embodiment of the present invention.

Fig. 6 is a cross-sectional view of the blade 14 of Fig. 4 in accordance with another embodiment of the present invention Fig. 7 is a top, plan view of a portion of the upper layer 11 of the erosion control and turf reinforcement mat 10 of Fig. 1.

Fig. 8 is a top, plan view of a portion of the middle layer 12 of the erosion control and turf reinforcement mat 10 of Fig. 1.

Fig. 9 is top, plan view of a portion of the upper layer 11 and middle layer 12 of the erosion control and turf reinforcement mat 10 of Fig. 1.

Fig. 10 is a side cross-sectional view of an erosion control and turf reinforcement mat 60 in accordance with another embodiment of the present invention.

Fig. 11 is a top, plan view of a portion of the middle layer 59 of the erosion control and turf reinforcement mat 60 of Fig. 10.

Fig. 12 is a side cross-sectional view of an erosion control and turf reinforcement mat 85 in accordance with another embodiment of the present invention.

Fig. 13 is a graph representing the erosion control performance over time upon exposure to water flow induced shear stress of conventional TRMs and the ECTRMs of the present invention.

Fig. 14 is a graph showing soil loss vs. shear stress in ASTM D6460 large-scale channel testing of unvegetated permanent erosion control products, both conventional and the ECTRMs 60 and 100 of the present invention.

Fig. 15 is a side cross-sectional view of an erosion control and turf reinforcement mat 100 in accordance with another embodiment of the present invention. Description of the Preferred Embodiment

For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, and any alterations or modifications in the illustrated device, and any further applications of the principles of the invention as illustrated therein are contemplated as would normally occur to one skilled in the art to which the invention relates.

Referring to Fig. 1-3, there is shown an erosion control and turf reinforcement mat

(“ECTRM”) 10 for placement upon the ground 5 or other earthen ground-like structure in accordance with the present invention. Generally, mat 10 includes upper, middle and lower layers 11, 12 and 13. Upper layer 11 is a porous, monolithic mat structure with a multitude of upwardly extending, relatively rigid blades 14, which function to simulate natural turf (typically green in color with apparently randomly extending blades 14 that look like grass); dissipate raindrop energy and deflect raindrops from falling through and/or heavily impacting the soil below mat 10; impede horizontal water flow over and along the top of mat 10; and impede water flow flowing from the top of mat 10, through apertures defined therein, down to and under mat 10. Furthermore, as the grass-like blades are somewhat rigid and extensions of the monolithic structure, the mat thus provides a strong framework for permanent reinforcement of vegetation roots and stems growing through the mat.

Upper layer 11 is made of low density polyethylene (LDPE), but other synthetic materials such as other polyethylenes, polypropylene, as well as perhaps rubber, vinyl, PVC, nylon, ABS, HIPS, biopolymers or polyester, that provide the desired strength, rigidity and flexibility, may be used. Upper layer 11 is made to be green and/or brown to simulate natural grass. In an alternative embodiment, upper layer 11 comprises a material that is infrared reflective and/or thermochromic. The infrared component will reflect some measure of the sun’s infrared rays to reduce solar heat buildup in the upper layer 11.

The thermochromic component will cause the upper layer 11 to change color (e.g. dark green to light green) if the upper layer 11 reaches a certain temperature (e.g. 95 degrees

Fahrenheit) so that the layer 11 will then reflect a greater percentage of the sun’s infrared rays. Upper layer 11 is monolithic, that is, it is formed as a single, uninterrupted piece, and it comprises a base 17 and blades 14. Base 17 forms a grid with evenly spaced, parallel arms 18 and a plurality of web flats 19. Each web flat 19 extends between a pair of grid arms 18 (such as between immediately neighboring arms 20 and 21), and the series of web flats 19 between each pair of arms (such as arms 20 and 21) are spaced generally evenly apart from each other, as well. Extending upwardly from each web flat 19 is a blade cluster 15 (Figs. 2 and 3a), each blade cluster 15 comprising a plurality of blades that, here, are configured in a circular patter. Each blade 14 is vertically cantilevered - that is, it is connected at only one end to a web flat 19. In one embodiment, grid arms 18 are about 0.125 inches wide (grid arm width at 24), are about 0.07 inches high (grid arm thickness at 25, Fig. 2, which is also thus the thickness of base 17) and are spaced about 0.5 inches apart (at 26). As used herein,“about” means plus or minus 10%. Each web flat

19 is generally square and is thus about 0.5 inches wide (26) and 0.5 inches long (27).

The circular patter (30) where blades 14 are connected to and extend from web flat 19 fills the web flat 19 and is thus about 0.5 inches in diameter. The distance 28 between adjacent web flats 19 extending between common arms 18 (e.g. web flats 31 and 32 between neighboring arms 20 and 21) is about 0.70 inches (28), and the open space that is thus defined between adjacent web flats (e.g. 31 and 32) and between the opposing adjacent arms (e.g. 20 and 21) defines a growth gap (or growth gap opening) 35 through which desired seeds can germinate and vegetation can grow. That is, each growth gap 35 extends all the way through the base thickness 25 and is defined by and between immediately neighboring pairs of web flats (such as 31 and 32) and by and between the corresponding pair of grid arms (20 and 21). Growth gaps 35 preferably comprise about

40 percent of the unit area of base 17 to optimize the balance between strength of the base

17 and the number and unit area of available growth gap openings 35 (and resulting growth gap openings 58, as described herein) through which vegetation can grow. (Thus, in a one foot square of base 17, about 57.6 square inches comprise growth gap opening).

Alternative embodiments are contemplated wherein the growth gaps may comprise between 30 and 50 percent of the unit area of base 17.

