Prepared for: Atterbury Property Fund Managers...

A WETLAND DELINEATION REPORT FOR THE PROPOSED

MIXED USE COMMERCIAL DEVELOPMENT ON THE

REMAINING EXTENT OF THE FARM WATERKLOOF 378,

PRETORIA, GAUTENG PROVINCE, GAUTENG PROVINCE

Prepared for: Atterbury Property Fund Managers (Pty)

Ltd

Prepared by: Exigo Sustainability (Pty) Ltd

3

A WETLAND DELINEATION REPORT FOR THE PROPOSED MIXED USE COMMERCIAL DEVELOPMENT ON THE REMAINING EXTENT OF THE FARM WATERKLOOF 378, PRETORIA, GAUTENG PROVINCE, GAUTENG PROVINCE

WETLAND DELINEATION REPORT

October 2016

Conducted on behalf of:

Atterbury Property Fund Managers (Pty) Ltd

Contact person: Ms. Ronel Van Coller

Compiled by:

Dr. BJ Henning Pr.Sci.Nat (PhD plant Ecology; MSc Botany - Soil Science related)

Although Exigo exercises due care and diligence in rendering services and preparing documents, Exigo accepts no liability, and the client, by receiving this document, indemnifies Exigo 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 Exigo and by the use of the information contained in this document.

This document contains confidential and proprietary information of Exigo and is protected by copyright in favour of Exigo and may not be reproduced, or used without the written consent of Exigo, which has been obtained beforehand. This document is prepared exclusively for Atterbury Property Fund Managers (Pty) Ltd and is subject to all confidentiality, copyright and trade secrets, rules, intellectual property law and practices of South Africa.

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REPORT DISTRIBUTION LIST

Name Institution

Ms. R. Van Coller Atterbury Property Fund Managers (Pty) Ltd CC

Mr. M. Dube Interdesign Landscape Architects

DOCUMENT HISTORY

Date Version Status

October 2016 1.0 Draft 1

Erasmuspark Mixed Use Development_Wetland Delineation

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Declaration

I, Barend Johannes Henning, declare that -

I act as the independent specialist;

I will perform the work relating to the project in an objective manner, even if this results in

views and findings that are not favourable to the project proponent;

I declare that there are no circumstances that may compromise my objectivity in performing

such work;

I have expertise in conducting the specialist report relevant to this project, including

knowledge of the National Environmental Management Act, 1998 (Act No. 107 of 1998; the

Act), regulations and any guidelines that have relevance to the proposed activity;

I will comply with the Act, regulations and all other applicable legislation;

I will take into account, to the extent possible, the matters listed in Regulation 8;

I have no, and will not engage in, conflicting interests in the undertaking of the activity;

I undertake to disclose to the project proponent and the competent authority all material

information in my possession that reasonably has or may have the potential of influencing -

any decision to be taken with respect to the project; and - the objectivity of any report, plan

or document to be prepared by myself for submission to the competent authority or project

proponent;

All the particulars furnished by me in this document are true and correct; and

I realise that a false declaration is an offence in terms of Regulation 71 and is punishable in

terms of section 24F of the Act.

___________________________________

SIGNATURE OF SPECIALIST

Company: Exigo Sustainability

Date: October 2016


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Table of contents

NOTATIONS AND TERMS ........................................................................................................................... 1

LIST OF ABBREVIATIONS ............................................................................................................................ 4

1. ASSIGNMENT ..................................................................................................................................... 5

1.1 INFORMATION SOURCES ................................................................................................................ 5

1.2 REGULATIONS GOVERNING THIS REPORT ........................................................................................ 5

1.2.1 NATIONAL ENVIRONMENTAL MANAGEMENT ACT, 1998 (ACT NO. 107 OF 1998) - REGULATION NO. R982 ....................................................................................................................... 5

1.2.2 THE NATIONAL WATER ACT (ACT NO. 36 OF 1998) .......................................................... 7

1.2.3 CONSERVATION OF AGRICULTURAL RESOURCES ACT (ACT NO. 43 OF 1983) .......... 7

1.2.4 THE NATIONAL ENVIRONMENTAL MANAGEMENT ACT (NEMA) (ACT NO. 107 OF 1998) 8

1.3 TERMS OF REFERENCE .................................................................................................................... 8

1.3.1 OBJECTIVES ........................................................................................................................... 8

