Chapter 11: Impacts of Freshwater Ecosystems
11
IMPACTS ON FRESHWATER ECOSYSTEMS
11.1
Background
The site supporting the proposed Langhoogte WEF contains moderate and steep
slopes, which form the numerous small valleys in which the rivers and valley-bottom
wetlands occur. The largest valley in the area is the Bot River valley, running along
the western boundary of the site.
Mathew Bird and Dean Ollis of the Freshwater Consulting CC were appointed to
undertake an independent impact assessment of the proposed development on
freshwater ecosystems (rivers, wetlands and open water bodies). A copy of the full
freshwater ecosystem impact report is included in Appendix E4.
11.2
Methodology
11.2.1 Scope and Limitations
The assessment of the potential impacts on freshwater ecosystems included:
Detailed mapping and description of freshwater ecosystems on the site
A preliminary map during a subsequent ground-truthing phase;
Assessment of ecological/conservation importance and sensitivity of
potentially affected freshwater ecosystems;
Assessment of significance of potential impacts on freshwater ecosystems
associated with the proposed WEF; and
Recommendation of mitigation measures to reduce the severity of potential
impacts on freshwater ecosystems, including refinement of the recommended
buffer areas.
The limitations of the study include the following:
The data used for the desk top mapping was obtained from layers produced
by the NFEPA and Overberg Wetland mapping projects. Both of these
projects were also desk top mapping exercises covering large areas.
The aerial photographic imagery used for the preliminary mapping were
images captured in summer, when wetlands are least visible given the winterrainfall climate of the area. This made it difficult to discern the presence of
wetlands on a desktop-basis with a high degree of confidence. This limitation
was ameliorated to some degree by systematic scanning of the site using
Google Earth satellite imagery, and later by field-based ground-truthing.
The major limitation involved in the assessment of the final development
layout for Langhoogte WEF was that changes since the previous layout
(considered in the initial draft Impact Assessment Report) were not groundtruthed. Thus, development conflicts with freshwater ecosystems that have
arisen since the layout assessed for the initial draft Impact Assessment
Report were investigated in the current report using a desktop-based
approach. This has resulted in low- to medium-confidence assessments of
conservation importance and sensitivity for those rivers and wetlands that
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Chapter 11: Impacts of Freshwater Ecosystems
conflict with the final development layout, but which were not previously
assessed in the field.
11.2.2 Establishing the Baseline Conditions
The approach used to establish baseline conditions on site is summarised below:
The approach taken to generate a preliminary, desktop-based map of freshwater
ecosystems for the site was as follows:
A GIS map of freshwater ecosystems was created using the following
resources:
o
1:50 000 scale topographical maps of the Chief Directorate: National
Geo-spatial Information (CD:NGI)
o
Rivers and wetlands mapped by the NFEPA project
o
Additional aquatic ecosystems on site were manually digitised in GIS,
based on visual cues, using geo-referenced digital aerial photographs
(from 2010) in conjunction with Google Earth satellite imagery.
The proposed wind turbine locations were overlaid on the preliminary map of
freshwater ecosystems in GIS.
A Freshwater Ecosystems Report was compiled to accompany and explain the
preliminary map, together with broad guidelines (of relevance to the proposed wind
farm) for the protection of the mapped freshwater ecosystems.
The desktop mapping was followed by a site visit, the purpose of which was to
ground-truth the relevant portions of the preliminary map of freshwater ecosystems
map. Information and data was gathered to determine the ecological importance and
sensitivity of the potentially affected ecosystems with a relatively high degree of
confidence. During the site visit, a rough delineation of the location and extent of
potentially affected wetlands on site was performed.
11.2.3 Sensitivity Assessment
The aquatic ecosystems on site were classified according to relevant policy and
legislation. The documents used are summarised below:
The aquatic ecosystems on site were characterised according to legislative
requirements.
(a)
National Freshwater Ecosystem Priority Assessment (NFCPA) project
The NFEPA project was a national-scale initiative with the primary aim of identifying
and mapping Freshwater Ecosystem Priority Areas. Different categories of FEPAs
were developed, each with different management implications. The categories include
river FEPAs and associated sub-quaternary catchments, wetland FEPAs, wetland
clusters, Fish Support Areas and associated sub-quaternary catchments, fish
sanctuaries, phase 2 FEPAs and associated sub-quaternary catchments, and
Upstream Management Areas.