Alternative embodiments are contemplated wherein the pluralities of blades 14 in each cluster 15 are configured in patterns other than circular, such as rectangular, a spaced array or completely random. Alternative embodiments are also contemplated wherein upper layer 11 is not monolithic. For example, in another embodiment, base layer 11 includes a base (same as or similar to base 17) with growth gaps, and the blade clusters are stitched, woven, tufted, glued or otherwise bonded to that base.

The spaced-apart web flats 19 and blade clusters 15 between one pair of neighboring grid arms (e.g. arms 20 and 21) are staggered relative to the web flats 19 and blade clusters 15 of the immediately adjacent pair of grid arms (e.g. 21 and 22), that is,

50% out of phase, as shown in Fig. 3. Consequently, the growth gaps 35 of one pair of grid arms (20/21) are likewise staggered relative to the growth gaps 35 of the immediately adjacent grid arms (21/22). This configuration - essentially a diagonally crisscrossing pattern of growth gaps 35 - provides an evenly distributed array of holes in upper layer 11 through which new and old vegetation can easily emerge and grow. Alternative embodiments are contemplated wherein the web flats 19 and their blade clusters 15 are staggered more unevenly or randomly - that is, in a partially repeating patter, or in a wholly non-repeating pattern. Thus, in the upper layer 11 of Fig. 3, the blade clusters 15 and growth gaps 35 in upper layer 11 are staggered where, along a straight line from left to right, it alternates evenly: blade cluster, growth gap, blade cluster, growth gap, etc.

This is a“repeating-staggered” pattern. In an alternative embodiment, there may be two or three rows arranged in the repeating-staggered pattern, then two or three rows not staggered and/or not repeating-staggered (i.e. two or three blade clusters 15 right next to each other, or maybe staggered a different distance than the prior three blade clusters), then two or three rows repeating-staggered again, and so on. In essence, this“partially- repeating-staggered” configuration means that there may be repeating groupings of blade clusters 15 (and/or growth gaps 35) in the upper layer. In yet another embodiment of the invention, the blade clusters 15 (and, consequently, the growth gaps 35) are oriented in a wholly non-regular, random patter, referred to as“randomly staggered”, as shown in Fig.

3c. Here, the web flats 19 and blade clusters 15 are randomly staggered (both laterally and longitudinally (here meaning left/right and up/down, as viewed) so that direct water flow“channels” 44 (generally, straight line water flow paths 44 that are largely uninterrupted by blade clusters 15), are fewer and shorter in any direction than may exist in other configurations. The staggering of blade clusters 15 and/or of growth gaps 35 acts to slow water flow and to restrict the soil and seed carrying impact of such water flow.

The configuration of upper layer 11 provides rectangular growth gaps 35, but other configurations that produce holes of other shapes (e.g. round, oval, square, starred, irregular) are also contemplated. The sizes of the growth gaps are here about 0.5 by 0.70 inches, thus about 0.35 square inches, but alternative embodiments are contemplated wherein the growth gaps 35 are configured to be from 0.06 square inches to 4.0 square inches in area.

The blades 14 extend up from their respective web flats 19, each along its own centerline 36 (Fig. 2a), and each being between about 0.7 inches and 1.0 inch long.

Alternative embodiments are contemplated wherein the blade lengths are as short as 0.2 inches and up to three inches, and even up to about five inches or more to provide a desired appearance, so long as the resulting mat 10 performs as described. Each blade 14 has a generally flat cross-section, in a plane perpendicular to its centerline 36, as shown in the alternative blade shapes 37, 38 and 39 in Figs. 4, 5 and 6, whereby opposing long sides may be generally straight 48 (a generally flat blade side) or have some degree of curvature

49 (a curved blade side), as desired. Alternative embodiments are contemplated wherein one or more of the blades may have other cross-sections, such as rectangular, square, oval or round. The composition of each blade 14 and its shape are configured so that it can allow some degree of deflection (elastic deformation). Referring to Fig. 3b, in one embodiment, 10 generally straight blades 14 (i.e. such blades did not bear twists, bends or turns) were mounted to a fixed block 40 side-by-side, in a row (i.e. generally mutually co- planar) as cantilever beams and a force F of 1.3 ounces was applied evenly and

perpendicularly to their axes (thus, 0.13 ounces per blade), at a force point 0.5 inches from their side-by-side mounting points 41 to block 40, which produced a common downward deflection D of 0.25 inches, as shown. The permissible deflection is desired to be 0.25 inches, plus or minus about 20 percent (thus between 0.2 inches and 0.3 inches). For the composition of blades 14 (LDPE), the preferred deflection of 0.25 inches in the described test will produce an optimum modulus of elasticity E(B) for the blades, which can be calculated by known methods. Where alternative materials are used for the blades 14, the same modulus of elasticity E(B), plus or minus 20 percent, is believed to provide optimum erosion control and turf reinforcement in mat 10, as described herein. Thus, blades with the stated resulting modulus of elasticity E(B) render them not too stiff to be undesirable to work with and walk upon and to not easily fracture, but rigid enough to well deflect and retard falling and flowing water and, in operational combination with the lower layer 13, to provide greatly superior resistance to soil erosion. While the modulus of elasticity for (all) the blades 14 is preferred to be comparable to the LDPE blades that produce a deflection 0.25 inches (plus or minus 20 percent) as in the recited test (Fig. 3b), it is understood that some small fraction (e.g. 10 percent) of the blades may fall outside this range for any number of reasons, yet“all” the blades are to be considered as having the desired modulus of elasticity.

In the embodiment of Fig. 3 each blade cluster 15 has 12 blades, but fewer or greater blades 14 per cluster are contemplated. Between 6 and 16 blades per cluster is desired, and in a preferred embodiment, each blade cluster 35 has 14 blades 14, and upper layer 11 contains about 210 blade clusters per square foot. Alternative embodiments are contemplated wherein there are between about 150 and 550 clusters per square foot. In another recital of the invention, there are preferred to be between about 1500 and 3500 blades per square foot, and between about 2700 and 3100 blades per square foot in the most preferred embodiment.

