Environmental Management

Bentonite clay for sealing dams

Bentonite clay for sealing dams

ENVIROBENT BENTONITE POWDER FOR DAM SEALING consists of high quality, 100% natural environment-friendly products used in the industrial, commercial, construction and retail markets in Southern and sub-Saharan Africa.

Industrial users comprise factories and foundries, civil engineering and construction firms, and petroleum companies, while retail users include farmers, automotive workshops, and trucking and logistics companies.

Specialized applications include oil spill clean-ups on floors, earth dam sealing, X-ray room protection applications and use in agricultural products such as soil nutrients.

The bentonite powder is a natural clay that has been modified to provide specific swelling capabilities.

Bentonite is suitable for:

  • Repair of leaking earth dams
  • The initial construction of dam floors and walls.

What Is Bentonite Clay

Envirobent bentonite powder for dam sealing can be defined as a transported stratified clay which has been formed by weathering of volcanic ash approximately 66 million years ago. Bentonite clay is easily distinguished from other similar materials by its fineness and its highly absorbent nature which causes it to swell significantly when coming into contact with water.

Every dam is unique with many variables, such as topographical features, soil conditions, local weather and installation quality that can influence the success of the project. Envirobent for dam sealing is applied by using two basic methods:

The application rates are determined according to the type of soil.

Suggested application Rates are:

Clay soils: 8-10 Kg/m2
Sandy Silt: >10-12 Kg/m2
Silty Sand: 12-15 Kg/m2
Clean Sand: 15-20 Kg/m2
Rock or Gravel: 20/25 Kg/m2 (Not Recommended)

Bentonite is easily applied, however, attention to detail in the application method is essential to avoid disappointment.

How to know if your dam is leaking?

It could be obvious and continuous: water flowing in never seems to fill it properly; water seeping through the walls; rushes growing around the base; the dam empties out much faster than evaporation or use should indicate.

It could also be insidious and only shows up sometimes: water level drops slightly faster than evaporation or use should indicate; vegetation or pastures and crops below the dam healthier than elsewhere; leakage increases after sudden inflows from summer storms.

Simple Soil Texture Analysis “The Jar Test” Procedure

Materials:

  • Straight edged, clear jar

  • Permanent marker

  • Ruler

  • Watch or stop watch

  • 1 Tablespoon of powdered dish washing detergent

  • Mesh sieve or old colander

Bentonite Clay
  1. Soil texture triangle to estimate the soil type for the site. Use the soil texture triangle to estimate the soil type for the site.
  2. The clay percentages are listed on the left side of the triangle. Lines corresponding to clay percentages extend from the percentages reading left to right (see red line).
  3. The silt percentage is on the right side, with lines extending downwardly, diagonally right to left (see green line).
  4. The sand percentage is on the right side, with lines extending upwardly, diagonally right to left (see blue line).
  5. Track the lines with the percentages measured and find the spot on the triangle where all three lines intersect. The region where these lines intersect indicates the soil type present. The example shown represents a loam soil texture.

Impermeable Dam Liners

Why you need Impermeable Liners…

  • Prevent water draining through a gabion wall.
  • Keep the area behind a gabion wall dry next to a river course.

  • Prevent water flow through and stop soil erosion alongside and around a gabion weir structure.

  • Liners prevent geotextiles clogging and stop lateral water flows though a gabion structure.

Save time and money by making your gabion installations impermeable to water. Impermeable liners are membranes which can be used to make gabions impermeable to water at low cost, normally used alongside a geotextile fabric placed against the soil for protection when placed alongside the gabion structure.

Impermeable liners are used in dams and waterways to prevent the passage of loss of valuable water, we often advise the use of a membrane to reduce water flows in hydraulic structures. The limiting of water movement through structures will reduce the possibility of later piping and embankment failure in earth dams for instance.

Impermeable Liners Features

  • Impermeable to water flows.

  • High strength and laid quickly against a gabion structure.

  • Supplied in rolls, with small volume for transport.

  • Special soil backfill not needed, no need for adding and mixing additives to make soil impervious.

