6. Impact description and assessment

advertisement
Kay Environmental Services / Kayode Okesanjo
Gamma-Omega 765 kV transmission line
Pedology Report
PROPOSED 765 kV TRANSMISSION LINE
GAMMA TO OMEGA
PEDOLOGY REPORT
Prepared by
Kayode Okesanjo
Kay Environmental Services
P.O. Box 1533
Paulshof 2056
Prepared for:
PBA International
February 2002
533569566
-1-
Kay Environmental Services / Kayode Okesanjo
Gamma-Omega 765 kV transmission line
Pedology Report
EXECUTIVE SUMMARY
Kay Environmental Services (KES) was approached by PBA to undertake pedological study of the proposed
Gamma – Omega 765 kV transmission line. The proposed 765 kV Transmission line forms a part of the
wider Cape Strengthening Programme being undertake by Eskom’s Transmission. The motivation for the
programme is set out in the report, however it sets out to address two key requirements:

To strengthen the transmission networks to the Western Cape such that reliability of the supply is
improved.

To enhance the capacity of the network such that predicted future demand may be met.
To comply with regulatory requirements of the Environmental Conservation Act (Act 73 of 1989 and
associated regulations), and to apply internationally acknowledged best management practice in its
activities, Eskom Transmission Group have undertaken this Environmental Impact Assessment (EIA)
process.
The aim of this study is:

To improve the reliability of the exiting transmission network to the Western Cape, and

To upgrade the electricity transmission capacity of the network in the short-term whilst providing for
the longer-term requirement.
This report is primarily comprised of a desktop study of the corridor supplemented by site visits and feedback
from I&APs. The primary sources of information were the Institute of Soil, Water and Climate maps and
land-type memoirs, and Eskom.
The environmental impacts of the construction phase would be particularly sensitive to the management and
sensible planning. These impacts include soil erosion and soil pollution.
The issues and activities connected to the construction phase include:

Clearing of vegetation for the installation of the transmission towers.

Clearing of areas for campsites.

Construction of access roads.

Soil erosion.
The soil types along the entire route are generally stable, though all are sensitive to disturbance. The areas
in section 2 are very sensitive and due to the position of the soil on the steep slopes along the mountain
range. Evidence of gully, water and wind erosion is present in the landscape. In sections 3 to 5 there is
evidence of erosion throughout the area, primarily due to infrastructure such as road crossings of
watercourses.
Construction activities should be carefully monitored to ensure compliance with the EMP. The EMP should
limit construction activities to those that are acceptable in preventing environmental damage. No scarring of
533569566
-2-
Kay Environmental Services / Kayode Okesanjo
Gamma-Omega 765 kV transmission line
Pedology Report
such areas would be allowed and proper rehabilitation would ensure recovery without any problems.
Erosion prevention measures should be taken right from inception of the construction process.
The proposed transmission line will have very little impact on the soil within the study corridor. However
there are some sensitive areas within the study corridor especially the areas within section 2 were the terrain
shows extensive evidence of gully and sheet erosion. Special attention needs to be giving to this area
during the construction of the proposed transmission line.
533569566
-3-
Kay Environmental Services / Kayode Okesanjo
TABLES OF CONTENTS
1.
2.
3
4
Gamma-Omega 765 kV transmission line
Pedology Report
Page
INTRODUCTION...................................................................................................... 5
BACKGROUND AND BRIEF ............................................................................... 5
STUDY APPROACH .............................................................................................. 5
STUDY AREA .......................................................................................................... 6
4.1
SOILS .................................................................................................................... 6
5. IDENTIFICATION OF RISK SOURCES ............................................................ 7
5.1
CONSTRUCTION .................................................................................................. 7
5.2
MAINTENACE DURING OPERATION ................................................................. 7
5.3
CRITERIA AGAINST WHICH EXPECTED IMPACTS ARE EVALUATED .......... 9
6. IMPACT DESCRIPTION AND ASSESSMENT .............................................. 11
7 GENERIC MANAGEMENT AND MITIGATION MEASURES .................... 21
7.1
MITIGATION ....................................................................................................... 21
7.2
MAINTENANCE .................................................................................................. 21
7.3
REHABILITATION OF FERTILE SOIL ............................................................... 22
8 ALTERNATIVES.................................................................................................... 22
9 CONCLUSION........................................................................................................ 23
10. REFERENCES ................................................................................................... 24
533569566
-4-
Kay Environmental Services / Kayode Okesanjo
1.
Gamma-Omega 765 kV transmission line
Pedology Report
INTRODUCTION
The proposed 765 kV Transmission line forms a part of the wider Cape Strengthening Programme being
undertake by Eskom’s Transmission. To comply with regulatory requirements of the Environmental
Conservation Act (Act 73 of 1989 and associated regulations), and to apply internationally acknowledged
best management practice in its activities, Eskom Transmission Group have undertaken this Environmental
Impact Assessment (EIA) process.
Although the new transmission line will only be brought into operation at the time when growth and demand
requires it, it is necessary to secure the corridor (servitude) that will accommodate the proposed 765 kV well
in advance. The study route is a 10km corridor centred on a preferred alignment for the new transmission
line. The length of the study corridor is some 520km. It may cross the Western/Northern Cape provincial
border at a number of locations, but the bulk of the route lies in the Western Cape province.
2.
BACKGROUND AND BRIEF
The Cape Strengthening Programme comprises a number of individual projects with the collective aim of
improving the reliability of electricity supply to the southern areas of the country, and to the Western Cape in
particular.
The primary aims of the Cape Strengthening Programme are:

To improve the reliability of the exiting transmission network to the Western Cape, and

To upgrade the electricity transmission capacity of the network in the short-term whilst providing for
the longer-term requirement.
3
STUDY APPROACH
This report is primarily comprised of a desktop study supplemented by site visits and feedback from I&APs.
The primary sources of information are the Institute of Soil, Water and Climate (ISWC) and Soil map produce
from the Environmental Impact Assessment software package.
The approach to this study was to review all soil land-type maps, from ISWC and topographical information
from 1: 50,000 maps. No soil mapping was conducted but site visits were undertaken at locations along the
route.. The erosion hazard criteria consists of two sub-criteria, namely slope gradient and soil erodibility
group. Both criteria need to be met for the land to qualify for a particular erodibility class.
533569566
-5-
Kay Environmental Services / Kayode Okesanjo
4
Gamma-Omega 765 kV transmission line
Pedology Report
STUDY AREA
The study route is a 20km corridor centred on a preferred alignment for the new transmission line. The
length of the study corridor is some 520km. It may cross the Western/Northern Cape provincial border at a
number of locations, but the bulk of the route lies in the Western Cape province. The pedology for the route
was reviewed. Critical and/or sensitive areas along the corridor were identified and mitigation factors area
discussed. Refer to Map 5a – Soils.
4.1
SOILS
Section 1 soils are dominate by soils with a marked clay accumulation also common within this section is
soils with minimal development (lime present) and greyish-sandy excessively drained soil, with some soils
with minimal development with lime rare in the landscape.
Section 2 of the study corridor is dominate by soils with minimal development with lime present and soils with
minimal development with lime rare in the landscape, also common is the landscape is rocks with limited
soils and soils with marked clay accumulation strong and reddish colour.
Section 3 soils are dominated by soils with marked clay accumulation strong and reddish with Red-massive
or weak structured soils with high base status and rock with limited soils.
Section 4 soils include both soils with minimal development (shallow on hard or weathering rock) with lime
present and rocks with limited soils.
Section 5 soils are dominated by soils with minimal development (shallow on hard or weathering rock) with
lime present, also present are rocks with limited soil, Red massive or weak structured with high base status.
Present in limited parts greyish-sandy excessively drained soils and soils with negligible to weak profile
development –usually on recent flood plains.
Erosion is seen to be a potential problem for the whole study area. The flatter terrain and extensive
agricultural practices in Section 1 result in the soils being highly disturbed, but largely protected and
therefore at lower risk. However, Sections 2 to 5 are seen to be very sensitive to disturbance, resulting in a
high erosion potential. Indeed, at locations in these Sections, erosion due to the existing lines is evident,
and this has been confirmed by repeated complaints from stakeholders along the route. However it is
understood that this erosion is largely due to poor maintenance of the access roads.
533569566
-6-
Kay Environmental Services / Kayode Okesanjo
5.
Gamma-Omega 765 kV transmission line
Pedology Report
IDENTIFICATION OF RISK SOURCES
This section presents the various biophysical impacts that may result from the construction of the
transmission line. The biophysical impacts are discussed in terms of the various project stages and the
activities connected to each stage. The project stages include construction and maintenance.
5.1
CONSTRUCTION
The environmental impacts of the construction phase would be particularly sensitive to the management and
sensible planning. These impacts include soil erosion and soil pollution.
The issues and activities connected to the construction phase include:

Clearing of vegetation for the installation of the transmission towers.

Clearing of areas for campsites.

Construction temporary access roads.

Disturbance of geological fossil sites.

Soil erosion.
5.2
MAINTENACE DURING OPERATION
As with disturbance to any soils, the potential problem of subsequent erosion is seldom solved by initial
rehabilitation after construction. A long-term maintenance programme needs to be established. Such a
programme will need to be drawn up prior to construction.
533569566
-7-
Kay Environmental Services / Kayode Okesanjo
Gamma-Omega 765 kV transmission line
Pedology Report
Summary of potential risk of each activity per description area
Table 1
Activity
Impact
Clearing of vegetation for installation of  Soil erosion
foundation and towers
 Loss of arable land
 Loss of wetland related soils
 Soil pollution
Clearing for campsite
 Soil erosion
 Soil pollution
 Soil Loss
Construction temporary road
 Soil erosion
 Soil pollution
 Loss of arable land
 Wetland related soils
533569566
Magnitude of impact
 High
 High
 High
 High
 High
 High
 High
 High
 High
 High
 High
-8-
Duration of impact
 Medium to long term
 Medium to long term
 Medium to long term
 Medium to long term
 Medium to long term
 Long term
 Long term
 Medium to long term
 Long term
 Short to long term
 Medium to long term
Kay Environmental Services / Kayode Okesanjo
5.3
Gamma-Omega 765 kV transmission line
Pedology Report
CRITERIA AGAINST WHICH EXPECTED IMPACTS ARE
EVALUATED
Nature of the impact
Extent of the impact
Description of impact
Describe whether the impact will be : local extending only as far
as the development site; or limited to the site and immediate
surroundings; or will have an impact on the region, or will have
an impact on a national scale or across international borders
Duration of the impact
Intensity

Short term (0-5 years)

Medium term (5-15 years)

Long term (f16-30 years)

Permanent
The specialist should
establish
whether
the
impact is
destructive or benign and should be qualified as low, medium or
high.
The specialist study must attempt to quantify the
magnitude of the impacts and outline the rationale used.
Probability of occurrence

Improbable, where the possibility of the impact to
materialise is very low

Probable, where there is a distinct possibility that the impact
will occur

Highly probable, where it is most likely that the impact will
occur

Status of the impact
Definite, where the impact will definitely occur
The specialist should determine whether the impacts are
negative, positive or neutral (“cost – benefit” analysis). The
impacts are to be assessed in terms of their effect on the
project and the environment. For example, an impact that is
positive for the proposed development may be negative for the
environment. It is important that this distinction is made in the
analysis.
Accumulative impact
Consideration must be given to the extent of any accumulative
impact that may occur due to the proposed development. Such
impacts must be evaluated with an assessment of similar
developments already in the environment. Such impacts will be
either positive or negative, and will be graded as being of
negligible, low, medium or high impact.
533569566
-9-
Kay Environmental Services / Kayode Okesanjo
6.
Gamma-Omega 765 kV transmission line
Pedology Report
IMPACT DESCRIPTION AND ASSESSMENT
The soils along the entire route are stable. However, the areas within section 2 are the most sensitive and critical areas along the entire route. This is due to the
position of the soil on the steep slopes along the mountain range. Evidence of gully, water and wind erosion is present in the landscape.
Sections 1 to 5
Theme
Nature of Impact
Legal requirements
Stage
Extent of impact
Duration of impact
Intensity
Probability of Occurrence
Status of impact
Accumulative Impact
Level of Significance
Mitigation measures
Clearing of vegetation for installation of foundation and towers
Soil Erosion
Conservation of Agriculture Resources Act (No. 43 of 1983)
Construction and Decommission
Operation
Local
NA
Potentially long term
NA
Medium
NA
Definite
NA
Negative
NA
Negative
NA
Potentially high on steep slopes, Moderate in
NA
valleys
 Construction to be done in dry season.

