Construction Specification for Geotextile Used in Municipal Solid Waste Landfill
Construction Specification for Geotextile Used in Municipal Solid Waste Landfill
Ⅰ. Key Points of Construction Technology (On-site Practical Operation)
1. Substrate and Lower-layer Geotextile Laying
The substrate shall be leveled, with all sharp debris removed, and the flatness error shall be ≤ 2cm.
Geotextile shall be laid from low elevation to high elevation, and the lap width requirement: transverse lap ≥ 300mm, longitudinal lap ≥ 200mm.
Lap joints shall be sealed with bentonite mastic to prevent leachate from seeping down along the joints.
2. HDPE Membrane Welding (the "Protected Object" of Geotextile)
The membrane is 1.5mm thick, double-track hot melt welding is adopted, and the weld width shall be ≥ 10mm.
Welds shall undergo air pressure / vacuum testing to ensure 100% no leakage.
3. Upper-layer Geotextile Laying (Key Protection)
The upper-layer geotextile shall be laid within 24 hours after the HDPE membrane passes the acceptance inspection.
Lap requirement: longitudinal lap ≥ 150mm, transverse lap ≥ 200mm.
Lap joints shall be sewn with nylon rope (stitch spacing ≤ 50mm), or bonded with special adhesive tape.
When laying on side slopes, geotextile is laid from top to bottom, and the reserved anchorage length at the slope top shall be ≥ 1.2m.
Ⅱ. Application of Geotextile in Closure Stage (Final Cover)
· Ecological closure shall be carried out after landfill is completed, and the structure is as follows:
Waste body shaping → 600g/㎡ long-fiber geotextile (isolation / drainage)
→ 1.0mm HDPE closure membrane → 300g/㎡ geotextile (protection)
→ drainage layer → planting soil → vegetation restoration
· Function: Prevent large amount of rainwater from seeping down, reduce leachate production, and prevent plant roots from piercing the anti-seepage membrane.
Ⅲ. Implementation Effect and Value
· Anti-seepage Safety: Geotextile effectively protects HDPE membrane. There was no puncture damage during construction, and the leachate collection rate is > 98%.
· Settlement Adaptability: Long-fiber geotextile features high tensile strength and high elongation, which can effectively resist uneven settlement. No obvious cracks have appeared in the anti-seepage layer after 5 years of operation.
· Smooth Drainage: Geotextile has excellent filtration and drainage performance, with no water accumulation or blockage, which reduces the water pressure on the membrane.
· Extended Service Life: The protection from geotextile extends the service life of HDPE membrane from 10–15 years to 20–30 years.
· Compliant Environmental Performance: Groundwater in monitoring wells has met relevant standards for a long term, with no pollution caused by leachate overflow.