2. STUDY AREA ...................................................................................................................................... 9

2.1 LOCATION AND DESCRIPTION OF ACTIVITY ...................................................................................... 9

2.2 CLIMATE ...................................................................................................................................... 13

2.3 GEOLOGY AND SOIL TYPES .................................................................................................. 13

2.4 TOPOGRAPHY .......................................................................................................................... 14

2.5 DRAINAGE ................................................................................................................................ 14

2.6 CRITICAL BIODIVERSITY & ECOLOGICAL SUPPORT AREAS OF THE PROJECT AREA ............................. 15

3. METHODS ........................................................................................................................................ 17

3.1 WETLAND DELINEATION AND CLASSIFICATION .............................................................................. 17

3.2 WETLAND CLASSIFICATION ........................................................................................................... 18

3.3 RIPARIAN DELINEATION AND CLASSIFICATION ............................................................................... 19

3.4 WETLAND INTEGRITY ASSESSMENTS ............................................................................................. 21

3.4.1 PRESENT ECOLOGICAL STATUS (PES) OF WETLANDS ................................................ 21

3.4.2 ECOLOGICAL IMPORTANCE AND SENSITIVITY (EIS) ..................................................... 24

3.5 GDARD RULES FOR SENSITIVITY MAPPING ..................................................................................... 25

3.5.1 WETLAND ZONES ................................................................................................................ 25

3.5.2 RIVERS (NON-PERENNIAL / PERENNIAL) ......................................................................... 25

4. RESULTS .......................................................................................................................................... 27

4.1 WETLAND / RIPARIAN CLASSIFICATION ......................................................................................... 29

4.1.1 UNCHANNELLED VALLEY-BOTTOM (VB) WETLANDS ................................................................... 29

4.1.2 ARTIFICIAL DEPRESSIONS (MAN-MADE DAMS) ........................................................................... 30

4.1.3 WATER COURSE AND RIPARIAN WOODLAND ............................................................................. 31


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4.2 WETLAND INTEGRITY ASSESSMENTS ............................................................................................. 34

5. POTENTIAL IMPACTS OF THE PROPOSED DEVELOPMENT ON THE WETLANDS AND RIPARIAN ZONES ... 35

5.1 PERMANENT LOSS OF WETLAND AND THEIR ASSOCIATED FUNCTIONS ........................................... 35

5.1.3 DESCRIPTION OF IMPACT: ................................................................................................. 35

5.1.3.1 DESTRUCTION OR LOSS OF RIPARIAN FLORAL DIVERSITY OR RIPARIAN COMMUNITIES ..................................................................................................................................... 35

5.1.3.2 LOSS OF RIPARIAN AND WATER DEPENDANT FAUNAL DIVERSITY THROUGH MIGRATION AND DECLINE IN ANIMAL NUMBERS ......................................................................... 36

5.1.4 MITIGATION MEASURES: .................................................................................................... 36

5.2 SOIL COMPACTION AND INCREASED RISK OF SEDIMENT TRANSPORT AND EROSION ....................... 37

5.2.1 DESCRIPTION OF IMPACT: ......................................................................................................... 37

5.2.2 MITIGATION MEASURES ........................................................................................................... 38

5.3 SOIL AND WATER POLLUTION ....................................................................................................... 39


5.3.2 MITIGATION MEASURES: .......................................................................................................... 39

5.4 SPREAD AND ESTABLISHMENT OF ALIEN INVASIVE SPECIES ............................................................ 39


5.4.2 MITIGATION MEASURES: .......................................................................................................... 40

5.5 IMPACT ASSESSMENT MATRIX FOR THE CONSTRUCTION PHASE OF THE DEVELOPMENT ................................................................................................................................... 41

6. MANAGEMENT STRATEGY FOR THE DEGRADED WETLANDS ............................................................... 43

6.1 CONSTRAINTS AND OPPORTUNITIES OF THE EXISTING ENVIRONMENT ...................... 43

6.1.1 CONSTRAINTS ...................................................................................................................... 43

6.1.2 OPPORTUNITIES .................................................................................................................. 43

6.2 MANAGEMENT STRATEGIES ................................................................................................. 43