Referring to Fig. 3a, each blade cluster 15 of blades 14 (of which there are at least four blades 15) defines a blade cluster area A(bc), which in this case would be pi times the square of the radius R of the circle 42 that defines the extents of the corresponding cluster of blades. Immediately adjacent the circle 42 (referring to one of the circles 42 in the upper layer 11 of Fig. 3) is one of the growth gaps (here designated 43), and the area A(g) of that growth gap 43 is here its length (the distance 28 between adjacent web flats) by its width (web width 26). Except for clusters 15 near edges of the layer 11, the area A(g) is between 75 percent and 300 percent of the area A(bc) of the adjacent cluster 15. It is preferred that the area A(g) is about 200 percent of the area A(bc) (that is, about twice the size). This ensures that there is sufficient open area between clusters for dissipation of excessive heat that can otherwise retard optimal seed germination and growth.

Also, each cluster 15 defines four directions 90 degrees apart (referred to here as north, south, east and west 45a-45d, respectively). Each cluster 15 is a cluster because, for at least 70 percent of the clusters not along an edge 47 of the upper layer 11 , there are defined in at least three of the four directions 45a-45d a separate growth gap 35, the areas

A(g) of each being between 75 percent and 300 percent (and preferably about 200 percent) of the area A(bc) of the reference cluster 15. In another embodiment, for at least half the clusters 15, and preferably for each cluster 15, (except, maybe, for some clusters those along an edge 47), there is an adjacent growth gap 35 with an area that is between 75 percent and 300 percent, and preferably 200 percent, of the area of that adjacent cluster

15.

As shown in Figs. 2 and 7, blades 14 extend generally upwardly from their web flats 19, perpendicular to the apparent plane of the upper layer 11, but some, many or most of the blades 14 are then configured in a bent, turned or twisted position. (In an alternative embodiment, every blade 14 is intended to extend straight up, preferably with little or no bend, turn or twist). Thus, many of the blades 14 extend laterally somewhat (that is, somewhat radially outwardly from the cluster center) to partially cover the growth gaps 35, preferably even more so than is shown in Fig. 7. Though the blades 14 originally rise vertically from the base 17 in clusters, the bending, turning and twisting of the blades

14 is desired to result in a blade pattern whereby the blades 14 appear to be generally evenly and randomly distributed across the entire upper portion of upper layer 11 - like real grass. Also, blades 14 are described as rising vertically (upwardly and

perpendicularly from a horizontally oriented base 17). This is intended to contemplate any blade that may have any laterally extending component where it may then bend, turn and/or twist from a non-vertical direction.

Referring to Fig. 8, middle layer 12 is a sheet of material 52, made of rubber, but like upper layer 11, it may be made of another sheet-like synthetic material such as polyethylene, polypropylene, vinyl, PVC or polyester, so long as it provides the desired strength, rigidity and flexibility described herein for the resulting erosion control and turf reinforcement mat 10. Middle layer 12 is about 0.12 inches thick and defines a plurality of through holes 55 having a diameter of about 1.0 inch and thus an area A(th) of about

0.79 square inches. The through holes 55 are spaced longitudinally and laterally in a generally consistent pattern, as shown in Fig. 8. That is, the center-to-center longitudinal and lateral dimensions 56 and 57 are identical and constant over the entire middle layer

12, and they are arranged in a non-staggered, orthogonally aligned grid, as shown.

Alternative embodiments are contemplated wherein the through holes 55 are configured in a partially- or wholly-random pattern, like the partially- and wholly-random patters described for web flats 19, blade clusters 15 and growth gaps 35 of upper layer 11. Such partially- or wholly-random pattern for middle layer 12 would be different than whatever pattern is used for the growth gaps 35 of the mating upper layer 11 so that, when the upper layer 11 and middle layer 12 are connected together, the growth gaps 35 and through holes

55 do not perfectly align, but still do overlap, as described herein. Middle layer 12 is bonded to the underside 51 of upper layer 11 by application of heat and/or pressure.

Alternative embodiments are contemplated wherein an adhesive is used to bond the upper and middle layers 11 and 12 together. As shown in Fig. 9, where (a portion of) upper layer 11 is shown in its position atop a slightly larger portion of middle layer 12, the arrangement of the through holes 55 is such that most, if not all of the through holes 55 do not align with the various growth gaps 35. A growth gap 35 would be“aligned” with a through hole 55, for example, if its entire area within its perimetrical boundary 66 were directly aligned over and entirely identical to or within the perimetrical boundary 67 of a through hole 55 (Fig. 9). Not aligned means some portion of the boundary 66 of a growth gap 35 crosses some portion of the boundary 67 of through hole 55. The 1.0 inch diameter of through holes 55 is large enough to provide significant overlap, whereby the overlap of through holes 55 and growth gaps 35 provides amply sized and numbered openings - termed resulting growth gaps 58 - for seed germination and growth therethrough. The resulting growth gaps 58 thus define openings all the way through both base 17 of upper layer 11 and of middle layer 12. The arrangement of through holes 55 is thus purposely different from the arrangement of growth gaps 35 in upper layer 11. That is, the center-to- center dimensions in both the longitudinal direction (at 56) and the lateral direction (at 57) of middle layer 12 is, in the present embodiment, the same and constant along the entire sheet of middle layer 12. The growth gaps 35 of upper layer 11 are likewise constantly spaced, though staggered in the diamond patter (the repeating-staggered pattern), with their center-to-center dimensions in the longitudinal direction 62 all being the same, and the center-to-center dimensions in the lateral direction 63 all being the same, but different than the longitudinal and lateral center-to-center dimensions 56 and 57. In addition, the area defined by each growth gap 35 (0.5 in. by 0.70 in. in the present embodiment) is 0.35 square inches, while the area defined by each through hole 55 (1 inch in diameter in this embodiment) is 0.79 square inches. Together, this non-alignment of growth gaps 35 and through holes 55 (see also Fig. 2) and because the areas of through holes 55 are about twice that of the areas of growth gaps 35, this ensures that there will be many overlaps thereof and that the resulting growth gaps 58 will be many and well dispersed, thus providing ample resulting growth gap space for vegetation to emerge and grow

therethrough. It is preferred that A(th) is between about 50 percent and 200 percent larger than A(g) or A(g) is between about 50 percent and 200 percent larger than A(th), and it is most preferred that A(g) is either about one half or about twice that of A(th).