Work from top of slope downward.

Clearing of vegetation should be kept to a
minimum.

If possible construction should happen without
vegetation removal.

Level of significance after mitigation
EMP requirements
Avoid pristine area.
Moderate to low
 The rehabilitation of any dongas will be
necessary in this area.

Erosion control will be necessary in this
section of the proposed transmission line.
533569566
- 11 -
Kay Environmental Services / Kayode Okesanjo
Gamma-Omega 765 kV transmission line
Pedology Report

Long-term
monitoring
and
maintenance
requirements to be identified.

EMP to control construction to ensure that the
best method is used.
Discussion
The steeper slopes long the route of the proposed transmission line are the most sensitive and critical area to be crossed by the line. These soils are highly
susceptible to erosion. Construction activities will either disturb the vegetation cover or breach the protective topsoil is likely to result in severe soil loss.
However, it is understood that limited vegetation clearing takes place during construction. Unless the vegetation is high or comprises large trees, it is merely
driven over within the working area around the pylon. Nevertheless, some damage to the vegetation will occur and rehabilitation and long-term monitoring will
be necessary, particularly in the Karoo areas where vegetation regeneration is slow.
533569566
- 12 -
Kay Environmental Services / Kayode Okesanjo
Section: 1, 2, 3, 4, and 5
Theme
Nature of Impact
Legal requirements
Stage
Extent of impact
Duration of impact
Intensity
Probability of Occurrence
Status of impact
Accumulative Impact
Level of Significance
Mitigation measures
Gamma-Omega 765 kV transmission line
Pedology Report
Clearing of vegetation for installation of foundation; towers and access roads
Loss of Wetland related soils
Conservation of Agricultural Resources Act (No 43 of 1983), Environmental conservation Act (No 73 of
1989)
Construction and Decommissioning
Operation
Local
Local
Potentially long – term
Potentially long-term
Moderate to high
Moderate
Highly probable
Probable
Negative
Negative
Moderate
Moderate
Moderate
Moderate
Ensure ongoing, regular monitoring and
 Wetland areas should be avoided at all cost
maintenance.
during the installation of towers
Level of significance after mitigation
EMP requirements
Low
 Wetlands should be avoided in planning
access roads for construction.

Any damage to wetlands must be rehabilitated
before the site is abandoned.

Self-supporting tower should be installed in
wetland area and pans.

No dumping of refuse and waste around
wetlands.

While working in an area efforts should made
to reduce compaction of soil.

Temporary road crossing wetland should not
be compacted and must be remove after
construction is finished.

533569566
For more site specific mitigation measures
- 13 -
Low
 Set out monitoring and maintenance
programme for each wetland.
Kay Environmental Services / Kayode Okesanjo
Gamma-Omega 765 kV transmission line
Pedology Report
refer to Eskom’s Environmental Management
Plan Report (EMPR) to the construction Phase
of this project.
Discussion
Wetlands are highly sensitive habitats being home to a group of highly specialized species, particularly bird species. Gaining access to construct this
proposed powerline has the potential to impact heavily the wetlands in this study area. These wetlands must be avoided, as it is unacceptable to route roads
through wetlands. The presence of wetlands along the study area is relatively low, and are all of a small scale. As such they can be avoided by careful
placing of pylons and access roads in the bird area. Also included in the area are river crossings, particularly the smaller watercourses where formal roads or
crossing points are not near to the route of the line. The same construction and management principles apply, though avoidance is seldom possible. The
protection and rehabilitation of these points will be important.
533569566
- 14 -
Kay Environmental Services / Kayode Okesanjo
Section 1
Theme
Nature of Impact
Legal requirements
Stage
Extent of impact
Duration of impact
Intensity
Probability of Occurrence
Status of impact
Accumulative Impact
Level of Significance
Mitigation measures
Gamma-Omega 765 kV transmission line
Pedology Report
Construction of access roads
Soil Erosion
Conservation of Agricultural Resources Act (No 43 of 1983), Environmental conservation Act (No 73 of
1989)
Construction
Operation
Local
Local
Long-term
Long-term
Low
Low
Probable
Probable
Negative
Negative
Negative
Negative
Low to moderate but potentially high on the
Low to moderate but potentially high on the
Southern Alternative
Southern Alternative
 During construction of access road track  All
rehabilitation
and
re-vegetation
based vehicle should be used especially in

wetland surroundings.

