Case Study: Application of HDPE Geomembrane for Seepage Control in a Reservoir
Case Study: Application of HDPE geomembrane for Seepage Control in a Reservoir
**Project Overview**
**Location**: Arid region with high agricultural water demand (hypothetical site)
**Objective**: Construct a 100,000 m³ reservoir to address irrigation water shortages.
**Challenge**: The site’s geology comprised loose sandy soil (permeability coefficient: 1×10⁻³ cm/s), requiring cost-effective seepage control. HDPE Geomembrane was
selected over conventional concrete lining due to its flexibility, durability, and 40% lower construction cost.
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Design Specifications
1. **Material Selection**
- **Primary Barrier**: 1.5mm-thick HDPE geomembrane
- Properties:
- Tensile strength: ≥25 kN/m (ASTM D6693)
- Permeability: ≤1×10⁻¹³ cm/s (ASTM E96)
- Carbon black content: 2-3% for UV resistance
- **Protection Layers**:
- Nonwoven geotextile (300 g/m²) above and below the geomembrane
- 50 cm compacted clay layer (k ≤1×10⁻⁶ cm/s) as subgrade
- 30 cm granular soil cover for mechanical protection
2. **Liner System Configuration**
- Composite liner system from bottom to top:
1. Compacted clay layer (30 cm)
2. Lower geotextile
3. HDPE geomembrane (primary barrier)
4. Upper geotextile
5. Soil cover layer (50 cm)
- Slope design: 1:2.5 (H:V) with 1.5m-deep anchor trenches at edges.
Construction Process
1. **Subgrade Preparation**
- Removal of sharp objects and compaction to 95% Proctor density.
- Laser-guided grading to achieve ≤0.5% surface unevenness.
2. **Geomembrane Installation**
- **Welding**: Dual-track thermal fusion welding (wedge method) with 10cm overlap.
- Temperature control: 280-320°C
- Seam testing: 100% air pressure testing (0.2 MPa, 5-minute hold)
- **Slope Installation**: Fan-fold deployment with minimal wrinkles.
3. **Quality Assurance**
- **Defect Detection**:
- Spark testing (15 kV) for pinholes
- Vacuum box testing (50 kPa) for seams
- **Acceptance Criteria**: ≤3 defects per 10,000 m² (GRI GM13 standard).
Performance Evaluation
1. **Short-Term Testing**
- **Water Tightness Test**:
- Initial 72-hour water loss: 0.3 mm/day (<1 mm/day allowable)
- Electrical leak detection survey: Zero significant leaks
2. **Long-Term Monitoring**
- **Projected Service Life**: >30 years (based on Arrhenius modeling of oxidative induction time)
- **Economic Benefits**:
- 60% reduction in maintenance costs vs. concrete lining
- Annual water savings: 22,000 m³
Key Lessons Learned
1. **Critical Success Factors**:
- Strict control of welding parameters (temperature/speed)
- Use of protective geotextiles prevented puncture damage
2. **Risk Mitigation Measures**:
- Installation of leak detection layer (optional sand layer with moisture sensors)
- 10% excess material allowance for thermal contraction/expansion
Conclusion
This project demonstrates HDPE geomembranes as a technically robust and economically viable solution for reservoir seepage control. The system achieved zero-leak
performance while reducing construction time by 35% compared to traditional methods. The success highlights the importance of material selection, precision installation,
and rigorous QA/QC protocols.
Appendices
- ASTM test certificates for HDPE geomembrane
- As-built drawings of anchor trench details
- Welding procedure qualification records (WPQR)
This template complies with international geosynthetics engineering standards (ISO 10318, ASTM) and can be adapted with project-specific data. For enhanced credibility,
include third-party inspection reports and 5-year performance monitoring data.
