Fin Drains and Subsoil Drainage
Fin drains combine a drainage core with a filter covering to collect and convey subsoil water. We supply and install the drain system with compatible pipe connections and discharge points for roads, earthworks and civil infrastructure.
Product description and supply
A fin drain combines a drainage core with a filtering geotextile in a prefabricated strip or panel arrangement. Water enters through the filter and travels through the core toward the designed collection and discharge route.
Geosynthetics South Africa supplies fin drains and drainage composites manufactured to the agreed configuration across our factories. Core, filter, dimensions, connections and supporting technical data are identified for the project.
Match the composite to the ground and load
Provide the soil grading, groundwater conditions, installation depth and expected loads. Selection should examine filter opening size, hydraulic behaviour, core deformation and flow capacity under the relevant pressure and hydraulic gradient.
A short-term compressive-strength result alone does not establish long-term drainage capacity. Request the test conditions and appropriate design reductions for the selected construction.
Applications and uses
We supply and install this product for:
- Subsoil and structural drainage behind retaining walls and below landscaped or paved areas.
- Drainage layers in designed civil and containment systems.
Why choose Fin Drains and Subsoil Drainage?
- Combined drainage and filtration
- Connections to collection pipes
- Manufacturing, supply and installation support
Installation and technical guidance
Installation and QA/QC
We prepare the product and fabrication scope around the required core, filter, width, lengths, joints and collection-pipe arrangement. Include drawings for end closures, corners, penetrations and discharge connections in the enquiry.
Retaining-wall drainage, roadside interceptor drains and drainage within containment works impose different requirements. Confirm any barrier, protection or chemical-resistance function separately from water collection.
Check the excavation and founding level, filter condition, joint continuity, core orientation, pipe connection and outlet before the drain is covered. Prevent backfill from entering open ends or bypassing the filter.
The inspection plan should record product identity, locations, connections, backfill acceptance and photographic evidence before concealment. Include access for cleaning or inspection where the design requires it.
Specification and quotation inputs
| Item | Confirm for this project |
|---|---|
| Filter | Soil compatibility, opening size, water flow and installation survivability. |
| Core | Construction, thickness, flow under design load and deformation behaviour. |
| Geometry | Drain height, width, lengths, depth and junction details. |
| Collection | Pipe diameter, capacity, connection, gradient and outlet level. |
| Production QA/QC | Material identification, fabrication dimensions, joint and filter inspections. |
Match the exact supplied grade to current documentation and the approved project specification. Product availability and lead time are confirmed with the quotation.
Questions engineers and contractors ask
Can a fin drain replace every granular French drain?
It may be considered as a designed alternative. Hydraulic capacity, filtration, loading, constructability and discharge arrangements must be checked against the project requirements.
Are fin drains and PVD wick drains interchangeable?
No. Fin drains collect subsurface water in a drainage arrangement; PVDs installed into soft ground form part of an engineered consolidation scheme.
What information is needed for a price?
Send the drain cross-section, total lengths, installation depth, filter requirements, core performance, pipe and outlet details, delivery location and programme.
Choose the scope you need
Supply only; manufacture or fabrication; supply and delivery; or supply with a defined installation and QA/QC scope. The quotation identifies materials, responsibilities, testing and the required handover records.
Design and procurement inputs
Specify in-plane flow at the design load and gradient, creep resistance, filter compatibility, connections and discharge points. A drainage layer requires a functioning outlet.
Provide the product grade or performance specification, drawings or BOQ, quantities, site location and required date. We will define supply, delivery and any agreed installation and QA/QC responsibilities in the quotation.
Request a product-specific quotation →Technical documentation and specification support
Request the current supplied-grade datasheet, applicable installation guidance and supporting quality records from our technical team.