FRESHWATER ECOLOGICAL ASSESSMENT AS PART OF
THE ENVIRONMENTAL ASSESSMENT AND
AUTHORISATION PROCESS FOR THE PROPOSED
REALIGNMENT OF THE PRIMARY RUNWAY AT THE CAPE
TOWN INTERNATIONAL AIRPORT, WESTERN CAPE
PROVINCE
Prepared for
SRK Consulting
March 2016
Prepared by:
Report authors
Report reviewers
Report Reference:
Date:
Scientific Aquatic Services
L. Zdanow (BSc hons)
N. van de Haar (Pr. Sci. Nat)
S. van Staden (Pr. Sci. Nat)
N. van de Haar (Pr. Sci. Nat)
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March 2016
Scientific Aquatic Services CC
CC Reg No 2003/078943/23
Vat Reg. No. 4020235273
PO Box 751779
Gardenview
2047
Tel: 011 616 7893
Fax: 086 724 3132/086 724 3132
E-mail: [email protected]
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March 2016
Declaration
This report has been prepared according to the requirements of Section 32 (3b) of the Environmental
Impact Assessments EIA Regulations, 2010 (GNR 543). We (the undersigned) declare the findings of
this report free from influence or prejudice.
Stephen van Staden Pr Sci Nat (Ecological Sciences) 400134/05
BSc. Hons (Aquatic Health) (RAU);
M.Sc. Environmental Management Rau.
___________________
Stephen van Staden
Date: 09/12/2013
Natasha van de Haar Pr Sci Nat (Botanical Science) 400229/11
M.Sc. Botany
___________________
Natasha van de Haar
Date: 09/12/2013
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EXECUTIVE SUMMARY
Scientific Aquatic Services (SAS) was appointed to conduct a freshwater ecological impact
assessment as part of the environmental assessment and authorisation process for the proposed
realignment of the primary runway at the Cape Town International Airport. This specialist study was
updated after the end of the comment period on the Draft Environmental Impact Assessment (EIA)
Report and associated specialist studies to produce this Freshwater Ecological Impact Assessment
Report for submission to the Department of Environmental Affairs along with the Final EIA Report. All
changes in this Final Freshwater Ecological Impact Assessment Report are underlined and italicised
for ease of reference.
As the first phase in the development of the Cape Town International Airport as envisaged in the
Master Plan, Airports Company South Africa (ACSA) proposes to construct a new (re-aligned)
runway, rotated through 11.5°, to replace the existing primary runway (Runway 01-19). The northern
end of the new runway will be positioned 220m to the east of the current Runway 01-19. It will comply
with international specifications for Code F aircraft, increase runway capacity and enable future airport
expansion.
In addition to the re-aligned runway, the current project will also include:
 A taxiway system;
 Infrastructure such as an aircraft isolation pad, a compass calibration pad and an aircraft runup area;
 Security facilities;
 Service roads;
 Buildings and service infrastructure;
 Upgrading of the stormwater management system; and
 Bulk earthworks for the sourcing and on site use of cut/fill material.
The proposed project footprint is approximately 700ha in extent (Figure 1 and 2). Construction is
expected to take 24 to 30 months to complete. Construction activities that disrupt operation of the
existing runway will take place at night (for approximately 4 months).
The following general conclusions were drawn upon completion of the freshwater ecological
assessment:
 The Cape Town International Airport falls within the Cape Flats which is documented as a
‘special case’ wetland area within the Western Cape due to the presence of a sandy soils
coastal aquifer (Job, 2009). Therefore, a large proportion of water augmenting wetlands will
be from the shallow water table. However, surface runoff from concrete surfaces, roads and
disturbed areas within the catchment, will also contribute significantly to the amount of water
reaching wetland features within the project footprint;
 According to the Prioritisation of City Wetlands Map (2009) the project footprint covers
numerous Dune Strandveld natural and semi natural, inland, isolated depression wetlands.
However, upon assessment of the project footprint it became evident that the majority of
these wetland features are in a significantly transformed Present Ecological State (PES);
 No additional surface water features were identified within the project footprint;
 Although the majority of wetland features within the project footprint are in a transformed
state, two wetland features are considered to be of a slightly higher Ecological Importance
and Sensitivity (EIS). These features include a large wetland feature (±15.5ha) within the
south eastern corner of the project footprint (hereafter referred to as the south eastern
wetland) and a smaller wetland feature (±0.28ha) located within the north-eastern portion of
the project footprint (hereafter referred to as the central wetland);
 Wetland features associated with the project footprint can be divided into five wetland groups
which include transformed depressions, brushcut depressions, mowed depressions, the south
eastern wetland and the central wetland;
 The function and service provision was calculated for each of the wetland groups associated
with the project footprint. From the results of the assessment, it is evident that none of the
features encountered within the project footprint are regarded as being of exceptional
importance in terms of function and service provision. The south eastern wetland and central
wetland as well as transformed and mowed depressions were determined to have a
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moderately low level of ecoservice provision and function and that brushcut depressions were
calculated to have a low level of ecoservice provision and function;
The PES of all wetland features was determined using the WET-health methodology. The
overall categories for the wetland features are as follows:
 South eastern wetland - PES Category E (seriously modified);
 Central wetland - PES Category D (largely modified);
 Transformed wetlands - PES Category E (seriously modified);
 Brushcut wetlands – PES Category F (critically modified); and
 Mowed wetlands - PES Category F (critically modified).
The EIS was calculated for each wetland group:
 The south eastern and central wetlands were calculated to have an EIS falling within
Category C (moderately sensitivity); and
 The transformed, brushcut and mowed depressions were calculated to have an EIS
falling within Category D (low sensitivity).
No evidence of connected surface flow was encountered during the field assessment
between the depressions assessed. However, a moderate aquifer activity has been indicated
by the Tygerberg District Plan (2012) for the eastern half of the project footprint;
Impermeable calcrete lenses were noted within 50cm of the soil surface in the majority of the
wetland features encountered. According to GEOSS (2014) these impermeable layers occur
as discontinuous lenses which would lead to the formation of perched depressions in areas
where they occur close to the soil surface. Sub-surface flow along this impermeable layer and
hydrological connectivity between individual wetland features within the project footprint was
confirmed by the Groundwater Specialist Study (GEOSS, 2014);
The habitat integrity of the wetland features has been lost to a great extent and the
reinstatement of functions and service provision of the features would require substantial
investment in order to improve the conditions of the systems to a level where they are
representative of the local vegetation type. However, if the wetlands are rehabilitated and
cleared of alien vegetation and dumped waste, it is deemed possible that the overall PES of
the features can be improved to some degree. The Recommended Ecological Category
(REC) deemed appropriate for the management of the features is Category C (moderately
modified);
Due to the highly disturbed nature of the project footprint and due to the severe encroachment
of Acacia saligna into wetland features, the accurate delineation of wetland features on site
was not deemed possible. Therefore, for the purpose of this assessment, wetlands were
delineated with the use of wetland boundaries as indicated by the City of Cape Town
Prioritisation of City Wetlands Map (2009) as well as with the use of aerial photography, and
where possible field verification of wetland boundaries was undertaken and used to assist in
making remote delineation techniques more accurate; and
All wetland features located to the east of the existing runway within the project footprint will
be infilled and lost. The provision of a buffer to wetland features was therefore not deemed
viable (for illustrative purposes a 32m wetland buffer has however been indicated in the
wetland delineation map – Figure 13). However, the infilling of wetland features is defined as
a water use that in terms of Section 21 (c) and (i) of the National Water Act (Act No. 36 of
1998) will require a Water Use Licence (WUL).
IMPACT ASSESSMENT
Table A below summarises the findings of the impact assessment, indicating the significance of each
impact before management takes place and the likely significance of the impacts if management and
mitigation takes place. Impacts assessed include:
 The loss of wetland habitat and ecological structure due to bulk earthworks and construction
activities;
 The loss of wetland ecological and socio-cultural service provision1;
 The loss of wetland hydrological function2 and sediment balance3; and
 Impacts on freshwater features located outside of the project footprint area.
Wetlands provide a range of ecosystem functions, these include: flood attenuation, streamflow regulation, sediment trapping, assimilation of chemicals,
erosion control, biodiversity maintenance, carbon storage, water supply, tourism and recreation, and education and research.
2 Wetland hydrology generally refers to the inflow and outflow of water through a wetland
3 Inputs and outputs of sediment through a feature that often reflect the amount of erosion and sedimentation of a feature
1
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Table A: Summary of impact assessment results.
Impact
Consequence
Probability
Significance
Status
Confidence
IMPACT 1: LOSS OF WETLAND HABITAT AND ECOLOGICAL STRUCTURE
Construction Phase
Without mitigation
With Mitigation
High
Medium
Definite
Definite
MEDIUM4
MEDIUM
–ve
–ve
High
High
–ve
–ve
High
High
Operational Phase
Without mitigation
With Mitigation
Very Low
Very Low
Possible
Improbable
INSIGNIFICANT
INSIGNIFICANT
IMPACT 2: LOSS OF WETLAND ECOLOGICAL AND SOCIO-CULTURAL SERVICE PROVISION
Construction Phase
Without mitigation
With Mitigation
Low
Low
Definite
Definite
LOW
LOW
–ve
–ve
High
High
–ve
–ve
High
High
Operational Phase
Without mitigation
With Mitigation
Very Low
Very Low
Possible
Improbable
INSIGNIFICANT
INSIGNIFICANT
IMPACT 3: LOSS OF WETLAND HYDROLOGICAL FUNCTION AND SEDIMENT BALANCE
Construction Phase
Without mitigation
With Mitigation
Low
Low
Definite
Definite
LOW
LOW
–ve
–ve
High
High
–ve
–ve
High
High
Operational Phase
Without mitigation
With Mitigation
Very Low
Very Low
Possible
Improbable
INSIGNIFICANT
INSIGNIFICANT
IMPACT 4: IMPACTS ON FRESHWATER FEATURES LOCATED OUTSIDE OF THE PROJECT FOOTPRINT
AREA
Construction Phase
Without mitigation
With Mitigation
Low
Low
Probable
Possible
LOW
VERY LOW
–ve
–ve
High
High
–ve
–ve
High
High
Operational Phase
Without mitigation
With Mitigation
Medium
Medium
Probable
Possible
MEDIUM
LOW
CONCLUSION
Bulk earthworks and construction related activities will result in the permanent loss of all wetland
features located to the east of the existing runway. Transformed, mowed and brushcut depressions
are in a significantly degraded condition and the PES and EIS of the features is considered low. The
loss of these wetlands from the project footprint is therefore considered to be of a low significance.
However, two wetland features, the south eastern wetland and the central wetland, are considered to
be of a slightly higher PES and EIS. The rehabilitation of these features may result in the reestablishment of indigenous floral species and it is therefore deemed likely that the future state and
EIS of the features can be further improved. However, it is noted that re-instatement of the wetland
PES is not compatible with the proposed land use and therefore it is recommended that ACSA enter
into an appropriate wetland offset or stewardship program in order to mitigate the impact and loss of
wetland resources that will take place since other mitigation mechanisms higher up in the mitigation
hierarchy are unlikely able to be pursued if the project proceeds.
Although the impact rating methodology provided by SRK resulting in a high significance rating, it is the opinion of the wetland specialist based on
professional judgement and experience that the significance ratings should be decreased from a high to a medium significance due to the current level of
transformation of the wetland habitat
4
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No evidence of connected surface flow was encountered between the wetland depressions during the
field assessment. However, it should be noted that this freshwater ecological assessment only took
into consideration the condition of soils within the first 50cm of the soil surface. However, a moderate
aquifer activity has been indicated by the Tygerberg District Plan (2012) for the eastern half of the
project footprint and Sub-surface flow along impermeable calcrete lenses and hydrological
connectivity between individual wetland features within the project footprint was confirmed by the
Groundwater Specialist Study (GEOSS, 2014); there is therefore a potential for some sub-surface
flow and hydrological connectivity between individual wetland features within the project footprint.
Impacts associated with the infilling of wetlands and the potential pollution of wetland features may
therefore extend beyond the project footprint boundary.
The need and desirability of a wetland offset was considered. Since the significance of the impact on
the hydrological functioning of the wetlands and the general landscape is expected to be insignificant
(GEOSS, 2014) it is the opinion of the specialist that no offset is required in terms of ‘wetland
functionality’. The transformed wetland habitat within the project footprint will be lost permanently.
Hence a wetland habitat conservation offset is required to ensure no net loss of wetlands.
Construction Phase
 Approval must be obtained from DWS for any activities within wetland areas. In this regard
special mention is made of water use licences in terms of Section 21 (c) and (i) of the
National Water Act;
 The wetland offset must be secured and initiation of the offset implementation must take
place;
 Incorporate adequate erosion management measures within the project footprint in order to
prevent erosion and the associated sedimentation of wetlands located to the west of the
existing runway and of freshwater features beyond the project footprint boundary.
Management measures may include berms, soil traps, hessian curtains, stormwater diversion
away from areas susceptible to erosion and stormwater attenuation. Care should however be
taken so as to avoid additional disturbance during the implementation of these measures;
 Sheet runoff from cleared areas and access roads must be curtailed;
 Any discharge of runoff into freshwater systems beyond the project footprint boundary must
be done in such a way as to prevent erosion. In this regard special mention is made of the
use of energy dissipating structures in stormwater discharge into existing stormwater
infrastructure;
 Cleared areas must be revegetated as soon as possible in order to reduce the erosion of
topsoils and the associated sedimentation of wetland features located to the west of the
existing runway and of freshwater features beyond the project footprint boundary;
 Implement general good housekeeping practices (see Appendix B) in order to avoid impact
on mowed depressions located to the west of the existing runway.
Operational Phase
 Minimise paved and sealed surfaces in order to reduce runoff;
 Sheet runoff from paved surfaces and access roads must be curtailed;
 Ensure that runoff drains from the operational areas, without overflowing drainage systems;
 Attenuate stormwater in order to prevent erosion;
 Regularly inspect all Airports Company South Africa vehicles for leaks. Re-fuelling must take
place in a designated area or off site;
 Spills must be immediately cleaned up and treated accordingly;
 Any discharge of runoff into freshwater systems beyond the project footprint boundary must
be done in such a way as to prevent erosion. In this regard special mention is made of the
use of energy dissipating structures in stormwater discharge;
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Maintain stormwater infrastructure;
Monitor the quantity and quality of stormwater entering into surrounding freshwater features
as part of the stormwater management plan; and
Implement general good housekeeping practices (see Appendix B) in order to avoid impact
on mowed depressions located to the west of the existing runway.
