SAND MINING REHAB.
GUIDELINES
Combatting The Effects of Sand Mining
12 FEBRUARY 2014
DUCT
4 Edmond Place, Campsdrift, 3201
Sand Mining Rehab Guidelines/Proposal
Executive summary
The relationship between man and the resources that water courses possess can be described as
one sided, with human beings being accused of over exploiting river resources solely for their own
ends. Often one forgets that a river has a tendency to continually evolve (naturally), together with
the flora and fauna of the adjacent land. But this evolution is hastened due to human activities such
as sand mining (unnatural).
As population increased and industry developed the relationship between man and the river
strengthened since communication routes were required for trade and social exchange.
Today it is becoming increasingly difficult to ignore problems associated with flooding of low lying
areas which is further exacerbated by sand-mining activities. Whilst safeguarding our infrastructure
on the one hand we must remember that a natural water course is a living entity in continual
development that should be protected as far as possible.
Introduction
Sand mining is a problem that could be labelled as one of the more serious environmental problems
that South Africa faces. The production and rehabilitation of fertile top sand/soil that will support
good plant growth and prevent soil erosion is an extremely slow process. Natural rehab of mined
land takes between 12 to 40 years. Loss of sand due to mining is estimated at 0.7 ton per hectare
per year.
Sand mining subsequently leads to a hastened soil erosion process. This is further worsened by the
subsequent heavy rains. Poor mining practices and the mechanical exposure of the sand are the
most important causes of soil erosion. The importance of plants in the rehab process and the
prevention of soil erosion can’t be over emphasized.
This proposal is solely interested in the protection and mitigation of river ecosystems from sand
mining.it illustrates the compatibility of incorporating environmentally sound concepts into the
design of making/engineering solutions for rehabilitation.
This proposal gives a brief background of soil protection and ecological systems and techniques,
which may be adopted for greening disturbed areas. This document discusses specific remedies and
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looks at erosion as it pertains to sand mining practices and the problems caused by erosion. Proper
remedies will have to be planned and implemented by experts.
Purpose
The purpose of this proposal is to highlight the need for the control of degradation/erosion in sand
mining sites and to introduce alternative methods for the prevention of erosion. With sand mining
practices, water from the adjacent river/stream gives the potential to maim, damage and destroy
the river ecology if not managed and rehabilitated correctly. This proposal highlights the protection
and stabilisation of river banks which reduces the erosion of slopes. This further protects
surrounding human settlements from impact floods.
Sand mining sites concerned
All sand mining sites concerned are found within the foothill and valley regions of the river/water
course.

Foothill region- this is the region where the river flows from mountains and into the valley, a
sharp reduction in river gradients occur here which has resulted in the deposition of the
larger material. The river beds are generally unstable. They are characterised by wide
sections and are not cut-in too deeply as the river is wide. Any widening of the channel
increases the channel movement which becomes very harmful and dangerous during severe
floods. In the foothill regions the presence of solid materials contributes to the stabilisation
of the river bed which is constantly compromised by mining activities.

Valley regions- a shallow channel is found in this region which forms a sinuous shape which
can assume various patterns

Straight and sinuous beds

Meandering beds

Multi-channel beds
These flat reaches within the valley region require course correction and back protection. This and
other rehabilitation measures require careful planning and can’t be generalised. Each affected site
must be analysed individually in a way appropriate to that mined site on the river bank.
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River habitat and morphology
When looking at the restoration and rehabilitation of the mine affected river habitat, one should not
only choose what materials are to be used, but also the proper design methodologies. The
environmental biodiversity of the river course needs to be maintained thus its morphological
diversity is retained. With this type of rehabilitation there can be gradual creation of habitats for the
distribution of vegetation and fauna. The bankside vegetation consisting of emergent plants, shrubs
and trees plays a significant part in stemming erosion of the valuable soil and habitats even during
oncoming flood conditions.
The threat of soil erosion/land degradation in the mining sites

In the first case, unrehabilitated mined land in the vicinity of the stream threatens the
structural integrity and channel of the adjacent water course. Failure to remedy the
situation may lead to an expanded river channel.