The only FEPA classified watercourses on site are wetlands along the Bot River and
some of its tributaries running through the western portion of the site. These
watercourses were identified as wetland FEPAs. Wetland FEPAs were also mapped
along the northern extremities of the site. In addition, a floodplain wetland associated
with the Swart River (a tributary of the Bot River to the south of the N2 freeway) was
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Chapter 11: Impacts of Freshwater Ecosystems
categorised as a wetland FEPA (although this wetland is outside of the site for the
proposed WEF, one of the proposed powerline routes encroaches into this wetland).
(b)
National Biodiversity Assessment (NBA) 2011
The primary purpose of the NBA is to provide a regular high-level summary of the
state of South Africa’s biodiversity, with a strong focus on spatial assessment. It
covers terrestrial, freshwater, estuarine and marine environments. All the
seasonal/perennial rivers located in the Lower Foothill or Lowland River Zones of the
Southern Folded Mountain Ecoregion that were mapped for NBA 2011 were
categorised as “Critically Endangered”. This includes portions of the Bot River in the
study area for the Langhoogte WEF and most of the Swart River to the south of the
main site for the proposed WEF.
All the wetlands mapped by the NFEPA project in the study area were categorised as
occurring within the “East Coast Shale Renosterveld” vegetation group, and NBA
categorised all of the wetland types in this vegetation group (regardless of FEPA
status) as either Critically Endangered or Endangered, with no or a poor level of
protection. This implies that all wetlands within or adjacent to the site for the proposed
Langhoogte WEF should be treated as endangered or critically endangered
ecosystems that are of at least moderate conservation importance.
(c)
Overberg District Municipality Critical Biodiversity Area (CBA) Map
The Overberg CBA Map indicates areas of land and mapped aquatic features that
must be safeguarded in their natural state if biodiversity is to persist and ecosystems
are to continue functioning. Such land was categorised a CBA. Ecological Support
Areas (ESAs) were then selected as the supporting zones required to prevent the
degradation of CBAs and Protected Areas.
The guidelines restrict the development of infrastructure requiring large areas of
undeveloped land within CBAs and ESAs.
In terms of the biodiversity-compatible land-use guidelines provided in the document,
the Langhoogte WEF should be kept out of wetland areas as far as possible. During
the preliminary mapping exercise, wetlands within terrestrial CBAs (as identified by
the Overberg CBA Map) were highlighted as features of particular conservation
importance. These areas were assumed to be of at least equal conservation status as
wetland FEPAs. The only places where such areas were identified were floodplain
wetlands along the Bot River to the south of the main site for the proposed WEF (on
land crossed by the proposed routes for the southern powerline options) and three
sections of valley-bottom wetland in the eastern portion of the site.
(d)
Theewaterskloof Municipality Spatial Development Framework (SDF)
The Theewaterskloof Municipality SDF has categorised the Bot River as a major
“river corridor”, while all other streams in the municipal areas have been categorised
as “minor streams”. This implies these aquatic features have been identified as
features of particular conservation concern at a local municipality level.
The following approach was then taken to delineating recommended buffer zones for
the initially mapped freshwater ecosystems:
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Chapter 11: Impacts of Freshwater Ecosystems
Following the generic guideline for buffers provided in the NFEPA
Implementation ManualError! Bookmark not defined., a 100 m ‘no-go’ buffer
zone was created around all FEPA priority wetlands on the GIS map.
A 100 m buffer zone was also allocated to the wetlands occurring within
CBAs, given their ecological importance.
A 30 m buffer zone was demarcated around all other wetlands and rivers.
A site visit was conducted to ground-truth the data incorporated into the preliminary
map.
11.3
Impact Identification and Assessment
A number of different aquatic ecosystems were identified on site during the mapping
exercise. These include wetlands which fall into two categories valley bottom
wetlands and floodplain wetlands, the majority of wetlands are valley-bottom
wetlands. There are also several small hillslope seep wetlands on the site. A number
of non-perennial river channels are located within the numerous small valleys in the
area. The only perennial river system in the area is the Bot River, which drains the
western edge of the site. Dams are numerous in the area and are mostly small farm
dams used for livestock or irrigation purposes.
Table 11.1 Ecological Importance and Sensitivity (EIS) categories (DWAF 1999)
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Chapter 11: Impacts of Freshwater Ecosystems
11.3.1 Sensitive Aquatic Environments in the Area
The maps in Figure 11.1 and Figure 11.2 show the conservation importance of the
rivers and wetlands that were mapped on the proposed site for the Langhoogte WEF
and in the areas through which the proposed powerlines would be routed,
respectively. In the case of the rivers, the conservation importance was taken as the
result of the EIS assessment. The stretch of river highlighted red is rated to be of
‘high’ conservation importance.
