Pipes, Drainage & Ducting
GeoPipe FS™ - Slotted HDPE Drainage Pipe with Integrated Filter Sock
Slotted HDPE subsoil drainage pipe supplied with a factory-fitted nonwoven polypropylene filter sock. DN110 and DN160 with 150gsm sock; DN200, DN250 and DN315 HD with 200gsm sock. The filter layer arrives correctly tensioned and continuous, so there is no wrapping operation on site and no gaps or folds in the filter. For fine, silty and clay-rich soils where unprotected drainage pipe blinds.
Overview
The Filter Fitted in the Factory, Not the Trench
GeoPipe FS is double-wall corrugated slotted HDPE drainage pipe supplied with a nonwoven polypropylene filter sock already fitted. Same smooth bore, same slot geometry, same ring stiffness as standard GeoPipe - with the filtration layer applied under factory conditions rather than assembled in a trench.
Why this matters. The most common cause of subsoil drainage failure is not the pipe. It is fines migrating into the pipe through an inadequate filter, progressively blinding the slots until the drain stops draining - usually years after handover, and always somewhere it can't be dug up cheaply. The standard defence is a wrapped aggregate zone, which depends entirely on a geotextile being lapped correctly around a stone surround, in a trench, under time pressure, by whoever is on site that day. Gaps, folds and short laps are routine, and none of them are visible once the trench is backfilled.
A factory-fitted sock removes that variable. The geotextile-to-pipe interface is consistent and correctly tensioned along the full length, the filter cannot be misplaced, and the pipe goes straight into the trench as a single unit. It also removes a labour operation and the separate geotextile line item.
Sock specification by size. DN110 and DN160 carry a 150gsm nonwoven polypropylene sock, matched to lateral duty in silty and fine sandy soils. The HD range in DN200, DN250 and DN315 carries a 200gsm sock, heavier to suit collector duty, greater cover depth, higher flow, and the rougher handling that large-diameter pipe gets on site.
Where to specify it. Expansive clay belts, laterite profiles and coastal fine sands - the soil conditions across much of sub-Saharan Africa where unprotected pipe is a known risk. Retaining wall and MSE back-drains in cohesive backfill, where clogging is the most common mode of failure. Agricultural laterals in fine silts. Road and rail formation drainage where later access for maintenance is effectively impossible. Mining underdrains and TSF seepage collection where the drain has to work for the life of the facility.
Installation. Trench, bed and backfill as standard GeoPipe, with the white apex line uppermost. Surround with clean free-draining aggregate to 150mm above the crown. The separate geotextile wrap around the aggregate zone is not required. Do not compact mechanically against the pipe, and do not drag the pipe across sharp material during placement.
A first for this market. No other supplier in the region offers subsoil drainage pipe with an integrated filter sock as a stocked specification - it has been a fabricate-to-order item or an on-site improvisation. Geosynthetics Africa supplies GeoPipe FS across South Africa and the wider continent on a single specification and lead time.
- MaterialHDPE pipe · nonwoven polypropylene filter sock
- StructureDouble-wall corrugated, slotted · factory-fitted filter sock
- ColourBlack pipe with white apex line · grey sock
- StandardEN ISO 9969 ring stiffness · ISO/TR 10358 chemical resistance
- Roll WidthDN110 · DN160 · DN200 · DN250 · DN315
- Roll Length150gsm sock (DN110–160) · 200gsm sock (DN200–315)
Typical Properties
| Property | Test Method | Unit | Typical Value |
|---|---|---|---|
| Material (GeoPipe) | - | - | HDPE |
| Material density | ISO 1183 | g/cm³ | 0.960 |
| Ring stiffness | EN ISO 9969 | kN/m² | >8 (HD) · >450 N normal duty |
| Crush resistance | SANS 61386-24 | N | >850 (HD) |
| Filter sock mass per unit area | EN ISO 9864 | g/m² | 150 (DN110–160) · 200 (DN200–315) |
| Filter sock opening size (O90) | EN ISO 12956 | µm | 100 |
| Filter sock permeability (Δh=50mm) | EN ISO 11058 | mm/s | 100 (150gsm) · 85 (200gsm) |
| Filter sock tensile strength MD/CMD | EN ISO 10319 | kN/m | 12 (150gsm) · 16 (200gsm) |
| Filter sock CBR puncture | EN ISO 12236 | kN | 1.75 (150gsm) · 2.35 (200gsm) |
Note: The above values are typical and not intended for specification purposes. Please refer to the product datasheet for full details.
Typical Applications
View all applicationsRoad & Rail Formation Drainage
Intercept groundwater beside roads, railway formations and platforms using a designed network of standard laterals and GeoPipe HD collectors. Select diameter, stiffness, cover, filters and outlet spacing from the pavement drainage and loading design.