In one embodiment, with the growth gaps 35 configured as shown in Fig. 3 and comprising about 40 percent of the area of base 17, the measured light penetration (under

ASTM D6567) of just upper layer 11, with its blade clusters 15, is 20 percent.

Alternative embodiments are contemplated wherein the through holes 55 may be made in shapes other than round and made smaller or larger with yet more varied spacing to optimize the resulting protection against soil erosion balanced against sufficient average resulting growth gap size. In the preferred embodiment of Fig. 9, holes 55 are about 1 inch in diameter and about 1.4 inches center-to-center, and the through holes 55 thus comprise about 40 percent of the unit area of middle layer. In an alternative preferred embodiment, holes 55 are about 1.5 inches in diameter and about 2.5 inches center-to- center and thus comprise about 30% of the unit area of the middle layer. In other embodiments, the through holes may comprise between about 30 percent and 80 percent of the unit area of the middle layer. In yet other embodiments, the middle layer may comprise a grid of any geometric configuration desired, so long as it provides additional strength and yet flexibility to the upper (and lower) layer(s) and provides a well- distributed array of through holes comprising between about 25 and 80 percent of the unit area, and preferably about 40 percent of the unit area. The configuration of middle layer 12 and its holes and their spacing thus provides structural strength and stability to the overall mat 10, and its configuration can be varied to provide a range of operational protection depending on the severity of the environmental conditions.

For example, referring to Figs. 10 and 11 , middle layer 12 is replaced with a scour mat 59 to produce an erosion control mat 60 in accordance with another embodiment of the present invention. Scour mat 59 is thicker, stronger and heavier than middle layer 12, but like middle layer 12, its through holes 61 are 1.0 inches in diameter and align (or rather mis-align) with the growth gaps 35 of upper layer 1 1 in the same manner as through holes 55 of middle layer 12. Erosion control mat 10 is deemed a medium weight erosion control and turf reinforcement mat with an areal density of between about 0.5 pounds per square foot (“psf’) and 1.5 psf, and preferably about 1.0 psf. This material gives mat 10 a specific gravity greater than 1.0 (i.e. its specific density is greater than that of water), and preferably about 1.15. This ballasts mat 10, meaning that it enhances the ability of mat 10 to resist being easily lifted off of the soil during a flow event. Erosion control mat 60 is deemed a heavy weight or scorn- erosion control and turf reinforcement mat with an areal density of between about 1.5 psf and 5.0 psf, and preferably about 2.5 psf. Consequently, the medium weight middle layer 12 has an areal density of between about 0.3 psf and 1.0 psf, and preferably about 0.65 psf, and the heavy weight scour mat 59 has an areal density of between about 1.3 psf and 4.5 psf, and preferably about 2.15 psf. Further, the heavy weight scour mat 59 has a specific gravity of about 1.15, as well. Alternative embodiments are contemplated wherein the middle layer 12 and heavy weight scour mat

59 may have specific gravities even greater than 1.15 to further ballast them against lifting away from the soil during flow events.

Lower layer 13 is a specially designed, lightweight, geotextile and fabric base or mat 64 configured to hold fine soil particles and seeds in place, while facilitating and supporting seed germination, emergence and growth. As a result, soil erosion is significantly retarded, while at the same time vegetation establishment is maximized. The specially designed lightweight filter fabric base 64 is comprised of very fine fibers that cling to soil particles when wetted and provide containment and protection of seed and fine soil particles beneath the mat, while also allowing seedling emergence therethrough.

Fabric mat 64 comprises polyester fiber strands or filaments that are inlermeshed and partially- to substantially-bonded together so that the strands contact and cross each other at various and random angles to form a three-dimensional mat. Materials other than polyester are contemplated such as polypropylene, nylon, acrylic, and non-synthetics such as cotton, jute and rayon, all so long as they provide the desired protection against soil erosion, while creating minimal inhibition to seed germination, emergence and growth, as described. Mat 64 is made by any suitable technique well known to those skilled in the art to produce a fibrous mat that is between about 0.1 and 0.2 inches thick, preferably 0.15 inches thick, and has an areal density of between about 1.0 and 3.0 oz. per square yard, preferably about 1.7 oz. per square yard (referred to as the“2 oz. mat”). The process to manufacture mat 64 results in fiber strands having finite lengths and that are crimped, or bent. For the 2 oz. mat 64, the fiber strands are between about 1.5 and 2.6 inches in length and have between about 7 and 11 crimps per fiber. In another embodiment, a 2.7 oz. mat

64 (referred to as the“3 oz. mat”), has fiber strands between about 1.5 and 3.3 inches in length and have between about 5 and 10 crimps per fiber. For the 2 oz. mat 64, the fiber strands are between about 1.8 and 9.0 mils in diameter, preferably about 6.3 mils in diameter. For the 3 oz. mat 64, the fiber strands are between about 3.4 and 18.0 mils in diameter, preferably about 8.7 mils in diameter. Manufacturing tolerances will permit deviation by about 10 percent, but the preferred values are a 1.7 oz. per square yard mat with fiber strand length, diameter and crimp frequency of about 1.5-2.6 inches, 6.3 mils and between about 7 and 11 per strand, respectively. Where heavier fabrics (2.5 oz. or greater) are used, the fabric may be mechanically treated, as with needles or hole punching or slitting to ensure a sufficient number and size of openings for vegetation emergence and growth.