Vetiver Grass

Vetiver grass

Vetiver grass (Vetiver zizanioides), recently reclassified as Chrysopogon zizanioides, is the main component of many vegetation-based bioengineering and environmental remediation programmes worldwide.

It is affordable and efficient for:

  • Water conservation
  • Soil stabilization
  • Pollution control
  • Phytoremediation technologies using living plants to clean up soil, air, and water contaminated with hazardous contaminants
  • Cost-effective plant-based approach of environmental remediation

  • Feasible solution using plants for environmental cleanup
  • Wastewater treatment
  • Storm damage mitigation and prevention
  • Mine rehabilitation. Vetiver grass is highly tolerant to heavy metals as well as to extreme edaphic and climatic conditions

Vetiver has proofed to be valuable in erosion prevention and control with engineers likening the roots to “living soil nails.” When planted in rows Vetiver plants will form a hedge, a living porous barrier which slows and spreads runoff water and traps sediment. As water flow is slowed down, its erosive power is reduced and at the same time allows more time for water to infiltrate to the soil, and any eroded material is trapped by the hedges.

The plant is palatable in the early stages of growth and reduces stomach parasites in livestock.

As they propagate by small offsets instead of underground stolons, they are non-invasive and easily controlled by cultivating the soil at the boundary of the hedge.

Some Special Characteristics of Vetiver Grass :

  • Vetiver grass does not produce above or underground runners.
  • The plant has a strong and massive root system, which is vertical in nature descending 2-3 meters in the first year, ultimately reaching some five meters
  • The depth of root structure provides the plant with great tolerance to drought, permits excellent infiltration of soil moisture and penetrates through compacted soil layers

  • Above ground, the shoots can grow to two meters and when planted close together it forms a solid vegetative barrier that retards water flow and filters and traps sediment in runoff water. Growth occurs from the crown, which rises relative to soil build-up.

  • It is also highly resistant to pests, diseases, fire and heavy grazing pressure.

  • Ability to regrow rapidly after being affected by drought, frost, fire, saline and other adverse conditions when the adverse effects are removed.

  • Tolerance to extreme climatic variations such as prolonged drought, flood, submergence and temperature levels.

Vetiver Grass

Erosion Control Grass Lines  with Vetiver Grass

Erosion control grass lines consist of planting vetiver grass lines following the contour lines, along stream banks and roadsides, to create a hedge.

These hedges act like semi-permeable barriers, aimed to hinder surface erosion as they slow down run-off and retain sediments picked up by excess rainwater. This set-up improves water infiltration and helps to increase the ground moisture level. Their root systems also help stabilize the soil and prevent further soil erosion.

Vetiver grass is a relatively low-cost erosion and sediment control technology with remarkably high benefit to cost ratio.

When used for water control for low and moderate intensity storms, its cost is about 1/20th of traditional engineered systems and designs. Vetiver’s cost-effectiveness makes vetiver grass a promising alternative to conventional erosion protection. It is highly recommended for you to work with an engineer, experienced in erosion restoration rehabilitation.

Gabion Basket Eyebrow Terrace

Gabion Basket Eyebrow Terraces

Eyebrow terraces are a form of micro catchment water harvesting system. They are handmade micro basins, in the shape of an eyebrow, and often made from gabion baskets lined with geotextile drainage membrane.

Their main goal is to collect runoff water from a small catchment area and infiltrate it into the soil. This way, it is stored in the root zone and will be available for vegetation and crops.

They are usually situated on hillsides and they can be used on slopes of up to 50%. The steeper the slope, the more wire baskets lined with geotextile drainage membrane.

Eyebrow terraces on steep slopes, reinforced with wire baskets filled with gabion stone, are resistant to the increased water speed, caused by the slope. Unlike some other forms of terracing, eyebrow terraces are not uninterrupted. Instead, they can be some meters apart. After completion, the pit uphill from the eyebrow may fill with sediments and soil and thereby terraces arise

Gabion Basket Contour lines

Stone Lines

Stone lines are stones grouped in the shape of a line and placed along the contours. The stones can be of different sizes.

The goal of these lines is soil conservation and runoff reduction, as they are used to slow down runoff water and break its velocity. Hence, they increase infiltration and retain sediment and seeds to make water and nutrients available for crops.

