Presto GEOWEB® Channel Protection System
For comprehensive information on the Geoweb® Channel Protection System, please click on the web site link listed above.

Presto Products Company, the leader in cellular confinement, provides fully engineered solutions to soil stabilization problems from engineering design, to quality documentation and on-site support availability.

Engineering advancements are ongoing at Presto. Recent advancements include the introduction of the perforated Geoweb® system, high-strength tendons, ATRA® Clips and the ATRA® Anchoring System.

ISO-Certified Quality
Presto’s commitment to quality begins with manufacturing and continues through final installation. The quality management system for the sale, design and manufacture of the Geoweb® system is certified to ISO 9001:2000 and materials are specifically engineered in accordance with established geosynthetic industry guidelines.

SPECMaker® Specification Development Tool
Presto developed the SPECMaker® Specification Development Tool, a user-friendly software program that lets designers and/or contractors develop complete material and construction specifications.

PR-Product Presentation
Presto’s Geoweb® system is an expandable polyethylene, honeycomb-like structure used to confine unstable soils, sands or gravel. The Geoweb system provides solutions to slope and channel protection, earth retention and load support problems.

The Geoweb® Channel Protection System provides a wide variety of flexible protection treatments for open channels and hydraulic structures. The system is ideal for protection of channels exposed to severe erosive conditions, as well as channels with continuous flows.

Single or multi-layer perforated channel protection systems meet a wide range of structural and hydraulic requirements. Vegetation, aggregate and concrete can be used as infills to address aesthetic, environmental, hydrodynamic and structural concerns. The concrete-filled system provides a flexible form that allows cells to flex and conform to subgrade movement, thereby preventing uncontrolled cracking of the concrete. The system greatly improves the hydraulic performance of conventional protection materials such as concrete, gravel, rip-rap and vegetation by confining them within the cellular structures.

The Geoweb system can be designed for a particular site based upon compatibility with local environmental, ecological and aesthetic requirements. The system is designed for maximum anticipated flow conditions, associated hydraulic stresses, surface roughness and hydraulic efficiency of the lining system. Subgrade drainage requirements and the deformation potential within the structure can also be addressed. A non-woven geotextile underlayer, combined with custom outlet ports, assures effective subgrade drainage and subsoil protection. Future maintenance and sediment cleaning operations can also be considered.

UA-Uses, Applications
A variety of infill materials can be used with the Geoweb system based upon the demands of the specific project/problem.  Infill materials include:

MF-Materials, Finishes
 The Presto Geoweb® cellular confinement system is available in two distinct cell wall types: perforated and non-perforated. Both have an engineered textured pattern of indentations that increase friction between the cell wall and infill material. The textured non-perforated surface works particularly well with finer grain infill.

The Perforated Geoweb System
The perforated Geoweb® system has an engineered hole pattern, increasing frictional interlock with a broad range of coarse infill materials, including gravels, crushed rock and concrete. The perforations allow lateral drainage through the cell walls, facilitating parallel slope drainage of the infilled cell.

In saturated conditions, an overall weight reduction of the infill material reduces down slope sliding potential, resulting in a more stable system. In vegetated systems, roots can grow from cell-to-cell, creating greater vegetative mass lockup. Perforations provide greater frictional resistance between the cell wall and aggregate and other coarse infill materials. Perforations allow concrete infill to flow through the cells, resulting in a superior armored channel system.

CP-Components, Parts
Tendons
Polymeric tendons incorporated into the Geoweb system through pre-drilled holes provide additional stability when anchoring Geoweb sections to embankments and slopes. Tendons are particularly useful when a geomembrane underlayer or naturally hard soil/rock prevents anchoring with stakes. Standard tendons are manufactured from knitted multi-filament high-strength polyester and polyproplylene. The tendons are available in ultimate tensile strengths from 3.11 kN (700 lbf) to 13.34 kN (3,000 lbf) to meet specific requirements.