Secondly, erosion on the river banks of the uMgeni may not threaten the river directly or
initially, but will have a negative cumulative impact further downstream.
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
Thirdly, the causing of erosion is a contravention of the conservation of agricultural
resources act.
Soil erosion of the site

During sand mining activities, the impacts of vegetation clearing and the formation of access
routes to sites for large vehicles has probably the most profound effect on erosion/land
degradation
The stabilization of soils, particularly in the vicinity of the watercourse, requires special attention.
The impact of sand mining activities during the excavation cycle of the plot/site is relatively high as
patrols and compliance monitoring on the site are sparsely carried out
Proposed solutions to combat soil erosion in sand mined sites
Since there is an understanding of the cause of the erosion/degradation which is as a result of the
alteration of the drainage/flow pattern of the river channel by the mining of the sand and other
interventions. Under these conditions the vegetation is reduced or even destroyed and the velocity
and quantity of runoff and stream flow is increased, with the resulting increase in erosion. Where
highly erodible soils occur, the effect/impact is more severe.
The main objectives in the planning of rehabilitation measures to be taken begins with slope
stabilisation. With biodegradable erosion control blankets. The correct placing of these structures
will be based on various aspects such as the volume of water passing through, soil/sand type and the
slope of the terrain which should be carried out by a specialist.
Preventing erosion/degradation caused by access roads

Roads are built to provide access for the removal of the sand as well as to provide access for
inspection and maintenance. Roads are one of the major causes of soil erosion and land
degradation.
Research tells us that roads should be planned according to principles of water runoff and
should be positioned on a watershed or ridge. Due to the sand being highly sensitive there
have been changes to many access routes. Degradation is further exacerbated by the steep
slopes of the access routes (slopes should not exceed 7%)
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Areas that have erodible soils/sands as well as areas in the vicinity of watercourses require
special measures
Erosion/degradation prevention structures
These structures or systems are to be used in eroded/disturbed areas and aim to halt active
erosion and re-establish vegetation
Three categories of solutions are suggested. They are:

Heavy systems: these solutions include concrete or brick structures and gabions and reno
mattresses etc. concrete or cement structures can be constructed on solid rock foundation.
Care should be taken not to disturb the environment where rocks are collected as this could
result in the creation of new erosion problems.

These structures are normally expensive and should be planned carefully by a specialist

Light systems: these systems include silk screens, erosion control blankets, turf
reinforcement mats and geocells.The re-establishment of vegetation is encouraged by using
soil reclamation rolls, eco logs or seeded coir mats, also referred to as small structures