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TABLE OF CONTENTS
EXECUTIVE SUMMARY ....................................................................................................................... iii
LIST OF FIGURES ................................................................................................................................ix
LIST OF TABLES ..................................................................................................................................ix
ACRONYMS ........................................................................................................................................... x
1
INTRODUCTION........................................................................................................................ 1
1.1
Background ................................................................................................................................ 1
1.2
Scope ......................................................................................................................................... 4
1.3
Assumptions and limitations ...................................................................................................... 4
1.4
Legislation and Policy ................................................................................................................ 5
1.5
Indemnity and Terms of use of this report ................................................................................. 6
2
METHOD OF ASSESSMENT .................................................................................................... 7
3
DESCRIPTION OF THE AFFECTED ENVIRONMENT ............................................................ 7
3.1
Regional Context........................................................................................................................ 7
3.2
General Freshwater Ecological Assessment Results ..............................................................11
3.2.1 Transformed Depressions ........................................................................................................14
3.2.2 Brushcut Depressions ..............................................................................................................14
3.2.3 Mowed Depressions .................................................................................................................15
3.2.4 South Eastern Wetland ............................................................................................................15
3.2.5 Central Wetland .......................................................................................................................16
3.3
Characterisation of Wetland Features .....................................................................................16
3.4
Wetland Vegetation ..................................................................................................................17
3.5
Wetland Function Assessment ................................................................................................18
3.6
WET-Health ..............................................................................................................................20
3.7
Hydrological Function...............................................................................................................21
3.8
EIS Determination ....................................................................................................................22
3.9
Recommended Ecological Category ........................................................................................25
3.10
Wetland Delineation .................................................................................................................25
3.11
Buffer Allocation .......................................................................................................................25
4
IMPACT ASSESSMENT..........................................................................................................27
4.1
Direct Impact ............................................................................................................................27
4.2
No-go Alternative .....................................................................................................................37
4.3
Cumulative Impacts..................................................................................................................37
4.4
Indirect Impacts ........................................................................................................................37
4.5
Offset Recommendations.........................................................................................................37
4.6
Monitoring Campaigns .............................................................................................................37
5
CONCLUSIONS .......................................................................................................................39
6
REFERENCES .........................................................................................................................44
APPENDIX A ........................................................................................................................................45
A – 1 Classification System for Wetlands and other Aquatic Ecosystems in South Africa ........46
A – 2 WET-Health ................................................................................................................................50
A – 3 Wetland function assessment ..................................................................................................52
A – 4 Defining Ecological Importance and Sensitivity ....................................................................53
A – 5 Recommended Ecological Category .......................................................................................54
A – 6 Wetland Delineation ..................................................................................................................54
APPENDIX B ........................................................................................................................................55
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LIST OF FIGURES
Figure 1:
Figure 2:
Figure 3:
Figure 4:
Figure 5:
Figure 6:
Figure 7:
Figure 8:
Figure 9:
Figure 10:
Figure 11:
Figure 12:
Figure 13:
Digital satellite image depicting the location of the project footprint in relation to
surrounding areas (it should be noted that the railway line indicated traversing the
project footprint no longer exists). ....................................................................................... 2
Location of the project footprint depicted on a 1:50 000 topographical map in relation to
surrounding areas. ............................................................................................................... 3
Quaternary catchments associated with the project footprint. ............................................ 9
Locations of the Lotus River canal, the Kuils River and the Kalksteenfontein canal
(adapted from SRK, 2013). ................................................................................................10
Prioritisation of City Wetlands Map (2009). .......................................................................12
Wetland groups identified within the project footprint. .......................................................13
Transformed wetland features ...........................................................................................14
Brushcut depressions and grey soils associated with brushcut depressions ...................15
The south eastern wetland feature ....................................................................................16
Central wetland feature .....................................................................................................16
Radar plot of wetland services provided by wetland features within the project footprint .19
Ecological Importance and Sensitivity of wetland features ...............................................24
Wetland delineation (32m buffer indicated for illustrative purposes only). ........................26
LIST OF TABLES
Table 1:
Table 2:
Table 3:
Table 4:
Classification System for Wetlands and other Aquatic Ecosystems in South Africa (2013).17
Wetland vegetation identified within the project footprint. ....................................................17
Wetland function and service provision. ...............................................................................18
Summary of the overall health of the wetlands based on impact score and change score
including the trajectory of change should the development proceed (→ = condition is
likely to remain stable and ↓↓ = condition is likely to rapidly deteriorate). ............................20
Table 5: EIS determination .................................................................................................................22
Table 6: The Mitigation Hierarchy and the forms of mitigation which are applicable to the project ...27
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ACRONYMS
BGIS
Biodiversity Geographic Information Systems
CESA
Critical Ecological Support Area
DWA
Department of Water Affairs
EIS
Ecological Importance and Sensitivity
GIS
Geographic Information System
ha
Hectares
m
Metres
NEMA
National Environmental Management Act
NEMBA
National Environmental Management Biodiversity Act
NFEPA
National Freshwater Ecosystem Priority Areas
NWA
National Water Act
PES
Present Ecological State
REC
Recommended Ecological Category
SANBI
South African National Biodiversity Institute
SAS
Scientific Aquatic Services
WUL
Water Use Licence
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INTRODUCTION
1.1 Background
Scientific Aquatic Services (SAS) was appointed to conduct a freshwater ecological impact
assessment as part of the environmental assessment and authorisation process for the proposed
realignment of the primary runway at the Cape Town International Airport. This specialist study was
updated after the end of the comment period on the Draft Environmental Impact Assessment (EIA)
Report and associated specialist studies to produce this Freshwater Ecological Impact Assessment
Report for submission to the Department of Environmental Affairs along with the Final EIA Report. All
changes in this Final Freshwater Ecological Impact Assessment Report are underlined and italicised
for ease of reference.
As the first phase in the development of the Cape Town International Airport as envisaged in the
Master Plan, Airports Company South Africa (ACSA) proposes to construct a new (re-aligned)
runway, rotated through 11.5°, to replace the existing primary runway (Runway 01-19). The northern
end of the new runway will be positioned 220m to the east of the current Runway 01-19. It will comply
with international specifications for Code F aircraft, increase runway capacity and enable future airport
expansion.
In addition to the re-aligned runway, the current project will also include:
 A taxiway system;
 Infrastructure such as an aircraft isolation pad, a compass calibration pad and an aircraft runup area;
 Security facilities;
 Service roads;
 Buildings and service infrastructure;
 Upgrading of the stormwater management system; and
 Bulk earthworks for the sourcing and on site use of cut/fill material.
The proposed project footprint is approximately 700ha in extent (Figure 1 and 2). Construction is
expected to take 24 to 30 months to complete. Construction activities that disrupt operation of the
existing runway will take place at night (for approximately 4 months).
This report, after consideration and description of integrity of freshwater ecosystems with the project
footprint as well as assessment of possible impacts, must guide the proponent, authorities and
professional team, by means of recommendations, as to viability of the proposed development and
provide recommendations on how best to minimise the impact on the freshwater resources in the
project footprint as well as immediate surroundings while still aiming to meet the operational
requirements of the proposed infrastructure.
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Figure 1: Digital satellite image depicting the location of the project footprint in relation to surrounding areas (it should be noted that the railway
line indicated traversing the project footprint no longer exists).
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Figure 2: Location of the project footprint depicted on a 1:50 000 topographical map in relation to surrounding areas.
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1.2 Scope
The following ToR are proposed for the freshwater ecology study:
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Describe and map existing freshwater ecosystems in the area potentially affected by the
proposed project;
Provide an indication of the sensitivity and importance of the affected environment, including
the wetland services (to ecology and to people) and the linkages between the various
freshwater systems i.e. wetlands, rivers, groundwater and stormwater management systems
on the development site and surrounds, and the importance of wetlands within the larger
system;
Map areas of higher and lower sensitivity on the site;
Define applicable legislative requirements regarding any permit applications required;
Identify potential impacts of the proposed project on freshwater ecology and systems;
Assess the impacts of the proposed project on freshwater ecology and systems in the area
using the prescribed impact assessment methodology;
Identify and assess potential cumulative ecological impacts resulting from the proposed
development in relation to proposed and existing developments in the surrounding area;
Recommend practicable mitigation measures to avoid and/or minimise/reduce impacts and
enhance benefits. Assess the effectiveness of proposed mitigation measures using the
prescribed impact assessment methodology; and
Recommend and draft a monitoring campaign to ensure the correct implementation and
adequacy of recommended mitigation and management measures, if applicable.
1.3 Assumptions and limitations
The following assumptions and limitations are applicable to this report:
 The freshwater ecological field assessment was confined to the project footprint and did not
include the neighbouring and adjacent properties. Access was not granted into private and
industrial properties surrounding the project footprint, however these properties were
considered as part of the desktop assessment;
 Wetlands within the existing airport property boundary have been significantly transformed as
a result of the development of infrastructure associated with the airport and a field survey of
the area was therefore not deemed necessary. The assessment of wetland features within the
Cape Town International Airport property was therefore undertaken with the use of aerial
photography, site photographs as provided by SRK and with the use of information as
obtained from previous wetland and vegetation assessments in the area (Helme, 2012 and
van Staden and van de Haar, 2013);
 A number of isolated depression wetlands are indicated within the northern and eastern
portions of the project footprint by the City of Cape Town Prioritisation of City Wetlands Map.
These features have been significantly disturbed and transformed by historic earth moving
activities and by the present brushcutting of Acacia saligna. Due to the high levels of
disturbance associated with the features, wetland indicators such as wetland vegetation and
surface water have been lost or significantly altered. However, grey soils and leaching of the
soils within 50cm of the soil surface were noted in all of these features with exception of three
features. Due to the disturbed nature of the site, the precautionary principle was applied and
all wetlands indicated by the Prioritisation of City Wetlands Map (with the exception of the
three features which lacked wetland soil indicators) were included in the assessment of
wetland features. However, at best, these features can be defined as significantly disturbed
temporary wetlands with a very low Ecological Importance and Sensitivity (EIS);
 Wetlands within the Cape Flats area are documented as ‘special case’ wetlands which are
considered difficult to delineate (Job, 2009). Due to the highly disturbed nature of the project
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footprint and the severe encroachment of A. saligna into these special case wetland features,
the accurate delineation of wetland features on site was not deemed possible. Therefore, for
the purpose of this assessment, wetlands were delineated with the use of wetland boundaries
as indicated by the City of Cape Town Prioritisation of City Wetlands Map (2009)
supplemented by aerial photography and digital satellite imagery. In this regard specific
mention is made of the use of variations in digital signatures such as textures, colours, linear
patterns and vegetation density within digital satellite imagery. Variations in elevations across
the site were also considered in order to determine areas in which wetland features are most
likely to occur;
The accuracy of mapping as presented in this report is limited by the highly disturbed nature
of the site and by dense stands of A. saligna. Therefore, it is possible that smaller cryptic
wetlands of very low EIS may have been missed. This would however not affect the
significance rating of the impacts;
The locality of all wetland features identified during the assessment of the project footprint are
indicated within the report, however, in the context of this freshwater ecology assessment it is
assumed that all wetland features within the project footprint will be infilled during the course
of development. The buffering of wetland features was therefore not deemed necessary; and
During this assessment the assumption has been made that all vegetation within the project
footprint will be removed or disturbed during the construction phase and that all wetland
features will be disturbed or infilled.
1.4 Legislation and Policy
The key legislation applicable to the project as identified and interpreted by the specialist is listed
below:
National Environmental Management Act (NEMA, Act No. 107 of 1998)

Sections 24 and 44 of NEMA make provision for the promulgation of regulations that identify
activities which may not commence without an Environmental Authorisation (EA) issued by
the competent authority (Department of Environmental Affairs, DEA). In this context the EIA
Regulations (2010) (which came into effect on 2 August 2010), promulgated in terms of
NEMA, list activities that require EA (“NEMA listed activities”) and govern the process,
methodologies and requirements for the undertaking of EIAs in support of EA application. The
proposed project may include activities that are listed in terms of the EIA regulations. These
activities are listed below:
 The construction of channels, bulk storm water outlets or infrastructure or structures
covering 50m2 or more where such construction occurs within a watercourse or within
32m of a watercourse, measured from the edge of a watercourse;
 The infilling or deposition of any material of more than 5 cubic meters into, or the
dredging, excavation, removal or moving of soil, sand, shells, shell grit, pebbles or rock
more than 5 cubic meters from a watercourse; and
 The expansion of channels or bulk stormwater outlet structures within a watercourse or
within 32m of a watercourse.
National Water Act (NWA, Act 36 of 1998)


The National Water Act (Act 36 of 1998) recognises that the entire ecosystem and not just the
water itself in any given water resource constitutes the resource and as such needs to be
conserved. No activity may therefore take place within a watercourse unless it is authorised
by DWA.
A water course is defined by the NWA as:
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a)
b)
c)
d)
A river or spring
A natural channel in which water flows regularly or intermittently;
A wetland, lake or dam into which, or from which, water flows; and
Any collection of water which the Minister may, by notice in the Gazette, declare to be a
watercourse, and a reference to a watercourse includes, where relevant, its bed and
banks.
Any area within a freshwater system is therefore excluded from development unless
authorisation is obtained from DWA in terms of Section 21 of the Act.

General Notice 1199 as published in the Government Gazette 32805 of 2009 as it relates to the
National Water Act, 1998 (Act 36 of 1998)

Wetlands are extremely sensitive environments and as such, the Section 21 (c) 5 and (i)6 water
use General Authorisation does not apply to any wetland or any water resource within a
distance of 500 meters upstream or downstream from the boundary of any wetland or
estuary.
Floodplain and River Corridor Management Policy (City of Cape Town, 2009)
In terms of the Floodplain and River Corridor Management Policy:
“Watercourses and wetlands with their adjacent riparian areas and associated fauna and flora
must be protected or buffered from the impacts of adjacent development or activity”;
 A buffer is “a strip of land adjacent to a watercourse, wetland or vlei required for the protection
and enhancement of these ecosystems”;
 The buffer is measured from watercourse “top of bank” or outer edge of the wetland (which
must be delineated according to nationally accepted guidelines / methodologies e.g. DWA
1999 and 2005) where the buffer can vary in width between 10 m and 40 m for watercourses
determined by the ecological condition and importance of the system, and up to 75 m for
wetlands. A minimum buffer of 10 m is required for concrete canals.

