Compare Survey Types

Survey Type
Applications
Typical Sensitivity
Typical Accuracy
Advantages
Limitations
Shallow Water Survey
Bottom of impoundments, sumps
0.001 square inch
1 inch
Most sensitive, tests under load, can be for in-service testing
Geomembrane must be flooded with water
Deep Water Survey
Impoundments with deep water or side slopes
0.001 square inch
24 inches
Deep or foul water surveys, can be for in-service testing
Accuracy of leak position, geomembrane must be flooded with water
Side Slope Survey
Side slopes of impoundments
0.001 square inch
2 inches
More accurate than towed survey
May require second mobilization
Soil Survey
Landfills, landfill caps, and heap leach pads
0.05 square inch
Half of thickness of soil cover, leaks are uncovered and exactly located
Detects leaks under soil, detects construction damage after high potential for damage is gone
Soil must have some moisture
Bare Liner Survey
Bare liners
0.001 square inch
Leaks are exactly located
Does not require flooding liner with water, can be done as construction progresses
Not as reliable for patches or tortuous leak paths, or for geomembranes with wrinkles, bridging, or desiccated subgrade
Electrical Leak Imaging and Monitoring System (ELIM)
Pre-installed monitoring system
0.1 to 1 percent of electrode spacing
10 percent of electrode spacing
Detects leaks under waste, continuous monitoring
Must be installed during liner installation, higher cost