For the preferred“2 oz. mat”, the resulting fabric base 13 has the following preferred properties and acceptable ranges, with the governing ASTM Standard indicated:

With the foregoing parameters, fabric base 64 provides a porosity and interwoven structure that resists heavy impacting of falling and flowing water therethrough which may disrupt seed germination and wash away unacceptable amounts of soil, that acts to hold soil particles and seeds in place when water does penetrate with any significant force, and that yet permits sufficient light to reach the germinating seedlings and permit them to emerge and grow through the fabric base. Additionally, the base 64 with the recited parameters, particularly the fineness of the fibers and the fiber density in base 64, which produce the above-listed parameters (opening size, number of fibers, etc.) acts to readily intermesh with the soil upon which mat 64 is placed to resist lifting therefrom and moving in any direction laterally therealong.

The manufacturing process that produces fabric base 64 typically employs some application of heat and pressure that causes a degree of bonding between mutually contacting fiber strands. Alternatively, adhesive may be added during the manufacturing process to increase the number of fibers bonded to one another and/or to further enhance the strength of the bonds between the fibers that are bonded to one another. Such bonding between some of the strands is weak enough that some of the emerging and rising vegetation buds or blades will bear against some fibers and break some of those bonds so that such buds/blades can continue to rise past those fibers. The strength of the individual fibers (with the foregoing parameters) is such that the rising vegetation buds/blades are also able to bend some of the fibers somewhat so they can more easily rise up through the superjacent resulting growth gaps 58.

The lower layer 13 is bonded to the underside 84 of middle layer 12 with some combination of heat and pressure, as desired. Alternative embodiments are contemplated wherein an adhesive is used to bond the middle and lower layers 12 and 13 together.

The three layers 11, 12 and 13, bonded together, even with the thicker and heavier scour mat 59 or other similar middle layer, comprise a sufficiently flexible structure that can easily be placed upon and readily conform to a non-planar soil surface, as is usually present with slopes, berms, earthen dams/levees, shorelines, culvert outlets, pipe outfalls and other high flow channels.

In another embodiment shown in Fig. 12, there is an erosion control and turf reinforcement mat 85, just like mat 10 (Fig. 1) or mat 60 (Fig. 10), except that it includes bottom blades 91 (which are like blades 14, though not as many) that extend downwardly, through lower layer 13. When laid upon the ground, the bottom blades 91 engage the ground, and help hold the mat 85 in place. Blades 91 have generally the same

configuration, composition, and behavioral characteristics as blades 14, but while there may be between about 2200 and 3500 upwardly extending blades 14 per square foot, there are contemplated to be about one fifth to one half as many blades 91 per square foot extending downwardly. Upon resting mat 85 on the ground, blades 91 will bend somewhat and rest against the ground and/or, depending on how loose or compacted the soil is, will penetrate the ground surface, simulating root structures, to help hold mat 85 in place. These simulated root structures penetrate into and interact with the underlying soil surface to further help adhere the mat to the soil surface, trap soil particles and grass seed, and decrease the velocity and thus the erosiveness of water flow that may occur beneath the mat. Alternative embodiments are contemplated wherein the blades 91 are more rigid than blades 14 to better enable them to engage with and penetrate the soil and better hold mat 85 in place. Mat 85 (as well as mats 10 and 60) may also be anchored in place with appropriate and well-known turf anchors, such as spikes, pins, sod staples, stakes or earth anchors, alone or in conjunction with other turf reinforcement mats and erosion control blankets. The embodiment of the erosion control and turf reinforcement mat 10 shown in

Figs. 1 and 9 shows only a partial view of the mat. Mat 10 is preferably made in segments or panels of about three or twelve feet in width by four to one hundred feet in length, transported in rolls or sheets that can then be unrolled or placed by one or two persons. Of course, mat 10 can be configured in any size and areal density (by varying the middle layer 12) to accommodate the particular earthen configuration and expected labor force capabilities.

In practice, once a prior art, conventional TRM is laid down, it will give some erosion control protection for the first 6 months or so before vegetation begins. Thus, referring to Fig. 13, which represents the limits of performance of conventional TRMs

(which include stitched, woven and extruded TRMs) versus ECTRMs in accordance with the present invention, a conventional stitched or woven TRM can initially protect the underlying soil against impermissible erosion (more than 0.5 inches of soil loss) when subjected to 30 minute water flow events (per ASTM 6460) with shear stresses up to only about 3 pounds per square foot (“psf’). As vegetation is established over between about 6 and 12 months (between trend lines 71 (fast growth) and 72 (slow growth)), the combined conventional TRM and its now interwoven vegetation will protect the soil (and