1.5 Indemnity and Terms of use of this report
The findings, results, observations, conclusions and recommendations given in this report are based
on the author’s best scientific and professional knowledge as well as available information. The report
is based on survey and assessment techniques which are limited by time and budgetary constraints
relevant to the type and level of investigation undertaken and SAS CC and its staff reserve the right to
modify aspects of the report including the recommendations if and when new information may
become available from ongoing research or further work in this field, or pertaining to this investigation.
Although SAS CC exercises due care and diligence in rendering services and preparing documents,
SAS CC accepts no liability and the client, by receiving this document, indemnifies SAS CC and its
directors, managers, agents and employees against all actions, claims, demands, losses, liabilities,
costs, damages and expenses arising from or in connection with services rendered, directly or
indirectly by SAS CC and by the use of the information contained in this document.
This report must not be altered or added to without the prior written consent of the author. This also
refers to electronic copies of this report which are supplied for the purposes of inclusion as part of
other reports, including main reports. Similarly, any recommendations, statements or conclusions
drawn from or based on this report must make reference to this report. If these form part of a main
5Impeding
6Altering
or diverting the flow of water in a watercourse.
the bed, banks, course or characteristics of a watercourse
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report relating to this investigation or report, this report must be included in its entirety as an appendix
or separate section to the main report.
2
METHOD OF ASSESSMENT
The freshwater ecology assessment included a literature review, followed by a site assessment
undertaken on the 13th and 14th of August 2013. All wetland features within the project footprint were
identified and a wetland classification assessment was undertaken according to the Classification
System for Wetlands and other Aquatic Ecosystems in South Africa. User Manual: Inland systems
(Ollis et al., 2013). In addition, the WET-Health (Macfarlane et al., 2009), wetland ecological and
socio-economic service provision (Kotze et al. 2008) and EIS of wetlands was determined. The
method used for the EIS determination was adapted from the method as provided by DWA (1999) for
floodplains. The method takes into consideration PES scores obtained for WET-Health as well as
function and service provision to enable the assessor to determine the most representative EIS
Category for the wetland feature or group being assessed.
Due to the highly disturbed nature of the project footprint and due to the severe encroachment of A.
saligna into wetland features, the accurate delineation of wetland features on site was not deemed
possible. Therefore, for the purpose of this assessment, wetlands were delineated with the use of
wetland boundaries as indicated by the City of Cape Town Prioritisation of City Wetlands Map (2009)
supplemented by aerial photography and digital satellite imagery as well as by in field verification
wherever possible.
The Freshwater Assessment aimed at determining the EIS of freshwater features associated with the
project footprint was undertaken making use of the freshwater assessment methodology provided in
Appendix A.
3
DESCRIPTION OF THE AFFECTED ENVIRONMENT
3.1 Regional Context
All wetland features within the project footprint are located within the Cape Flat Dune Strandveld
vegetation type and it has therefore been assumed that all wetlands will fall within the Western
Strandveld depression wetland vegetation group. Western Strandveld depression wetlands are
considered to be endangered within the region which increases the significance of their loss from the
project footprint in terms of a regional context.
The Cape Town International Airport falls within the Cape Flats which is documented as a ‘special
case’ wetland area within the Western Cape due to the presence of a sandy soils coastal aquifer (Job,
2009). Therefore, a large percentage of water contributing to sustaining wetlands in the area will be
from the shallow water table. However, surface runoff from concrete surfaces, roads and disturbed
areas within the catchment, will also contribute significantly to the amount of water reaching wetland
features within the project footprint. Due to the presence of the coastal aquifer, located to the east of
the existing airport boundary, the wetland features within the project footprint as well as wetland
features falling outside of the project footprint boundaries are connected by sub-surface flow,
confirmed by the Groundwater Specialist Study (GEOSS, 2014). Impacts associated with the infilling
of wetlands within the project footprint and the potential pollution of wetland features within the project
footprint may therefore extend beyond the project footprint boundary.
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The project footprint is situated on the divide of three major river catchment areas. These include
catchment G22C which drains into the Kalksteenfontein canal, catchment G22D which drains into the
Lotus River canal and catchment G22E which drains into the Kuils River.
Stormwater from the project footprint enters into the Lotus River canal which is situated just to the
west of the airport and into the Kalksteenfontein canal which is located approximately 4km to the west
of the airport. Stormwater conveyed by the Lotus River canal is transported in a southerly direction to
the Zeekoevlei and stormwater conveyed by the Kalksteenfontein canal is transported to the Salt
River. The Lotus River and Kalksteenfontein canals are highly degraded and polluted systems. These
canals flow through surrounding urban, industrial and agricultural areas and are likely to have already
been significantly impacted as a result of stormwater runoff from these areas.
The Kuils River is located approximately 3km to the east of the project footprint. The Kuils River is a
perennial river which has been classified as a largely modified river. It is not free flowing and the river
has not been classified as a river FEPA. The Kuils River has been impacted as a result of agricultural
and industrial runoff and has been impacted as a result of the discharge of waste water effluent into
the system. Although the system is in a poor ecological condition, it is still regarded to be of some
importance as it supports important downstream wetlands such as the Khayelitsha Wetlands (EwartSmith and Ractliffe, 2002).
Studies undertaken by the Institute for Water Quality Studies assessed all quaternary catchments as
part of the Resource Directed Measures for Protection of Water Resources. In these assessments,
the EIS, Present Ecological Management Class (PEMC) and Desired Ecological Management Class
(DEMC) of each of the catchments associated with the project footprint have been evaluated.
Aquatic ecosystems associated with catchments G22C and G22D can be classified as Moderate to
Low Sensitivity Systems which, in their present state, can be considered to be in a Class E or F
condition (not acceptable). Aquatic ecosystems associated with catchments G22E can be classified
as Moderately Sensitive Systems which, in their present state, can be considered to be in a Class C
condition (Largely modified). Only a small portion of this quaternary catchment is covered by the
project footprint.
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Figure 3: Quaternary catchments associated with the project footprint.
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PROJECT FOOTPRINT
HYDROLOGY OF
SURROUNDING AREA
Figure 4: Locations of the Lotus River canal, the Kuils River and the Kalksteenfontein canal (adapted from SRK, 2013).
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3.2 General Freshwater Ecological Assessment Results
According to the Prioritisation of City Wetlands Map (2009) the project footprint covers numerous
Dune Strandveld natural and semi natural, inland, isolated depression wetlands. Wetland features
located within the current airport boundaries have been indicated as critically modified features with a
less than 25% natural land cover and are indicated as Critical Ecological Support Areas (CESAs) and
Other Ecological Support Areas (OESA). However, wetland features located within the eastern and
northern portions of the project footprint are indicated as wetlands with a greater than 75% natural
land cover and are classified as Critical Biodiversity Area (CBA) 2 wetlands. Although wetlands within
the project footprint have been classified as CBA 2, CESA and OESA wetlands by the Prioritisation of
City Wetlands Map (2009) (Figure 5), upon assessment of the project footprint it became evident that
the majority of these wetland features are in a significantly transformed Present Ecological State
(PES).
Although the majority of wetland features within the project footprint are in a transformed state, two
wetland features are considered to be of a slightly increased EIS. These features include a large
wetland feature (±15.5ha) within the south eastern corner of the project footprint (hereafter referred to
as the south eastern wetland) and a smaller wetland feature (±0.28ha) within the north-eastern portion
of the project footprint (hereafter referred to as the central wetland). The remainder of the wetland
features are all considered depression wetlands and are therefore referred to as ‘depressions’ in the
remainder of the report.
Wetland features associated with the project footprint could be divided into five wetland groups which
include transformed depressions, brushcut depressions, mowed depressions, the south eastern
wetland and the central wetland (Figure 6). All wetland features encountered within the project
footprint were assessed further in order to determine their EIS. The locations of the features assessed
are depicted in the Figure 5 below and characteristics discussed in detail in the sections that follow.
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Figure 5: Prioritisation of City Wetlands Map (2009).
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Legend
PROJECT FOOTPRINT
SOUTH EASTERN
A
CENTRAL
TRANSFORMED
BRUSHCUT
MOWED
3
B
2
WETLAND
GROUPS
1
Figure 6: Wetland groups identified within the project footprint.
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3.2.1 Transformed Depressions
The majority of the transformed depressions are located within the eastern portion of the project
footprint. These depressions were encroached by the alien invasive species A. saligna, however, the
obligate7 wetland species Typha capensis was identified in the majority of the features. Two additional
wetland features which are not located within the eastern portion of the project footprint have also
been included within the transformed depression wetland group. One depression is indicated by the
Prioritisation of City Wetlands Map (2009) and is located within the northern portion of the project
footprint (marked as wetland A in Figure 6). This feature contained surface water at the time of the
assessment, however, the feature was significantly encroached by invasive grass species. The
second feature is located within the centre of the project footprint (marked as wetland B in Figure 6)
and appears to have been created as a result of historic excavation activities.
Although in a transformed state, a small volume of surface water was encountered within a number of
the depressions at the time of the assessment and these features may therefore be of importance in
terms of habitat provision for faunal species with special mention of breeding habitat and cover for
amphibian, avifaunal and invertebrate species. It should however be noted that the majority of
depressions within the project footprint are seasonal and temporary wetlands which only retain water
for limited periods of the year. Surface water is therefore restricted to the wetter winter months and
wetlands cannot sustain faunal species which rely on permanent aquatic environments. These
depressions are therefore only considered to be of increased EIS for aquatic and terrestrial species
which rely on them for parts of their life cycles.
Figure 7: Transformed wetland features
3.2.2 Brushcut Depressions
A number of isolated depression wetlands are indicated within the northern and central portions of the
project footprint by the Prioritisation of City Wetlands Map. These features have been significantly
disturbed and transformed by historic earth moving activities and by the present brushcutting of A.
saligna. Due to the high levels of disturbance associated with the features, wetland indicators such as
wetland vegetation and surface water have been lost. However, grey soils and leaching of the soils
within 50cm of the soil surface were noted in the majority of these features with exception of features
1, 2, and 3 (please refer to Figure 6). Due to the disturbed nature of the site, the precautionary
principle was applied and all wetlands indicated by the Prioritisation of City Wetlands Map (2009), with
exception of features 1, 2 and 3, were included in the freshwater ecological assessment. However, at
7
Species almost always found in wetlands (greater than 99% of occurrence) (DWAF, 2005)
14
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best, brushcut depressions can be defined as significantly disturbed temporary wetlands with a very
low EIS.
Figure 8: Brushcut depressions and grey soils associated with brushcut depressions
3.2.3 Mowed Depressions
The majority of wetland features within the current Cape Town International Airport boundaries have
been infilled, planted with invasive grass and maintained as lawn thereafter. The infilling of wetland
features within the airport boundary has resulted in the significant transformation of the wetland
habitat. This wetland habitat is therefore considered to be largely unsuitable for faunal species. A few
avifaunal species may forage within these features during the wet season, however, faunal and
avifaunal species are actively discouraged in the area and are removed from the airport property due
to the safety risks they pose to aircraft and/or airport infrastructure. Mowed wetland features within the
airport boundary are therefore considered to be almost insignificant in terms of wetland faunal and
floral conservation.
3.2.4 South Eastern Wetland
The south eastern wetland is a large depression wetland dominated by the obligate wetland species
Typha capensis. This feature has been disturbed as a result of A. saligna encroachment, dumping
and ongoing disturbance as a result of anthropogenic activity. However, it is likely to provide the
habitat to support faunal species with special mention of breeding habitat and shelter for amphibian,
avifaunal and invertebrate species. Furthermore, although indigenous floral species diversity within
this feature is low and alien grass species as well as A. saligna are present, the rehabilitation of the
feature may result in the re-establishment of additional indigenous floral species and it is therefore
deemed likely that the PES of the feature can be improved.
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Figure 9: The south eastern wetland feature
3.2.5 Central Wetland
The central wetland was not included in the Prioritisation of City Wetlands Map (2009) however, upon
assessment of the site, the feature was indicated by the Custodians of Rare and Endangered
Wildflowers (CREW) as a feature which may be worth rehabilitating (pers. comm, CREW). This
feature is encroached by A. saligna, however, it supports indigenous floral species such as Elegia
nuda, Tetraria sp., Restio sp. and Helichrysum revolutum. Furthermore, amphibian calls of Amietia
fuscigula (Cape River Frog) were heard from within the wetland feature further increasing the
importance of the feature in terms of wetland faunal and floral conservation. The rehabilitation of the
feature could result in the re-establishment of additional indigenous floral species and it is therefore
deemed likely that its PES can be improved.
Figure 10: Central wetland feature
3.3 Characterisation of Wetland Features
Wetland features within the project footprint were categorised with the use of the Classification
System for Wetlands and other Aquatic Ecosystems in South Africa (Ollis et al., 2013). The results as
illustrated in the table below are representative of all features within the project footprint. No evidence
was encountered within the first 50cm from the soil surface during the site survey that wetland
features within the project footprint are connected. All wetland features are therefore considered
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largely isolated, endorheic features8 with closed contours and without channelled inflow and are
therefore classified as depression wetlands within this report.
Table 1: Classification System for Wetlands and other Aquatic Ecosystems in South Africa
(2013).
Level 1: System
An ecosystem that
has no existing
connection to the
ocean but which is
inundated or
saturated with
water, either
permanently or
periodically.
Level 2: Regional
Setting
Level 3:
Landscape unit
The project footprint
falls within the South
Western Coastal Belt
Ecoregion and the
Western Strandveld
wetland vegetation
group (National
Freshwater
Ecosystem Priority
Areas (NFEPA)
WetVeg).
Plain: An extensive
area of low relief
characterised by
relatively level,
gently undulating
or uniformly
sloping land.
Level 4: Hydrogeomorphic (HGM) unit
Longitudinal zonation /
HGM Type
landform / Inflow
drainage
Depression: A
Endorheic- without
landform with closed
channelled inflow
elevation contours
that increases in
depth from the
perimeter to a central
area of greatest
depth, and within
which water typically
accumulates.
3.4 Wetland Vegetation
Within the project footprint, the various wetland vegetation components were assessed. Dominant
species were characterised as either wetland or terrestrial species. The wetland species were then
further categorised as temporary, seasonal and permanent zone species.
