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Dam Sealing with Envirobent®: The Mixed Blanket Method

Dam Sealing with Envirobent®: The Mixed Blanket Method

Is the precious water in your current earth dam slowly seeping away, or leaking rapidly? Are you concerned about possible ground water contamination? Perhaps you are planning to build a new dam and want to ensure that it remains strong and securely sealed. Whatever challenge you face, Envirobent® dam sealing products are the long-lasting, environment-friendly and cost-effective solutions.


Envirobent® dam sealing is suitable for use in the initial construction of earth dam floors and walls, and is also ideal for fixing leaking dams by emptying the dam and treating as recommended.

Envirobent® AB 50 dam sealing is suitable for use in the initial construction of silt-dam floors & walls as well as landfill floors and capping.

There are 2 recommended methods of dam sealing: the Pure Blanket Method and the Mixed Blanket Method. In the following guide, we focus on the latter method.

The Mixed Blanket Method: Guidelines

  • Prepare the area to be sealed but do not compact.
  • Remove any and all stone and vegetation.
  • Place 40kg bags of Envirobent in a grid formation (depending on the application rate).
  • Mix the Envirobent with selected soil to a depth of 100-150mm, followed by wetting/damping and compaction (must be able to roll without crumbling).
  • Compact the mixed layer well.
  • Cover the mixed layer with 150-200mm of cover soil.
  • Remove any remaining stones and vegetation.
  • Compact the 150-200mm cover soil.
  • Earth dam sides/walls should not be steeper than 1 in 3.

Typical application rate:

  1. Clayey sand/soil – 9kg/m2
  2. Sand/soil with low clay – 12kg/ m2
  3. Sand/soil with very low clay – 18kg/ m2

Note: To seal around pipes, etc. put a puddle flange around the pipe, and form a 100mm bead of one part Envirobent and three parts soil to create a tight interface with all penetrating structures.

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