(a)
Wetlands
A number of FEPA wetlands were identified on site these include:
Wetlands along the Bot River and some of its tributaries
Wetlands in the northern extremities of the site
A floodplain wetland associated with the Swart River
(b)
Rivers
Sections of the Bot River and most of the Swart River which lies to the south of the
main WEF site are classified as critically endangered.
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Chapter 11: Impacts of Freshwater Ecosystems
Figure 11.1 of freshwater ecosystems for the proposed Langhoogte WEF site in relation to the proposed turbine positions and proposed
roads/trenches, showing the conservation importance of all mapped wetlands and potentially affected river reaches / drainage lines. Note turbine 15
has been dropped
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Chapter 11: Impacts of Freshwater Ecosystems
Figure 11.2: Map of freshwater ecosystems in the vicinity of the proposed powerline routes, including the three options for the southern route,
showing the conservation importance of all mapped wetlands and potentially affected river reaches / drainage lines. Note turbine 15 has been dropped
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Chapter 11: Impacts of Freshwater Ecosystems
Figure 11.3 Freshwater ecosystems for the entire development are for the proposed Langhoogte WEF, including turbine and powerline areas. Note turbine
15 and its access road have been dropped.
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Chapter 11: Impacts of Freshwater Ecosystems
11.3.2 Identification of Potential Impacts
Aquatic ecosystems could be impacted by the proposed development in the following
ways:
Direct loss of riverine and wetland habitat;
Damage or destruction of aquatic habitat;
Pollution of freshwater ecosystems;
Contamination of soils and groundwater;
Disturbance of aquatic and semi-aquatic flora and fauna;
Alteration of hydrology of valley bottom wetlands; and
Alteration of hydrology and water quality through increase run off
(a)
Direct Loss of Riverine and Wetland Habitat
Direct loss of riverine and wetlands habitat will result if turbines or associated
infrastructure encroach on aquatic ecosystems. This impact has been rated as
negative of low significance.
The impact of the four proposed powerline routes on the aquatic ecosystems was
rated. Option 1, the preferred southern route, was rated as incurring impacts of
medium significance. The other two southern routes options Option 2 and Option 3
were rated as medium to high significance due to the likelihood of the powerline
traversing wetlands. The northern route option was rated to be of low significance as
it has a low level of interaction with aquatic ecosystems. The northern is hence the
preferred route from an aquatic environment perspective.
(b)
Damage or Destruction of Aquatic Habitat
Damage or destruction of aquatic habitat may occur should the site be poorly
management. Storage of stockpiles, machinery and materials can all result in damage
to the habitat. Damage and destruction of ecosystems is rated to be of medium
significance. Mitigation measures may reduce the impact significance to low to
medium.
(c)
Pollution of Freshwater Ecosystems
Pollution of freshwater ecosystem may occur due to vehicle oil or fuel leaks and
spillages and the storage and use of potentially polluting substances on site. Pollution
of ecosystems is rated to be of medium significance. Mitigation measures may reduce
the significance to low to medium.
(d)
Contamination of Soil and Groundwater
Anticipated impacts would be similar to those on freshwater ecosystems.
(e)
Disturbance of Aquatic and Semi-aquatic Flora and Fauna
The presence of personnel on site and the use of vehicles and heavy machinery may
cause disturbance to both aquatic and terrestrial flora and fauna, which may result in
alteration of fauna breeding cycles. The disturbance of flora and fauna has been rated
as negative and of low significance.
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Chapter 11: Impacts of Freshwater Ecosystems
(f)
Alternation of Hydrology of Valley Bottom Wetlands
The construction of access roads and bridges within valley bottom wetlands may alter
the hydrology of the systems. This impact is rated as medium significance; but if
mitigated, may reduce the significance to low to medium.
(g)
Alternation of Hydrology and Water Quality through Increased Run Off
Increased storm water runoff may result from the clearing of vegetation and
construction of access roads.
11.3.3 Assessment of Potential Impacts
The potential impacts identified above have been assessed in line with the
methodology set out in Chapter 6 of the EIA Report.
