- Bentonite-based Sealing Solution


Many waterways, independent of size and function, are constructed in porous or permeable soils that are not adequately compacted or amended during construction to reliably hold water. Even when soil basins or synthetic 'liners' are properly prepared from the onset, a variety of environmental factors (e.g. repeated freeze/thaw cycles, prolonged desiccation, pockets of more permeable soils, animal damage, and even subtle seismic activity) can compromise an earthen basin, causing problems over time. Additionally, structural failures or oversights (e.g. a faulty overflow structure or a hydrologicly connected remnant agriculture tile) can eventually cause noticeable (and undesirable) water loss.

Once a water body is determined to be leaking, traditional techniques often limit the remedy options. Many professionals advise that a basin be completely drained to effectively repair a compromised seal. Beyond the substantial cost and significant aesthetic downside, this is often not a desirable option, particularly in more mature waterways, due to the tremendously disruptive impact such a disturbance has on fish communities and the overall ecology in the system.


PONDSEAL™ utilizes a solid aggregate (limestone) core to deliver Wyoming-derived bentonite clay through a water column to any area where a leak is suspected. Due to the extreme low permeability, considerable weight, and robust swelling characteristics of this novel composite particle, each individual 'pebble-like' unit swells into adjacent particles to produce a uniform and durable layer – stopping the leak at its source.

Applications through standing water (i.e. treatment without drawdown) provided the impetus for the creation of PONDSEAL - and more broadly, AquaBlok. While this continues to be a common way in which the material is used, the technology provides tremendous versatility beyond these applications.


  • Effective for leak prevention and repair - both during and after initial construction
  • Appropriate before inundation and through standing water - often eliminating the need to drain the basin
  • Blanket over permeable soils or other suspected problem areas
  • Easily backfill around pipes and control structures as a durable anti-seep plug - without the need for compaction
  • Create a cut-trench or vertical barrier wall to reinforce compromised dams, levees, or earthen berms
  • Use in ponds, lakes, canals, wetlands, or anywhere that leaks can be problematic

Other Notables:

  • A labor saver - saves time, effort, and money because there is no need for compaction in lifts or layers; no need to be tilled or mixed with parent soil
  • Structurally stable - due to internal matrix of individual stones
  • Erosion-resistant - can also be surface dressed with sand, soil, or stone for additional protection
  • Eco-friendly - will not adversely alter water chemistry (or hurt fish)
  • Available in two packaging options - 50-lb. bags and 2,400-lb. bulk totes

Think of PONDSEAL as Nature's Duct Tape™ - all earthen and highly versatile. It's just a good material to have in the toolbox!

Clays and sodium bentonite in particular have long been recognized as effective materials for sealing or lining basins and other areas with direct exposure to water due to their low-permeability and relative erosion resistance. However, the challenges associated with handling these materials - particularly through a standing water column - can often limit construction and repair options

If you have ever poured pure powdered bentonite into water, then you have witnessed the clouds of dust and watched helplessly as the majority of the material simply dissipates with wind and wave action (rather than sinking to the bottom where it was intended to go). If you have ever attempted to uniformly mix raw bentonite into native soil in a traditional 'blend and compact' application, then you have experienced the challenge of consistent coverage and even blending

PONDSEAL has the density (weight) to stay where it is placed. Through water it literally 'sinks like a stone.' Due to its stone and clay construction, it is also essentially 'pre-blended' to form a uniform and durable sealant layer –without the need for soil blending or compaction.

So, what has pond managers, water resource professionals, construction contractors, engineers, and pond owners themselves so interested in this novel approach to preventing and repairing leaking waterways? There are many responses to this question:

PONDSEAL offers both reliable delivery to a target site and the density to 'self-compact' (adding structural integrity), unlike with other bentonite-based alternatives (powders, chips, pellets)
PONDSEAL is made from the same high quality Wyoming sodium bentonite used in landfills and other demanding sealing applications
PONDSEAL is highly durable; it will gradually dry when exposed to the atmosphere for prolonged periods, but will re-hydrate and 'self-heal' an infinite number of times as water levels fluctuate (or if the material is punctured or cut)
PONDSEAL is erosion-resistant and can be further fortified using a surface dressing of stone or gravel (especially in areas of high velocity – e.g. direct exposure to sustained currents, prop wash, etc.)
PONDSEAL withstands repeated freeze/thaw cycles (unlike many native clays) and will not 'liquefy' during seismic events
PONDSEAL is made completely of natural materials and is non-toxic to a waterway's ecology (including its fish)

Additionally, PONDSEAL takes on the appearance and characteristics of clay-based native substrate (especially as fresh deposits of sediment accumulate on the sealant layer). The product can be installed either by hand (directly from original packaging), or for larger areas, from bulk storage bags – using a wide range of standard construction equipment (e.g. front end loaders, stone slingers, conveyors, and other readily available application methods).

Despite its significant technical advantages, PONDSEAL pricing is similar to equivalent bentonite alternatives and can also be very competitive with non-bentonite options. As a cautionary note, please keep in mind that NOT ALL BENTONITE IS CREATED EQUAL, and as with most things, quality impacts performance.

PONDSEAL material costs are volume-driven. Freight must also be taken into consideration. However, it is important to compare 'apples to apples' when considering construction and/or repair alternatives. Even though local clay may be 'free' from a materials perspective, associated expenses should be taken into consideration - i.e. labor to access the material, trucking costs to move the material, labor costs to reapply and properly compact the material (assuming that proper compaction can be achieved). It is important to consider not just material price but the overall (i.e. installed) project cost. After all 'time is money.'

