Geocomposites & Drainage
Combined drainage and containment systems — geonets, drainage composites, dimple sheets and clay liners — that reduce installation layers and total project cost.
What It Is
Geocomposites combine two or more geosynthetic functions into a single product — typically a drainage core (geonet, dimple sheet or three-dimensional mat) bonded to one or two layers of non-woven geotextile, or a layer of sodium bentonite bonded between geotextile carriers to form a geosynthetic clay liner (GCL). The drainage core provides a high-flow channel for water or leachate while the geotextile layers filter out fine soil particles. GCLs provide a low-permeability barrier equivalent to a thick compacted clay layer at a fraction of the thickness. Willem Olaf's geocomposite range simplifies drainage and containment design, reducing the number of separate material layers — and the total installation time — on site.
Key Properties / Technical Overview
Representative values across the range. Confirm exact figures for the selected grade on the product datasheet.
| Property | Value |
|---|---|
| Geonet core thickness | 5 – 7 mm |
| Transmissivity | ≥ 1.0 × 10⁻³ m²/s |
| GCL bentonite content | ≥ 4,500 g/m² |
| GCL permeability | ≤ 5 × 10⁻¹¹ m/s |
| Dimple height | 8 – 20 mm |
| Compressive strength | ≥ 200 kPa |
Applications
- Basement and retaining wall waterproofing and drainage
- Green roof and podium deck drainage
- Landfill leachate collection and gas venting layers
- Highway edge and subsurface drainage
- Secondary containment beneath geomembrane liners (GCL)
- Sports field and golf course drainage
Benefits
Multi-Function Design
Combines drainage, filtration and/or sealing in a single product.
Reduced Excavation & Cost
A thinner profile than traditional granular drainage layers cuts excavation volumes.
Reliable Long-Term Drainage
Maintains flow capacity under sustained load over the design life.
Available Specifications
| Product | Configuration | Thickness | Roll Size |
|---|---|---|---|
| Geonet | Single, double or triple layer HDPE | 5 – 7 mm | 4.0 m × 50 m |
| Drainage Geocomposite | Geonet core + non-woven filter (1 or 2 sides) | 6 – 9 mm | 2.0 – 4.0 m × 50 m |
| Dimple Sheet | HDPE studded sheet, with or without bonded fabric | 8 – 20 mm | 2.0 m × 20 – 30 m |
| Geosynthetic Clay Liner (GCL) | Needle-punched, woven/non-woven carriers | 6 – 8 mm (hydrated) | 4.0 – 5.0 m × 40 – 60 m |
Download the Datasheet
Get full technical specifications, test methods and installation notes for this product range.
Download PDF DatasheetSpecify Geocomposites & Drainage for your project
Send us your project details and our technical team will respond within 24 hours with recommendations and a quote.