Enkamat®

Permanent Erosion Prevention MatEROSION CONTROL

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ColbondColbond is a leading producer and supplier of high-qualitysynthetic nonwovens for flooring, automotive and constructionapplications and of three-dimensional polymeric mats andcomposites for civil engineering, building and industrialapplications.

The company’s production facilities are based in Emmen andArnhem (NL), Obernburg (D), and Asheville (NC, USA).Regional sales offices are located all over the world. Forproduct and application development, the company maintainsa Development and Application Centre at the Arnhem headoffice and a Development Laboratory in Asheville.

Colbond is part of the Technical Textiles Division of Low &Bonar. Listed on the London Stock Exchange, Low & Bonaremploys more than 2,700 people worldwide.

The range of specialty geosynthetic products for civilengineering includes Enkamat®, Enkadrain®, Enkagrid®,Colbonddrain® and Armater®. These products are used allover the world for erosion control, drainage, wastecontainment, soil reinforcement, stabilization andconsolidation.

ISO 9001

The Quality Management System of Colbond at Arnhem,Emmen, Obernburg and Asheville has been approved by Lloyd’s Register Quality Assurance to the NEN-EN-ISO 9001:2000 Quality Management SystemStandard (Certificate No. 935136).

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Erosion - the problemErosion by wind and water often causes a great deal ofinconvenience and considerable damage. Various erosionproblems are too serious to be corrected by simple “natural”methods, such as planting vegetation, or using biodegradableproducts. Instead, an additional, permanent rootreinforcement system is required that stops erosion, but is notin any way harmful to man or the environment.This is where Enkamat comes in. It is designed for situationswhere nature alone cannot cope and where permanenterosion protection is essential.

Enkamat - the solutionEnkamat is a proven, lightweight, flexible alternative to rigidconcrete, asphalt and stone riprap systems for controllingerosion. It is designed to help nature develop strongvegetation for permanent erosion protection of slopes, rivers,banks, ditches, channels, spillways, landfills, shorelines, andother vulnerable erosion-prone areas.

The structureEnkamat is a dense three-dimensional permanent erosionprevention mat, made of thick polyamide filaments fusedwhere they cross. Over 90% of the volume of the mat isavailable for soil filling, which ensures positive integration andimmediate stabilization of slope surfaces, while providing anenhanced environment for seed germination. Once a layer ofvegetation is established, Enkamat provides root systemswith permanent reinforcement, resulting in an integrated,effective erosion control system. On steep slopes, Enkamatis sometimes used only with hydromulching acting as aprotective layer.Enkamat’s filament core structure slows down wind speedand percolating water, thus preventing erosion and evenpromoting sedimentation.

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• Integrated systemEnkamat has a three-dimensional structure whichprovides root systems with permanent reinforcementand offers an integrated, effective erosion controlsystem.

• Superior Area Holding CapacityThe quantity of soil which is retained in the mat isdefined as Area Holding Capacity (AHC). Enkamat has a superior AHC. In addition, Enkamat’seffective thickness is equal to its nominal thickness.The effective thickness indicates the AHC and can,as such, be considered as an indication of theperformance of the mat.

• Specific gravityIn contrast to mats of polypropylene or polyethylene,Enkamat’s specific gravity exceeds 1.0 g/cm3.(Erosion control mats with a specific gravity of lessthan 1 g/cm3 will float in the water and are difficult toinstall.)

• Multiwidth: economical installationEnkamat can be supplied in widths up to 5.75 mand comes in different lengths. 5.75 m is the largestwidth available in erosion prevention mats andcontributes to economical installation due to the reduced number of overlaps.The mats have to be pinned at the overlaps; thewider the mat, the less overlaps, and less pinning.Material cost savings can amount to 5% in dryapplications with 100 mm overlaps and 15% in wetapplications with 300 mm overlaps. It is only logical that less labour costs and fasterinstallation go with the multiwidth.

• Economies of scaleEnkamat is produced in large quantities because itis used all over the world. This allows forcompetitive prices, enabling selection of the best product for the various application areas at favourable costs.

Enkamat - keeping erosion under control

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Enkamat - the product rangeThe Enkamat range consists of varioustypes of products.

