I. Construction Preparation
A. Subgrade Preparation
- Clear construction area of debris and sharp objects
- Verify subgrade meets specifications:
- Dryness (≤15% moisture content)
- Compaction (≥95% Proctor density)
- Surface regularity (±10mm/3m tolerance)
B. Material Readiness
- Procure composite liners meeting ASTM D5994/D7007 standards
- Verify geosynthetic properties:
- Geotextile mass (g/m²)
- Geomembrane thickness (mm)
- Peel strength (N/cm)
- Confirm roll dimensions against shop drawings
II. Deployment Sequence
A. Primary Geotextile Layer
- Unroll nonwoven geotextile without stretching
- Achieve full contact with subgrade
- Secure with corrosion-resistant anchors (300mm spacing)
B. Geomembrane Placement
- Align HDPE geomembrane over primary geotextile
- Maintain ≥150mm side overlaps
- Anchor perimeter with continuous trench backfill
C. Secondary Geotextile Layer
- Install protective nonwoven layer over geomembrane
- Apply minimal tension during placement
- Secure with U-pins at 1m grid intervals
III. Seaming Procedures
A. Joint Techniques
| Method | Applicability | Overlap |
|---|---|---|
| Thermal Fusion | Geomembrane | ≥100mm |
| Sewn Seams | Geotextiles | ≥75mm |
| Adhesive Tape | Emergency repair | ≥200mm |
B. Quality Assurance
- Conduct seam integrity tests per ASTM D4437:
- Air lance testing (200kPa)
- Vacuum box (35kPa)
- Ultrasonic scanning
- Document all test results
IV. Protective Measures
A. Transition Layer
- Apply 100mm sand/clay cushion layer
- Compact to 90% relative density
B. Armor System
- Install 200-300mm riprap or precast blocks
- Critical placement protocol:
- Use geotextile-protected equipment
- Limit drop height to ≤0.5m
- Sequential installation with liner deployment
V. Critical Considerations
A. Environmental Controls
- Prohibit work during precipitation
- Achieve daily backfill coverage on GCL
B. Material Handling
- Enforce non-smoking zones
- Prevent hydrocarbon contamination
C. Backfilling Protocol
- Layered placement sequence:
- Coarse sand → Graded aggregate → Rockfill
- Lift thickness limits:
Material Max. Thickness Sand 200mm Aggregate 300mm Rockfill 500mm - 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