A summary of potential impacts and mitigation measures are given in Tables 11.211.5
(a)
Design Phase
The impacts presented in Table 11.2 below are presented in the specialist report
under the heading “design phase”. While these may be the result of poor design
approach, these impact would only be realised on t he ground during the construction
and operational phases.
Confidence
Significance
Probability
Consequence
Impact on
Irreplaceable
Resources
Reversibility
Intensity
Duration
Extent
Impact
Nature
Table 11.2: Impact assessment summary for design phase
Impact 1: Encroachment of turbines, roads and trenches into riverine corridors and wetlands
Impact Description:
Direct loss and fragmentation of riverine and wetland habitat as a result of the encroachment of turbines, roads and trenches
associated with the proposed WEF into these ecosystems
Without
Mitigation
Negative
Low
High
Low
High
Medium
Low*
High
Low
High
Mitigation Description:
In cases where conflicts between the development layout and freshwater ecosystems occur (indicated by stars in Figure 11.1),
the recommended mitigation is to move the development outside of a 30 m ‘no-go’ buffer area around each given freshwater
ecosystem (or a 100 m buffer area for the single instance in which a high priority FEPA wetland is encroached upon. The
implementation of these mitigation measures would imply minor alterations to the currently proposed layout plan.
With
Mitigation
Negative
Low
High
Low
High
Medium
Low*
High
**Low
High
Cumulative Impact:
Contribution to further loss of wetlands in the region as a result of the proposed Langhoogte WEF would be an insignificant
cumulative impact
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Confidence
Significance
Probability
Consequence
Impact on
Irreplaceable
Resources
Reversibility
Intensity
Duration
Extent
Impact
Nature
Chapter 11: Impacts of Freshwater Ecosystems
Impact 2: Encroachment of power lines into riverine corridors and wetlands (Southern route, option 1)
Impact Description:
Direct loss and fragmentation of riverine and wetland habitat as a result of encroachment of power lines associated with the
proposed WEF into these ecosystems
Without
Mitigation
Negative
Low
High
Low
High
Medium
Medium
Medium
Medium
Medium
Mitigation Description:
Where the southern route power lines share a common pathway, it is recommended that, after crossing the wetland of high
importance, the power line should run along the northern edge of this wetland at a distance of at least 30 m from the wetland
edge rather than crossing it twice before reaching the split for option 1, as is the current scenario.
With
Mitigation
Negative
Low
High
Low
High
Medium
*Low
Medium
Low
Medium
Cumulative Impact:
Further loss of wetlands as a result of power line development would be an insignificant cumulative impact
Impact 3: Encroachment of power lines into riverine corridors and wetlands (Southern route, option 2)
Impact Description:
Direct loss and fragmentation of riverine and wetland habitat as a result of encroachment of power lines associated with the
proposed WEF into these ecosystems
Without
Mitigation
Negative
Low
High
Low
High
Medium
Medium
High
Mediumto-high
Medium
Mitigation Description:
Where the southern route power lines share a common pathway, it is recommended that, after crossing the wetland of high
importance (see Figure 3), the power line should run along the northern edge of this wetland at a distance of at least 30 m
from the wetland edge rather than crossing it twice before reaching the split for option 1, as is the current scenario.
The southern route options 2 and 3 exert a considerable footprint within wetland corridors and it is recommended that, if
these routes were to be pursued as viable alternatives, the power line routes should re-aligned so as to stay at least 30 m
outside of the wetland edges. This recommended mitigation measure is applicable to the areas where the power lines are
proposed to run parallel to a watercourse and not for cases where power lines cross perpendicularly over a watercourse.
With
Mitigation
Negative
Low
High
Low
High
Medium
*Low
Medium
Low
Medium
Cumulative Impact:
Further loss of wetlands as a result of power line development would be an insignificant cumulative impact
Impact 4: Encroachment of power lines into riverine corridors and wetlands (Southern route, option 3)
Impact Description:
Direct loss and fragmentation of riverine and wetland habitat as a result of encroachment of power lines associated with the
proposed WEF into these ecosystems
Without
Mitigation
Negative
Low
High
Low
High
Medium
Medium
High
Mediumto-high
Medium
Mitigation Description:
It is recommended that, after crossing the wetland of high importance (see Figure 3), the power line should run along the
northern edge of this wetland at a distance of at least 30 m from the wetland edge rather than crossing it twice before
reaching the split for option 1, as is the current scenario.
