Soil Survey Services: ASTM D7007 Geomembrane Testing
Soil-Covered Geomembrane Leak Location Surveys (ASTM D7007)
The Most Cost-Effective Method to Find Construction Damage After Protective Soil Placement
Leak Location Services, Inc. (LLSI) provides industry-leading soil-covered geomembrane surveys using the ASTM D7007 covered survey method. Our proven leak location testing identifies construction-related damage in landfill liners and containment systems after protective soil placement, when damage is most likely to occur.
What Is a Soil Survey?
A soil survey, also known as a soil-covered geomembrane survey, is a leak location method used to detect holes, tears, and defects in geomembrane liners that are covered with earthen materials. This specialized form of geomembrane leak testing is conducted after protective soil layers have been placed over the liner, making it the most effective method for identifying damage caused during construction activities.
Soil surveys are performed using the dipole method geomembrane testing procedure outlined in ASTM D7007. Technicians collect point-by-point electrical measurements on the soil surface using specialized probes and a portable data acquisition system. Because geomembranes are electrical insulators, electrical current can only pass through breaches in the liner, allowing leaks to be detected with exceptional precision.
Data is processed in real time using field-portable computers, enabling immediate identification and marking of leak locations. This makes soil surveys an essential post-construction leak detection tool for landfill liner soil surveys, mining facilities, and covered containment systems.
Why Soil Surveys Are Critical
The greatest risk to a geomembrane liner does not occur during manufacturing or seaming; it happens during construction. Industry experience consistently shows that heavy construction equipment is the number one cause of geomembrane damage, particularly during the placement of protective soil cover.
Bulldozers, excavators, haul trucks, and loaders exert high point loads that can puncture or tear liners, especially when sharp rocks or uneven subgrades are present. Without post-construction leak detection, these defects often remain hidden until contamination occurs.
A soil-covered liner survey provides a critical safeguard by testing the liner after all construction stress, loading, and soil placement have occurred, but before the facility becomes operational. This timing ensures that any construction damage is identified when repairs are still practical and cost-effective.
Many state environmental agencies require ASTM D7007 soil surveys as part of landfill Construction Quality Assurance (CQA) programs. Early detection prevents costly remediation, protects groundwater resources, and provides regulatory confidence that the containment system is performing as designed.
When You Need a Water Survey
✓ Pre-service inspection after pond or tank is filled
✓ Periodic compliance testing for operational facilities
✓ When monitoring wells show unexpected leakage
✓ After extreme weather events (freeze/thaw or seismic activity)
✓ Before and after maintenance activities
✓ When product loss is suspected
✓ Following repairs to verify effectiveness
✓ As part of a long-term asset management program
How Soil Surveys Work
The Geoelectric Method
The dipole method geomembrane survey relies on fundamental electrical principles. A controlled voltage is applied to an electrode placed in the soil covering the geomembrane. A second electrode is connected to a leak detection zone in double-lined systems or to earth ground in single-lined systems.
Because the geomembrane is an electrical insulator, current cannot pass through it unless a defect is present. At leak locations, electrical current flows through the hole, creating localized zones of high current density. These anomalies are detected at the surface and indicate the precise location of damage.
Technicians systematically traverse the site in a grid pattern, collecting electrical measurements across the entire lined area. Visual indicators immediately alert the technician when a leak is detected.
Equipment & Process
- Specialized dipole survey probes
- Portable data acquisition loggers
- Field-portable computers for real-time analysis
- Visual leak indicators
- Field photos and detailed documentation
Each detected leak is marked on-site for repair and documented for final reporting.
Site Conditions Required
- Adequate soil moisture for electrical conductivity
- Minimum of 3 inches of soil cover (effective up to 60+ inches)
- Electrical isolation from the surrounding ground
- No nearby construction during testing
Sensitivity & Accuracy
Soil surveys conducted by LLSI offer exceptional sensitivity and reliability:
- Detection capability: Leaks as small as 26 mm² (0.04 in²)
- Coverage depth: Effective through soil layers up to 1.5 m (5 feet)
- Accuracy: Leak locations pinpointed within inches and up to 2 feet depending on soil cover depth
- Reliability: Over 30 years of proven field performance
ASTM D7007 requires verification of minimum leak detection distance, ensuring consistent and defensible results. The method’s performance has been validated through blind leak testing protocols worldwide.