Compaction should minimised

Any foreign material used to maintain the
temporary
road
programmes must be monitored.
must
be
Existing access road should be used were
ever possible.
remove
after
construction, unless used to improve the road
and for erosion control
Level of significance after mitigation
EMP requirements
Low
 During
vegetation
construction
removal
and
site
the
preparation,
erection
of
buildings must happen simultaneously, to
ensure that no large tracts of land are left
exposed at any point in time. Vegetation
clearance should be kept to the dry season.
533569566
- 15 -
Low
 All access roads must be maintained and
storm water drainage system implemented.

Vegetation removal must be kept to a
minimum.
Kay Environmental Services / Kayode Okesanjo
Gamma-Omega 765 kV transmission line
Pedology Report
Discussion
This section of the proposed transmission has a low erosion rating as much of the land has been “improved” by agriculture and access is generally well
established. Although the erosion rating is low the activities involved in the construction of access road could course erosion. Utilisation of existing access
road is a must. Avoid pristine area. However, an area of concern will be the Southern Alternative where the line will pass through the Elandsberg
Private Nature Reserve. This area is undisturbed with the exception of the existing lines and, with the steeper slopes, soil erosion risk is much
higher than the surrounding area of Section 1.
533569566
- 16 -
Kay Environmental Services / Kayode Okesanjo
Section 3 - 5
Theme
Nature of Impact
Legal requirements
Stage
Extent of impact
Duration of impact
Intensity
Probability of Occurrence
Status of impact
Accumulative Impact
Level of Significance
Mitigation measures
Gamma-Omega 765 kV transmission line
Pedology Report
Construction of access roads
Soil Erosion
Conservation of Agricultural Resources Act (No 43 of 1983), Environmental conservation Act (No 73 of
1989)
Construction and Decommissioning
Operation
Local
Local
Potentially long-term
Potentially long-term
Low to high
Low to high
Probable
Probable
Negative
Negative
Moderate to high
Moderate to high
Moderate to high
Moderate to high
 Utilise existing access roads where possible.
 All
rehabilitation
and
re-vegetation

Address existing erosion problems.

Construction to be done in dry season.

Work from top of slope downward.

During construction of the proposed
programmes must be monitored.

Existing access road should be used were
ever possible.
transmission line areas with fertile soil present
this should removed and stored.
Level of significance after mitigation
EMP requirements
Low
 EMP to control construction to ensure that the
Low
 Clear monitoring and maintenance plan to be
best method is used.

During
vegetation
set out, including responsibilities.
construction
removal
and
site
the
preparation,
erection

of
buildings must happen simultaneously, to
storm water drainage system implemented.

ensure that no large tracts of land are left
exposed at any point in time. Vegetation
clearance should be kept to the dry season.
533569566
- 17 -
All access roads must be maintained and
Vegetation removal must be kept to a
minimum.