Soil bioengineering techniques: this refers to the use of a variety of plant species without
any inert(artificial) materials
Small structures
Recently the use of “small structures” has been suggested to combat the type of soil erosion/land
degradation typically found in sand mining sites. These structures can be erected with minimal
labour and at a low cost and have been shown to be effective in the re-establishment of vegetation
in disturbed areas. As previously mentioned, these structures are cheap to construct and the
materials used will not pollute the environment.
Soil reclamation rolls
With sand mining, most of the topsoil has been removed and vegetation also becomes absent.
Water penetration is low and runoff is high. The rehabilitation of vegetation is normally achieved by
the removal of animals, human activity, the ploughing and planting of vegetation. The success of
these measures is also highly dependent on sufficient rainfall.
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The remedies which involve the re-establishment of vegetation will necessitate the co-operation of
the concerned affected stakeholders. Where possible, areas under rehabilitation should be fenced
off but this is often not practical for sand mined sites.
It is therefore vitally important for the successful rehabilitation of a mined site to involve the miner
in solving the problem.
In many cases, the miners have the means to implement some of the remedies suggested above,
with their own equipment and labour. This work may be carried out during slack times and in this
way contribute to sustainable job creation in the rural areas.
This approach is also certain to reduce any complaints about work. The contractor/miner will have a
stake in ensuring success of the project
Guidance to solutions that combine various practices and ecological principles
Soil/sand protection
Purpose of soil protection/rehab- vegetation is an excellent defence mechanism which nature has
produced to protect soil against erosion.Sometimes,however erosive forces are too large or
vegetation needs to be developed under difficult conditions and nature needs a helping hand with
erosion control. In such analysis inert materials can be brought into the solution. Vegetation
improves the stability of the subsoil against erosion and deterioration of the riverbank. Rehabilitated
areas improve the water quality, habitat and aesthetic appeal of the river channel.
Vegetation
Plant roots function as soil reinforcing agents. This further reduces slope instability and erosion due
to vegetation’s capability of increasing surface roughness flow of rainfall and water is retained and
seepage is reduced. As previously mentioned, plants provide immediate river habitat improvements.
Biodiversity and habitat value are increased as vegetative growth increase and natural succession
occurs.
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Benefits and features of soil protection/rehabilitation
Benefit
Feature
Cost effective
A combination of solutions whether it be soil engineering or vegetation of
structural solution
Minor site
Rehab techniques generally require minimal access for equipment and
disturbance during
workers, and cause relatively minor site disturbance during installation
installation works
Techniques are
Useful on even the most sensitive/steep site where machinery is not
useful on almost any
feasible
site
Appropriate for
These practices are appropriate for environmentally and aesthetically
environmentally and
sensitive areas such as rivers.
aesthetically
sensitive areas
Immediate
These rehab. Systems can be designed to withstand heavy events after
protection
installation/implementation
Strong initially and
Rehab. Systems are strong initially and grow stronger with time as the
grows stronger with
vegetation becomes established
time.
Erosion control
The vegetation traps sediment, which further promotes growth and
erosion control
Natural plant
Enhances conditions for the natural colonisation and establishment of
colonisation
plants from surrounding plant community
Increase in soil
Dries excessively wet sites through transpiration as the vegetation grows
quality by reducing
soil moisture
Increase in soil
Reinforces soil as roots develop adding resistance to the sliding and
stability to plant
displacement of slopes
growth
Soil temperature
Plants provide protection from the extremes of heat and cold, which lead
moderation
to a healthier environment for the plant germination and growth
Improves water
Heavily vegetated banks filter and slow storm water runoff and trap
quality
sediment, thereby improving water quality
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Air quality
The removal of dust offer air quality improvement and increased oxygen
improvement
production
Low maintenance
Rehabilitated sites become self-maintaining and self-repairing
Jobs
Implementing rehab. Systems is often labour intensive, due to difficult
access to sites and hand planting requirements for vegetation
Environmental
Supports indigenous plant species and wildlife habitat and speeds up
benefits
ecological succession
Positive impact on
Vegetation provides:
wildlife

Shelter and nesting sites protection from predators and floods

Shade-keeping the water cooler in summer and slowing the
growth of algae

Aesthetics
A source of food
Rehab measures support plant species and wildlife habitats which improve
the aesthetic appeal of the river bank and channel
Improved biological
The growth of the vegetation tend to improve the biological conditions
conditions
thereby restoring the natural ecosystem
Rehab systems will use biological, mechanical and ecological concepts to control erosion while
preserving ecological value. It will rely on various tools such as living plants, traditional construction
material to stabilize the soil and to provide good wildlife and fisheries habitat in riparian systems.
Rehab. Considerations
Cost: the project/s will need to fulfil all the functional requirements while staying within budget for
both construction and maintenance.
Safety: considerations must be given to eliminating potential risks to the labour force and the public.
All factors relating to safety should be incorporated, including consideration of all possible activities
that may take place on and around the site, whether authorised or not.
Maintenance: rehab. Should allow for maintenance including the repair of any damages.
Durability: the rehab. Should remain effective for the duration of the river life at least
Flexibility: the ability to absorb any deformations without impairment of its original shape/function.
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Stability: the rehab. Structure must be capable of supporting the riverbanks, stabilising the
underlying soil and preventing soil erosion
Factors involved in the rehab. Process
Soil/sand: when establishing plants for rehab the soil must be consolidated which allows root growth
to thrive in the site.
The features of topsoil that are significant to successful plant growth and therefore rehabilitation
are:

Air in the soil profile is important as roots derive air for biochemical activity from the soil and
not from the leaves.

Aerated soils regulate the soil temperature, making it suitable for plant growth.