vegetation) against impermissible soil loss (0.5 inches) and vegetation destruction for water flow events of increasing shear stress. The ECTRM 60, however, will immediately, upon installation (that is, immediately upon laying it or them on and affixing it or them to the ground with appropriate and well-known turf anchors, as needed), provide protection against water flow events with a shear stress of 14 psf and more (at 74). In another embodiment described below, a light ECTRM 100 will immediately upon installation provide protection against water flow events with a shear stress of 12 psf and more (at 75). Other embodiments within the spirit of the invention will exhibit similar behavior, some perhaps slightly less than the line 75, but typically at or above line 75. Thus, if a big storm, surge, gravity wave or other heavy flow event occurs, where shear stresses exceeding 4, 8, 12 or greater psf are realized, the conventional TRMs will not for many months provide sufficient resistance to the flow, and there will be significant washout of soil, seed and/or young vegetation. The ECTRM of the present invention, however, provides significant erosion control and turf reinforcement immediately upon installation, and importantly, without significant restriction to vegetation growth. In large-scale channel testing of unvegetated permanent erosion control products in accordance with ASTM D6460 (Fig. 14), mats are placed over a controlled soil bed (i.e. no vegetation) in a sloped channel and subjected to water flow with a known shear stress value for 30 minutes at a time. (Shear stress is the force or drag that water exerts on the bed and bank of a channel as it flows over them). Thereafter, the depth of soil loss is measured. Multiple tests (four, 30-minute flow events) at varying shear stresses were performed for each sample. Typical known prior art organic and synthetic mats (three dimensional woven polypropylene TRM; double net poly fiber mat; and triple net coconut fiber mat) exhibited failure (0.5 inches cumulative soil loss) or trended to failure, as shown at 77, 78 and 79, respectively, at between 2.0 and 4.0 psf, which would be a mild flow event. That is, these prior art, conventional TRMs, upon initial installation before vegetation is established, provide little protection from soil erosion under low to moderate flow conditions. The rubber scour/transition mat with triple net poly fiber TRM underlay (another well-known

TRM) performed slightly better, providing erosion protection up to about 8.0 psf, as shown at 80. The light ECTRM 100 of the present invention (discussed below), however, performed roughly the same as (at 81) the tied concrete block mats (at 82). A tied concrete block mat consists of small to medium-sized concrete shapes that are tied together (formed onto) a metal lattice or synthetic geogrid. These are typically heavy, unsightly and unwieldy; are more labor-intensive to install; require heavy equipment to transport and install; and the resulting vegetation that does emerge is difficult to maintain - mowers and their operators do not typically like to roll over the rocky, bumpy, jagged surfaces.

A further particular advantage to the configuration of upper layer 11 with its clusters 15 of blades 14, which are preferably green in color, is that the ECTRM 60 and

100 (and other ECTRMs within the spirit of the invention) both provide significant erosion control and turf reinforcement like real grass, but it (they) also look like real grass immediately upon installation, thus providing a grassed-in finished look to a project and maintaining that look in the case of slow vegetation establishment, die-off or dormancy.

As to the scour ECTRM 60 (line 83), it performed extraordinarily better than the tied concrete block mats 82. More importantly, however, both the light and scour ECTRMs lOOand 60 - with no vegetation assistance - withstood the flow events with shear stresses of nearly 12 psf with not even half the impermissible soil loss - in the case of the scour ECTRM 60, less than a tenth of an inch of soil was lost under nearly 12 psf shear stress!

Referring to Fig. 15, there is shown an erosion control and turf reinforcement mat (“ECTRM”) 100 for placement upon the ground 5 or other earthen ground-like structure in accordance with another embodiment of the present invention. Mat 100 - the light weight erosion control and turf reinforcement mat - is the same as mat 10 (the“medium” mat) except without middle layer 12 so that lower layer 13 is bonded directly to the underside of the upper layer 11. Compared to mat 10, mat 100 does not benefit from the added strength and ballast of the middle layer 12, but is lighter than mat 10. This light erosion control mat 100 has an areal density of between about 0.2 psf and 0.5 psf, and preferably about 0.35 psf. As there is no middle layer, the open spaces are defined exclusively by the growth gaps 35, which for the base 17 of upper layer 11 defines about 40 percent of the total area of base 17. This provides even more space for seed germination and growth, but less protection from falling and flowing water. Thus, while it is not as strong as mat 10, mat 100 is lighter and can be more easily transported and installed and still provides greatly superior performance - especially immediately upon installation - as compared to conventional TRMs.

Alternative embodiments are contemplated wherein the upper and middle layers 11 and 12 are formed together in a monolithic structure comprising both the plurality of clusters 15 of blades 14 and a strong, but pliable base structure from which the blade clusters 15 extend. Such configuration will define the same or closely similar resulting growth gaps, sufficiently dispersed and staggered to permit vegetation growth, while still being pliable enough to conform to the earthen or earthen-like contour. A main advantage of having separate, but then bonded together upper and middle layers 11 and 12 is the ease of varying the weight, strength, pliability, hole size and hole dispersement pattern in the middle layer 12 to pair with a varying configuration and number of blade clusters, blades and growth gaps in the upper layer 11. Nevertheless, combining the upper and middle layers 11 and 12 together in one monolithic layer can lessen manufacturing costs and ensure a stronger bond between such layers.

Alternative embodiments are contemplated wherein the web flats 19 define some opening(s) in addition to the adjacent growth gaps 35. For example, as shown in Fig. 3, a web flat 19 typically is solid both inside the blades 14 (at 102) and outside the blades 14 (at 103), but one or more web flats 19 may define openings, as shown for a blade cluster

101, where the entire center section 104 of which defines an opening all the way through upper layer 11, thus providing even more growth space for seedlings.

In another embodiment, an ECTRM comprises just the upper layer 11 with its array of clusters 15 of blades 14, it being referred to simply as a blade mat (11). The blade mat 11 is secured to the ground with appropriate turf anchors. In one use of the blade mat

11, hydromulch - a combination of mulch, seed and/or fertilizer, in a slurry form - is sprayed onto the anchored blade mat 11. Some or a significant portion of the hydromulch will fall down to a position disposed among the blade clusters 14 as well as down through the growth gaps 35 in contact with the soil below. In conjunction with the hydromulch, the lower layer 13 is not needed, and the blade mat 11 provides a reliable base framework for holding the hydromulch in place and resisting it being easily washed away during a flow event. The hydromulch is understood to contain only one or any combination of mulch, seed and fertilizer, as well as any other additives or fillers desired such as soil and synthetic materials.