Burning along the entire route should be
avoided if possible. Burning will leave the
Kay Environmental Services / Kayode Okesanjo
Gamma-Omega 765 kV transmission line
Pedology Report
topsoil exposed, which increases the chances
of soil erosion. If possible, the veld along the
entire route should be cut mechanically to
prevent soil exposure.
Discussion
Their is evidence of soil erosion along this section of the line on both sides of the study area, most of the erosion along this section occurs at river crossings
this will affect the water quality in the river, because of the sediment load eroding into the river. Utilisation of existing access road is a must. Avoid pristine
area. It is evident that erosion associated with the existing lines is problematic, and in some cases severe. The repeated complaint from landowners is that
rehabilitation and maintenance of the existing access roads is not undertaken by Eskom Transmission. It its therefore considered that two opportunities exist
by running the new line adjacent to the existing lines; a) the same access roads can be used in most circumstances, thereby limiting new impacts elsewhere,
and b) there is opportunity for existing erosion to be addresses as part of the construction of the new line.
It is vital, however, that a formal procedure of long-term monitoring and maintenance of erosion in these areas is established prior to construction.
This procedure must identify responsibilities of Eskom Transmission (Regional and National) as well as the landowner.
533569566
- 18 -
Kay Environmental Services / Kayode Okesanjo
Section 2
Theme
Nature of Impact
Legal requirements
Stage
Extent of impact
Duration of impact
Intensity
Probability of Occurrence
Status of impact
Level of Significance
Mitigation measures
Gamma-Omega 765 kV transmission line
Pedology Report
Construction of access roads
Soil Erosion
Conservation of Agricultural Resources Act (No 43 of 1983), Environmental conservation Act (No 73 of
1989)
Construction
Operation
Local
Local
Potentially long-term
Potentially long Term
High
Low
Definite
Highly Probable
Negative
Negative
High in mountain areas, moderate to low in valleys High in mountain areas, moderate to low in valleys
 Utilise existing access roads where possible.
 Access by foot on steep slopes and mountain

ridges.
Utilise helicopter construction on mountain

slopes and ridges.

Construction to be done in dry season.

Work from top of slope downward.

Clearing of vegetation should be kept to a
The rehabilitation of dongas will be necessary
in this area.

Erosion control will be necessary in this
section of the proposed transmission line.
minimum.
Level of significance after mitigation
EMP requirements
Moderate in mountain areas, low in valleys
 The rehabilitation of donga will be necessary
Low
 Clear monitoring and maintenance plan to be
in this area.

set out, including responsibilities.
Erosion control will be necessary in this

section of the proposed transmission line.

Erosion must be monitored in the section of
storm water drainage system implemented.

the transmission line

All access roads must be maintained and
Vegetation removal must be kept to a
minimum.
EMP to control construction to ensure that the
best method is used.

All rehabilitation and re-vegetation
programmes must be regularly checked and
monitored with reseeding of any bare soil
533569566
- 19 -
Kay Environmental Services / Kayode Okesanjo
Gamma-Omega 765 kV transmission line
Pedology Report
patches.

Burning along the entire route should be
avoided if possible. Burning will leave the
topsoil exposed, which increases the chances
of soil erosion. If possible, the veld along the
entire route should be cut mechanically to
prevent soil exposure.

Erosion should be monitored during the
maintenance of the proposed transmission
line.
Discussion
This section of the proposed transmission line is the most sensitive and critical area to be crossed by the proposed line. These soils are highly susceptible to
erosion. Construction activities will either disturb the vegetation cover or breach the protective topsoil is likely to result in severe soil loss. In general, the
concerns are similar to those raised for Sections 3 to 5 and the same mitigation and management requirements will apply.
533569566
- 20 -
Kay Environmental Services / Kayode Okesanjo
7
Gamma-Omega 765 kV transmission line
Pedology Report
GENERIC MANAGEMENT AND MITIGATION MEASURES
Objectives:

To reduce the erosion potential when soils are denuded of vegetation or otherwise disturbed.

To maximise the use of suitable topsoil for rehabilitation.

Control and suitable dispersion of runoff on slopes.

Minimise the potential for soil pollution.
7.1

MITIGATION
During construction site preparation, vegetation removal and the erection of buildings must happen
simultaneously, to ensure that no large tracts of land are left exposed at any point in time. Vegetation
clearance should be kept to the dry season.

Construction camps should not be sited on steep slopes or near wetland, as this will increase soil
erosion. It is advisable to locate construction camps near watershed in order to minimise run-off and
erosion. Re-vegetation will prevent erosion after closure.

Catch water drains or berms must be constructed above embankments and cuttings to prevent runoff from flowing down and across the slopes. This is especially important while slopes are still bare.
For optimum control of soil erosion on embankments and cuttings, vegetation must be established.

All topsoil removed from an area during site preparation and construction must be stockpiled for use
during rehabilitation. The rehabilitation of the site must occur immediately after construction phase,
and should not be left until the end of the project.