6.2.1 STORMWATER MANAGEMENT: THE SUSTAINABLE DRAINAGE SYSTEM (SUDS) .... 44

6.2.2 EROSION CONTROL AND REHABILITATION .................................................................... 50

6.2.3 DISTURBANCE TO WETLAND SOIL ................................................................................... 50

6.2.4 EROSION PREVENTION ....................................................................................................... 51

6.2.5 PREVENTION OF SEDIMENTATION ................................................................................... 51

6.2.6 POLLUTION PREVENTION .................................................................................................. 51

6.2.7 LITTERING PREVENTION .................................................................................................... 52

6.2.8 BUILDING ACTIVITY ASSOCIATED IMPACTS ................................................................... 52

6.3 IMPLEMENTATION ................................................................................................................... 52

7. REHABILITATION PLAN FOR DEGRADED WETLANDS / STORMWATER CANALS .................................... 54

7.1 WETLAND REHABILITATION PROBLEMS ......................................................................................... 54

7.2 WETLAND REHABILITATION OBJECTIVES ........................................................................................ 54

7.3 REHABILITATION WORKS / METHODS ........................................................................................... 54


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7.3.1 IDENTIFICATION AND PROTECTION OF ENVIRONMENTALLY SENSITIVE AREAS............................. 55

7.3.2 COMPREHENSIVE PHOTOGRAPHIC RECORD ............................................................................... 55

7.3.3 SEARCH AND RESCUE ACTIVITIES ............................................................................................... 55

7.3.4 CLEARED INDIGENOUS PLANT MATERIAL ................................................................................... 56

7.3.5 REMOVAL OF OVERBURDEN ...................................................................................................... 56

7.3.6 COMPACTION REHABILITATION MEASURES (RIPPING AND / OR SCARIFYING) ............................. 56

7.3.7 EROSION REHABILITATION MEASURES ...................................................................................... 57

7.3.8 REINSTATEMENT OF TOPSOIL .................................................................................................... 58

7.3.9 RE-VEGETATION ....................................................................................................................... 58

7.3.10 SURFACE REHABILITATION OF EXPOSED AREAS .......................................................................... 60

7.3.11 ALIEN INVASIVE SPECIES ........................................................................................................... 60

7.3.12 FIRE MANAGEMENT .................................................................................................................. 60

7.3.13 RIVER BANK STABILISATION’ ..................................................................................................... 61

7.4 MAINTENANCE AND MONITORING OF REHABILITATION .................................................. 62

8. MONITORING PLAN FOR STORMWATER CONTROL STRUCTURES AND WETLANDS .............................. 62

9. DISCUSSION & CONCLUSION ............................................................................................................ 65

10. REFERENCES ................................................................................................................................. 67

APPENDIX A PES SCORES OF THE WETLANDS IN THE STUDY AREA ...................................... 68

APPENDIX B EIS SCORES OF THE WETLANDS IN THE STUDY AREA ........................................ 69


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List of Figures

Figure 1. Regional Location Map .......................................................................................................... 10 Figure 2. Satelite image showing the project area (Google Pro, 2010) ................................................ 11 Figure 3. Detailed layout map of the first phase of the proposed development ................................... 12 Figure 4. Terrestrial CBA areas of the study area (2014) ..................................................................... 16 Figure 5. A cross section through a wetland showing how the soil form indicators and vegetation changes from the centre to the edge of the wetland (adapted from Kotze, 1996)................................ 17 Figure 6. Cross section of topography associated with a channel and floodplains .............................. 20 Figure 7. Typical cross section of a river channel displaying riparian habitat (DWA, 2003) ................. 21 Figure 8. Wetland / riparian map for the proposed development with buffer zones as recommended by GDARD regulations (2014) ................................................................................................................... 28 Figure 9. Natural hydrological system ................................................................................................... 45 Figure 10. Stormwater management approach with little concern for natural environment ................. 45 Figure 11. Responsible approach to stormwater management ............................................................ 46 Figure 12. Stormwater design hierarchy of the SuDS .......................................................................... 48