The ATRA® Anchoring System
Presto’s high-strength polyethylene ATRA® Clip provides time and material cost savings during Geoweb system installation.  Inserted on the end of a stake, the ATRA® Anchor provides an in-line, easy to drive anchoring system, replacing J-Pin anchors. When used with tendons, the ATRA® Anchor provides resistance to excessive sliding and/or uplift forces and toe or crest anchoring for slope protection systems.

The ATRA® Clip restraint pin connects to tendons at specific load-transfer points replacing the need for dowels or other less-secure load-transfer mechanisms.

Perforated GEOWEB® System Performance & Material Specification

Base Material
Material Composition
Polymer – Polyethylene with density of 0.935 – 0.965/cm3 (58.4-60.2 lb/ft3)
Test Method: ASTM D1505
Minimum Environmental Stress Crack Resistance (ESCR): 3,000 hr
Test Method: ASTM D1693

Color
Black – from Carbon Black
Stabilizer: Carbon black content 1.5% - 2% by weight
Tan, Green, Other Colors with no heavy metal content
Stabilizer: Hindered amine light stabilizer (HALS) 1.0% by weight of carrier

Strip Properties

Sheet Thickness
1.27 mm -5% +10% (50 mil –5% +10%)
Test Method: ASTM D5199

Surface Treatment
All Geoweb material shall be textured with a multitude of rhomboidal (diamond shape) indentations having a surface density of 22-31 per cm² (140 – 200 per in²).
Performance:  The polyethylene strips shall be perforated such that the peak friction angle between the surface of the perforated plastic and a #40 silica sand at 100% relative density shall be no less than 85% of the peak friction angle of the silica sand in isolation when tested by the direct shear method per ASTM D 5321.  The quantity of perforations shall remove 19.6% ± 3% of the cell wall area.
Material:  The polyethylene strips shall be perforated with horizontal rows of 10 mm (0.4 in) diameter holes.  Perforations within each row shall be 19 mm (0.75 in) on-center. Horizontal rows shall be staggered and separated 12 mm (0.50 in) relative to the hole centers. The edge of strip to the nearest edge of perforation shall be 8 mm (0.3 in) minimum and the centerline of the weld to the nearest edge of perforation shall be 18 mm (0.7 in) minimum.

Cell & Seam Properties for Channel Protection Applications

Geoweb® Cell Dimension
GW20V Cell
Cell Depth:  75 mm (3 in), 100 mm (4 in), 150 mm (6 in) and 200 mm (8 in)
Nominal Cell Width: 259 mm (10.2 in)
Nominal Cell Length: 224 mm (8.8 in)
Nominal Cell Area: 289 cm² (44.8 in²)
Use 3, 4 or 6-inch depth for only the most severe conditions

GW30V Cell
Cell Depth:  75 mm (3 in), 100 mm (4 in), 150 mm (6 in) and 200 mm (8 in)
Nominal Cell Width: 320 mm (12.6 in)
Nominal Cell Length: 287 mm (11.3 in)
Nominal Cell Area:  460 cm² (71.3 in²)
Use 3, 4 or 6-inch depth for all general conditions.

GW40V Cell
Cell Depth: 75 mm (3 in), 100 mm (4 in), 150 mm (6 in) and 200 mm (8 in)
Nominal Cell Width: 508 mm (20.0 in)
Nominal Cell Length: 475 mm (18.7 in)
Nominal Cell Area: 1206 cm² (187.0 in²)
Use 3, 4 or 6-inch depth for only the most mild conditions.

Short-Term Seam Peel Strength

Short-term cell seam peel-strength shall be uniform over the full depth of the cell. Minimum short-term seam peel-strengths shall be:
Cell Depth Minimum 
Cell Seam Strength
75 mm (3 in) 
1060 N (240 lbf)
100 mm (4 in) 
1420 N (320 lbf)
150 mm (6 in) 
2130 N (480 lbf)
200 mm (8 in) 
2840 N (640 lbf)

Long-Term Seam Hang Strength Test
Long-term seam peel-strength test shall be performed on all resin or pre-manufactured sheet or strips. A 100 mm (4.0 in) wide seam sample shall support a 72.5 kg (160 lb) load for a period of 168 hours (7 days) minimum in a temperature-controlled environment that undergoes change on a 1-hour cycle from room temperature to 54°C (130°F). Ambient room temperature is per ASTM E 41.