Stone lines are most suitable for water harvesting on slightly sloping plains (up to 5%). For slopes starting from 5%, stone bunds can be used (see eyebrow terraces).

Stone lines are an easy and cheap intervention if stones are available in the immediate surroundings.

This intervention is widely used, both in dry and humid areas. Moreover, stone lines are often used in combination with planting pits intervention for the rehabilitation of degraded and crusted lands.

Gabion Baskets Contour Bunds

Gabion Basket Contour Bunds

Gabion basket contour bunds lined with geotextile membrane, are a form of micro catchment, requiring civil engineering techniques and structures. It is an amazingly simple and cheap form of water control.

This practice consists in making a comparatively narrow-based embankment at intervals across the slope of the land on a level that is along the contour. There are also small gabion basket ties, perpendicular to the contour gabion bunds, that subdivide the system into micro catchments.

Contour bunds aims to slow down runoff and improve water infiltration in the soil. For this reason, contour bunds are often associated with the cultivation of crops, fodder or trees between the bunds. Contour bunds also help to control soil erosion.

Contour bunds for tree planting and it can be applied on slopes up to 5% but it requires even terrains, without the presence of gullies or rills. The soil should preferably be 1.5 or 2 m deep to ensure proper root development and water storage.

Environmental Management

Water spreading gabion bunds

Water spreading gabion bunds are storm water drainage solutions, used to manage concentrated floodwater that has been diverted from a watercourse.

The technique of water spreading bunds is very site-specific, as it can only be used on lands close to a watercourse to spread concentrated floodwater.

The gabion bunds, lined with geotextile, slow down the runoff and let it spread over the cultivated land, thus they increase the infiltration rate.

There are several different options for water spreading bunds and the choice for the most effective one needs to take into account the quantity of water that will reach the structures, the slope of the land, the type of soil.

Bio-degradable erosion control blanket

Bio-degradable erosion control blanket

The jute mat germination blanket promotes vegetation growth and help retain topsoil for vegetation growth. Their purpose is to keep the soil moist and cool during the initial growing phase of young plants and seedlings, encouraging vegetation growth before the soil is moved or transported away in heavy rains.

Both the woven and non-woven blankets are eco-friendly and degrade into the soil over time, providing nitrogen into the soil during the initial growth phase.

We offer rolls of biodegradable soil blankets for installation in areas where soil erosion is a pressing problem on steep slopes or newly constructed fills.

These blankets can be made of hessian, jute, coconut fiber and synthetic materials for a slightly longer lifespan. Ranging from a life span of about 6 months to 3 years for the synthetic blankets. Roll sizes available are dependent on grade or product type requested. Please contact us for further information.

Soil Bio-engineering

Soil Bio-engineering

SOIL BIOENGINEERING is the activity of nature conservation and landscape management through the application of engineering design and technology, to living systems.

It is an overly broad term encompassing many different techniques. Many of these were refined over thousands of years prior to being actively grouped together under the umbrella of “Bioengineering”.

Others have been developed more recently as practitioners’ experiment with new ways to address environmental challenges.

Depending upon how it is defined, Bioengineering could include techniques used in combination with civil and social engineering measures, offering an environmentally friendly and highly cost and time effective solution, amongst other things, for:

  • Soil erosion

  • Slope failure

  • Landslides and debris flows

  • Reed bed wetlands treating wastewater

  • Plants grown to bio-accumulate heavy metals in order to decontaminate a site (phytoremediation), such as Vetiver Grass

The combination of physical and vegetative measures offers a combination of immediate and long-term protection, as well as mitigation of the ecologically damaging effects of some physical constructions

Erosion control blankets and erosion control textiles are playing an important role in preventing erosion by, among other things, reducing the erosive force of the rainwater. At the same time, erosion control blankets and textiles reduce the drying out of the soil, particularly during dry periods in the summer.

This accelerates the germination process and contributes to even growth. Since erosion control textiles as well as erosion control blankets have only a limited life span of a few months to a maximum of 5 years, they only offer temporary erosion protection.

Their main purpose is to protect the embankment from the sowing until the vegetation is completely established.

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