Municipal Solid Waste Landfill (Woven Geotextile, Geomembrane Protection Layer)

Municipal Solid Waste Landfill (Woven Geotextile, Geomembrane Protection Layer)

1. Project Background

This project covers the anti-seepage system for the base and side slopes of a municipal solid waste sanitary landfill cell. The primary anti-seepage material is HDPE geomembrane. Compacted clay lies beneath the membrane, while a crushed stone drainage layer is placed above it. The sharp edges of crushed stone may easily puncture the geomembrane, hence a protective layer is required, which shall also provide filtration to avoid clogging of the drainage layer.

2. Geotextile Specification & Consumption

Type: High-strength woven geotextile

Specification: 400 g/m²; warp tensile strength ≥40 kN/m; CBR burst strength ≥6.0 kN

Laying scope: Cell base + side slopes; net area: 21,500 m². Due to high wastage on slopes, the procurement quantity is 24,300 m².

3. Functions & Performance of Geotextile

✅ Protection + Filtration

Protection: Separate angular crushed stone from the HDPE membrane, distribute concentrated stress and prevent puncture damage to the anti-seepage membrane.

Filtration: Stop fine particles of overlying soil from entering the crushed stone drainage layer and maintain smooth leachate conveyance.

✅ Performance outcome: The damage rate of the anti-seepage membrane is greatly reduced; the leachate drainage system stays unobstructed without clogging over the long term.

4. Construction Parameters

Laying: Manual spreading, laid from top to bottom on slopes; relaxation allowance controlled at 2%–3%.

Joints: Sewing is preferred. Anti-ageing polypropylene thread is adopted for stitching; overlap width ≥30 cm.

Slope fixation: Geotextile nails at a spacing of 1.0 m horizontally and 1.5 m vertically; spacing shall be reduced at slope crests and toes.

Control requirements: It is forbidden to drop crushed stone directly onto the geotextile or geomembrane; crushed stone shall be delivered via chutes.

5. Division of Work with Other Components

HDPE geomembrane: Primary anti-seepage layer to block downward seepage of leachate.

Lower geotextile (beneath membrane): Protect the membrane from scratches caused by sharp objects on the subgrade.

Upper geotextile (above membrane): Buffer protection and filtration layer between the membrane and crushed stone drainage layer.

Clay liner / GCL: Auxiliary anti-seepage.

Crushed stone drainage layer: Collect and convey leachate to lift wells.