List of Tables

Table 1. Land types, geology and dominant soil types of the proposed development site .................. 14 Table 2. State of major streams / rivers in the project area (DWA) ...................................................... 15 Table 3. Wetland Unit types based on hydrogeomorphic characteristics (Adapted from Kotze et al. 2005). .................................................................................................................................................... 18 Table 4. Habitat integrity assessment criteria for wetlands (Adapted from DWAF, 2003).................... 22 Table 5. Present Ecological Status Class Descriptions ........................................................................ 23 Table 6. Criteria for assessing the Ecological Importance and Sensitivity of Wetlands ....................... 24 Table 7. Ecological Importance and Sensitivity Classes ...................................................................... 25 Table 8. Present Ecological State (PES) and Ecological Importance & Sensitivity (EIS) of the wetlands and riparian zones of the proposed development site .......................................................................... 34 Table 9. Impact assessment matrix for the proposed Erasmuspark Mixed Use Development ............ 42 Table 10 SuDS conceptual design matrix ............................................................................................. 49 Table 11. Potential stormwater pollutants and impacts that needs to be assessed and monitored during the development phases ............................................................................................................ 50 Table 12. Monitoring framework for the rehabilitation plan on stormwater structures and canals proposed for the area ............................................................................................................................ 64


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NOTATIONS AND TERMS

_________________________________________________________________________________

Biota: living things; plants, animals, bacteria

Bottomland: the lowlands along streams and rivers, on alluvial (river deposited) soil.

Connectivity: in this context, referring to either the upstream-downstream or lateral (between the

channel and the adjacent floodplain) connectivity of a drainage line. Upstream-downstream

connectivity is an important consideration for the movement of sediment as well as migratory

aquatic biota. Lateral connectivity is important for the floodplain species dependent on the wetting

and nutrients associated with overbank flooding

Endorheic: closed drainage e.g. a pan.

Floristic: of flora (plants).

Floodplain: wetland inundated when a river overtops its banks during flood events resulting in the wetland

soils being saturated for extended periods of time.

Gley: soil material that has developed under anaerobic conditions as a result of prolonged saturation with

water. Grey and sometimes blue or green colours predominate but mottles (yellow, red, brown and black)

may be present and indicate localised areas of better aeration.

Groundwater: subsurface water in the zone in which permeable rocks, and often the overlying soil, are

saturated under pressure equal to or greater than atmospheric.

Horizon: see soil horizons.

Hydrophyte: any plant that grows in water or on a substratum that is at least periodically deficient in oxygen

as a result of soil saturation or flooding; plants typically found in wet habitats.

Hydro-geomorphic: refers to the water source and geology forms.

Hydrology is defined in this context as the distribution and movement of water through a wetland and its soils.

Geomorphology is defined in this context as the distribution and retention patterns of sediment within the

wetland.

Infilling: dumping of soil or solid waste onto the wetland surface. Infilling generally has a very high and

permanent impact on wetland functioning and is similar to drainage in that the upper soil layers are rendered

less wet, usually so much so that the area no longer functions as a wetland.

Mottles: soils with variegated colour patters are described as being mottled, with the "background colour"

referred to as the matrix and the spots or blotches of colour referred to as mottles.

Organic soil material: soil material with a high abundance of un-decomposed plant material and humus.

Palustrine (wetland): all non-tidal wetlands dominated by persistent emergent plants (e.g. reeds) emergent

mosses or lichens, or shrubs or trees (see Cowardin et al., 1979).


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Perched water table: the upper limit of a zone of saturation in soil, separated by a relatively impermeable

unsaturated zone from the main body of groundwater.

Permanently wet soil: soil which is flooded or waterlogged to the soil surface throughout the year, in most

years.

Riparian: the area of land adjacent to a stream or river that is influenced by stream-induced or related

processes. Riparian areas which are saturated or flooded for prolonged periods would be considered wetlands

and could be described as riparian wetlands. However, some riparian areas are not wetlands (e.g. an area

where alluvium is periodically deposited by a stream during floods but which is well drained).

Roughness coefficient: an index of the roughness of a surface; a reflection of the frictional resistance offered

by the surface to water flow.

Runoff: total water yield from a catchment including surface and subsurface flow.

Seasonally wet soil: soil which is flooded or waterlogged to the soil surface for extended periods (>1 month)

during the wet season, but is predominantly dry during the dry season.

Sedges: grass-like plants belonging to the family Cyperaceae, sometimes referred to as nutgrasses. Papyrus is

a member of this family.