Moisture retained by humus is constantly available to be drawn by the root system while
plants are growing

Nutrients are maintained in the humus and are available over an extended period
“The quality of soil/sand will directly determine the growth of surface vegetation”
Vegetation
It is recommended to consult a local plant specialist when determining which vegetation to
use for a rehab. Project.
Root contribution to soil stability
The most obvious way in which vegetation stabilises soils is by root reinforcement. The
intermingled roots of the plants bind the soil to slope and increases resistance to sliding.
Roots: deep roots penetrate the subsoil for anchorage
It has a positive effect on soil moisture depletion and interception, thus increasing soil
strength by mitigating or delaying the onset of saturated conditions in the soil.
Trees together with grasses and shrubs have been used to control erosion on slopes and to
stabilise landslides for many years. The vegetation has a net stabilising effect on most slopes
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Effects of vegetation on slope stability
Mechanism
effect
Hydrological
1
Foliage intercepts rainfall, causing absorptive and evaporative losses that reduce
↑
rainfall for infiltration
2
Roots and stems increase the roughness of the ground surface and the permeability
↓
of the soil, leading to increased infiltration capacity.
3
Roots extract moisture from the soil, which is lost to the atmosphere via
↑
transpirtation,leading to lower pore-water pressure
4
Depletion of soil moisture may accentuate desiccation cracking in the soil, resulting
↓
in higher infiltration capacity
Mechanical
5
Roots reinforce the soil, increasing soil shear strength
↑
6
Tree roots may anchor into firm strata, providing support to the upslope soil mantle
↑
through buttressing and arching
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Weight of trees surcharge the slope, increasing normal and downhill force
↑↓
components
8
Vegetation exposed to the wind transmits dynamic forces via the tree stem into the
↓
slope.
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Roots bind the soil particles at the ground surface, reducing their susceptibility to
↑
erosion.
↑
Beneficial to stability
↓
Adverse to stability
Plant selection for rehab.
The success of rehab. Solutions is greatly dependent on plant stem density and length, root
penetration, rooting habits, uniformity of vegetation, soil erodability and the physical and
chemical characteristics of the remaining soil/sand.
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There are five biological factors for plant growth and rehab.
1. Temperature
2. Moisture
3. Nutrients
4. Oxygen
5. Light
Choosing the most appropriate solution for rehab. Requires consideration of a no. of
factors. Plants chosen need to be able to establish easily, thus they become fast
growing and give immediate protection. These plant species usually require a great
deal of nutrients so growth in most cases is slow to take off.
Another important consideration is what the end function of the chosen plant will
be .Various plants have differing characteristics, from the strength of their root
systems to whether they provide good ground cover.
Inspection and maintenance
Regular inspection and maintenance of installed rehab. Practices should be
conducted, particularly during the first year. Prompt correction of any fault is
essential to prevent major problems from developing.
Plant establishment is most critical in the success of the rehab. Adequate watering
requirements must be met at this stage of the plant life cycle. Care must be taken
not to over-water the sites, as this could lead to failure of rehab. Due to slope
instability.

Plants should be monitored for four to five weeks after rehab. To ensure the
success and survival of the plants

The plants roots need to be covered and kept moist

All plants should be checked periodically or after storms to ensure they
remain properly secured. Make necessary repairs promptly
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Conclusion
Vegetation can make better many of the factors and conditions causing earth slope and river
instability. Rehab measures must be suitable for the life of animals and plant communities thus a full
restoration of our natural ecosystem can take place
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REFERENCES
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Ellis, H., 2001. Natural Progression. In: Soil Bioengineering: Integrating Ecology with Engineering
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with Engineering Practice, Ground Engineering, March 2001.
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Ferraiolo, F, 1999. Application of Inert Materials in Bioengineering, Officine Maccaferri SpA,
Bologna (Italy). In: Proceedings of the First Conference on Groundwater bioengineering for
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Greenway, D.R., 1987. Vegetation and slope stability pp187-230 In: Anderson, M G, Richards, K S
(Eds) Slope stability Chichester, Wiley.
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APPENDICES
Photos of erosion control implements:
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