EnkamatA three-dimensional polyamide mattingfor immediate and permanent protectionof all types of slopes. The open mattype, which has the same appearanceon both sides, is particularly suited foruse in erosion-prone situations wheregrass is also required. The toughfilament core structure of Enkamateffectively prevents the soil from beingeroded into a barren, channelled slopeby rain and wind, but at the same timehelps to reinforce the root system of thevegetation.

Enkamat flatback is a variant with amore closed, flat structure on theunderside to enable 2 - 6 mm stonechippings (with which the mat is filledafter installation) to be retained in themat where no vegetation is present,usually below the water level and forlow velocity streams and rivers or onreservoir banks. The filament corestructure securely holds the stonechippings and provides protection belowthe water line.

Enkamat AEnkamat A is a high performancespecial Enkamat, 22 mm thick, prefilledwith a mineral filter of 2 - 6 mm chippings with a bitumenbinder. The prefabricated permanenterosion mat is flexible and permeableand allows vegetation to grow through.Enkamat A is used where vegetationhas little chance to develop, usually atand below the water level on the banksof watercourses.

Enkamat WEnkamat W is a flexible lightweightgeocomposite that consists of anEnkamat grip layer sewed to areinforcing woven grid or fabric.The combination of the open-structuredEnkamat and the high tensile strengthwoven grid or fabric rendersEnkamat W very suitable for the use onsteep slopes and slippery liners thatrequire vegetation cover on a reinforcedlayer of soil.

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Application areasProtection of river banksagainst erosion

Dense vegetation is the basis of naturalprotection of banks against erosion. Toachieve this, a strong root system isrequired, supported by an artificial rootsystem or some other means. Greenbanks are an ecologically acceptablebarrier which blends harmoniously intothe landscape. This aspect is alsoincreasingly being incorporated into thedesign and (re)construction ofenvironmentally friendly banks forimproving the habitat in residential andrecreational areas.On account of its high permeability, itsweight (20 kg/m2) and the immediateprotection it offers with velocities up toapproximately 2.5 m/s, the prefilled Enkamat A20 is being widely used forbank protection, controlling erosiveaction at and below the waterline.Standard Enkamat can be installedfrom approximately 0.50 m above thewaterline. In this area, these types ofEnkamat offer efficient protection.

Enkamat is used in three mainapplication areas.

• Erosion prevention forembankments and slopes

• Protection of river banksagainst erosion

• Support of vegetationon steep slopes andgeomembranes

Erosion control forembankments and slopes

Since Enkamat already offers adequateprotection before any vegetation isestablished, it is often used to protectnew or repaired embankments andslopes.For example, road and railwayembankments are protected byEnkamat, either seeded and filled withtopsoil or hydroseeded after installation.Enkamat can keep the fertile soil fill andthe germinating seeds in place,preventing the seeds from beingwashed out by heavy rain andencouraging active plant growth.Although proper filling is most efficient,Enkamat may, under special conditions,be installed unfilled. The matting must then be secured withextra pegs to ensure firm contact withthe subsoil. When Enkamat is to beused to repair eroded banks, thesurface has to be regraded. Any largeholes must be filled and wellcompacted, and any potential surfacewater runoff channels should bediverted.

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• Vegetation on steep and rockyslopesEnkamat 7010W/20PET is used forprojects involving seeding on steep,rocky subsoil. Enkamat 7010W/20PETcombines the mat’s characteristicthree-dimensional structure with anopen PET reinforcing grid. This grid ismade of high modulus polyesteryarns, protected with a PVC coating.The combination of a mattingstructure with a high strength grid(18 kN/m) helps dense vegetationdevelop under the often unfavourablecircumstances on rocky, erodedslopes. Enkamat 7010W/20PET formsa flexible grip layer in which soil isretained and seeds are encouraged togerminate.Enkamat 7010W/20PET is used onweathered rocky slopes in urbanareas and on slopes in cut-and-fillsituations in road construction.On very steep slopes,Enkamat 7010W/20PET is filled andseeded hydraulically.Creeping and climbing plants mayalso reinforce the vegetation.