Soil drainage classes: describe the soil moisture conditions as determined by the capacity of the soil and the

site for removing excess water. The classes range from very well drained, where excess water is removed very

quickly, to very poorly drained, where excess water is removed very slowly. Wetlands include all soils in the

very poorly drained and poorly drained classes, and some soils in the somewhat poorly drained class. These

three classes are roughly equivalent to the permanent, seasonal and temporary classes

Soil horizons: layers of soil that have fairly uniform characteristics and have developed through pedogenic

processes; they are bound by air, hard rock or other horizons (i.e. soil material that has different

characteristics).

Soil profile: the vertically sectioned sample through the soil mantle, usually consisting of two or three horizons

(Soil Classification Working Group, 1991).

Soil saturation: the soil is considered saturated if the water table or capillary fringe reaches the soil surface

(Soil Survey Staff, 1992).

Temporarily wet soil: the soil close to the soil surface (i.e. within 50 cm) is wet for periods > 2 weeks during

the wet season in most years. However, it is seldom flooded or saturated at the surface for longer than a

month.

Terrain unit classes: areas of the land surface with homogenous form and slope. Terrain may be seen as being

made up of all or some of the following units: crest (1), scarp (2), midslope (3), footslope (4) and valley bottom

(5).

Transpiration: the transfer of water from plants into the atmosphere as water vapour


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Unchannelled valley bottom: linear fluvial, net depositional valley bottom surfaces which do not

have a channel. The valley floor is a depositional environment composed of fluvial or colluvial

deposited sediment. These systems tend to be found in the upper catchment areas.

Vegetation is defined in this context as the vegetation structural and compositional state.

Water regime: when and for how long the soil is flooded or saturated.

Water Quality largely self-explanatory and reflecting the changes in quality as a consequence of changes in

land use or as a direct result of activities within the wetland itself that could lead to changes in the quality of

the water flowing through and within the wetland

Waterlogged: soil or land saturated with water long enough for anaerobic conditions to develop.

Wetland: land which is transitional between terrestrial and aquatic systems where the water table is usually at

or near the surface, or the land is periodically covered with shallow water, and which under normal

circumstances supports or would support vegetation typically adapted to life in saturated soil.

Wetland catchment: the area up-slope of the wetland from which water flows into the wetland and including

the wetland itself.

Wetland delineation: The determination and marking of the boundary of a wetland on a map.


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LIST OF ABBREVIATIONS

_________________________________________________________________________________

Abbreviation Description

ARC Agricultural Research Council

C-Plan Gauteng Conservation Plan

CSIR Council for Scientific and Industrial Research

DAFF Department of Agriculture, Forestry and Fisheries

DEA Department of Environmental Affairs

DME Department of Minerals and Energy Affairs

DWS Department of Water and Sanitation

EAP Environmental Assessment Practitioner

EIA Environmental Impact Assessment

EIS Ecological Importance and Sensitivity

EMPR Environmental Management Programme Report

ENPAT Environmental Potential Atlas

GDARD Gauteng Department of Agriculture and Rural Development

GIS Geographic Information Systems

GPS Geographical Positioning System

HGM Hydro-Geomorphic

HFI Hydrological Function and Importance

IHI Index of Habitat Integrity

IUCN World Conservation Union

MAE Mean Annual Evaporation

MAMSL Meter Above Mean Sea Level

MAP Mean Annual Precipitation

MAR Mean Annual Runoff

NEMA National Environmental Management Act

PES Present Ecological State

PESC Present Ecological Status Class

PQ4 Priority Quaternary Catchment

QDS Quarter Degree Square

SADC Southern African Development Community

SANBI South African National Biodiversity Institute

WMA Water Management Area

WHO World Health Organisation


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1. ASSIGNMENT

Exigo Sustainability was appointed by Atterbury Property Fund Managers (Pty) Ltd to conduct a

wetland delineation study that forms part of the Basic Assessment process for the proposed mixed

use commercial development to be known as Erasmuspark situated on Portion 22 and the remaining

extent of the Farm Waterkloof 378 JR, City of Tshwane, Gauteng Province.

The study includes a wetland delineation and functionality assessment, with descriptions of the

anticipated impacts (risks) associated with the proposed development activities and mitigation to

reduce impacts. This assessment is essential as it will contribute to meeting the requirements of the

National Environmental Management Act (NEMA), 1998 (Act No. 107 of 1998) in conjunction with

Regulation 543 of 18 June 2010, promulgated in terms of Section 24 (5) of NEMA and Chapter 4 of the

National Water Act, Act 36 of 1998.