The southern route options 2 and 3 exert a considerable footprint within wetland corridors and it is recommended that, if
these routes were to be pursued as viable alternatives, the power line routes should re-aligned so as to stay at least 30 m
outside of the wetland edges. This recommended mitigation measure is applicable to the areas where the power lines are
proposed to run parallel to a watercourse and not for cases where power lines cross perpendicularly over a watercourse.
With
Mitigation
Negative
Low
High
Low
High
Medium
*Low
Medium
Low
Medium
Cumulative Impact:
Further loss of wetlands as a result of power line development would be an insignificant cumulative impact
Impact 5: Encroachment of power lines into riverine corridors and wetlands (Northern route)
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Chapter 11: Impacts of Freshwater Ecosystems
Impact Description:
Direct loss and fragmentation of riverine and wetland habitat as a result of encroachment of power lines associated with the
proposed WEF into these ecosystems
Without
Mitigation
Negative
Low
High
Low
High
Low
Low*
High
Low
Medium
Mitigation Description: No mitigation is necessary
Cumulative Impact:
Further loss of wetlands as a result of power line development would be an insignificant cumulative impact
* The consequence rating obtained by applying the prescribed method is very sensitive to the duration of an impact, with
long-term impacts rated to be of relatively high consequence, irrespective of the extent or intensity of the impact.
Therefore, in certain cases, a revised rating was provided based on professional judgement.
** Although the category is not included, our judgment is that the significance of the impact with a mitigated design should
be ‘very low’ (i.e. considerably lower than if no mitigation is incorporated into the design).
(b)
Construction Phase
Confidence
Significance
Probability
Consequence
Impact on
Irreplaceable
Resources
Reversibility
Intensity
Duration
Extent
Impact
Nature
Table 11.3: Impact assessment summary for construction phase
Impact 1: Destruction/damage of wetland, river and riparian areas through construction-related activities
Impact Description:
Physical destruction or damage of wetlands and/or riparian vegetation through the storage of building materials, the temporary
lay-down of equipment (sand, soil, bricks, steel, pipes, etc.), and/or the establishment of temporary roads in or adjacent to
wetland and/or riparian areas
Without
Mitigation
Negative
Low
Medium
Medium
Medium
Medium
Medium
High
Medium
Medium
Mitigation Description:
Construction camps should be located at least 30 m from freshwater ecosystems identified to be of low or moderate
conservation importance and 50 m from freshwater ecosystems identified to be of high conservation importance.
Wetlands, rivers and river riparian areas should be treated as “no-go” areas and appropriately demarcated as such. No
vehicles, machinery, personnel, construction material, fuel, oil, bitumen or waste should be allowed into these areas without
the express permission of and supervision by the ECO, except for rehabilitation work in these areas.
The temporary track for the crawler crane should not encroach within 10m of any wetlands or river corridors.
Workers should be made aware of the importance of not destroying or damaging the vegetation along rivers and in wetland
areas, and this awareness should be promoted throughout the construction phase.
Freshwater ecosystems located in close proximity to the construction areas should be inspected on a regular basis by the
ECO for signs of disturbance from construction activities. If signs of disturbance are noted, immediate action should be
taken to remedy the situation and, if necessary, a freshwater ecologist should be consulted for advice on the most suitable
remediation measures.
With
Mitigation
Negative
Low
Medium
Low
Medium
Medium
Medium
Low
Low to
medium
Medium
Cumulative Impact:
Not applicable
Impact 2: Pollution of freshwater ecosystems, resulting from the runoff of fuel and oil from vehicles and machinery,
and from construction-related activities
Impact Description:
Pollution of wetlands and/or rivers through leakage of fuels, oils, etc. from construction machinery, or from washing of equipment
or flushing of concrete mixers and other vehicles as well as sediments from de-watering of excavations
Without
Mitigation
Negative
Medium
Low
Medium
Medium
Medium
Medium
High
Medium
Medium
Mitigation Description:
Toilets must be located at least 30 m from freshwater ecosystems identified to be of low or moderate conservation
importance and 50 m from freshwater ecosystems identified to be of high conservation importance.
No fuel storage, refuelling, vehicle maintenance or vehicle depots should be allowed within 30 m of freshwater ecosystems
identified to be of low or moderate conservation importance and 50 m from freshwater ecosystems identified to be of high
conservation importance.
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Negative
Medium
Low
Low
Medium
Medium
Impact on
Irreplaceable
Resources
With
Mitigation
Reversibility
Refuelling and fuel storage areas, and areas used for the servicing or parking of vehicles and machinery, should be located
on impervious bases and should have bunds around them. Bunds should be sufficiently high to ensure that all the fuel kept
in the area will be captured in the event of a major spillage.