Ideal Applications
Soil-covered geomembrane surveys are ideal for:
- Landfills: Post-construction CQA for cells, caps, and closures
- Heap Leach Pads: Mining operations after soil or ore placement
- Waste Impoundments: Covered containment systems
- Secondary Containment: Double-lined systems with protective layers
- Any project: where geomembranes are covered with soil or earthen materials
- Timing is critical: Soil surveys should be conducted after protective cover placement and before waste or material loading.
When to Schedule a Soil Survey
✓ After protective soil layer placement
✓ Before final waste or material placement
✓ As the final CQA step in landfill construction
✓ When required by regulatory agencies
✓ As part of a comprehensive quality assurance program
✓ Before the facility becomes operational
ASTM D7007 Compliance
ASTM D7007 is the governing standard for geoelectric leak location surveys on geomembranes. It includes separate procedures for soil-covered and water-covered liners and establishes performance-based requirements for detection sensitivity, leak location distance, data analysis, and reporting.
Compliance with ASTM D7007 is essential for regulatory acceptance, defensible documentation, and consistent results. LLSI strictly adheres to all ASTM requirements, ensuring surveys meet state and federal environmental agency expectations.
Advantages of Soil Surveys
✓ Tests liners after all construction stress and loading
✓ Most cost-effective method for detecting construction damage
✓ No excavation or soil removal required
✓ Non-destructive testing method
✓ Covers 100% of the liner area
✓ Fast results with minimal project disruption
✓ Regulatory acceptance nationwide
✓ Compatible with long-term ELIM monitoring systems
Common Construction Damage Found
Soil surveys routinely identify damage caused during protective cover placement, including punctures from heavy equipment, tears from sharp rocks, stress cracks from uneven loading, and previously undetected seam defects.
On a recent 10-acre landfill cell, LLSI identified 23 construction-related leaks, all of which were repaired before waste placement, preventing long-term environmental risk and significant remediation costs.
Soil Survey vs Other Leak Detection Methods
| Feature | Soil Survey | Bare Liner Survey | Water Survey |
| Timing | After soil placement | Before covering | After filling |
| Detects | Construction damage | Pre-existing defects | All leak types |
| Coverage | Soil-covered areas | Exposed liner only | Water-covered areas |
| Cost | Most economical for landfills | Lower per acre | Variable |
| Depth | Up to 5 ft soil | N/A | Any water depth |
The LLSI Advantage for Soil Surveys
Soil-covered geomembrane surveys are a core specialty at LLSI. Our expertise is recognized industry-wide.
We use proprietary data processing techniques, own and maintain all equipment, and deploy technicians with thousands of hours of field experience. From challenging site conditions to tight construction schedules, LLSI delivers reliable results with comprehensive documentation and rapid turnaround.
Frequently Asked Questions
How deep can soil be for effective testing?
Up to 60 inches under suitable conditions.
What soil moisture is required?
Moderate moisture is needed for electrical conductivity.
Can you test through clay layers?
Yes, with adequate moisture content.
How long does a soil survey take?
Typically 1–3 days, depending on site size.
What happens if leaks are found?
Leaks are marked, documented, and repaired before retesting.
Do we need to stop construction?
Yes, active construction must pause during testing in the immediate area of testing.
Can you survey slopes?
Yes, including landfill side slopes.
What about GCLs?
Surveys can detect defects impacting geomembranes over GCLs.
Technical Specifications
- Standards: ASTM D7007, ASTM D6747
- Detection Sensitivity: 26 mm² (0.04 in²)
- Soil Depth: Up to 1.5m (60 inches)
- Accuracy: ± 1 foot / ± 0.3 meters
- Documentation: GPS coordinates, maps, photos, full reports
Regulatory Compliance
LLSI soil surveys support state environmental agency requirements and EPA landfill CQA guidelines. Our third-party testing provides defensible documentation for permit compliance, closure approvals, and regulatory review.
Request a Soil Survey Quote
Protect your facility before it becomes operational. Contact Leak Location Services, Inc. today for expert ASTM D7007 soil-covered geomembrane leak detection and ensure your containment system performs as designed.
WATER SURVEYS
Geomembrane leak location surveys of surface impoundments and tanks can be conducted with water covering the geomembrane.
BARE LINER SURVEYS
To avoid the logistics of flooding the geomembrane with water, the exposed geomembrane can be tested for leaks using a water puddle test.
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