The assignment is interpreted as follows: Compile a study on the wetlands of the site according to

guidelines and criteria set by the Gauteng Department of Agriculture and Rural Development

(GDARD) and the Department of Water and Sanitation (DWS).

1.1 INFORMATION SOURCES

The following information sources were obtained for the study:

1. All relevant topographical maps, aerial photographs and information (previous studies and

environmental databases) related to wetlands in the study area;

2. Requirements regarding the wetland survey as stipulated in the following guidelines:

a. National Water Act (1998);

b. A practical field procedure for identification and delineation of wetlands and

riparian areas (DWAF, 2006);

c. National Wetland Classification System for South Africa (SANBI, 2009);

3. Guidelines regarding development in and around wetlands as stipulated by DWA and

GDARD;

1.2 REGULATIONS GOVERNING THIS REPORT

1.2.1 National Environmental Management Act, 1998 (Act No. 107 of 1998) - Regulation No. R982

This report was prepared in terms of the National Environmental Management Act, 1998 (Act No. 107

of 1998) Gazette No. 38282 Government Notice R. 982. Appendix 6 – Specialist reports includes a list

of requirements to be included in a specialist report:

1. A specialist report or a report prepared in terms of these regulations must contain:


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a. Details of

i. The specialist who prepared the report; and

ii. The expertise of that specialist to compile a specialist report, including a

curriculum vitae;

b. A declaration that the specialist is independent in a form as may be specified by the

competent authority;

c. An indication of the scope of, and purpose for which, the report was prepared;

d. The date and season of the site investigation and the relevance of the season to the

outcome of the assessment;

e. A description of the methodology adopted in preparing the report or carrying out

the specialized process;

f. The specific identified sensitivity of the site related to the activity and its associated

structures and infrastructure;

g. An identification of any areas to be avoided, including buffers;

h. A map superimposing the activity including the associated structures and

infrastructure on the environmental sensitivities of the site including areas to be

avoided, including buffers;

i. A description of any assumptions made and any uncertainties or gaps in knowledge;

j. A description of the findings and potential implications of such findings on the

impact of the proposed activity, including identified alternatives, on the

environment;

k. any mitigation measures for inclusion in the EMPr;

l. any conditions for inclusion in the environmental authorisation;

m. any monitoring requirements for inclusion in the EMPr or environmental

authorisation

n. a reasoned opinion –

i. As to whether the proposed activity or portions thereof should be

authorised and

ii. If the opinion is that the proposed activity or portions thereof should be

authorised, any avoidance, management and mitigation measures that

should be included in the EMPr and where applicable, the closure plan;


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o. A description of any consultation process that was undertaken during the course of

preparing the specialist report;

p. A summary and copies of any comments received during any consultation process

and where applicable all responses thereto; and

q. Any other information requested by the competent authority.

1.2.2 The National Water Act (Act No. 36 of 1998)

Chapter 4 of the National Water Act, Act 36 of 1998 specifies that:

“In general a water use must be licensed unless it is listed in Schedule I, is an existing lawful use, is

permissible under a general authorisation, or if a responsible authority waives the need for a licence.

The Minister may limit the amount of water which a responsible authority may allocate. In making

regulations the Minister may differentiate between different water resources, classes of water

resources and geographical areas.”

In section 21 of the NWA water uses are listed as:

a. Taking water from a water resource;

b. Storing water;

c. Impeding or diverting the flow of water in a watercourse;

d. Engaging in a stream flow reduction activity contemplated in section 36;

e. Engaging in a controlled activity identified as such in section 37(1) or declared under section

38(1);

f. Discharging waste or water containing waste into a water resource through a pipe, canal,

sewer, sea outfall or other conduit;

g. Disposing of waste in a manner which may detrimentally impact on a water resource;

h. Disposing in any manner of water which contains waste from, or which has been heated in,

any industrial or power generation process;

i. Altering the bed, banks, course or characteristics of a watercourse;

j. Removing, discharging or disposing of water found underground if it is necessary for the

efficient continuation of an activity or for the safety of people; and

k. Using water for recreational purposes.

1.2.3 Conservation of Agricultural Resources Act (Act No. 43 of 1983)

This Act controls the utilization and protection of wetlands, soil conservation and all matters relating

thereto including prevention of veld fires, control of weeds and invader plants, prevention of water


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pollution resulting from farming practices and losses in biodiversity.

