Eco

Cha

nnel

C A S E H I S T O R Y - N O . 0 3 0 3

Rural counties, as well as cities andurban communities continue to faceproblems with soil erosion alongstream banks, shorelines, tributaries,and creeks. In addition to the ero-sion problems, they are also facingthe effect of chemical constituentswithin the water from runoff of agri-culture, recreation areas, and resi-dential areas that apply fertilizationto their crops, plants, and vegeta-tion. This problem is particularlyincreasing within areas of concen-trated or dense development.

The City of San Juan Capistrano,located in Southern California, wasfacing such a situation with a chan-nel built in the 1960’s that wasseverely eroding and undercuttingthe concrete side slopes - causingsediment to be transported to theSan Juan Creek basin that drainsdirectly into the Pacific Ocean. TheCity’s objectives for rehabilitating thechannel were: minimize erosion dur-ing precipitation events, increaseaesthetics along the channel, mini-mize long term maintenance issues,reduce chemical particulate matterfrom the residential runoff water,

and minimize construction andmaintenance costs. City engineerscalled P&D Consultants, an environ-mental planning and engineeringfirm in Orange, California to studythe problem, provide recommenda-tions, and submit a design to repairthe channel while meeting theirobjectives. P&D reviewed manyoptions including conventional riprap, Reno mattresses, concrete,and TRMs (turf reinforcementmats.)

P&D began their assessment by cal-culating the flow of water within thelocalized tributary flowing directlyinto the channel. The existing chan-nel collects runoff from over 300acres. The area is within a valleywith hillsides over 200 ft. high.Storm drains from the existingdevelopment discharge directly intothe channel. The initial flow of waterentering the channel is from a 10’ x4’ concrete box culvert. The 1700 ft.long trapezoidal channel measured4 ft. deep with a 10 ft. bottom andside slopes of 1.5:1. The estimatedflow rate of the channel was 500cfs. This type of flow generates a

R2M Technology Solves Soil ErosionProblem in California City

Enkamat R2M

DIVISION 2Site Construction

Trapezoidal Channel

Contractor:

Valley Coast Landscape

Construction, Inc.

San Diego, CA

Engineer:

P&D Consultants

Orange, CA

Distributor:

White Cap Industries, Inc.

Santa Ana, CA

C O L B O N D G E O S Y N T H E T I C S

LaRonda channel after vegetation is established.

Continued on reverse side...

shear force on the channel bottom ofapproximately 4.5 psf for an extremestorm event.

After reviewing all of the options, P&Dand San Juan Capistrano representa-tives determined that a root reinforce-ment matrix would be the best solutionto meet the project requirements. Ameeting was held with city officials,Valley Coast Landscape, and ColbondGeosynthetics to determine the mosteffective construction and installationmethods for the channel. Low growthvegetation that would require little orno maintenance and remove pollutantsfrom the water prior to discharge intothe basin was also selected at thistime. A discussion took place aboutwhich root reinforcement matrix wouldnot restrict vegetation growth and stillmeet the required flow conditions ofthe channel.

Colbond Geosynthetics’ engineersreviewed all the information and rec-ommended using Enkamat R2M.

Enkamat is a three-dimensional, rootreinforcement matrix that is sufficientlyopen to eliminate vegetation restric-tion. It is made from nylon, which willnot float like polypropylene. Enkamatkeeps the vegetation and soil fromeroding during extreme hydraulic flowconditions. City officials and P&D alsoliked the fact that Enkamat would

never unravel or lose its structuralintegrity both during and after installa-tion - aquatic life within the basin

would never be endangeredfrom loose synthetic fibersfloating downstream.

Valley Coast Landscape sug-gested a mulch be applied ontop of the Enkamat to ensurerapid germination, minimizeseed displacement, and aidthe establishment of maturevegetation. The overall cost ofusing the Enkamat and mulchlayer provided considerablesavings compared to othererosion control alternatives.

“Choosing Enkamat for the rehab ofthe channel saved considerably overtraditional methods of reconstructionand provided an environmentallyfriendly solution to the existing erosionproblem. Rip rap would have cost anadditional 15 - 20% and concreteabout 40%. With these savings wewere able to armor more of the chan-nel - not to mention nearby homeown-ers were extremely satisfied with oursolution. Adding native plants to thechannel was much more pleasing tothe eye than concrete or rip rap.” saidRichard Wilson of P&D Consultants.

Once construction began, the projectwas completed in two weeks. ValleyCoast Landscape was very satisfiedwith how conformable the EnkamatR2M was during installation and thatthe product didn’t unravel or lose itsstructural integrity (reduction in perfor-mance) when cut in the field duringinstallation. TRM’s they have used inthe past have tended to unravel uponarrival at the job site and during instal-lation, making them more difficult forcrews to work with. These same TRMslose their fibers when cut, compromis-ing the integrity of the product andcausing environmental concerns whenloose fibers migrate into ecologicalsystems.

Since the installation, several 25 yearstorm events have occurred in thisarea. Both the channel and vegetationhave not been damaged - even duringpeak rainfall and hydraulic activity. Cityofficials in San Juan Capistrano arevery pleased with the success of theproject and that all of the federal andstate requirements of the Phase II

Rules of the NPDES (EPA’s NationalPollutant Discharge EliminationSystem) were met.

Eco Channels provide manybenefits to your environment:

• Minimizes Sediment Loss

• Filters Pollutants

• Increases Aquatic Life

• Stimulates Oxygen Production

• Enhances Cooling Effect

• Creates Recreation Areas

• Beautifies your Surroundings

1301 Sand Hill Road

P.O. Box 1057

Enka, N.C. 28728

Tel. (+1) 828-665-5050

Toll Free: (+1) 800-365-7391

Fax (+1) 828-665-5009

EnkaTech Fax Back (+1) 888-288-2132

email: enka-engineered@colbond.com

website: www.colbond-usa.com

For more information about Enkamat R2M

and other quality products manufactured

and marketed by Colbond, Inc. please call

our toll free number or visit our website.

C A S E H I S T O R Y - N O . 0 3 0 3 C O N T I N U E D . . .

EnkaGreen e-ngineering with Enkamatdesign software was used to verify theengineer’s calculations.

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