Vehicles and machinery should not be washed within 30 m of freshwater ecosystems identified to be of low or moderate
conservation importance and 50 m from freshwater ecosystems identified to be of high conservation importance;
No discharge of effluents or polluted water shall be allowed into any rivers or wetland areas.
If construction areas are to be pumped of water (e.g. after rains), this water must be pumped into an appropriate settlement
area, and not allowed to flow into any rivers or wetland areas.
No spoil material, including stripped topsoil, should be temporarily stockpiled within 30 m of freshwater ecosystems
identified to be of low or moderate conservation importance and 50 m of freshwater ecosystems identified to be of high
conservation importance.
There should be as little disturbance to surrounding vegetation as possible when construction activities are undertaken, as
intact vegetation adjacent to construction areas will assist in the control of sediment dispersal from exposed areas.
Workers should be made aware of the importance of not polluting rivers or wetlands and of not undertaking activities that
could result in such pollution, and this awareness should be promoted throughout the construction phase.
Freshwater ecosystems located in close proximity to the site should be inspected on a regular basis (but especially after
rainfall) by the ECO for signs of sedimentation and pollution. If signs of sedimentation or pollution are noted, immediate
action should be taken to remedy the situation and, if necessary, a freshwater ecologist should be consulted for advice on
the most suitable remediation measures.
Medium
Low
Low to
medium
Medium
Confidence
Significance
Probability
Consequence
Intensity
Duration
Extent
Impact
Nature
Cumulative Impact:
Not applicable
Impact 3: Increased disturbance to aquatic and semi-aquatic fauna
Impact Description:
Increased disturbance of aquatic and semi-aquatic fauna – the presence of construction teams and their machinery will lead to
noise pollution in the area, which will disturb aquatic and terrestrial fauna, and potentially disrupt breeding cycles for some
species
Without
Mitigation
Negative
Low
Low
Medium
Low
Low
Low
Medium
Low
Medium
Mitigation Description:
Construction camps and temporary laydown areas should be located at least 30 m from freshwater ecosystems identified to
be of low or moderate conservation importance and 50 m from freshwater ecosystems identified to be of high conservation
importance.
Wetlands, rivers and river riparian areas should be treated as “no-go” areas and appropriately demarcated as such. No
vehicles, machinery, personnel, construction material, fuel, oil, bitumen or waste should be allowed into these areas without
the express permission of and supervision by the ECO, except for rehabilitation work in these areas.
Workers should be made aware of the importance of not killing or harming any animals that they encounter and this
awareness should be promoted throughout the construction phase.
Appropriate site management
With
Mitigation
Negative
Low
Low
Low
Low
Low
Low
Medium
Low
Medium
Cumulative Impact:
Not applicable
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Chapter 11: Impacts of Freshwater Ecosystems
(c)
Operational Phase
Significance
Confidence
Probability
Consequence
Impact on
Irreplaceable
Resources
Reversibility
Intensity
Duration
Extent
Impact
Nature
Table 11.4: Impact assessment summary for operational phase
Medium
Medium
Impact 1: Hydrological alteration of rivers and wetlands at road crossings
Impact Description:
Alteration of the hydrology of valley-bottom wetlands at road crossings associated with the proposed WEF
Without
Mitigation
Negative
Low
High
Medium
Low
Low
Medium
Medium
Negative
Low
High
Low
Low
Low
Impact on
Irreplaceable
Resources
With
Mitigation
Reversibility
Mitigation Description:
Formalisation of road crossings using structures that minimise the alteration of flows (e.g. box culverts with a wide span)
Low to
Medium
Medium
Low to
Medium
Medium
Significance
Confidence
Probability
Consequence
Intensity
Duration
Extent
Impact
Nature
Cumulative Impact:
Insignificant
Medium
Medium
Impact 2: Stormwater runoff-related impacts
Impact Description:
Alteration of the hydrology and water quality of freshwater ecosystems from increased stormwater runoff
Without
Mitigation
Negative
Medium
Medium
Low
Medium
Low
Medium
Medium
Negative
Low
Medium
Low
Low
Low
Impact on
Irreplaceable
Resources
With
Mitigation
Reversibility
Mitigation Description: Employ a stormwater management system that follows the principles of a sustainable urban drainage
system, with input from a freshwater ecologist on the design.