1.2.4 The National Environmental Management Act (Nema) (Act No. 107 Of 1998)

This Act embraces all three fields of environmental concern namely: resource conservation and

exploitation; pollution control and waste management; and land-use planning and development. The

environmental management principles include the duty of care for wetlands and special attention is

given to management and planning procedures.

1.3 TERMS OF REFERENCE

1.3.1 Objectives

The project was done according to the following objectives:

Conduct a desktop and field investigation to confirm the presence or absence of wetlands

and riparian areas within the study area;

Delineate and map the identified wetland and riparian areas on site;

Classify wetlands according to their hydro-geomorphic characteristics;

Determine the Present Ecological State (PES) and Ecological Importance and Sensitivity (EIS)

of all wetlands and riparian areas on site;

Determine the impacts associated with the proposed development on the wetlands;

Specify mitigation measures and management plan for the wetlands on site (including

rehabilitation measures);

Compile a report with the findings and maps.

Erasmuspark Mixed Use Development_Biodiversity Impact Assessment

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2. STUDY AREA

2.1 LOCATION AND DESCRIPTION OF ACTIVITY

The project is located to the south of Solomon Mahlangu Drive, northwest of the N1 freeway and east

of the R21 road (Figure 1). The project entails the proposed mixed use commercial development to be

known as Erasmuspark situated on the Remaining Extent and Portion 22 of the Farm Waterkloof 378

JR.

The first phase of the development is for the development on Erven 1 and 2 situated on a Portion of

the Remaining Extent of the Farm Waterkloof 378-JR, south east of Pretoria between the R21 and N1

highway. A portion of the Remaining Extent of the Farm Waterkloof 378 JR measures approximately

70.8711 Hectares in total extent, while Erven 1 and 2 occupy approximately a third of the total extent

(±22 Hectares). The main future access to the development site will be from Solomon Mahlangu

Drive, proposed for upgrade into a dual carriage-way within the existing road reserve.

The aerial image of the site is indicated in figure 2, while a detailed layout map of the first phase of

the development is illustrated in Figure 3.


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Figure 1. Regional Location Map


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Figure 2. Satelite image showing the project area (Google Pro, 2010)


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Figure 3. Detailed layout map of the first phase of the proposed development

Erasmuspark Mixed Use Development_Biodiversity Impact Assessment

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2.2 CLIMATE

Climate in the broad sense is a major determinant of the geographical distribution of species

and vegetation types. However, on a smaller scale, the microclimate, which is greatly

influenced by local topography, is also important. Within areas, the local conditions of

temperature, light, humidity and moisture vary greatly and it is these factors which play an

important role in the production and survival of plants (Tainton, 1981). In terrestrial

environments, limitations related to water availability are always important to plants and

plant communities. The spatial and temporal distribution of rainfall is very complex and has

great effects on the productivity, distribution and life forms of the major terrestrial biomes

(Barbour et al. 1987). Furthermore, aspects like topography, slope and altitude may further

result in differences in precipitation and water availability to plants within the study area.

The Pretoria area has a moderately dry subtropical climate, specifically a humid subtropical

climate, with long hot and rainy summers and short cool and dry winters. Effectively three

seasons occurs annually namely a cool, dry season from May to August, a hot, dry season

from mid-August to October, and a hot, wet season from November to April.

Summer (October to April) rainfall patterns predominate with the traditional heavy deluges

in the afternoon (cumulonimbus induced thundershowers being the norm). December and

January are the peak rainfall months with hail being prevalent. Frontal climatic systems bring

soft soaking rains on occasion. Mean annual precipitation (MAP) varies between 600 and

800mm. During certain years large-scale flooding occurs in this catchment which wreaks

tremendous damage on irrigation farming operations. The average annual temperature is

18.7°C, while the mean monthly maximum and minimum temperatures for the area are

35.3˚C and -3.1˚C for November and June, respectively.