The permanent zone of the larger south eastern wetland was dominated by the obligate wetland
species Typha capensis (Bulrush), and seasonal and temporary zones were characterised by
facultative9 graminoid species such as Cynodon dactylon (Couch Grass) and Pennisetum
clandestinum (Kikuyu) as well as shrub species such as Senecio halimifolius (Tabakbos) which has
been documented as a common shrub species in dune strandveld wetlands (Snaddon and Day,
2009).
The central wetland was characterised by wetland species including E. nuda (no common name),
Ficinia lateralis (no common name) and Isolepis sp (no common name).
The remainder of the depressions within the project footprint are largely transformed with significant
A. saligna (Port Jackson Willow) and invasive graminoid species encroachment. However, the
obligate wetland species Typha capensis (Bulrush) was identified in some transformed wetland
features as well as the facultative wetland species Elegia nuda and Imperata cylindrica (Cotton Wool
Grass). This indicates the presence of periodic surface water sufficient to support obligate wetland
species.
Table 2: Wetland vegetation identified within the project footprint.
Terrestrial species
Temporary species
Seasonal species
Acacia saligna*
Acacia cyclops*
Acacia longifolia*
Dicerothamnos rhinocerotis
Acacia saligna*
Acacia cyclops*
Acacia longifolia*
Cynodon dactylon
Carpobrotus edulis
Cynodon dactylon
Pennisetum clandestinum*
Stenatophratum secundatum
Imperata cylindrica
Elegia nuda
8
9
Permanent Zone
Species
Phragmites australis
Typha capensis
Elegia tectorum
Elegia nuda
An endorheic basin is a closed drainage basin that retains water and allows no outflow to other external bodies of water
Species usually found in wetlands (67% to 99% of occurrence) but occasionally found in non-wetland areas (DWAF, 2005)
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March 2016
Temporary species
Seasonal species
Pennisetum clandestinum*
Stenatophratum secundatum
Imperata cylindrica
Metalasia muricata
Moraea flaccida
Senecio halimifolius
Trachyandra ciliata
Ficinia lateralis
Isolepis sp.
Cotula coronopifolia
Permanent Zone
Species
3.5 Wetland Function Assessment
Wetland function and service provision were assessed separately for the south eastern wetland, the
central wetland, transformed depressions, brushcut depressions and mowed depressions. The
average score for the different groups is presented in the following table as well as in the radar plot in
the figure that follows the table below.
Table 3: Wetland function and service provision.
South eastern
Wetland
Central
Wetland
Transformed
Wetlands
Brushcut
Wetlands
Mowed
Wetlands
1.1
1
0.7
0.7
1.1
0
0
0
0
0
Sediment trapping
0.8
0.2
0.4
0.4
0.4
Phosphate assimilation
1.8
1.5
1.2
1.1
1.5
Nitrate assimilation
2.3
1.8
1.3
1.5
1.5
Toxicant assimilation
2
1.3
1.2
1
1.1
Erosion control
2
1.5
1
1
1
1.2
1.6
1
0.6
0.6
Carbon Storage
0
0
0
0
0
Water Supply
0
0
0.2
0
0
0.8
0.6
0.8
0
0
Cultural value
0
0
0
0
0
Cultivated foods
0
0
0
0
0
Tourism and recreation
0.25
0.25
0
0
0
Education and resource
0.25
0
0
0
0
SUM
12.6
9.8
7.8
6.2
7.1
Average score
0.8
0.7
0.5
0.4
0.5
Moderately low
Moderately low
Moderately low
Low
Moderately low
Ecosystem service
Flood attenuation
Streamflow regulation
Biodiversity maintenance
Harvestable resources
Class
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Education and
resource
Flood attenuation
Tourism and recreation
4
3
Streamflow regulation
Sediment trapping
2
Cultivated foods
Phosphate assimilation
1
0
Cultural value
Nitrate assimilation
Harvestable resources
Toxicant assimilation
Water Supply
Carbon Storage
Erosion control
Biodiversity
maintenance
South eastern Wetland
Central Wetland
Transformed Depressions
Brushcut Depressions
Mowed Depressions
Figure 11: Radar plot of wetland services provided by wetland features within the project
footprint
From the results of the assessment, it is evident that the south eastern and central wetlands as well
as transformed and mowed depressions have a moderately low level of ecoservice provision and
function and that the brushcut depressions have a low level of ecoservice provision and function. All
wetland features within the project footprint are depressions and are therefore not connected to
downstream features by means of surface flow. As a result, depressions do not play any role in terms
of stream flow regulation and would only be of limited importance in terms of flood attenuation and
sediment trapping. However, the locality of these features in a quaternary catchment in which urban
development and industrialization dominate, increases the importance of these features in terms of
the assimilation of phosphates, nitrates and toxicants which may enter into the features through
surface runoff as well as through subsurface flow. In this regard special mention is made of the south
eastern wetland which is located in close proximity to the N2 highway and the Delft settlement area,
as well as the mowed depressions which are located in between existing airport infrastructure. Runoff
from roads and infrastructure surrounding these features is likely to carry an increased quantity of
phosphates and nitrates into these features.
Due to the degree of vegetation transformation in combination with alien vegetation encroachment,
the transformed, brushcut and mowed depressions provide limited indigenous vegetation and habitat
19
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and are therefore considered to play a limited role in the maintenance of biodiversity in the area. The
south eastern and central wetlands provide increased habitat for indigenous wetland species
including avifauna and amphibians, however encroachment of alien A. saligna into these features is
considered significant and these features are therefore considered of a moderately low to
intermediate importance in terms of biodiversity maintenance.
Evidence was encountered during the field visit that the A. saligna (Port Jackson) growing within the
south eastern, central and transformed wetlands is harvested by the local community as a source of
firewood. However, A. saligna is not restricted to wetland features and is therefore more likely to be
harvested from surrounding terrestrial areas. These features are therefore considered of a low
importance in terms of natural resource provision. No wetland features are considered important in
terms of water supply, cultivated foods or cultural value.
3.6 WET-Health
A level 2 WET-health assessment was undertaken to determine the PES of the wetland features
associated with the project footprint. Although all wetland features within the project footprint are
considered to fall within the depression HGM Unit, aspects of their hydrology and vegetation differed
slightly and so the south eastern wetland, the central wetland, transformed depressions, brushcut
depressions and mowed depressions were assessed separately. It should also be noted that the
present geomorphological state of wetland features can only be assessed for wetland features which
are connected to the drainage network in some way (Macfarlane et. al 2009). The depression wetland
features associated with the project footprint are endorheic features and the geomorphological health
of these features was therefore not assessed.
Table 4: Summary of the overall health of the wetlands based on impact score and change
score including the trajectory of change should the development proceed (→ =
condition is likely to remain stable and ↓↓ = condition is likely to rapidly deteriorate).
Hydrology
Vegetation
Feature Type
Impact Score
Change Score
Impact Score
Change Score
South Eastern Wetland Feature
E
↓↓
D
↓↓
Central Wetland Feature
E
↓↓
D
↓↓
Transformed depressions
E
↓↓
E
↓↓
Brushcut depressions
F
→
F
→
Mowed depressions
F
→
F
→
The present hydrological state of the south eastern wetland, central wetland and transformed
depressions calculated scores that fall within Category E (Seriously modified). The encroachment of
A. saligna into the catchments of these wetland features was considered to significantly decrease the
inflow quantities of water into these depressions from the catchments. Furthermore, the presence of
A. saligna within wetland features is likely to result in further hydrological impact as a result of the
direct loss of water from the features due to uptake of water by trees not associated with the natural
setting of these wetlands. Impacts as a result of canalisation and stream modification are not deemed
applicable to the depressions and were therefore not assessed as part of the overall hydrological
module; however, a gravel road traversing the south eastern wetland may impede the flow of water
within the feature and has resulted in a small modification in the hydrology of the wetland.
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The present hydrological state of the brushcut and mowed depressions calculated a score that falls
within Category F (Critically modified). Brushcut depressions are temporary wetlands which have
been significantly disturbed as a result of historic earth moving activities and A. saligna encroachment
and as a result of current brushcutting activity with heavy machinery. The hydrology of these features
has therefore been significantly impacted. In addition, the mowed depressions have been affected by
historic earth moving activities and the hydrology of these features has therefore been severely
transformed.
The present vegetation state of the south eastern wetland and central wetland calculated scores that
fall within Category D (Largely modified). The vegetation within both features has been transformed
by the encroachment of A. saligna into the wetland seasonal zone; however, the degree of
encroachment is not as high as that encountered within transformed wetland features which
calculated a present vegetation state score falling within Category E (Seriously modified).
The present vegetation state of the brushcut and mowed depressions calculated scores that fall within
Category F (Critically modified). Current brushcutting activities have removed A. saligna from the
features but the disturbance caused by the movement of heavy machinery through the area has
resulted in the proliferation of additional weed species. Vegetation within mowed depressions has
undergone transformation as a result of the development of the airport and associated infrastructure
and as a result of the infilling and mowing of the wetland features. The vegetation assemblage within
these features has therefore been significantly transformed.
The overall score for the wetland features assessed aggregating the scores for the two modules,
namely hydrology and vegetation, was calculated using the formula 10 as provided by the Wet-Health
methodology. The overall categories for the wetland features are presented in Table 4 above
 South eastern wetland - PES Category E (seriously modified);
 Central wetland - PES Category D (largely modified);
 Transformed wetlands - PES Category E (seriously modified); and
 Brushcut wetlands – PES Category F (critically modified).
 Mowed wetlands - PES Category F (critically modified).
The PES was then used as a benchmark for the identification of an appropriate category for the EIS
of the wetland features (Section 3.8).
In terms of anticipated trajectory11, should the development of the project footprint not take place, it is
considered highly likely that the PES of the south eastern, central and transformed wetland features
would decrease and that the PES of the brushcut and mowed depressions would remain the same.
The PES of the south eastern, central and transformed wetland features would decrease as a result
of the proliferation of A. saligna and the further encroachment of A. saligna into the features.
However, should the development of the project footprint take place, all wetland features within the
project footprint will be infilled and will be permanently lost.
3.7 Hydrological Function
Wetland hydrology generally refers to the inflow and outflow of water through a wetland, therefore
land is characterised as having wetland hydrology when, under normal circumstances, the land
surface is either inundated or the upper portion of the soil is saturated at a sufficient frequency and
duration to create anaerobic conditions 12.
10
((Hydrology score) x 3 + (geomorphology score) x2 + (vegetation score) x 2))/ 7 = PES
Anticipated change over the next 5 years.
12www.forestandrange.org/new_wetlands
11
21
SAS 213036
March 2016
The hydrology of all wetland features within the project footprint is likely to have been significantly
altered as a result of past and present anthropogenic and earthmoving activities and as a result of the
encroachment of alien and invasive species into wetland features 13. No evidence of connected
surface flow was encountered during the field assessment between the depressions assessed.
However, a moderate aquifer activity has been indicated by the Tygerberg District Plan (2012) for the
eastern half of the project footprint and an impermeable calcrete layer was noted within 50cm of the
soil surface in the majority of the wetland features encountered. Sub-surface flow along these
impermeable calcrete lenses and hydrological connectivity between individual wetland features within
the project footprint as well as between wetland features within the project footprint and freshwater
features outside of the project footprint boundary were confirmed by the Groundwater Specialist Study
(GEOSS, 2014). Impacts associated with the infilling of wetlands and the potential pollution of wetland
features may therefore extend beyond the project footprint boundary.
3.8 EIS Determination
A series of determinants for EIS are assessed on a scale of 0 to 4, where a score (Scr) of 0 indicates
no importance and 4 indicates very high importance. In addition, the confidence of scores is indicated
within the table below (Conf), where 0 indicates a very low confidence and 4 indicates a high
confidence. The median of the determinants is used to assign the EIS Category as listed in Table 5
below.
Table 5: EIS determination
Determinant
PRIMARY DETERMINANTS
1. Rare & Endangered Species
2. Populations of Unique Species
3. Species/taxon Richness
4. Diversity of Habitat Types or
Features
5. Migration route/breeding and
feeding site for wetland species
6. PES as determined by WET-Health
assessment
7. Importance in terms of function and
service provision
MODIFYING DETERMINANTS
8. Protected Status according to
NFEPA Wetveg
9. Ecological Integrity
TOTAL
MEDIAN
OVERALL EIS
South
eastern
Scr
Conf
Central
wetland
Scr
Conf
Transformed
Brushcut
Mowed
depressions
depressions
depressions
Scr
Conf Scr
Conf
Scr
Conf
1
0
1
1
3
3
4
3
1
0
1
1
3
3
4
3
0
0
0
0
4
4
4
3
0
0
0
0
4
4
4
4
0
0
0
0
4
4
4
4
2
3
2
3
1
3
0
4
0
4
1
4
2
4
1
4
0
4
0
4
1
4
1
4
0
4
0
4
0
4
1
4
1
4
1
4
1
4
1
4
2
10
1.1
C
3
2
11
1.2
C
3
0
3
0.3
D
3
0
1
0.1
D
4
0
1
0.1
D
4
Based on the findings of the study it is evident that the south eastern and central wetlands have an
EIS falling within Category C (moderate EIS) and that transformed, brushcut and mowed depressions
have an EIS falling within Category D (low EIS). The south eastern and central wetlands are
considered to be in a slightly less disturbed ecological condition when compared to transformed,
brushcut and mowed depressions and provide the habitat to support indigenous floral, faunal and
avifaunal species. Although floral species diversity within these features is considered to be moderate
to low and alien grass species as well as A. saligna are present, the rehabilitation of the features may
13
Alien and invasive species are likely to reduce the inputs of water into wetland features and are likely to absorb large volumes of water from features.
22
SAS 213036
March 2016
result in the reinstatement of indigenous floral species and may improve the function and service
provision of the features and it is therefore deemed likely that the PES of the features can be
improved. The south eastern and central wetlands are therefore considered to be of a moderate
sensitivity.
Transformed, brushcut and mowed depressions have been significantly disturbed and the resultant
decrease in the habitat integrity, functionality and service provision of the features has reduced the
EIS of the features.
23
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March 2016
Legend
PROJECT FOOTPRINT
MODERATE
LOW
EIS
Figure 12: Ecological Importance and Sensitivity of wetland features
24
SAS 213036
March 2016
3.9 Recommended Ecological Category
All wetland features within the project footprint were determined to have moderately low to low levels
of ecological function and service provision and are considered to be in largely modified, seriously
modified and critically modified conditions. A. saligna encroachment, dumping and ongoing
disturbance due to anthropogenic activities have had a negative impact on the wetland features and
have resulted in the decrease of the EIS of wetland features. However, the south eastern and central
wetland features are considered to be in a better ecological condition when compared to transformed,
brushcut and mowed depressions.