Low
Low
Low
Medium
Confidence
Significance
Probability
Consequence
Intensity
Duration
Extent
Impact
Nature
Cumulative Impact:
Insignificant
Impact 3: Ongoing faunal disturbance
Impact Description:
Disturbance to aquatic and semi-aquatic fauna from operation of wind turbines (which would generate noise, possible vibration
and increased air movement)
Without
Mitigation
Negative
Low
High
Low
Low
Low
Low
Medium
Low
Medium
Mitigation Description: Not possible.
Cumulative Impact:
Potential cumulative impact (low to medium significance)
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Chapter 11: Impacts of Freshwater Ecosystems
(d)
Decommissioning Phase
The potential impacts on freshwater ecosystems that could be associated with the
decommissioning phase of the proposed Langhoogte WEF would be very similar to
the construction-phase impacts. All of the potential impacts are predicted to be of low
or low to medium significance.
Confidence
Significance
Probability
Consequence
Impact on
Irreplaceable
Resources
Reversibility
Intensity
Duration
Extent
Impact
Nature
Table 11.5: Impact assessment summary for decommissioning phase
Impact 1: Destruction/damage of wetland, river and riparian areas through decommissioning-related activities
Impact Description:
Physical destruction or damage of wetlands and/or riparian vegetation through the storage of building materials, the temporary
lay-down of equipment (sand, soil, bricks, steel, pipes, etc.), and/or the establishment of temporary roads in or adjacent to
wetland and/or riparian
Without
Mitigation
Negative
Low
Medium
Medium
Medium
Medium
Medium
High
Medium
Medium
Mitigation Description:
Construction camps and temporary laydown areas should be located at least 30 m from freshwater ecosystems identified to
be of low or moderate conservation importance and 50 m from freshwater ecosystems identified to be of high conservation
importance.
Wetlands, rivers and river riparian areas should be treated as “no-go” areas and appropriately demarcated as such. No
vehicles, machinery, personnel, construction material, fuel, oil, bitumen or waste should be allowed into these areas without
the express permission of and supervision by the ECO, except for rehabilitation work in these areas.
The temporary track for the crawler crane should not encroach within 10m of any wetlands or river corridors.
Workers should be made aware of the importance of not destroying or damaging the vegetation along rivers and in wetland
areas, and this awareness should be promoted throughout the decommissioning phase.
Freshwater ecosystems located in close proximity to the working areas should be inspected on a regular basis by the ECO
for signs of disturbance from decommissioning activities. If signs of disturbance are noted, immediate action should be
taken to remedy the situation and, if necessary, a freshwater ecologist should be consulted for advice on the most suitable
remediation measures.
With
Mitigation
Negative
Low
Medium
Low
Medium
Medium
Medium
Low
Low to
medium
Medium
Cumulative Impact:
Not applicable
11.3.4 Mitigation Measures
Mitigation measures are detailed in the tables above. The majority of mitigation
measures are centred around three main principals
(a)
Avoiding freshwater ecosystem and their buffer areas
Development and activity in or within close proximity to aquatic ecosystems can result
in negative impacts. The main mitigation method is to treat all aquatic ecosystems
and their respective buffers as no-go areas where possible. There should be no
development, construction camps or storage in no-go areas.
(b)
Correct site management
Correct site management can mitigate the risk of pollution of groundwater, aquatic
ecosystems and soils. No use or storage or potentially polluting substances within
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Chapter 11: Impacts of Freshwater Ecosystems
30 m of aquatic ecosystems of low conservation importance and within 50 m of
aquatic ecosystems of high conservation importance.
(c)
Education of work force
The presence of a number of workers on site may also impact negatively on aquatic
ecosystems through pollution and disturbance of flora and fauna. The work force
must be educated about the importance of preserving aquatic ecosystems, avoiding
pollution and limiting disturbance to aquatic fauna.
11.3.5 Monitoring Programme
No monitoring programme is proposed for the Langhoogte WEF.
11.4
Summary and Conclusions
The proposed area contains moderate and steep slopes, which form the numerous
small valleys in which the rivers and valley-bottom wetlands occur. The largest valley
in the area is the Bot River valley, running along the western boundary of the site.
The site contains a number of wetlands characterised as FEPAs this includes
wetlands along the Bot and Swart Rivers. Sections of the Bot River on site are also
identified as critically endangered. All wetlands on site which are situated within
Renosterveld vegetation are classified as endangered or critically endangered.