Alternative embodiments are contemplated wherein lower layer 13 comprises a woven or non-woven scrim or netting made of fiberglass, polypropylene, polyethylene or other man-made materials and/or a woven or non-woven scrim or netting made of jute, hemp, coconut fiber or other natural materials and with opening sizes ranging from 0.1 - 1.5 inches, and preferably between.125 - .25 inches. Such alternative lower layer is contemplated to be heat bonded, glued or stitched to bottom of top layer 11.

Alternative embodiments are further contemplated wherein lower layer 13 comprises a degradable erosion control blanket made of randomly oriented straw fibers, wood excelsior fibers, jute, hemp, coconut fiber or other natural materials, or comprises a non-degradable erosion control blanket made of randomly oriented polypropylene fibers, polyethylene fibers, or other synthetic fibers. Such alternative degradable or non- degradable erosion control blanket may or may not include one or more natural or synthetic nettings to hold such fibers together, and such alternative lower layer is contemplated to be heat bonded, glued or stitched to bottom of top layer 11.

Alternative embodiments are contemplated wherein lower layer 13 comprises a water soluble, biodegradable or photodegradable film or tissue-like sheet that is designed to dissolve or degrade before and during seedling emergence. Such alternative lower layer is contemplated to be heat bonded, glued or stitched to bottom of top layer.

While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment and limited additional embodiments have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected. It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein.

Claims

What is claimed is:

1. An erosion control and turf reinforcement mat, comprising:

an upper layer having an underside and a plurality of spaced-apart clusters of upwardly extending, cantilevered blades and defining a plurality of growth gaps dispersed between the clusters; and

a lower layer comprising a geotextile fabric mat connected to the underside of said upper layer.

2. The erosion control and turf reinforcement mat of claim 1 wherein said upper layer includes a base with a grid having a plurality of spaced apart grid arms and a plurality of spaced apart web flats extending between immediately neighboring pairs of the spaced apart grid arms.

3. The erosion control and turf reinforcement mat of claim 2 wherein each of the plurality of clusters of blades is connected to and extends upwardly from a

corresponding one of the web flats.

4. The erosion control and turf reinforcement mat of claim 3 wherein the blades of at least one of the clusters is configured in a circular pattern at its connection to its corresponding web flat.

5. The erosion control and turf reinforcement mat of claim 3 wherein the spaced-apart web flats and blade clusters between one pair of neighboring grid arms are staggered in a repeating staggered pattern relative to the web flats and blade clusters of the immediately adjacent pair of grid arms.

6. The erosion control and turf reinforcement mat of claim 3 wherein at least some of the spaced-apart web flats and blade clusters between one pair of neighboring grid arms are staggered in a randomly staggered pattern relative to the web flats and blade clusters of the immediately adjacent pair of grid arms.

7. The erosion control and turf reinforcement mat of claim 3 wherein the grid arms are mutually parallel.

8. The erosion control and turf reinforcement mat of claim 3 wherein the web flats between each pair of arms are mutually evenly spaced apart from each other.

9. The erosion control and turf reinforcement mat of claim 3 wherein the grid arms are about 0.5 inches apart from one another, the web flats are about 0.7 inches apart from one another.

10. The erosion control and turf reinforcement mat of claim 9 wherein the web flats are about 0.5 inches long and about 0.5 inches wide, and the circular pattern is about

0.5 inches in diameter.

11. The erosion control and turf reinforcement mat of claim 2 wherein the base has a thickness and a unit area and defines growth gaps, each growth gap having an area, extending all the way through the base thickness and being defined by and between immediately neighboring pairs of web flats and by and between the corresponding pair of grid arms.

12. The erosion control and turf reinforcement mat of claim 11 wherein the growth gaps comprise between about 30 and 50 percent of the unit area of the base.

13. The erosion control and turf reinforcement mat of claim 12 wherein the growth gaps comprise about 40 percent of the unit area of the base.

14. The erosion control and turf reinforcement mat of claim 11 wherein each growth gap has an area of between about 0.06 square inches and 4.0 square inches.

15. The erosion control and turf reinforcement mat of claim 11 wherein each growth gap has an area of about 0.35 square inches.

16. The erosion control and turf reinforcement mat of claim 11 wherein each blade cluster defines a blade cluster area, and each growth gap area is between 75 percent and 300 percent of the area of an adjacent blade cluster.

17. The erosion control and turf reinforcement mat of claim 16 wherein each growth gap area is about 200 percent of the area of an adjacent blade cluster.

18. The erosion control and turf reinforcement mat of claim 1 wherein said upper layer has between 150 and 300 clusters per square foot.

19. The erosion control and turf reinforcement mat of claim 18 wherein said upper layer has about 210 clusters per square foot.

20. The erosion control and turf reinforcement mat of claim 1 wherein each cluster has between 6 and 16 blades.

21. The erosion control and turf reinforcement mat of claim 1 wherein said upper layer has between about 1500 and 3500 blades per square foot.

22. The erosion control and turf reinforcement mat of claim 21 wherein said upper layer has between about 2700 and 3100 blades per square foot.

23. The erosion control and turf reinforcement mat of claim 1 wherein the blades each have a first end, an axis and a modulus of elasticity whereby, for each generally straight blade held at one end at a mounting point as a cantilever beam by a fixed block, application of a force of 0.13 ounces perpendicular to the blade axis at a force point 0.5 inches from its mounting point elastically deflects the blade between 0.2 inches and 0.3 inches.

24. The erosion control and turf reinforcement mat of claim 1 wherein said upper layer is monolithic and made of LDPE.

25. The erosion control and turf reinforcement mat of claim 1 wherein said lower layer comprises polyester fiber strands.