The habitat integrity of the wetland features has been lost to a great extent. However, if the wetlands
are rehabilitated and cleared of alien vegetation and dumped waste, it is deemed possible that the
overall PES of the features can be increased. The Recommended Ecological Category (REC)
deemed appropriate for the management of the features is Category C (moderately modified).
3.10 Wetland Delineation
All wetland features identified at the time of the assessment have been indicated in the map to follow
(Figure 13). It should however be noted that the extents of wetland areas as identified by the
Prioritisation of City Wetlands Map and indicated in the map below may have in some areas been
drastically reduced due to the encroachment of A. saligna into the features and due to current edge
effects as a result of activities at the airport.
3.11 Buffer Allocation
All wetland features located to the east of the existing runway within the project footprint will be lost.
The provision of a buffer to wetland features to inform project planning was therefore not deemed
viable (for illustrative purposes a 32m wetland buffer has however been indicated in the map to
follow). However, the infilling of wetland features is defined as a water use that in terms of Section 21
(c) and (i) of the National Water Act (Act No. 36 of 1998) will require a Water Use Licence (WUL).
25
SAS 213036
March 2016
Figure 13: Wetland delineation (32m buffer indicated for illustrative purposes only).
26
SAS 213036
4
March 2016
IMPACT ASSESSMENT
4.1 Direct Impact
The tables below serve to summarise the significance of perceived impacts on the freshwater ecology
and biodiversity of the project footprint and surrounding freshwater ecosystems. All wetland habitat
located to the east of the existing runway will be lost during the construction phase of the
development. Therefore, impact due to loss of wetland habitat was assessed for the construction
phase of the development only. However, mowed depressions located to the west of the existing
runway will not be permanently removed during the construction phase and impacts on these features
could therefore be assessed for both the construction and operational phases of the development.
Furthermore, activities within the project footprint may have an impact on freshwater features and the
hydrological systems located beyond the project footprint boundaries, although very limited, and these
impacts may extend into the operational phase of the development. Impacts on freshwater features
located beyond the project footprint boundary were therefore assessed for both phases of the
development.
The tables below present the impact assessment according to the method provided by SRK. The
sections also indicate the required mitigatory measures needed to minimise the impact, if any
mitigation is deemed possible. The tables present an assessment of the significance of the impacts
taking into consideration the available mitigatory measures assuming that they are fully implemented.
Table 6 below illustrates the mitigation hierarchy, a fundamental tool for impact mitigation (DEA et. al.,
2013), as well as the forms of mitigation which may be applicable to this project.
Table 6: The Mitigation Hierarchy and the forms of mitigation which are applicable to the
project
Forms of mitigation
Avoid or prevent impacts
Minimise impacts
Rehabilitate impacts
Offset impacts
Applicability
The entire project footprint to the east of the existing runway will be cleared of
vegetation and all wetland features will be lost, therefore impacts cannot be avoided
or prevented.
The entire project footprint to the east of the existing runway will be cleared of
vegetation and all wetland features will be lost, therefore impacts cannot be
minimised. However, any wetland features not falling directly within the footprint of
the project should not be disturbed.
The re-instatement of the wetland PES is not compatible with the proposed land use
and all wetlands located to the east of the existing runway within the project footprint
will be lost. Rehabilitation of wetland features will therefore not take place.
An offset area may be considered in order to compensate for residual negative
impacts on wetland habitat and biodiversity.
27
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March 2016
IMPACT 1: LOSS OF HABITAT AND ECOLOGICAL STRUCTURE
Construction Phase
All wetland habitat and ecological structure located to the east of the existing runway within the
project footprint will be lost as a result of bulk earthworks and construction related activities, and
mowed depressions located to the west of the existing runway, although not earmarked for
development, are likely to be disturbed as a result of the edge effects of construction activities.
Although the loss of wetland habitat from the project footprint will be local in extent, the loss of these
endangered Western Strandveld wetland habitat is considered to be of a regional significance due to
the already significant loss of wetland features from the region as a result of urban sprawl.
The intensity of impacts associated with the loss of the more intact habitat associated with the south
eastern and central wetland is considered to be higher than the loss of less intact habitat associated
with transformed, brushcut and mowed depressions. The overall intensity of the loss of wetland
habitat was determined to be medium and the overall significance of the impact was determined to be
medium prior to mitigation.
Operational Phase
The wetland habitat that will not be lost due to construction activities may be impacted as a result of
operational activities including the indiscriminate movement of operational vehicles through the
features as well as maintenance activities undertaken during the operational phase such as the
mowing of grass. However, mowed depressions have already been significantly impacted as a result
of historic earth moving activities and activities associated with current airport operations, and the
wetland habitat is therefore considered to be of a low conservation value. Therefore, impacts
associated with the disturbance of this habitat, are considered to be of a low intensity and are
considered insignificant prior to and after the implementation of mitigation measures.
28
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Without
Mitigation
March 2016
Extent
Intensity
Duration
Consequence
Probability
Significance
Status
Confidence
MEDIUM14
– ve
High
Construction Phase
Without
mitigation
Regional
Medium
2
2
Longterm
3
High
Definite
7
Operational Phase
ShortLocal
Low
Very Low
Without
term
Possible
INSIGNIFICANT
– ve
High
mitigation
1
1
1
3
Essential mitigation measures during the construction phase
 Approval must be obtained from DWA for any activities within wetland areas. In this regard special mention is made
of water use licences in terms of Section 21 (c) and (i) of the National Water Act;
 Implement general good housekeeping mitigation measures (see Appendix B) in order to avoid impact on mowed
depressions located to the west of the existing runway.
Recommended mitigation measures during the construction phase
 N/A
Essential mitigation measures during the operational phase
 Implement general good housekeeping mitigation measures (see Appendix B) in order to avoid impact on mowed
depressions located to the west of the existing runway.
Recommended mitigation measures during the operational phase
 N/A
With
Extent
Intensity
Duration Consequence Probability
mitigation
Construction Phase
LongRegional
Low
Medium
With
term
Definite
mitigation
2
1
3
6
Significance
Status
Confidence
MEDIUM
– ve
High
INSIGNIFICANT
– ve
High
Operational Phase
With
mitigation
Local
Low
1
1
Shortterm
1
Very Low
Improbable
3
it is the opinion of the wetland specialist that the significance ratings should be decreased from a high to a medium significance due to the current level of
transformation of the wetland habitat
14
29
SAS 213036
March 2016
IMPACT 2: LOSS OF ECOLOGICAL AND SOCIO-CULTURAL SERVICE
PROVISION
Construction Phase
All wetland features within the project footprint were calculated to be of a low to moderately low
importance in terms of ecological function and service provision (refer to Section 3.5) and the impact
is therefore considered to be of a low intensity. Bulk earthworks and construction activities will result
in loss of function and services pertaining to biodiversity maintenance, assimilation and flood
attenuation capability. Due to limited surface connectivity between wetlands within the project footprint
and wetlands within surrounding areas, the impact would be restricted to the project footprint and was
therefore determined to be local in extent. The overall impact on ecological and socio-cultural service
provision is therefore considered to be of a low significance prior to the implementation of mitigation
measures.
Although general housekeeping mitigation measures (refer to Appendix B) may reduce impacts on
mowed depressions located to the west of the existing runway, this is not likely to reduce the overall
impact on the loss of wetland ecoservice and function of wetlands located to the east of the existing
runway. Therefore, the overall impact significance associated with the loss of ecoservice and function
will remain low after mitigation.
Operational Phase
Only the mowed depressions located to the west of the existing runway will remain intact within the
project footprint during the operational phase of the development. It is possible that these features will
be impacted as a result of the edge effects of maintenance activity which may result in a further
decline of their importance in terms of service and function provision. However, these features were
calculated to play a limited role in the provision of ecoservices and function and the intensity of impact
is therefore considered low. Furthermore, services which are provided by the features are likely to be
limited to the project footprint and immediate surroundings and impact is therefore considered to be of
a local extent. The impact associated with the loss of ecoservice and function from these features is
therefore considered to be insignificant prior to and after the implementation of mitigation measures.
30
SAS 213036
Unmanaged
March 2016
Extent
Intensity
Duration
Consequence
Probability
Significance
Status
Confidence
LOW
– ve
High
Construction Phase
Without
mitigation
Local
Low
1
1
Longterm
3
Low
Definite
5
Operational Phase
ShortVery Low
term
Possible
INSIGNIFICANT
– ve
High
1
1
1
3
Essential mitigation measures during the construction phase
 Implement general good housekeeping mitigation measures (see Appendix B) in order to avoid impact on mowed
depressions located to the west of the existing runway.
Without
mitigation
Local
Low
Recommended mitigation measures during the construction phase
 N/A
Essential mitigation measures during the operational phase
 Implement general good housekeeping mitigation measures (see Appendix B) in order to avoid impact on mowed
depressions located to the west of the existing runway.
Recommended mitigation measures during the operational phase
 N/A
Managed
Extent Intensity Duration Consequence Probability
Significance
Status
Confidence
LOW
– ve
High
INSIGNIFICANT
– ve
High
Construction Phase
With
mitigation
Local
Low
1
1
Longterm
3
Low
Definite
5
Operational Phase
With
mitigation
Local
Low
1
1
Shortterm
1
Very Low
3
31
Improbable
SAS 213036
March 2016
IMPACT 3: IMPACTS ON HYDROLOGICAL FUNCTION AND SEDIMENT
BALANCE
Construction Phase
All wetland features within the project footprint will be disturbed as a result of bulk earthworks and
construction activities and the hydrological functioning of the features will therefore be altered to some
degree. The groundwater levels are also expected to increase following the removal of alien
vegetation from the project footprint. The Groundwater Specialist Study (GEOSS, 2014), however
determined that the alteration of the hydrological regime due to the proposed development will not be
significant. As a result, the intensity of the impact was determined to be low and would most likely only
be local in extent. The impact associated with the loss of the hydrological function and sediment
balance was therefore determined to be of a low significance prior to the implementation of mitigation
measures. With the implementation of general housekeeping measures and well-considered,
implemented and managed mitigation measures as listed within this report as well as all additional
mitigation measures provided in the Groundwater Specialist Study (GEOSS, 2014) the impact
significance can be reduced to an even lower significance which becomes insignificant in the regional
ground and surface water regime.
Operational Phase
Impact on wetland hydrology associated with wetlands located within the proposed project footprint is
considered marginal and sediment balance will no longer be applicable. Only the mowed depressions
located to the west of the existing runway will remain intact within the project footprint during the
operational phase of the development. It is possible that the hydrological function and sediment
balance of these features may be altered as a result of an increase in stormwater runoff entering into
the features from surrounding hardened surfaces and as a result of an increase in sediment carried
into the features from surrounding disturbed areas. However, the hydrological function and sediment
balance of the features have already been significantly altered as a result of historic earthmoving
activities, existing hard surfaces and current airport operations. The impact associated with the further
modification of the hydrological regime was therefore determined to be of a low intensity.
Furthermore, the impact is likely to be confined to the project footprint and was therefore determined
to be of a local extent. The impact was therefore determined to be insignificant prior to and after the
implementation of mitigation measures.
32
SAS 213036
Unmanaged
March 2016
Extent
Intensity
Duration
Consequence
Probability
Significance
Status
Confidence
LOW
– ve
High
Construction Phase
Without
mitigation
Local
Low
1
1
Longterm
3
Low
Definite
5
Operational Phase
ShortLocal
Low
Very Low
Without
term
Possible
INSIGNIFICANT
– ve
High
mitigation
1
1
1
3
Essential mitigation measures during the construction phase
 Implement general good housekeeping mitigation measures (see Appendix B) in order to avoid impact on mowed
depressions located to the west of the existing runway;
 Incorporate adequate erosion management measures within the project footprint in order to prevent erosion and the
associated sedimentation of wetlands located to the west of the existing runway. Management measures may include
berms, soil traps, hessian curtains, stormwater diversion away from areas susceptible to erosion and stormwater
attenuation. Care should however be taken so as to avoid additional disturbance during the implementation of these
measures;
 Sheet runoff from cleared areas and access roads must be curtailed; and
 Cleared areas must be revegetated as soon as possible in order to reduce the erosion of topsoils and the associated
sedimentation of wetland features located to the west of the existing runway.
Recommended mitigation measures during the construction phase
 N/A
Essential mitigation measures during the operational phase
 Ensure that runoff drains from the operational areas, without overflowing drainage systems;
 Sheet runoff from paved surfaces and access roads must be curtailed;
 Attenuate stormwater in order to prevent erosion;
 Maintain stormwater infrastructure;
 Implement general good housekeeping mitigation measures (see Appendix B) in order to avoid impact on mowed
depressions located to the west of the existing runway.
Recommended mitigation measures during the operational phase
 N/A
Managed
Extent Intensity Duration Consequence Probability
Significance
Status
Confidence
Construction Phase
With
mitigation
Local
Low
1
1
Longterm
3
Low
Definite
LOW
– ve
High
INSIGNIFICANT
– ve
High
5
Operational Phase
With
mitigation
Local
Low
1
1
Shortterm
1
Very Low
3
33
Improbable
SAS 213036
March 2016
IMPACT 4: IMPACTS ON FRESHWATER FEATURES LOCATED OUTSIDE OF
THE PROJECT FOOTPRINT AREA
Construction Phase
During the construction phase of the development bulk earthworks and construction activities will
result in the removal of vegetation and the compaction of soils within the project footprint. Surface
runoff from compacted areas is therefore likely to increase and the erosion of areas with disturbed
soils is likely to occur. This will result in an increase in the volume of sediment laden surface water
entering into surrounding stormwater systems and hence surrounding freshwater features. Therefore,
construction related activities within the project footprint could ultimately result in the sedimentation
and erosion of downstream areas.
The loss of wetland habitat from the project footprint during the construction phase may also impact
on the quality of surface water entering downstream systems. Depressions within the project footprint
play a small role in the assimilation of nitrates, phosphates and toxicants from surface water before it
enters into surrounding stormwater drainage systems and are likely to play a role in the attenuation of
stormwater and runoff from the site. With the development of the project footprint all depressions
located to the east of the existing airport runway will be lost together with the associated assimilation
and attenuation capabilities. Therefore, the quality of stormwater entering surrounding drainage
systems and downstream features may be marginally reduced.