The proposed wind farm development could result in a number of impacts on
freshwater ecosystems. The most significant of these are:
Direct loss of aquatic ecosystems
Damage and destruction of aquatic freshwater ecosystems
Pollution of aquatic ecosystems, soil and groundwater
The assessment undertaken identified that the impacts arising during the design,
construction and operation of the proposed wind farm would be local, negative and of
low to medium – high significance without mitigation. Various mitigation measures
have been proposed to reduce these impacts. These include implementing
appropriate working practices to avoid sensitive habitats, correct site management
and use of appropriate infrastructure. As a result the residual impacts are all of low to
low-medium significance.
The northern route option is the preferred option with respect to impacts of aquatic
ecosystems. All of the three southern proposed powerlines will have negative impacts
of low significance when mitigation measures are implemented. Of the three southern
route options, southern route option 1 will have the least impact of freshwater
ecosystems. Southern route options 2 and 3 are the most damaging options, if these
routes are pursued the route should be aligned to stay at least 30m outside wetland
edges.
All of the turbines will the exception of two (turbine numbers 27 and 30) are located
outside aquatic ecosystems and their buffer areas. Turbines 27 and 30 are located
within 30 m of a drainage channel of low conservation importance. Due to the low
conservation importance of the drainage lines the impact has been rated as low
significance.
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Chapter 11: Impacts of Freshwater Ecosystems
With regard to the road and trench layout there are a total of 17 cases of
encroachment of freshwater ecosystems. The impact on these ecosystems has been
assessed to be a negative impact of low significance. It is strongly recommended that
the following specific and relatively minor alterations to the currently proposed layout
plan be considered so as to reduce the overall significance of the impact to an even
lower level:
The connection road to the east of turbine 41 should not be built. Instead,
turbines 3, 35 and 41 should connect with the road leading to turbines 17 and
19 via the loop between turbines 3 and 24. This would eliminate the need for a
road crossing of the drainage channel of moderate conservation importance
immediately south of turbine 41.
The road to the north of turbine 10 should be moved at least 30 m (although
preferably > 100 m) away from the edge of the wetland of high conservation
importance to the north.
The loop road north of turbine 20 should be moved at least 30 m away from
the edge of the drainage channel of moderate conservation importance.
The road to the east of turbine 29 should be moved at least 30 m away from
the edge of the section of drainage channel marked as being of moderate
conservation importance.
The road immediately to the east of turbine 32 should be moved at least 30 m
away from the edge of the wetland of moderate conservation importance.
The road to the west of turbine 26 should not cross the wetland of moderate
conservation importance twice. Instead, a single crossing at the northern end
of the wetland (against the railway line) should suffice. From this crossing the
road could link with turbine 26, making sure that the road does not encroach
within 30 m of the eastern edge of this wetland.
It should be noted that these recommendations have been accepted and have
informed the very last iteration of road layout as presented in Figure .11.3. The
implementation of the above changes has reduced the negative impacts on
freshwater ecosystems of moderate and high importance to lower levels of
significance.
Table 11.6: Summary assessment of the different impacts for the different phases of the
development, before and after mitigation
Design / Construction
Operation
Decommissioning
Impact
PrePostPrePostPrePostmitigation
mitigation
mitigation
mitigation
mitigation
mitigation
Encroachment of
infrastructure into riverine
Low
Low
corridors and wetlands
Impact of powerline southern
route option 1 on riverine
Medium
Low
corridors and wetlands
Impact of powerline southern
Mediumroute option 2 on riverine
Low
High
corridors and wetlands
Impact of powerline southern
Medium –
route option 3 on riverine
Low
High
corridors and wetlands
Impact of powerline northern
route on riverine corridors
Low
N/A
and wetlands
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Chapter 11: Impacts of Freshwater Ecosystems
Impact
Design / Construction
PrePostmitigation
mitigation
Operation
PrePostmitigation
mitigation
Decommissioning
PrePostmitigation
mitigation
Destruction / damage of river
and riparian areas
Medium
LowMedium
-
-
Medium
LowMedium
Pollution of freshwater
ecosystems
Medium
LowMedium
-
-
Medium
Low to
Medium
Disturbance of aquatic and
semi-aquatic flora and fauna
Low
Low
Low
N/A
Low
Low
Alteration of hydrology of
valley bottom wetlands from
road crossings
-
-
Medium
LowMedium
-
-
Stormwater run off
-
-
Medium
Low
-
-
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