PVD and Wick Drain Manufacturing

Core geometry and filter-jacket selection

The manufacturing schedule defines core material, channel geometry, overall dimensions, filter grade and the method of enclosing the core. The jacket must remain continuous through handling and installation, with a joint arrangement that preserves the specified filtration and tensile behaviour.

A nominal 100 mm band width is common in PVD systems, but width and thickness are confirmed against the project grade and installation equipment. Filter selection considers the in-situ soil grading, water chemistry and required hydraulic behaviour. Opening-size values must identify their test method and characteristic; O90 and O95 values should not be interchanged.

Discharge capacity under realistic conditions

The required flow depends on drain length, soil conditions and consolidation design. Drain performance is assessed at a stated confining pressure and hydraulic gradient, with the specified straight or deformed configuration. An unconfined flow result cannot establish capacity at depth.

Core compression, filter intrusion and drain deformation can affect the available flow path. The product submission should identify the test arrangement and provide the properties needed to check well resistance and the proposed installation depth.

PVDs, strip drains and South African specifications

The contract specification determines the applicable product category and acceptance requirements. COTO Chapter 3, October 2020, includes geocomposite strip-drain requirements in Table A3.1.5-3. This reference must be read with the contract amendments and the intended drain application.

A deep-ground-improvement band drain is selected against the geotechnical design and its confined-flow requirements. Road strip-drain dimensions should not be treated as a universal sizing rule for every PVD system. Where a legacy contract cites COLTO, we review that edition and the project particulars.

Manufacturing release and installation interface

Production checks cover material identification, dimensions, jacket continuity, roll length and the specified mechanical and hydraulic properties. Rolls are identified for traceability and protected during packing and transport.

The geotechnical designer establishes drain spacing, depth, surcharge or vacuum preload, loading sequence and settlement monitoring. The manufacturing quotation identifies whether the scope includes supply only or coordination with an installation package. Mandrel compatibility and handling are confirmed before release.

Manufacturing inspection and release

Applicable methods, sampling frequencies, acceptance limits and independent testing requirements are agreed for the supplied grade and manufacturing scope.