In addition, edge effects associated with construction activities may result in the disturbance of
freshwater features as indicated by the Prioritisation of City Wetlands Map (refer to Figure 4) which
are located adjacent to the project footprint. Edge effects may include the indiscriminate movement of
construction vehicles through the features or the dumping of construction material within features.
However, with the implementation of general housekeeping mitigation, the impact can be largely
avoided.
Although the bulk earthworks and construction activities would be restricted to the local area the
development of the project footprint and the associated removal of vegetation and disturbance of soil
may result in impacts which could extend beyond the project footprint boundaries. The volume and
velocity of stormwater exiting the project footprint from cleared areas may increase as stormwater
entering the site will no longer be intercepted by vegetation or attenuated by wetlands. The increased
velocity and volume of stormwater moving over disturbed areas may also result in the erosion of
disturbed soils and may affect the sediment load and quality of stormwater entering into existing
stormwater drainage systems15 and therefore into surrounding freshwater features. The impact is
therefore perceived to be of a regional scale. However, stormwater exiting the project footprint moves
through a series of canals and pipelines before eventually reaching surrounding freshwater systems.
The sediment load and velocity of stormwater is therefore likely to decrease significantly before it
enters into more sensitive downstream features such as the Zeekoevlei and the Kuils River, and the
impact intensity was therefore determined to be low. In addition, the construction phase of the
development is expected to last 24 to 30 months and impacts associated with increase quantity and
decrease quality of stormwater associated with this phase of the development will therefore extend
over a medium duration.
The overall impact on freshwater features falling outside of the project footprint was therefore
determined to be of a low significance. It is also deemed possible that impacts can be further reduced
with the implementation of mitigation measures such as the attenuation of stormwater which would
The Lotus River receives discharge from the existing airport drainage system, via the airport stormwater detention pond located in Airport Industria; and
the existing stormwater detention pond at the corner of Borchards Quarry Road and Modderdam Road is situated on ACSA property and drains towards the
Kalksteenfontein culvert via a series of ponds (SRK, 2013).
15
34
SAS 213036
March 2016
result in a decrease in intensity and probability of the impact and a decrease in the significance of the
impact to a very low level.
Operational Phase
An increase in hardened surfaces during the operational phase is likely to result in an increase in
stormwater runoff entering into surrounding stormwater systems. Furthermore, if disturbed areas are
not revegetated after construction activities have been completed, there is a high potential for the
continued erosion of topsoils and the associated sedimentation of surrounding freshwater system. In
addition, fuel spills from operational vehicles and aircraft may occur and these chemicals may be
carried to surrounding freshwater features in surface runoff.
Although sediment laden stormwater originates within the project footprint, stormwater infrastructure
will carry the water to surrounding freshwater systems and the impact was therefore determined to be
of a regional extent. However, as previously mentioned, stormwater exiting the project footprint moves
through a series of canals and pipelines before eventually reaching surrounding freshwater systems
such as the Kuils River and the Zeekoevlei. The sediment load and velocity of stormwater is therefore
likely to decrease significantly before it enters into surrounding features and the impact intensity was
therefore determined to be low. However, stormwater will continue to leave the project footprint for the
duration of the operation of the airport and the impact was therefore determined to be of a long term
duration.
The overall impact on freshwater features falling outside of the project footprint was therefore
determined to be of a medium significance. Although the implementation of mitigation measures will
likely result in the reduction of the intensity and probability of impacts, the duration and scale would
not be able to be reduced. Impact significance can therefore only be reduced to a low level.
35
SAS 213036
Unmanaged
March 2016
Extent
Intensity
Duration
Consequence
Probability
Significance
Status
Confidence
LOW
– ve
High
Construction Phase
Without
mitigation
Regional
Low
2
1
Mediumterm
2
Low
Probable
5
Operational Phase
LongRegional
Low
Medium
Without
term
Probable
MEDIUM
– ve
High
mitigation
2
1
3
6
Essential mitigation measures during the construction phase
 Incorporate adequate erosion management measures within the project footprint in order to prevent erosion and the
associated sedimentation of freshwater features beyond the project footprint boundary. Management measures may
include berms, soil traps, hessian curtains, stormwater attenuation facilities and stormwater diversion away from
areas susceptible to erosion. Care should however be taken so as to avoid additional disturbance during the
implementation of these measures;
 Sheet runoff from cleared areas and access roads must be curtailed;
 Any discharge of runoff into freshwater systems beyond the project footprint boundary must be done in such a way as
to prevent erosion. In this regard special mention is made of the use of energy dissipating structures in stormwater
discharge into existing stormwater infrastructure; and
 Cleared areas must be revegetated as soon as possible in order to reduce the erosion of topsoils and the associated
sedimentation of freshwater features.
Recommended mitigation measures during the construction phase
 N/A.
Essential mitigation measures during the operational phase
 Ensure that runoff drains from the operational areas, without overflowing drainage systems;
 Sheet runoff from paved surfaces and access roads must be curtailed;
 Minimise paved and sealed surfaces in order to reduce runoff;
 Regularly inspect all Airports Company South Africa vehicles for leaks. Re-fuelling must take place in a designated
area or off site;
 Spills must be immediately cleaned up and treated accordingly;
 Maintain stormwater infrastructure; and
 Any discharge of runoff into freshwater systems beyond the project footprint boundary must be done in such a way as
to prevent erosion. In this regard special mention is made of the use of energy dissipating structures in stormwater
discharge.
Recommended mitigation measures during the operational phase
 Monitor the quantity and quality of stormwater entering into surrounding freshwater features as part of the stormwater
management plan.
Managed
Extent Intensity Duration Consequence Probability
Significance
Status Confidence
Construction Phase
With
mitigation
Regional
Low
2
1
Mediumterm
2
Low
Possible
VERY LOW
– ve
High
LOW
– ve
High
5
Operational Phase
With
mitigation
Regional
Low
2
1
Longterm
3
Medium
6
36
Possible
SAS 213036
March 2016
4.2 No-go Alternative
Should the development of the project footprint not take place, it is considered highly likely that the
PES of the south eastern, central and transformed wetland features would decrease as a result of the
proliferation of A. saligna and the further encroachment of A. saligna into the features. The PES of the
brushcut and mowed depressions would remain the same due to ongoing maintenance activities.
4.3 Cumulative Impacts
The project footprint covers wetlands which fall within the Western Strandveld wetland vegetation
group. This wetland vegetation group is considered to be endangered in the region and is under
threat as a result of urban sprawl and the spread of alien invasive vegetation. The development of the
project footprint will therefore contribute to the loss of endangered Western Strandveld wetland
vegetation from the region. However, the majority of the wetland features within the project footprint
are significantly transformed, therefore the loss of the vegetation from the project footprint is
considered of a reduced significance.
4.4 Indirect Impacts
Impacts on wetland ecology will occur within the project footprint as a result of activities associated
with the development of the realigned runway. The activities on the project footprint that could lead to
an impact have been comprehensively discussed in the impact assessment for the site specific
activities. However, the development of the project footprint may result in additional indirect impacts
as a result of an increase in stormwater runoff from hardened surfaces and as a result of an increase
in chemicals carried by stormwater runoff from developed runway areas.
4.5 Offset Recommendations
Various mitigation measures that could eliminate the need for a wetland offset were identified by the
specialists in line with the mitigation hierarchy, including the rehabilitation and recreation of wetlands
on site, as well as the revegetation of disturbed areas with Cape Flats Dune Strandveld, rather than
grass species. These mitigation measures were considered by ACSA, however due to safety
concerns associated with the potential for wetlands to attract birds to the area (increasing the risk of
bird strikes) as well as concerns raised by the Airport’s Fire and Rescue department in terms of
accessibility to the airfield, ACSA have confirmed that they are not able to implement these mitigation
measures and a wetland habitat conservation offset would thus be required while no wetland
functionality offset is deemed necessary.
A wetland offset must be considered in order to compensate for the unavoidable loss of wetland
habitat from the south eastern and central wetlands in order to ensure no net loss of wetland habitat.
Wetland offsets requirements were determined by making use of the DWS wetland offset calculator
tool. A wetland offset should ideally conserve habitat which is similar to that which will be lost. The
DWS should be consulted on how to proceed in this regard.
4.6 Monitoring Campaigns
The proposed project would result in loss of all wetlands, except for wetland features presently
located to the west of the existing runway. The degree of transformation of the wetlands that would
remain as part of the development is considered very high and therefore, presently, these features
were determined to have almost no probability of supporting viable wetland faunal or floral
populations. Faunal wetland species diversity and abundance would also decrease significantly with
37
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the loss of wetland vegetation in combination with the increase of anthropogenic activities within the
remaining project footprint. In summary the proposed development will result in the decrease in
abundance as well as diversity of all wetland faunal and floral assemblages assessed and therefore it
is the opinion of the specialist that no monitoring would be necessary during the operation phase of
the development. However, the monitoring of the quantity and quality of stormwater entering into
surrounding freshwater features should be undertaken as part of the stormwater management plan.
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CONCLUSIONS
SAS was appointed to conduct a freshwater ecological impact assessment as part of the
environmental assessment and authorisation process for the proposed realignment of the primary
runway at the Cape Town International Airport. As the first phase in the development of the Cape
Town International Airport as envisaged in the Master Plan, ACSA proposes to construct a new (realigned) runway, rotated through 11.5°, to replace the existing primary runway (Runway 01-19). The
northern end of the new runway will be positioned 220m to the east of the current Runway 01-19. It
will comply with international specifications for Code F aircraft, increase runway capacity and enable
future airport expansion.
In addition to the re-aligned runway, the current project will also include:
 A taxiway system;
 Infrastructure such as an aircraft isolation pad, a compass calibration pad and an aircraft runup area;
 Security facilities;
 Service roads;
 Buildings and service infrastructure;
 Upgrading of the stormwater management system; and
 Bulk earthworks for the sourcing and on site use of cut/fill material.
The following general conclusions were drawn upon completion of the freshwater ecological
assessment:
 The Cape Town International Airport falls within the Cape Flats which is documented as a
‘special case’ wetland area within the Western Cape due to the presence of a sandy soils
coastal aquifer (Job, 2009). Therefore, a large proportion of water augmenting wetlands will
be from the shallow water table. However, surface runoff from concrete surfaces, roads and
disturbed areas within the catchment, will also contribute significantly to the amount of water
reaching wetland features within the project footprint;
 According to the Prioritisation of City Wetlands Map (2009) the project footprint covers
numerous Dune Strandveld natural and semi natural, inland, isolated depression wetlands.
However, upon assessment of the project footprint it became evident that the majority of
these wetland features are in a significantly transformed PES;
 No additional surface water features were identified within the project footprint;
 Although the majority of wetland features within the project footprint are in a transformed
state, two wetland features are considered to be of a slightly higher EIS. These features
include a large wetland feature (±15.5ha) within the south eastern corner of the project
footprint (hereafter referred to as the south eastern wetland) and a smaller wetland feature
(±0.28ha) located within the north-eastern portion of the project footprint (hereafter referred to
as the central wetland);
 Wetland features associated with the project footprint can be divided into five wetland groups
which include transformed depressions, brushcut depressions, mowed depressions, the south
eastern wetland and the central wetland;
 The function and service provision was calculated for each of the wetland groups associated
with the project footprint. From the results of the assessment, it is evident that none of the
features encountered within the project footprint are regarded as being of exceptional
importance in terms of function and service provision. The south eastern wetland and central
wetland as well as transformed and mowed depressions were determined to have a
moderately low level of ecoservice provision and function and that brushcut depressions were
calculated to have a low level of ecoservice provision and function;
 The PES of all wetland features was determined using the WET-health methodology. The
overall categories for the wetland features are as follows:
 South eastern wetland - PES Category E (seriously modified);
 Central wetland - PES Category D (largely modified);
 Transformed wetlands - PES Category E (seriously modified);
 Brushcut wetlands – PES Category F (critically modified); and
 Mowed wetlands - PES Category F (critically modified).
 The EIS was calculated for each wetland group:
39
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





The south eastern and central wetlands were calculated to have an EIS falling within
Category C (moderately sensitivity); and
 The transformed, brushcut and mowed depressions were calculated to have an EIS
falling within Category D (low sensitivity).
No evidence of connected surface flow was encountered during the field assessment
between the depressions assessed. However, a moderate aquifer activity has been indicated
by the Tygerberg District Plan (2012) for the eastern half of the project footprint
Impermeable calcrete lenses were noted within 50cm of the soil surface which is the
geological conditions which supports the majority of the wetland features encountered. Subsurface flow along these impermeable calcrete lenses and hydrological connectivity between
individual wetland features within the project footprint as well as between wetland features
within the project footprint and freshwater features outside of the project footprint boundary
were confirmed by the Groundwater Specialist Study (GEOSS, 2014).;
The Groundwater Specialist Study (GEOSS, 2014), however determined that the alteration of
the hydrological regime due to the proposed development will not be significant. As a result,
the intensity of the impact was determined to be low and would most likely only be local in
extent.
Due to the highly disturbed nature of the project footprint and due to the severe encroachment
of Acacia saligna into wetland features, the accurate delineation of wetland features on site
was not deemed possible. Therefore, for the purpose of this assessment, wetlands were
delineated with the use of wetland boundaries as indicated by the City of Cape Town
Prioritisation of City Wetlands Map (2009) as well as with the use of aerial photography, and
where possible field verification of wetland boundaries was undertaken and used to assist in
making remote delineation techniques more accurate; and
All wetland features located to the east of the existing runway within the project footprint will
be infilled and lost. The provision of a buffer to wetland features was therefore not deemed
viable (for illustrative purposes a 32m wetland buffer has however been indicated in the
wetland delineation map – Figure 13). However, the infilling of wetland features is defined as
a water use that in terms of Section 21 (c) and (i) of the NWA (Act No. 36 of 1998) will require
a WUL.
40
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IMPACT ASSESSMENT
Table B below summarises the findings of the impact assessment, indicating the significance of each
impact before management takes place and the likely significance of the impacts if management and
mitigation takes place.
Table B: Summary of impact assessment results.