Support of vegetation on steep slopes and geomembranes

120 mm soil cover

Enkamat ® W

Liner

11.5

h = 11 m

• Stabilization of earth ongeomembranes and other smoothsurfacesEnkamat W is also used on slopescovered with geomembranes or whichhave other smooth surfaces that mustbe covered by a layer of soil uponwhich vegetation should develop. Insuch cases, a stable cover isestablished by the combination of thehigh tensile strength of the grid andthe friction between Enkamat W andthe soil. Enkamat W is anchored in atrench at the top of the slope.Examples of other applications ofEnkamat W on slippery surfaces arerain and potable water reservoirs,lined with a geomembrane orgeosynthetic clay liner.Enkamat W is also used on the insideof refuse dumps with geomembraneswhere durable protection against UVradiation and mechanical damageduring tipping operations is required.

Special applications

Enkamat’s vast potential also allows forapplications other than erosion controland (re)vegetation, for example inplaygrounds with natural grass andgreen parking areas. In these cases,Enkamat 7020 permits greaterutilization. On soccer fields, forexample, the use of Enkamat doublesor even triples the frequency in whichthe fields can be used.

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• Permanent solutionEnkamat provides root systems with permanentreinforcement and offers an integrated, effectiveerosion control system.

• Various application possibilitiesRanging from bank protection to stabilization of soillayers.

• Tailor-made dimensionsFor large quantities.

• Excellent product properties- light weight and high flexibility - thus easy

to install- excellent bonding of the

individual filaments- over 90% open spacing- non-toxic- high resistance to weathering

and UV radiation- frost-proof- low flammability - does not

support combustion

• Proven performanceIntroduced in the Seventies, today over 18 million m2

have been installed world wide.

• International recognitionCIRIA (Construction Industry Research andInformation Association), 1987Delft Hydraulics Lab, M 1421, report 116Karlsruhe University, 1983Silsoe University, 1984

• Quality managementColbond’s materials are produced and supplied inaccordance with the NEN-EN-ISO 9001:2000Quality Management System Standard, certified byLloyd’s Register Quality Assurance under approvalno. 935136.

• Various types of productsEnkamat is available in various thicknesses. Therange comprises several types, including Enkamatwith a reinforcing grid and a type prefilled with 2 - 6 mm stone chippings bound with bitumen. It is available in various widths (1 - 5.75 m).

Enkamat - the right dimension in erosion prevention

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InstallationIntegration of the roots with Enkamat’sfilament core structure provides the bestpossible protection for banks andembankments.The embankment subsoil must bestable and the surface should be evenlygraded. Cutting back is preferable tofilling hollows in a slope, but large openareas and gullies need to be filled andwell compacted.

After pinning Enkamat to the slope, thegrass seed mixture selected should beplaced into the matting at a rate ofapproximately 20-30 g/m2.

Topsoil is then raked into the mat untilthe area is completely covered.For the prefilled Enkamat A, the subsoilmust be seeded before installation ofthe matting.Enkamat flat-back below the water levelis to be filled with stone chippings (2 - 6 mm) and also to approximately0.5 m above the normal water level.Always lay Enkamat from thedownstream end with all overlapsupstream over downstream.To ensure evenly distributed contactwith the subsoil, Enkamat must besecured with pegs or pins. All edges(top, bottom and sides) should be firmlyanchored in spade-deep trenches withpins. All overlaps should be pinnedtightly. Any concentrated flow of surfacerunoff that could cause problems shouldbe dealt with.If rainfall causes some washout beforevegetation has been established,replenish what is lost with friabletopsoil.

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Wet conditionsDesignIn the simplified design methoddeveloped for the use ofEnkamat, a distinction is madebetween use in wet and dryconditions.Wet conditions are defined asapplications where Enkamat is incontact with flowing water instreams, watercourses, ditchesor waterstorm drainagechannels.Dry conditions coverapplications where no direct flowwater along the mat occurs anderosion is only caused byrainfall.

10

5

3

2

1

0.5

0.3

0.2

0.1

Wat

erve

loci

ty(m

/s)

Average particle size (mm)

Enkamat required

No Enkamat required

0.001 0.01 0.1 1

Clay Silt Sand Gravel Stones

0.20

Run up (see table)

High water level

Low water level

0.50

1.00

1. Check the need for erosion protection with Enkamat.

2. Determine the length of the mat.

L = 0.20 + 0.50 + (run-up + (HW-LW) x conversion factor) + 1.00

Slope

0.100.200.30

Waveheight Hs (m)

0.100.200.30

1 : 2

0.400.801.20

1 : 3

0.250.550.80

1 : 4

0.200.400.60

Run upWave run up (m) (measured vertically above the high waterlevel), depending on significant wave height (Hs) and slopeangle. The run-up height and the difference between HW andLW have to be multiplied by the slope conversion factor tofind the length of the mat on the slope.