Section Properties
Geoweb® Section Dimensions
   
Section Length
(Cells Long: 18, 21, 25, 29, 34)
 
Section Width (Variable) 
Minimum
Maximum
GW20V
2.3 m (7.7 ft) to 2.8 m (9.2 ft)
3.7 m (12.0 ft)
8.3 m (27.3 ft)
GW30V
2.3 m (7.7 ft) to 2.8 m (9.2 ft)
4.7 m (15.4 ft)
10.7 m (35.1 ft)
GW40V
2.3 m (7.7 ft) to 2.8 m (9.2 ft)
7.7 m (25.4 ft)
17.8 m (58.2 ft)

OP-Overall Product
Vegetative Protection
Vegetated soil with the Geoweb system is ideal for areas where low to moderate, intermittent flows occur, such as in swales, ditches and on upper slopes of large channels. Vegetation is a logical choice when project aesthetics are an important consideration.

The Geoweb cell walls that contain the topsoil infill form a series of check-dams extending throughout the channel protection system. Rill and gully development, produced when concentrated flows cut into the soil, is prevented since the flow is continuously redirected to the surface.

A predetermined depth of topsoil and the developing vegetative root mass is confined and protected within the individual cells. Roots readily penetrate through the non-woven geotextile underlayer into the subsoil, reinforcing and anchoring the entire protection system. Confinement and anchorage of the root structure increases the limiting shear resistance of the protection and the permissible flow duration.

Color Options
The Geoweb system can be provided in a variety of colors to meet desired aesthetic requirements. The system is available in natural colors of black, green or tan.  Green and tan colors are typically only used as the facia panel of stacked channel systems. Coloring pigments contain no heavy metals and the polyethylene is ultraviolet light stabilized with carbon black or Hindered-Amine Light Stabilizer (HALS) to resist system deterioration.

Aggregate Protection
Aggregate is ideal in low to moderate flow channels.  This system fills the “gap” between vegetated and concrete channel lining applications.  Contact Presto for specific recommendations regarding size of aggregate versus flow conditions.

Concrete Armoring
Poured concrete provides hard, durable protection for channels that are exposed to severe hydraulic or mechanical stresses:

Critical velocities, Manning’s “n” and other hydraulic design parameters have been established for the Geoweb cellular confinement system.

Stacked Geoweb System
Stacked Geoweb sections along channel side slopes provide the structural integrity to withstand high flows and differential settlement without loss of system integrity.  The use of vegetation along the facia offers a natural appearance and the ability to withstand higher flows for short durations. In the stacked configuration, colored face panels may be utilized allowing the system to blend naturally with the environment.

AI-Assembly, Installation
The Geoweb system is designed with ease of installation in mind. Geoweb sections collapse into lightweight, compact bundles for easy shipment. During installation, sections remain flexible and easy to handle. Various methods are used for expanding the Geoweb sections. Stretcher frames are typically used for installations where dimensional tolerances are critical or in underwater applications.

TS-Technical Support
Presto offers complete design and construction tools for the designer and/or contractor. These tools are available on Presto’s Technical Resources Library CD or at Presto’s web site www.prestogeo.com.

MR-Manufacturer

Presto Products Company - Geosystems® Products
A Business of Alcoa
P.O. Box 2399
670 N. Perkins Street
Appleton, WI 54912-2399
Tel: (920) 738-1336
Toll-Free: (800) 548-3424
Fax: (920) 738-1222
Toll-Free Fax: (800) 535-8221
Web site: http://www.prestogeo.com

PRESTO®, GEOSYSTEMS®, GEOWEB®, ATRA® and SPECMaker® are registered trademarks of Presto Products Company. © 1998-2004
This information has been prepared for the benefit of customers interested in the Geoweb cellular confinement system. It was reviewed carefully prior to publication.  Presto Products Company assumes no liability for its accuracy or completeness. Final determination of the suitability of any information or material for the use contemplated, or for its manner of use, is the sole responsibility of the user.