Impact
Consequence
Probability
Significance
Status
Confidence
IMPACT 1: LOSS OF WETLAND HABITAT AND ECOLOGICAL STRUCTURE
Construction Phase
Without mitigation
With Mitigation
High
Medium
Definite
Definite
MEDIUM16
MEDIUM
–ve
–ve
High
High
–ve
–ve
High
High
Operational Phase
Without mitigation
With Mitigation
Very Low
Very Low
Possible
Improbable
INSIGNIFICANT
INSIGNIFICANT
IMPACT 2: LOSS OF WETLAND ECOLOGICAL AND SOCIO-CULTURAL SERVICE PROVISION
Construction Phase
Without mitigation
With Mitigation
Low
Low
Without mitigation
With Mitigation
Very Low
Very Low
Definite
Definite
LOW
LOW
–ve
–ve
High
High
–ve
–ve
High
High
Operational Phase
Possible
Improbable
INSIGNIFICANT
INSIGNIFICANT
IMPACT 3: LOSS OF WETLAND HYDROLOGICAL FUNCTION AND SEDIMENT BALANCE
Construction Phase
Without mitigation
With Mitigation
Low
Low
Definite
Definite
LOW
LOW
–ve
–ve
High
High
–ve
–ve
High
High
Operational Phase
Without mitigation
With Mitigation
Very Low
Very Low
Possible
Improbable
INSIGNIFICANT
INSIGNIFICANT
IMPACT 4: IMPACTS ON FRESHWATER FEATURES LOCATED OUTSIDE OF THE PROJECT FOOTPRINT
AREA
Construction Phase
Without mitigation
With Mitigation
Low
Low
Probable
Possible
LOW
VERY LOW
–ve
–ve
High
High
–ve
–ve
High
High
Operational Phase
Without mitigation
With Mitigation
Medium
Medium
Probable
Possible
MEDIUM
LOW
CONCLUSION
Bulk earthworks and construction related activities will result in the permanent loss of all wetland
features located to the east of the existing runway. Transformed, mowed and brushcut depressions
are in a significantly degraded condition and the PES and EIS of the features is considered low. The
loss of these wetlands from the project footprint is therefore considered to be of a low significance.
However, two wetland features, the south eastern wetland and the central wetland, are considered to
be of a slightly higher PES and EIS.
Although the impact rating methodology provided by SRK resulting in a high significance rating, it is the opinion of the wetland specialist based on
professional judgement and experience that the significance ratings should be decreased from a high to a medium significance due to the current level of
transformation of the wetland habitat
16
41
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March 2016
No evidence of connected surface flow was encountered during the field assessment between the
depressions assessed. However, a moderate aquifer activity has been indicated by the Tygerberg
District Plan (2012) for the eastern half of the project footprint and an impermeable calcrete layer was
noted within 50cm of the soil surface in the majority of the wetland features encountered. According to
GEOSS (2014) these impermeable layers occur as discontinuous lenses which would then lead to the
formation of perched depressions in areas where they occur close to the soil surface. Sub-surface
flow along these impermeable lenses and hydrological connectivity between individual wetland
features within the project footprint was confirmed by the Groundwater Specialist Study (GEOSS,
2014);
The habitat integrity of the wetland features have been lost to a great extent and the reinstatement of
functions and service provision of the features would require substantial investment in order to
improve the conditions of the system to a level where they are representative of the local vegetation
type. However, if the wetlands are rehabilitated and cleared of alien vegetation and dumped waste, it
is deemed possible that the overall PES of the features can be improved to some degree. The
Recommended Ecological Category (REC) deemed appropriate for the management of the features is
Category C (moderately modified). However, it is noted that re-instatement of the wetland PES is not
compatible with the proposed land use and therefore it is recommended that ACSA enter into an
appropriate wetland offset or stewardship program in order to mitigate the impact and loss of wetland
resources that will take place since other mitigation mechanisms higher up in the mitigation hierarchy
are unlikely able to be pursued if the project proceeds.
Various mitigation measures that could eliminate the need for a wetland offset were identified by the
specialists in line with the mitigation hierarchy, including the rehabilitation and recreation of wetlands
on site, as well as the revegetation of disturbed areas with Cape Flats Dune Strandveld, rather than
grass species. These mitigation measures were considered by ACSA, however due to safety
concerns associated with the potential for wetlands to attract birds to the area (increasing the risk of
bird strikes) as well as concerns raised by the Airport’s Fire and Rescue department in terms of
accessibility to the airfield, ACSA have confirmed that they are not able to implement these mitigation
measures and a wetland habitat conservation offset would thus be required while no wetland
functionality offset is deemed necessary.
A wetland offset must be considered in order to compensate for the unavoidable loss of wetland
habitat from the south eastern and central wetlands in order to ensure no net loss of wetland habitat.
Wetland offsets requirements were determined by making use of the DWS wetland offset calculator
tool. A wetland offset should ideally conserve habitat which is similar to that which will be lost. The
DWS should be consulted on how to proceed in this regard.
Due to the low EIS of the majority of the wetland features within the project footprint, it is the opinion
of the wetland specialist that impacts associated with the development of the project footprint are
considered acceptable and that the proposed development be considered favourably, provided that
an appropriate wetland offset or stewardship program is entered into and provided that the mitigation
measures below are adhered to:
Construction Phase
 Approval must be obtained from DWA for any activities within wetland areas. In this regard
special mention is made of water use licences in terms of Section 21 (c) and (i) of the
National Water Act;
 Incorporate adequate erosion management measures within the project footprint in order to
prevent erosion and the associated sedimentation of wetlands located to the west of the
existing runway and of freshwater features beyond the project footprint boundary.
Management measures may include berms, soil traps, hessian curtains, stormwater diversion
42
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



March 2016
away from areas susceptible to erosion and stormwater attenuation. Care should however be
taken so as to avoid additional disturbance during the implementation of these measures;
Sheet runoff from cleared areas and access roads must be curtailed;
Any discharge of runoff into freshwater systems beyond the project footprint boundary must
be done in such a way as to prevent erosion. In this regard special mention is made of the
use of energy dissipating structures in stormwater discharge into existing stormwater
infrastructure;
Cleared areas must be revegetated as soon as possible in order to reduce the erosion of
topsoils and the associated sedimentation of wetland features located to the west of the
existing runway and of freshwater features beyond the project footprint boundary; and
Implement general good housekeeping practices (see Appendix B) in order to avoid impact
on mowed depressions located to the west of the existing runway.
Operational Phase
 Minimise paved and sealed surfaces in order to reduce runoff;
 Sheet runoff from paved surfaces and access roads must be curtailed;
 Ensure that runoff drains from the operational areas, without overflowing drainage systems;
 Attenuate stormwater in order to prevent erosion;
 Regularly inspect all Airports Company South Africa vehicles for leaks. Re-fuelling must take
place in a designated area or off site;
 Spills must be immediately cleaned up and treated accordingly;
 Any discharge of runoff into freshwater systems beyond the project footprint boundary must
be done in such a way as to prevent erosion. In this regard special mention is made of the
use of energy dissipating structures in stormwater discharge;
 Maintain stormwater infrastructure;
 Monitor the quantity and quality of stormwater entering into surrounding freshwater features
as part of the stormwater management plan; and
 Implement general good housekeeping practices (see Appendix B) in order to avoid impact
on mowed depressions located to the west of the existing runway.
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March 2016
REFERENCES
Bromilow, C. 2001. Revised Edition, First Impression. Problem Plants of South Africa. Briza
Publications, Pretoria, RSA.
City of Cape Town 2012. Tygerberg District Plan – Technical Report
Dada R., Kotze D., Ellery W. and Uys M. 2007. WET-RoadMap: A Guide to the Wetland
Management Series. WRC Report No. TT 321/07. Water Research Commission, Pretoria.
Department of Water Affairs and Forestry. 2005. A practical field procedure of identification and
delineation of wetlands and riparian areas. DWA, Pretoria
Department of Water Affairs and South African National Biodiversity Institute 2013. Wetland
Offsets: A Best Practice Guideline for South Africa. Pretoria. 100 pages
De Villiers, C., Driver, A., Clark, B., Euston-Brown, D., Day, L., Job, N., Helme, N.,
GEOSS. 2014. Groundwater Specialist Study – Cape Town International Airport Runway Realignment and Associated Infrastructure Project.
Holmes, P., Brownlie, S., Robelo, T. 2005. Fynbos Forum Ecosystem Guidelines for Environmental
Assessment in the Western Cape. Fynbos Forum and Botanical Society of South Africa,
Kirstenbosch, Cape Town
De Villiers, C., Driver, A., Clark, B., Euston-Brown, D., Day, L., Job, N., Helme, N., Van Ginkel,
CE., Glen, RP., Gordon-Gray, KD., Cilliers, CJ., Muasya, M and van Deventer, PP. 2011. Easy
identification of some South African Wetland Plants. WRC Report No TT 479/10.
Ewart-Smith, J. and Ractliffe, G. 2002. Assessment of the Potential Impacts of the Proposed N1 N2
Winelands Toll Highway Project on Aquatic Ecosystems. Southern Waters and The Freshwater
Consulting Group.
Helme, N. 2012. Ecological Assessment of Two Proposed Development Areas at Cape Town
International Airport. Nick Helme Botanical Surveys, Scarborough.
Henderson, L. 2001. Alien Weeds and Invasive Plants. Agricultural Research Council, RSA.
Job, N. 2009. Application of the Department of Water Affairs and Forestry (DWAF) wetland
delineation method to wetland soils of the Western Cape.
Kotze D.C., Marneweck G.C., Batchelor A.L., Lindley D.S. and Collins N.B. 2008. WETEcoServices: A technique for rapidly assessing ecosystem services supplied by wetlands. WRC
Report No. TT 339/08. Water Research Commission, Pretoria.
Macfarlane D.M., Kotze D.C., Ellery W.N., Walters D., Koopman V., Goodman P. and Goge C.
2009. WET-Health: A technique for rapidly assessing wetland health. WRC Report No. TT 340/09.
Water Research Commission, Pretoria.
Ollis, DJ; Snaddon, CD; Job, NM & Mbona, N. 2013. Classification System for Wetlands and other
Aquatic Ecosystems in South Africa. User Manual: Inland Systems. SANBI Biodiversity Series 22.
South African Biodiversity Institute, Pretoria.
SRK, 2013. Cape Town International Airport Runway Realignment and Associated Infrastructure
Environmental Impact Assessment: Scoping Report.
The South African National Biodiversity Institute - Biodiversity GIS (BGIS) [online]. Retrieved
2013/03/11 URL: http://bgis.sanbi.org
Van Staden, S. and van de Haar, N. 2012. Wetland Assessment as Part of the Environmental
Assessment and Authorisation Process for the Proposed Development of a Stormwater Outlet at
Cape Town International Airport
Van Oudtshoorn, F. 2004. Second Edition, Third Print. Guide to Grasses of South Africa. Briza
Publications, Pretoria, RSA.
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APPENDIX A
Wetland Assessment Methodology
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A – 1 Classification System for Wetlands and other Aquatic Ecosystems in South
Africa
All wetland features encountered within the project footprint were assessed using the
Classification System for Wetlands and other Aquatic Ecosystems in South Africa. User
Manual: Inland systems (Ollis et al., 2013).
A summary of Levels 1 to 4 of the proposed Classification System for Inland Systems are
presented in Table 1 and 2, below.
Table 1: Proposed classification structure for Inland Systems, up to Level 3.
WETLAND / AQUATIC ECOSYSTEM CONTEXT
LEVEL 1:
SYSTEM
LEVEL 2:
REGIONAL SETTING
LEVEL 3:
LANDSCAPE UNIT
DWA Level 1 Ecoregions
Valley Floor
OR
Inland Systems
Slope
NFEPA WetVeg Groups
Plain
OR
Other special framework
46
Bench
(Hilltop / Saddle / Shelf)
SAS 213036
March 2016
Table 2: Hydrogeomorphic (HGM) Units for the Inland System, showing the primary HGM
Types at Level 4A and the subcategories at Level 4B to 4C.
FUNCTIONAL UNIT
LEVEL 4:
HYDROGEOMORPHIC (HGM) UNIT
HGM type
Longitudinal zonation/ Landform / Outflow
drainage
Mountain headwater stream
Mountain stream
Transitional
Upper foothills
River
Lower foothills
Lowland river
Rejuvenated bedrock fall
Rejuvenated foothills
Upland floodplain
Channelled valley-bottom wetland
Unchannelled valley-bottom wetland
Floodplain wetland
(not applicable)
(not applicable)
Floodplain depression
Floodplain flat
Exorheic
Depression
Endorheic
Dammed
Seep
Wetland flat
With channelled outflow
Without channelled outflow
(not applicable)
47
Landform / Inflow drainage
Active channel
Riparian zone
Active channel
Riparian zone
Active channel
Riparian zone
Active channel
Riparian zone
Active channel
Riparian zone
Active channel
Riparian zone
Active channel
Riparian zone
Active channel
Riparian zone
Active channel
Riparian zone
(not applicable)
(not applicable)
(not applicable)
(not applicable)
With channelled inflow
Without channelled inflow
With channelled inflow
Without channelled inflow
With channelled inflow
Without channelled inflow
(not applicable)
(not applicable)
(not applicable)
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Level 1: Inland systems
For the proposed Classification System, Inland Systems are defined as an aquatic ecosystem that
have no existing connection to the ocean 17 (i.e. characterised by the complete absence of marine
exchange and/or tidal influence) but which are inundated or saturated with water, either
permanently or periodically. It is important to bear in mind, however, that certain Inland Systems
may have had an historical connection to the ocean, which in some cases may have been relatively
recent.
Level 2: Ecoregions
For Inland Systems, the regional spatial framework that has been included at Level 2 of the proposed
Classification System is that of Department of Water Affairs (DWA) Level 1 Ecoregions for aquatic
ecosystems (Kleynhans et al., 2005). There are a total of 31 Ecoregions across South Africa,
including Lesotho and Swaziland (figure below). DWA Ecoregions have most commonly been used to
categorise the regional setting for national and regional water resource management applications,
especially in relation to rivers.
Level 2: NFEPA Wetland Vegetation Groups
The Vegetation Map of South Africa, Swaziland and Lesotho (Mucina & Rutherford, 2006) groups
vegetation types across the country according to Biomes, which are then divided into Bioregions. To
categorise the regional setting for the wetland component of the NFEPA project, wetland vegetation
groups (referred to as WetVeg Groups) were derived by further splitting Bioregions into smaller
groups through expert input (Nel et al., 2011). There are currently 133 NFEPA WetVeg Groups. It is
envisaged that these groups could be used as a special framework for the classification of wetlands in
national- and regional-scale conservation planning and wetland management initiatives.
