Wherever soil and water meet infrastructure, drainage decides longevity. Geonets are the drainage core behind a surprising amount of US civil work: landfill leachate collection layers, retaining wall drains, landfill caps, tunnel and plaza drainage. A geonet is an HDPE net structure of parallel ribs that creates continuous in-plane flow channels; bonded with geotextile skins it becomes a geocomposite that filters, drains and protects in one roll. We produce geonets and composites for US geosynthetic distributors, and here is the spec level that matters.
Transmissivity is the headline number
Flow capacity in-plane, tested under load, is the number a designer cares about: transmissivity under normal stress, at the confining pressures the installation will actually see. Rib geometry, height and spacing set that number. landfill leachate layers, wall drains and caps each carry different load and flow requirements, which is why quoting a geonet without design conditions is meaningless; send the cross-section and loads, and we spec the structure rather than guessing.
Composite or bare net?
Bare geonet suits applications where an adjacent layer provides filtration already. The geocomposite, geonet with one or two geotextile skins heat-bonded, is the common order because filtration and drainage arrive as one installed layer, fewer rolls to handle and no risk of a skipped filter. Bonding quality matters: delaminated skins in a trench are a warranty conversation nobody enjoys, so bond strength is tested per lot, and we ship the test reports with the rolls.
Where US work uses geonets
- Landfill leachate collection and detection layers above liners.
- Retaining wall and MSE wall drainage behind facings.
- Landfill final cover drainage above the barrier layer.
- Plaza decks and tunnel drainage where a thin, high-flow layer replaces thick gravel.
The recurring theme: geonets replace a foot of graded stone with a thin manufactured layer, which changes excavation volumes, haul-off and schedule. On urban walls especially, that space saving is the entire justification for the product.
Indicative pricing and logistics
Bare geonets run roughly $0.25 to $0.50 per square foot FOB India; geocomposites with bonded geotextile run higher depending on fabric weight. Rolls are wide and light for their coverage, so containers carry large areas and freight per square foot stays modest. Production is 3 to 4 weeks; ocean 4 to 6 weeks East Coast. Certification paperwork, lot test reports and conformance data, ships with the rolls, which landfill and DOT projects will require, so ask any supplier for theirs before the PO.
Specifier questions
How does geonet compare to a gravel drainage layer?
Engineered flow in a thin layer versus gravity flow in thick stone. Where excavation volume and vertical clearance matter, geonets win; where free stone is cheap and space is abundant, gravel still competes. The design cross-section settles it.
What about creep under load?
HDPE formulations are selected for long-term creep performance at design stress; insist on creep-reduced transmissivity values in specs, which is what conformance testing should state.
Structures and composites are on the Geonet page. Related systems: geocell confinement and drainage cells.
