Installation Guide for Dual-Geotextile Composite Liner

‌I. Construction Preparation‌

‌A. Subgrade Preparation‌

1. Clear construction area of debris and sharp objects
2. Verify subgrade meets specifications:
   • Dryness (≤15% moisture content)
   • Compaction (≥95% Proctor density)
   • Surface regularity (±10mm/3m tolerance)

‌B. Material Readiness‌

1. Procure composite liners meeting ASTM D5994/D7007 standards
2. Verify geosynthetic properties:
   • Geotextile mass (g/m²)
   • Geomembrane thickness (mm)
   • Peel strength (N/cm)
3. Confirm roll dimensions against shop drawings

‌II. Deployment Sequence‌

‌A. Primary Geotextile Layer‌

1. Unroll nonwoven geotextile without stretching
2. Achieve full contact with subgrade
3. Secure with corrosion-resistant anchors (300mm spacing)

‌B. Geomembrane Placement‌

1. Align HDPE geomembrane over primary geotextile
2. Maintain ≥150mm side overlaps
3. Anchor perimeter with continuous trench backfill

‌C. Secondary Geotextile Layer‌

1. Install protective nonwoven layer over geomembrane
2. Apply minimal tension during placement
3. Secure with U-pins at 1m grid intervals

‌

III. Seaming Procedures‌

‌A. Joint Techniques‌

‌B. Quality Assurance‌

1. Conduct seam integrity tests per ASTM D4437:
   • Air lance testing (200kPa)
   • Vacuum box (35kPa)
   • Ultrasonic scanning
2. Document all test results

‌IV. Protective Measures‌

‌A. Transition Layer‌

1. Apply 100mm sand/clay cushion layer
2. Compact to 90% relative density

‌B. Armor System‌

1. Install 200-300mm riprap or precast blocks
2. Critical placement protocol:
   • Use geotextile-protected equipment
   • Limit drop height to ≤0.5m
   • Sequential installation with liner deployment

‌V. Critical Considerations‌

‌A. Environmental Controls‌

1. Prohibit work during precipitation
2. Achieve daily backfill coverage on GCL

‌B. Material Handling‌

1. Enforce non-smoking zones
2. Prevent hydrocarbon contamination

‌C. Backfilling Protocol‌

1. Layered placement sequence:
   • Coarse sand → Graded aggregate → Rockfill
2. Lift thickness limits:
   

   Material	Max. Thickness
   Sand	200mm
   Aggregate	300mm
   Rockfill	500mm

3. Monitor settlement rates (<5mm/day)

‌D. Crew Composition‌

• Certified welder (1 per 500m²)
• Survey technician
• Heavy equipment operator
• General laborers (3:1 ratio)

Compliance: ASTM D5819, GRI GM19, ISO 9001:2015