17
Most rivers are indirectly connected to the ocean via an estuary at the downstream end, but where marine exchange (i.e. the presence of seawater) or
tidal fluctuations are detectable in a river channel that is permanently or periodically connected to the ocean, it is defined as part of the estuary.
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Figure 1: Map of Level 1 Ecoregions of South Africa, with the approximate position of the project footprint indicated in red.
49
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Level 3: Landscape Setting
At Level 3 of the proposed classification System, for Inland Systems, a distinction is made between
four Landscape Units (Table 3) on the basis of the landscape setting (i.e. topographical position)
within which an HGM Unit is situated, as follows (Ollis et al., 2013):




Slope: an included stretch of ground that is not part of a valley floor, which is typically located
on the side of a mountain, hill or valley.
Valley floor: The base of a valley, situated between two distinct valley side-slopes.
Plain: an extensive area of low relief characterised by relatively level, gently undulating or
uniformly sloping land.
Bench (hilltop/saddle/shelf): an area of mostly level or nearly level high ground (relative to
the broad surroundings), including hilltops/crests (areas at the top of a mountain or hill flanked
by down-slopes in all directions), saddles (relatively high-lying areas flanked by down-slopes
on two sides in one direction and up-slopes on two sides in an approximately permendicular
direction), and shelves/terraces/ledges (relatively high-lying, localised flat areas along a
slope, representing a break in slope with an up-slope one side and a down-slope on the other
side in the same direction).
Level 4: Hydrogeomorphic Units
Eight primary HGM Types are recognised for Inland Systems at Level 4A of the proposed National
Wetland Classification Systems (NWCS) (Table 3), on the basis of hydrology and geomorphology
(Ollis et al., 2013), namely:
 River: a linear landform with clearly discernible bed and banks, which permanently or
periodically carries a concentrated flow of water.
 Channelled valley-bottom wetland: a valley-bottom wetland with a river channel running
through it.
 Unchannelled valley-bottom wetland: a valley-bottom wetland without a river channel
running through it.
 Floodplain wetland: the mostly flat or gently sloping land adjacent to and formed by an
alluvial river channel, under its present climate and sediment load, which is subject to periodic
inundation by over-topping of the channel bank.
 Depression: a landform with closed elevation contours that increases in depth from the
perimeter to a central area of greatest depth, and within which water typically accumulates.
 Wetland Flat: a level or near-level wetland area that is not fed by water from a river channel,
and which is typically situated on a plain or a bench. Closed elevation contours are not
evident around the edge of a wetland flat
 Seep: a wetland area located on (gently to steeply) sloping land, which is dominated by the
colluvial (i.e. gravity-driven), unidirectional movement of material down-slope. Seeps are often
located on the side-slopes of a valley but they do not, typically, extend into a valley floor.
The above terms have been used for the primary HGM Units in the Classification System to try and
ensure consistency with the wetland classification terms currently in common usage in South Africa.
Similar terminology (but excluding categories for “channel”, “flat” and “valleyhead seep”) is used, for
example, in the recently developed tools produced as part of the Wetland Management Series
including WET-Health (Macfarlane et al., 2009) and WET-EcoServices (Kotze et al., 2008).
A – 2 WET-Health
Healthy wetlands are known to provide important habitats for wildlife and to deliver a range of
important goods and services to society. Management of these systems is therefore essential if these
attributes are to be retained within an ever changing landscape. The primary purpose of this
50
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assessment18 is to evaluate the ecophysical health of wetlands, and in so doing promote their
conservation and wise management.
Level of Evaluation
Two levels of assessment are provided by WET-Health:


Level 1: Desktop evaluation, with limited field verification. This is generally applicable to
situations where a large number of wetlands need to be assessed at a very low resolution;
and
Level 2: On-site evaluation. This involves structured sampling and data collection in a single
wetland and its surrounding catchment.
Framework for the Assessment
A set of three modules has been synthesised from the set of processes, interactions and interventions
that take place in wetland systems and their catchments: hydrology (water inputs, distribution and
retention, and outputs), geomorphology (sediment inputs, retention and outputs) and vegetation
(transformation and presence of introduced alien species).
Units of Assessment
Central to WET-Health is the characterisation of HGM units, which have been defined based on
geomorphic setting (e.g. hillslope or valley-bottom; whether drainage is open or closed), water source
(surface water dominated or sub-surface water dominated) and pattern of water flow through the
wetland unit (diffusely or channelled) as described under the Classification System for Wetlands and
other Aquatic Ecosystems.
Quantification of Present State of a wetland
The overall approach is to quantify the impacts of human activity or clearly visible impacts on wetland
health, and then to convert the impact scores to a Present State score. This takes the form of
assessing the spatial extent of impact of individual activities and then separately assessing the
intensity of impact of each activity in the affected area. The extent and intensity are then combined to
determine an overall magnitude of impact. The impact scores and Present State categories are
provided in Table 3.
Table 3: Impact scores and categories of present State used by WET-Health for describing the
integrity of wetlands.
Impact
category
Present
State
category
Impact
score range
Description
None
Unmodified, natural
0-0.9
A
Small
Largely natural with few modifications. A slight change in ecosystem processes is
discernible and a small loss of natural habitats and biota may have taken place.
1-1.9
B
Moderate
Moderately modified. A moderate change in ecosystem processes and loss of
natural habitats has taken place but the natural habitat remains predominantly
intact.
2-3.9
C
Large
Largely modified. A large change in ecosystem processes and loss of natural
habitat and biota and has occurred.
4-5.9
D
Serious
The change in ecosystem processes and loss of natural habitat and biota is great
but some remaining natural habitat features are still recognizable.
6-7.9
E
Critical
Modifications have reached a critical level and the ecosystem processes have
been modified completely with an almost complete loss of natural habitat and
biota.
8-10
F
18
Kleynhans et al., 2007
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Assessing the Anticipated Trajectory of Change
As is the case
activities in the
downstream of
vegetation, five
(Table 4).
with the Present State, future threats to the state of the wetland may arise from
catchment upstream of the unit or from within the wetland itself or from processes
the wetland. In each of the individual sections for hydrology, geomorphology and
potential situations exist depending upon the direction and likely extent of change
Table 4: Trajectory of Change classes and scores used to evaluate likely future changes to the
present state of the wetland.
Change Class
Description
HGM change
score
Symbol
Substantial
improvement
State is likely to improve substantially over the next 5 years
2
↑↑
Slight improvement
State is likely to improve slightly over the next 5 years
1
↑
Remain stable
State is likely to remain stable over the next 5 years
0
→
Slight deterioration
State is likely to deteriorate slightly over the next 5 years
-1
↓
Substantial deterioration
State is expected to deteriorate substantially over the next 5 years
-2
↓↓
Overall health of the wetland
Once all HGM units have been assessed, a summary of health for the wetland as a whole needs to
be calculated. This is achieved by calculating a combined score for each component by areaweighting the scores calculated for each HGM unit. Recording the health assessments for the
hydrology, geomorphology and vegetation components provides a summary of impacts, Present
State, Trajectory of Change and Health for individual HGM units and for the entire wetland.
A – 3 Wetland function assessment
“The importance of a water resource, in ecological social or economic terms, acts as a modifying or
motivating determinant in the selection of the management class”. 19 The assessment of the
ecosystem services supplied by the identified wetlands was conducted according to the guidelines as
described by Kotze et al (2008). An assessment was undertaken that examines and rates the
following services according to their degree of importance and the degree to which the service is
provided:
 Flood attenuation
 Stream flow regulation
 Sediment trapping
 Phosphate trapping
 Nitrate removal
 Toxicant removal
 Erosion control
 Carbon storage
 Maintenance of biodiversity
 Water supply for human use
 Natural resources
 Cultivated foods
 Cultural significance
19
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Tourism and recreation
Education and research
The characteristics were used to quantitatively determine the value, and by extension sensitivity, of the
wetlands. Each characteristic was scored to give the likelihood that the service is being provided. The
scores for each service were then averaged to give an overall score to the wetland.
Table 5: Classes for determining the likely extent to which a benefit is being supplied.
Score
Rating of the likely extent to which the benefit is being supplied
<0.5
Low
0.6-1.2
Moderately low
1.3-2
Intermediate
2.1-3
Moderately high
>3
High
A – 4 Defining Ecological Importance and Sensitivity
The method used for the Ecological Importance and Sensitivity (EIS) determination was adapted from
the method as provided by DWA (1999) for floodplains. The method takes into consideration PES
scores obtained for WET-Health as well as function and service provision to enable the assessor to
determine the most representative EIS category for the wetland feature or group being assessed.
A series of determinants for EIS are assessed on a scale of 0 to 4, where 0 indicates no importance
and 4 indicates very high importance. The median of the determinants is used to assign the EIS
category. A confidence score is also provided on a scale of 0 to 4, where 0 indicates low confidence
and 4 high confidence.
Table 6: EIS Category definitions
EIS Category
Range of Median
Very high
Wetlands that are considered ecologically important and sensitive on a national or even
international level. The biodiversity of these wetlands is usually very sensitive to flow and
habitat modifications.
High
Wetlands that are considered to be ecologically important and sensitive. The biodiversity
of these wetlands may be sensitive to flow and habitat modifications.
Moderate
Wetlands that are considered to be ecologically important and sensitive on a provincial or
local scale. The biodiversity of these wetlands is not usually sensitive to flow and habitat
modifications.
Low/marginal
Wetlands that are not ecologically important and sensitive at any scale. The biodiversity
of these wetlands is ubiquitous and not sensitive to flow and habitat modifications.
20
Ed’s note: Author to confirm exact wording for version 1.1
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>3 and <=4
>2 and <=3
>1 and <=2
>0 and <=1
Recommended
Ecological
Management
Class20
A
B
C
D
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A – 5 Recommended Ecological Category
“A high management class relates to the flow that will ensure a high degree of sustainability and a low
risk of ecosystem failure. A low management class will ensure marginal maintenance of sustainability,
but carries a higher risk of ecosystem failure.” 21
The Recommended Ecological Category (REC) was determined based on the results obtained from
the Present Ecological State (PES), reference conditions and Ecological Importance and Sensitivity of
the resource (sections above). Followed by realistic recommendations, mitigation, and rehabilitation
measures to achieve the desired REC.
A wetland may receive the same class for the PES, as the REC if the wetland is deemed in good
condition, and therefore must stay in good condition. Otherwise, an appropriate REC should be
assigned in order to prevent any further degradation as well as to enhance the PES of the wetland
feature.
Table 7: Description of REC classes.
Class
Description
A
Unmodified, natural
B
Largely natural with few modifications
C
Moderately modified
D
Largely modified
A – 6 Wetland Delineation
For the purposes of this investigation, a wetland habitat is defined in the National Water Act (NWA,
1998) as including the physical structure and associated vegetation of the areas associated with a
watercourse which are commonly characterized by alluvial soils, and which are inundated or flooded
to an extent and with a frequency sufficient to support vegetation of species with a composition and
physical structure distinct from those of adjacent areas.
Due to the highly disturbed nature of the project footprint and due to the severe encroachment of A.
saligna into wetland features the accurate delineation of wetland features on site was not deemed
possible. Therefore, for the purpose of this assessment, wetlands were delineated with the use of
wetland boundaries as indicated by the City of Cape Town Prioritisation of City Wetlands Map (2009)
supplemented by aerial photography and digital satellite imagery. In this regard specific mention is
made of the use of variations in digital signatures such as textures, colours, linear patterns and
vegetation density within digital satellite imagery. Variations in elevations across the site were also
considered in order to determine areas in which wetland features are most likely to occur and where
possible ground truthing was undertaken utilising the DWA (2005) method.
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APPENDIX B
General “Housekeeping” mitigation measures
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The list below provides an indication of the general housekeeping mitigation measures that need to
be undertaken to ensure that impacts on wetland features located to the west of the existing runway
are avoided or reduced.
Construction Phase:
 Ensure that construction related activities do not encroach into the mowed wetlands located
to the west of the existing runway;
 Limit the footprint area of the construction activity to what is absolutely essential in order to
minimise environmental damage;
 Restrict vehicles to travelling only on designated roadways Do not allow vehicles to
indiscriminately drive through wetland zones;
 Prevent run-off from work areas entering wetland habitats;
 No dumping of building material or waste should take place within wetlands and associated
buffer zones;
 Implement waste management as contemplated in the Environmental Management
Programme in order to prevent construction related waste from entering the wetland
environment;
 Do not allow any temporary storage of construction material within wetland areas;
 Remove all waste, with special mention of waste rock and spoils and remaining construction
material from the site on completion of the project;
 Regularly inspect all Airports Company South Africa vehicles for leaks. Re-fuelling must take
place in a designated area or off site;
 Spills must be immediately cleaned up and treated accordingly;
 Provide appropriate sanitation facilities for the duration of the proposed development and
remove all waste to an appropriate facility. These facilities must be located outside of the
wetland features and associated buffers and must be regularly serviced;
 Remove alien and weed species encountered within the project footprint in order to comply
with existing legislation (amendments to the regulations under the Conservation of
Agricultural Resources Act, 1983 and Section 28 of the National Environmental Management
Act, 1998);
 Incorporate adequate erosion and stormwater management measures in order to prevent
erosion and the associated sedimentation of the wetland areas. In this regard specific
attention should be given to the attenuation of stormwater in order to prevent erosion; and
 Sheet runoff from cleared areas and access roads must be curtailed.
Operational Phase:
 Restrict vehicles to travelling only on designated roadways Do not allow vehicles to
indiscriminately drive through wetland zones;
 Implement waste management as contemplated in the Environmental Management
Programme in order to prevent operational related waste from entering the wetland
environment;
 Regularly inspect all Airports Company South Africa vehicles for leaks. Re-fuelling must take
place in a designated area or off site;
 Spills must be immediately cleaned up and treated accordingly;
 Remove alien and weed species encountered within the project footprint in order to comply
with existing legislation (amendments to the regulations under the Conservation of
Agricultural Resources Act, 1983 and Section 28 of the National Environmental Management
Act, 1998);
 Incorporate adequate erosion and stormwater management measures in order to prevent
erosion and the associated sedimentation of the wetland areas. In this regard specific
attention should be given to the attenuation of stormwater in order to prevent erosion; and
 Sheet runoff from paved and sealed surfaces must be curtailed.
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