Slope(v:h)

1 : 11 : 21 : 31 : 4

Conversionfactor

1.402.253.154.10

Conversion factor

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3. Select mat type:

• determine the maximum flow in theperiod with no vegetation (v - no vegetation)

• determine the maximum time for thisflow (t - no vegetation)

• determine the maximum flow in the period after permanentvegetation has developed (v - permanent)

• determine the maximum time for thisflow in a condition of permanentvegetation (t - permanent)

The flow v can be calculated e.g. byusing a channel design method,applying Manning’s equation:

v = km. rhy

2/3 . i1/2

withv = velocity (m/s)i = hydraulic gradientrhy = hydraulic radius (m)km = Manning’s roughness

coefficient (m1/3/s)

For calculations with Enkamat km = 52 (m1/3/s)

Enkamat A20

Enkamat + chippings

Enkamat + soil

Bare soil

5

4

3

2

1

0

Max

.wat

erve

loci

ty(m

/s)

1 2 5 10 20 50 100

Time (hrs) No vegetation

18 mm 8 mm18 mm 8 mm

Matthickness

Enkamat + grass

Plain grass on clay

Plain grassC

heck

ifth

eve

geta

tion

rem

ains

inta

ct

6

5

4

3

2

1

0

Max

.wat

erve

loci

ty(m

/s)

1 2 5 10 20 50 100

Time (hrs) Permanent vegetation

Select the mat types based on the most critical conditionsusing the following graphs.

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Dry conditions

0.50

H = height of the slope

L = 0.50 + H x conversion factor

100

80

60

40

20

0

Max

imum

rain

inte

nsity

(mm

/hr)

Average particle size (mm)

Enkamat required

No Enkamat required

0.001 0.01 0.1 1 10 100 1,000

Clay Silt Sand Gravel Stones

1. Check the need for erosion protection with Enkamat.

2. Determine the length of the mat.

For anchoring details see installation manual.

The height has to be multiplied by the conversion factor to find the length of themat on the slope.

Slope(v:h)

1 : 11 : 21 : 31 : 4

Conversionfactor

1.402.253.154.10

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Polar

Temporate

Subtropic

Tropical

Subtropic

Temporate

Polar

A. Germination effects:When you expect enough rainfall Þ "germination factor" = 2In case you expect less rainfall or temperatures less than 10°C Þ "germination factor" = 3If you do not know if you will get enough water Þ "germination factor" = 3

B. Slope angle effects:Determination of the “slope effect factor”:

Determine the required volume ofrainfall in the month after installation forrelatively rapid germination, related tothe temperature and the climatic area.

Required, mean volume of rainfall(mm/month) necessary for vegetation.

Compare this volume of rainfall withwhat you expect to get.

Select mat type:“germination factor” + “slope effect factor”≤ 5 Þ Enkamat with thickness of 8 mm“germination factor” + “slope effect factor”> 5 Þ Enkamat with thickness of 18 mm

Slope (v:h)

1 : 3 and smoother1 : 2.51 : 21 : 1.51 : 1 and steeper

“Slope effect factor”

12345

3. Determine the type of the mat.

10-15

3070

Temperature °C

Climate

TropicalHumidArid

SubtropicHumid

Arid

TemporateHumidArid

15-20

30757590

7090

20-30

90130

90

145

90110

30-40

110165

110

200

130165

Winter

Summer

Winter

Summer

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Enkamat - product details

Material properties

Polymer type:Polyamide 6

Enkamat density:Approximately 25 kg/m3

Strength at filament crossing points:Excellent because of total fusion of the filaments where they cross.

Ageing:Good resistance to weatheringand UV radiation because of theaddition of carbon black and UV stabilizers.

Chemical resistance:Resistant to all chemicals inconcentrations which arenormally contained in the earthand surface water.

Temperature resistance:From -30°C to +100°C; can easilybe installed during winter periods.

Flammability:Low flammability and low smoke formation; approved foruse in tunnels.

Toxicity:None; approved for use inpotable water reservoirs;Enkamat is inert and not harmfulto the environment.

Rodent damage:No nutritive value; the tangledstructure of the mat is unpleasant to burrowing animals and rodents.