26. The erosion control and turf reinforcement mat of claim 25 wherein the fiber strands are between about 1.5 and 2.6 inches in length.

27. The erosion control and turf reinforcement mat of claim 25 wherein the lower layer has an areal density of between about 1.0 and 3.0 oz. per square yard and its fiber strands have a diameter of between 1.8 and 9.0 mils.

28. The erosion control and turf reinforcement mat of claim 25 wherein the lower layer has an areal density of between about 1.5 and 3.3 oz. per square yard and its fiber strands have a diameter of between 3.4 and 18.0 mils.

29. The erosion control and turf reinforcement mat of claim 26 wherein said lower layer has an areal density of between about 1.0 and 3.0 ounces per square yard and an apparent opening size of between 0.01 and 0.06 inches.

30. The erosion control and turf reinforcement mat of claim 26 wherein said lower layer is connected to said upper layer by the application of at least one of heat, pressure and adhesive.

31. The erosion control and turf reinforcement mat of claim 1 further including a middle layer comprising a sheet having a thickness and defining a plurality of through holes extending all the way through the thickness, the middle layer being connected to and between said upper layer and said lower layer.

32. The erosion control and turf reinforcement mat of claim 31 wherein the growth gaps each define a first shape and the through holes each define a second shape that is different than the first shape.

33. The erosion control and turf reinforcement mat of claim 31 wherein the growth gaps each define an area A(g) and the through holes each define an area A(th), and wherein one of A(g) and A(th) is between about 50 percent and 200 percent larger than the other of A(g) and A(th).

34. The erosion control and turf reinforcement mat of claim 31 wherein the growth gaps each define an area A(g) and the through holes each define an area A(th), and wherein one of A(g) and A(th) is about 100 percent larger than the other of A(g) and

A(th).

35. The erosion control and turf reinforcement mat of claim 31 wherein the through holes comprise between about 25 and 80 percent of the unit area of the middle layer.

36. The erosion control and turf reinforcement mat of claim 31 wherein the growth gaps and through holes are not in mutual alignment.

37. The erosion control and turf reinforcement mat of claim 31 wherein the growth gaps overlap the through holes to define resulting growth gaps extending all the way through both said middle and upper layers.

38. The erosion control and turf reinforcement mat of claim 31 wherein the base has a thickness and a unit area and defines growth gaps, each growth gap having an area, extending all the way through the base thickness and being defined by and between immediately neighboring pairs of web flats and by and between the corresponding pair of grid arms and wherein the growth gaps comprise between about 30 and 50 percent of the unit area of the unit area of the base and the through holes comprise about 40 percent of the unit area of the middle layer.

39. The erosion control and turf reinforcement mat of claim 31 wherein the base has a thickness and a unit area and defines growth gaps, each growth gap having an area, extending all the way through the base thickness and being defined by and between immediately neighboring pairs of web flats and by and between the corresponding pair of grid arms and wherein the growth gaps comprise between about 30 and 50 percent of the unit area of the unit area of the base and the through holes comprise about 70 percent of the unit area of the middle layer.

40. The erosion control and turf reinforcement mat of claim 1 wherein said upper layer includes a plurality of bottom blades extending downwardly through the bottom layer.

41. The erosion control and turf reinforcement mat of claim 1 wherein said upper layer comprises at least one of an infrared reflective material and a thermochromic material.

42. An erosion control and turf reinforcement mat, comprising:

an upper layer having an underside and a plurality of clusters of upwardly extending, cantilevered blades and defining a plurality of growth gaps dispersed between the clusters;

a middle layer comprising a sheet defining a plurality of through holes and bonded to the underside of said upper layer; and

a lower layer comprising a geotextile fabric mat connected to the underside of said middle layer.

43. The erosion control and turf reinforcement mat of claim 42 wherein said upper layer includes a base with a grid having a plurality of spaced apart grid arms and a plurality of spaced apart web flats extending between immediately neighboring pairs of the spaced apart grid arms.

44. The erosion control and turf reinforcement mat of claim 43 wherein each of the plurality of clusters of blades is connected to and extends upwardly from a

corresponding one of the web flats.

45. An erosion control and turf reinforcement mat, comprising:

a base having an underside and a thickness and defining a plurality of growth gaps, each growth gap having an area and extending all the way through the base thickness; and a plurality of clusters of blades dispersed between the growth gaps and connected to and cantileveredly extending upwardly from said base.

46. The erosion control and turf reinforcement mat of claim 45 wherein said base includes a plurality of spaced apart grid arms and a plurality of spaced apart web flats extending between immediately neighboring pairs of the spaced apart grid arms.

46. The erosion control and turf reinforcement mat of claim 46 wherein each cluster is connected to and extends upwardly from one of the web flats.

47. The erosion control and turf reinforcement mat of claim 45 further including a lower layer comprising a geotextile fabric mat connected to the underside of said base.

48. The erosion control and turf reinforcement mat of claim 45 further including a second layer connected to the underside of said upper layer and defining a plurality of through holes that at least partially align with the growth gaps.

49. The erosion control and turf reinforcement mat of claim 48 further including a lower layer comprising a geotextile fabric mat connected to the underside of the second layer.

50. The erosion control and turf reinforcement mat of claim 45 further including hydromulch disposed among the blade clusters.

51. The erosion control and turf reinforcement mat of claim 45 wherein said base has an edge and each cluster has an area, and wherein for each of at least half of the clusters, except for clusters along the edge, the area of the growth gap adjacent said each of at least half of the clusters is between 75 percent and 300 percent of the area of that adjacent cluster.

52. The erosion control and turf reinforcement mat of claim 51 the area of the growth gap adjacent said each of at least half of the clusters is about 200 percent of the area of that adjacent cluster.