Construction activities should be carefully monitored to ensure compliance with the EMP. The EMP
should limit construction activities to those that are acceptable in preventing environmental damage.
No scarring of such areas would be allowed and proper rehabilitation would ensure recovery without
any problems. Erosion prevention measures should be taken right from inception of the construction
process.
7.2
MAINTENANCE
Objective:

To ensure that rehabilitation measures are effective.
Mitigation:
533569566
- 21 -
Kay Environmental Services / Kayode Okesanjo

Gamma-Omega 765 kV transmission line
Pedology Report
All rehabilitation and re-vegetation programmes must be regularly checked and monitored with
reseeding of any bare soil patches.

Burning along the entire route should be avoided if possible. Burning will leave the topsoil exposed,
which increases the changes of soil erosion. If possible, the veld along the entire route should be cut
mechanically to prevent soil exposure. Although soil erosion is very extensive in some areas along
the proposed transmission line route due to bad management practice or neglects Eskom should
look at improving the land practices along this route because this will help slow down a lot of the
erosion currently taking place.
7.3
REHABILITATION OF FERTILE SOIL
In all areas disturbed by construction activities, the topsoil must be removed and stockpiled close to the site
for use during rehabilitation. This may involve separating the 0 and A Horizon, depending on the nature of
the soil profile.
In cases where these horizons are separated, the material must be stored in different stockpiles. This
material should not be stockpiled in natural drainage channels, even during the dry season, as this will leave
it exposed to the processes of water erosion. Stockpiles should be placed in areas where they are not
susceptible to wind erosion.
For more site specific mitigation measures refer to Eskom’s Environmental Management Plan Report
(EMPR) to the construction Phase of this project.
8
ALTERNATIVES
The assessment given above addresses the issues that are representative of the study corridor as a whole.
The preferred line and alternatives identified do not differ significantly such that different levels of impact will
emerge.
It is considered that, in all cases erosion can be avoided or mitigated and the need for
rehabilitation, monitoring and maintenance is equally important. However, preference may be awarded to
the routes in the different sections of the study area as follows:
Section 1:
Preference is given to the Central Route as this avoids the higher erosion risk areas on the
Southern Alternative.
Section 2:
All of the routes identified will be very sensitive to erosion.
However, the Southern
Alternative passes over the high and complex terrain of the Skurweberg and Witsenberg,
which is seen to be more sensitive than the other mountain ridges considered in this Section.
Erosion problems in this area have taken many years to resolve.
In comparison, the
Northern Alternative is relatively pristine, though the narrow valley on the eastern sections of
this route (near Section 3) already exhibits erosion. It is considered preferable to leave each
533569566
- 22 -
Kay Environmental Services / Kayode Okesanjo
Gamma-Omega 765 kV transmission line
Pedology Report
of these routes alone and give preference to either the Central Route or the Central
Alternative, where erosion risk and accessibility is seen to be better.
Sections 3 to 5: It is considered that there is significant benefit in following either of the existing 400kV lines
through these areas. Many of the existing access roads may be used as a result and current
erosion problems may therefore be addressed. No particular preference can be given to
which of the existing lines the new line should follow. Deviation away from the existing lines
raises concern for the spread of erosion impacts.
9
CONCLUSION
It is considered that, overall, the impact of a new 765kV Transmission line through the study area may be
mitigated and managed to an overall rating of low. There are areas where careful planning of construction
will be required, particular the mountain ridges.
However, of particular concern is the need for long-term monitoring and maintenance of the access roads
and constructions sites. It is recommended that clear management plans, with responsibilities, are set out
and approved prior to construction.
Maintenance agreements with landowners may offer reasonable
solutions to this issue.
533569566
- 23 -
Kay Environmental Services / Kayode Okesanjo
10.
Gamma-Omega 765 kV transmission line
Pedology Report
REFERENCES
Satellite Application Centre
Division of Information and Communication Technology, CSIR
Institute of Soil Climate and Water
Maps and type Memoirs.
Institute of Soil Climate and Water
Data centre for Weather.
533569566
- 24 -
Download
Related flashcards
Soil science

15 Cards

Soil biology

34 Cards

Soil scientists

51 Cards

Create flashcards