Dimensions and weights

Enkamat Thicknessmm

101820

18

1111

22

Tensile strength

1.6 kN/m 1.8 kN/m 2.0 kN/m

1.9 kN/m

Characteristic strength

80 kN/m200 kN/m

n.a. Weight 20 kg/m2

The above dimensions and weights are indicative values which can vary slightly.

Roll dimensionsEnkamat can be supplied in 1.0; 1.95 and 3.85 m wide rolls.Enkamat 7010 is available in up to 5.75 m wide rolls.Enkamat 7010W mattings are 4.90 m wide. The length of the rolls varies between 50 and 150 m, depending on which type andwidth is selected.Enkamat A20 mattings are 4.80 m wide and 20 m long.

Contact your national agent to obtain detailed product data sheets.

Type

Open matting701070187020

With flatback7220

Withreinforcement(W types)7010W/80.30PP7010W/200.50PET

PrefilledA 20

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Material specifications

Enkamat type 7010The erosion prevention mats are athree-dimensional filament structurepolyamide mattings with a thickness of10 mm and supplied in rolls1.00/1.95/3.85/5.75 m wide. The lengthof the mat is 150 m. The free volume is95%, the AHC* 9.7 x 106 mm3/m2. Thespecific gravity of the polymer is 1.14g/cm3.

Enkamat type 7018The erosion prevention mats are athree-dimensional filament structurepolyamide mattings with a thickness of18 mm and supplied in rolls1.0/1.95/3.85 m wide. The length of themat is 120 m. The free volume is 95%,the AHC* 17.7 x 106 mm3/m2. Thespecific gravity of the polymer is 1.14g/cm3.

Enkamat type 7020The erosion prevention mats are athree-dimensional filament structurepolyamide mattings with a thickness of20 mm and supplied in rolls1.0/1.95/3.85 m wide. The length of themat is 100 m. The free volume is 95%,the AHC* 19.7 x 106 mm3/m2.The specific gravity of the polymer is1.14 g/cm3.

Enkamat type 7220The erosion prevention mats are athree-dimensional filament structureof polyamide mattings with a flatbackand thickness of 18 mm.The rolls are1.0 m wide.The length of the mat is60 m. The free volume is 95%, theAHC 19.7 x 106 mm3/m2.Thespecific gravity of the polymer is 1.14g/cm3.

* AHC - Area Holding Capacity

EM-10-GB-A-06/2008

© Colbond bv

® registered trademark

The information set forth in this brochure reflects our

best knowledge at the time of issue. The brochure is

subject to changes arising from new developments and

findings; the same applies to our products.

We undertake no liability for the results of usage of our

products and information.

Enkamat type A20The erosion prevention mats are athree-dimensional filament structurepolyamide mattings with a thicknessof 22 mm and supplied in rolls 4.80 mwide. The length of the mat is 20 m.The mat is factory filled with 20 kg/m2

of bilumen bound aggregate. The fillhas a water permeability of 30 l/(s.m2)at 100 mm head.

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Colbond bvPostbus 96006800 TC ArnhemThe Netherlands

Phone: +31 26 366 4600Fax: +31 26 366 5812E-mail: geosynthetics@colbond.comInternet: www.colbond-geosynthetics.com

Colbond 510 Thomson Road #17-01Singapore 298135Singapore

Phone: +65 6 258 1333Fax: +65 6 259 8607E-mail: colbond@singnet.com.sgInternet: www.colbond-geosynthetics.com

Colbond GmbH & Co. KGPostfach63784 ObernburgGermany

Phone: +49 6022 812020Fax: +49 6022 812800E-mail: geosynthetics@colbond.comInternet: www.colbond-geosynthetics.de

Colbond Inc.Sand Hill Road / P.O. Box 1057Enka, North Carolina 28728U.S.A.

Phone: +1 828 665 5050Fax: +1 828 665 5009E-mail: info@colbond-usa.comInternet: www.colbond-usa.com

Colbond Geosynthetics Sarl”le Pressense”268, Avenue du Président Wilson93218 Saint-Denis la Plaine CedexFrance

Phone: +33 1 49 46 24 30Fax: +33 1 49 46 24 35E-mail: france.colbond@colbond.comInternet: www.colbond-geosynthetics.fr

www.colbond.com

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