Water Surveys

Water-Covered Geomembrane Leak Location Surveys (ASTM D7007)

Precise Leak Detection for Operational Ponds, Tanks, and Liquid Containment Systems

Leak Location Services, Inc. (LLSI) provides industry-leading water-covered geomembrane testing services to accurately locate leaks in water-covered liners without draining your facility. Our surveys are conducted in strict accordance with ASTM D7007 water survey standards and are trusted across mining, industrial, municipal, and energy sectors.

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What Is a Water Survey?

A water survey is an electrical leak location method used to identify breaches in geomembranes that are covered by water. This non-invasive technique allows facilities to test the geomembrane while ponds, tanks, or impoundments remain at operational levels.

During an ASTM D7007 water survey, low-voltage current is applied to the water above the geomembrane while an electrode is grounded beneath the liner. Because geomembranes are electrically insulating, current can only pass through defects such as holes, punctures, or seam failures, allowing precise leak detection.

Water surveys are commonly performed on newly filled containments prior to commissioning, as well as on long-term operational systems as part of routine quality assurance. Two primary methods are used: shallow-water wading survey methods and deep-water leak detection using towed arrays.

This approach provides unmatched sensitivity, detecting leaks as small as 1 mm, and is one of the few methods capable of testing 100% of a liner system without draining.

Water-covered containment systems represent a significant financial and environmental investment. Even small liner defects can result in serious consequences if left undetected.

Two Water Survey Methods

Equipment Used

Water surveys commonly identify seam defects, punctures from debris, stress cracking, animal damage, aging liners, maintenance-related damage, and manufacturing defects that would otherwise remain undetected.

All leak locations are documented with detailed maps. LLSI can provide post-repair verification surveys to confirm repairs are effective and support regulatory documentation. Ongoing monitoring recommendations are also available.

Can you test without draining the pond?

Yes. Water surveys are specifically designed to test water-covered geomembranes without draining the pond, tank, or impoundment. The survey is performed while the facility remains operational, allowing the liner to be evaluated without interrupting production, treatment processes, or storage operations.

What water depth is required?

For the wading survey method, an ideal water depth of approximately 2–3 feet is required to allow technicians to safely and accurately traverse the liner surface. For deeper ponds, deep water leak detection using a towed array can be performed at virtually any depth, including very large or steep-sided impoundments.

How long does a water survey take?

Survey duration depends on pond size, water depth, and the selected survey method. Small to medium ponds can often be completed in one to two days using the wading method. Larger or deeper facilities surveyed with a towed array may require additional time. A detailed schedule is provided during pre-survey planning.

What if the water is very deep?

When water depth exceeds safe wading limits, LLSI performs towed array leak location surveys. This method allows large and deep ponds, sometimes exceeding 100 feet in depth, to be surveyed efficiently from the perimeter of the pond. The towed array identifies leaks, which can later be investigated more precisely once drained.

Can chemical or saltwater ponds be tested?

Yes. Water surveys can be conducted in most conductive liquids, including saltwater and many chemical solutions, provided the fluid has sufficient electrical conductivity. LLSI evaluates water chemistry during pre-survey planning to ensure the ASTM D7007 water survey method is appropriate for the specific application.

Does turbid or murky water affect results?

No. Electrical leak detection is not affected by visibility or turbidity. Unlike visual inspection methods, water surveys rely on electrical current flow rather than line-of-sight, making them effective in murky, sediment-laden, or low-visibility water conditions.

Is testing safe for fish and aquatic life?

Yes. Water surveys use low-voltage, low-current power that is safe for fish, aquatic organisms, and water quality. The method is non-destructive and widely accepted for use in environmentally sensitive applications, including drinking water reservoirs and aquaculture facilities.

What happens after a leak is found?

Leak locations are immediately identified and documented. LLSI provides detailed maps and reporting to support efficient repairs. Once repairs are completed, a follow-up water survey can be performed to verify repair effectiveness and document compliance.

How accurate is the leak location?

The wading survey method can pinpoint leaks to within inches of their exact location, making it one of the most precise liner testing methods available. Deep water surveys accurately identify leak, which can then be refined using targeted follow-up surveys if required for very large ponds.

LLSI brings unmatched experience in deep water leak detection, including surveys exceeding 100 feet in depth. We own all specialized equipment, employ highly trained technicians, and operate safely in remote and challenging environments. Our comprehensive documentation, rapid mobilization, and strict ASTM compliance set us apart.

ASTM D7007 establishes standardized practices for water-covered geomembrane leak detection, including sensitivity requirements, and quality assurance procedures. Compliance ensures reliable results, regulatory acceptance, and defensible documentation.