Suggested application rates and specific pricing for your individual circumstances can be made available upon request.

ASIDE: AquaBlok®, PONDSEAL's 'parent' product, has undergone extensive evaluation by the U.S. Environmental Protection Agency (E.P.A.) for use in the capping (i.e. isolation) of contaminated sediments. Projects have successfully been implemented through the U.S. and Canada (and beyond) since 1994. The superior sealing qualities and reliable delivery of AquaBlok and its family of products have proven to surpass alternatives, providing improved ease of implementation and lower project costs.

PONDSEAL can be a relevant solution in about any aquatic environment that is unintentionally leaking water. Such environments include, but are not limited to: 'farm ponds' (used for agriculture, swimming, fishing, wildlife viewing, aesthetic appeal, etc.), natural lakes, reservoirs, quarries, irrigation ponds/canals, golf course water features, stormwater retention/detention ponds, commercial aquaculture, and even wetland settings. The versatility of the bentonite-stone composite also makes it well-suited for the installation and repair of affiliated water management structures - e.g. dams, levees, subsurface pipes, control structures, etc. PONDSEAL is derived completely of earthen materials and is non-toxic to fish and the broader aquatic ecosystem.

Think of PONDSEAL not only as a repair tool (after a problem has been detected) but also as preventative maintenance. Utilizing the product during the construction phase (i.e. as an anti-seep plug around pipes and control structures or as a reinforcement blanket over an isolated pocket of marginal soil) often means spending pennies now compared to dollars down the line - when problems arise.

PONDSEAL is available in a variety of packaging options. Standard material packaging includes 50-lb. bags (for easy manual handling and placement) and ~ one cubic yard bulk bags (2,400-lbs. each), for larger applications. For very large installation projects, product can even be delivered 'loose' (unpackaged) by bulk container. Standard formulations are held in inventory by a growing group of distributors for prompt shipment (see 'Ordering Information'). Custom formulations can be manufactured to meet project-specific needs.

Product can be applied either by hand (for small, localized installations) or using a wide array of commonly available equipment. Machinery used to date for product placement includes:

  • Stone Slinger (radial conveyor mounted on the back of a modified dump truck) - can accurately place material to distance of ~90'; ideal for application through standing water
  • Telebelt (similar to above but with longer reach capability - up to ~130')
  • Excavator (either in bulk or by suspending bulk bags for direct placement from the shipping package)
  • Payloader or Skid Steer (particularly effective prior to inundation)
  • Trencher (for vertical 'cut-off wall' applications)
  • Crane with Clamshell Bucket (operated from on-shore or even on a barge)
  • Helicopter (equipped with specially designed material drop bags) - for access to extremely remote locations

Experimentation is ongoing to identify equipment and techniques to accurately and quickly apply intermediate quantities of product over relatively small areas (i.e. one to several tons over hundreds of square feet). Some have found success using fertilizer or rock salt spreaders. Others have worked with a trash pump to deliver the material using water. As more gain experience with the product in these volumes, new options will undoubtedly be identified and refined. NOTE: We welcome you to share your experiences fro the good of all those preparing for an application.

Conveyor systems (like the stone slinger) are ideal for larger quantities of product where access can be achieved in fairly close proximity to the area to be treated. An experienced operator can readily off-load and accurately place 20 tons of PONDSEAL in 30 minutes or less. Provided that product is readily available and equipment is on-site for reloading, a single truck can sling 200 or more tons of PONDSEAL in a single work day. Assuming availability and physical access, the slinger can be an extremely cost effective means to broadcast the product – whether working in the dry (prior to inundation) or through standing water. Such equipment can typically be rented with an operator on an hourly basis.

Continuous “liner” applications of PONDSEAL (i.e. product added to the bottom of a basin) typically involve the addition of 5 – 15 lbs of product per square foot. Application rates depend on site circumstances – e.g. the source and location of a leak (if known), water depths, substrate characteristics, side slopes, etc. Keep in mind that while full-basin linings are an option, so are spot treatments in targeted or highly suspicious areas. If you are not a water management professional or experienced engineer, consider collaborating with a local expert to optimize your results – especially when the location of the leak is not obvious. For recommendations on practitioners in your area or to discuss the specifics of your application, please contact AquaBlok, Ltd.

For additional information, including technical support, please contact us either by phone at (800) 688-2649 or via email at pondmanagement@aquablokinfo.com. A representative will be happy to assist you. To order PONDSEAL, please contact any of our growing network of distributors. See 'Ordering Information') for direct contact information.

IMPORTANT NOTES: Absorption of atmospheric moisture should be avoided following the opening of the original package. PONDSEAL packaging is NOT waterproof and product should therefore be stored either under roof or with the protection of a seamless, well drained tarp. Premature direct contact with water will degrade product integrity and compromise the ability to apply the material in a uniform manner.

Conversely, direct exposure to sun, low humidity, and drying winds can crack the clay coating of individual particles. The material “insulates” itself, meaning surface particles are prone to drying in open packaging while underlying particles (>1” into a mass of product) remain unaffected. Product can be stored for extended periods (years), provided it is not exposed to moisture or extremely dry conditions in open containers.

Allow one to two days for full hydration once PONDSEAL is inundated. While the material will expand significantly within the initial several hours following hydration, a full 48 hours will allow the individual particles to completely coalesce to form a 'water-tight' and uniform layer. For relatively thin applications (i.e. 2” or less), hydrated PONDSEAL thicknesses are typically nearly twice the thickness of the product in a dry state.

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