Retaining Walls & MSE Back-Drains
Collect water at the base of retaining walls, MSE structures and basements through a designed drainage layer and pipe system. Select the filter for the actual backfill; provide accessible outlets and maintenance points.
Mining Underdrain & TSF Drainage
Use engineered slotted collection systems for seepage beneath mine platforms, TSFs or containment works only after checking load, hydraulic capacity and compatibility with the actual fluids. GeoPipe HD collectors extend to 315 mm; project-specific engineering governs selection.
Sports Fields & Landscaping
Use slotted laterals and collectors to manage groundwater beneath turf, golf courses and landscaped areas. Set pipe spacing, depth and gradient from soil permeability and required drainage rate; select coil or straight formats for installation access.
Agricultural & Farmland Drainage
Manage waterlogging using designed field laterals feeding collector mains and an approved outlet. Specify filtration from soil grading and clogging risk. Standard drainage coils are 50 m in 75-160 mm; HD collectors are available to 315 mm.
Compatible Systems
View all systemsGeoPipe 75 & 110 mm - Standard Drainage
75 and 110 mm OD standard slotted pipe for French drains, foundation perimeters, field laterals and landscape drainage. Choose 6 m lengths with 270° slots or 50 m coils with 360° slots. Typical IDs 60 (±1) and 90 mm. Filter selection and loading must suit the design.
GeoPipe™ DN160 - Normal Duty Collector
160 mm OD standard drainage pipe with typical 137 mm ID. Standard formats are 50 m coils with 360° slots or 6 m lengths with 270° slots. Use hydraulic design to size collector lines and define gradients, filters and outlets.
GeoPipe HD™ DN200 - Heavy Duty Collector
200 mm OD / typical 173 mm ID in 6 m lengths. SN8 base pipe to SANS 21138-3; 120° partial or 360° full slots with project-specified dimensions. Confirm finished slotted performance and burial design.
GeoPipe HD™ DN250 - Heavy Duty Collector
250 mm OD / typical 217 mm ID in 6 m lengths for designed collector systems. SN8 base pipe to SANS 21138-3; choose 120° partial or 360° full slots. Chemical compatibility must be checked for mining or landfill fluid collection.
GeoPipe HD™ DN315 - Primary Main
315 mm OD / typical 273 mm ID in 6 m lengths for larger collector and gravity drainage duties. Specify slotted collection or solid-wall conveyance, joint and seal requirements. Cover, backfill, loading and capacity require engineering review.
Installation Guidance
Standard Method Statement
Excavate to the engineered depth, width and gradient. Select bedding and flexible-pipe support for the pipe, soil, groundwater and loading. Refer to the project specification and applicable buried-pipeline requirements, including SANS 10102-2 and SANS 2001-DP1 where specified.
Verify diameter, configuration and condition before laying. Orient partially slotted pipe using the product marking with the solid invert below: standard 270° lengths and HD 120° crown slots differ. Fully slotted coils or lengths collect around the circumference. Maintain coil bend radius of at least 15 × OD and inspect joint engagement.
Install compatible filter aggregate and geotextile or the specified sock arrangement. Filter selection must match soil and hydraulic requirements. Provide uniform side support and protect pipe and filtration layers against displacement or damage during backfill.
Backfill and compact to the approved sequence and cover before plant access. Verify gradient, outlet, inspection and flushing access. Record material identification, slot pattern, line and level, joints, filters, bedding and cover as the installation QA/QC record.
Quality Assurance & Testing
Field QA/QC Checklist
- Delivery & Storage: Materials checked against the delivery note and conformance certificates, stored off the ground, covered from UV and kept clear of sharp objects and fuel.
- Material Conformance: Pipe certificates checked for diameter, ring stiffness and perforation pattern against the specification.
- Trench & Bedding: Trench excavated to line and grade; bedding and filter material placed as designed (geotextile wrap or sock where specified).
- Laying & Joints: Pipe laid to the design fall with couplers fitted; perforations oriented as specified.
- Backfill & Flushing: Backfilled with the specified drainage aggregate; outlets and rodding points installed and the line flushed or CCTV-inspected where required.
Manufacturing Standards
- Manufacturer pipe specification and certificates
- Project drainage specification
- EN ISO 9969 ring stiffness · ISO/TR 10358 chemical resistance
Documents
Product Selection Guide
Compare performance properties across the entire category hierarchy before specifying.
Installation & Method Statement
Standard deployment procedures, installation specifications, and field application method statements.
QA/QC Site Checklist
Field quality control procedures, inspection checklists, and testing standards to verify installation integrity.
Technical Data Sheet (TDS)
Guaranteed minimum average roll values (MARV) and material testing properties.
Chemical Resistance / Accessories Guide
Chemical compatibility matrix and list of auxiliary materials needed for installation.
Projects Using GeoPipe FS™ - Slotted HDPE Drainage Pipe with Integrated Filter Sock
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