2.3 GEOLOGY AND SOIL TYPES

Geology is directly related to soil types and plant communities that may occur in a specific

area (Van Rooyen & Theron, 1996). A Land type unit is a unique combination of soil pattern,

terrain and macroclimate, the classification of which is used to determine the potential

agricultural value of soils in an area. The land type unit represented within the study area

include the Ab1 land type (Land Type Survey Staff, 1987) (ENPAT, 2001). The land type,

geology and associated soil type is presented in Table 1 below as classified by the

Environmental Potential Atlas, South Africa (ENPAT, 2000).

http://en.wikipedia.org/wiki/Subtropical_climate

http://en.wikipedia.org/wiki/Humid_subtropical_climate

http://en.wikipedia.org/wiki/Humid_subtropical_climate

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Table 1. Land types, geology and dominant soil types of the proposed development site

Landtype Soils Geology

Ab1 Red-yellow apedal, freely drained soils, red,

dystrophic and/or mesotrophic (ROCK 55%, Ms

24%)

Dolomite

Soils associated with the site vary between shallow, gravelly soils associated with outcrops,

deep sandy-loam soils of the Hutton or Clovelly soil forms on the plains to vertic, black clay

soils adjacent to the drainage channels and on the plains.

2.4 TOPOGRAPHY

When assessing the ecology of an area, it is important to know in which eco-region it is

located. The study area forms part of the Eastern Bankenveld Eco-region. According to the

Environmental Potential Atlas of South Africa (ENPAT, 2000) the project area is classified as

being “Dissected Plains” or a “High Gradient Valley”. The slopes of the study area are

classified as being between 1 and 8 degrees. The project area is characterised by slightly

undulating to flat plains with a wetland area bisecting the site in the south. The topography

across the site is slightly undulating with the average elevation of 1500 mamsl.

2.5 DRAINAGE

The ecosystem integrity of surface waters has responded to different environmental impacts

within the Gauteng Province and integrity scores range between poor and fair for the

majority of systems studied within the Rivers Health Programme. Furthermore, it would

seem that due to impacts on quality of water and flow regimes, the desired ecological state

for the majority of systems could never again attain states higher than fair. Major

rehabilitation of river banks, alien tree removal and removal of impoundments would be

required to achieve this. The latter would not easily be attained due to the scarcity of water

resources within the region and the critical need for water storage mechanisms.

At a basin or sub-basin scale, particularly in semi-arid and arid areas, priority is often placed

on monitoring and management of water quantity. Equally important, however, is the

monitoring and management of water quality (DWAF, 2004). Water quality is often

characterised in terms of the concentration of different chemicals in the water (Hatfield,

2008). What determines “good” or “bad” water quality depends on the purpose of the

assessment - for example, water with naturally elevated concentrations of some metals may

be unsafe to drink, but still suitable for industrial uses. Assessment involves comparing

measured chemical concentrations with natural, background, or baseline concentrations, and

with guidelines established to protect human health or ecological communities.

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The project area is situated within the quaternary catchments, A23D. The Apies River is

located in the south of the site as a wetland, although this section of the river is non-

perennial. The study area is drained mainly by surface run-off (i.e. sheetwash) with surface

water flowing into non-perennial streams of the study area. This water eventually drains into

the Apies River. It must be noted that stream flow along the non-perennial drainage channels

occurs only during and directly after heavy precipitation events, and may continue for a short

period directly after a particularly good rainy season.

The state of the Apies River is summarized in Table 2.

Table 2. State of major streams / rivers in the project area (DWA)

2.6 CRITICAL BIODIVERSITY & ECOLOGICAL SUPPORT AREAS OF THE PROJECT AREA

Critical Biodiversity Areas (CBAs) are areas required to meet biodiversity targets for

ecosystems, species and ecological processes, as identified in a systematic biodiversity plan.

Ecological Support Areas (ESAs) are not essential for meeting biodiversity targets but play an

important role in supporting the ecological functioning of Critical Biodiversity Areas and/or in

delivering ecosystem services. Critical Biodiversity Areas and Ecological Support Areas may

be terrestrial or aquatic. The primary purpose of a map of Critical Biodiversity Areas and

Ecological Support Areas is to guide decision-making about where best to locate

development. It should inform land-use planning, environmental assessment and

authorisations, and natural resource management, by a range of sectors whose policies and

decisions impact on biodiversity. It is the biodiversity sector’s input into multi-sectoral

planning and decision-making processes. Figure 4 indicates the CBA and ESA areas for the

project area. The study area is largely CBA areas, with the most important areas to the north

on the private land on Irreplaceable Classed Land and the remainder of the site on Important

CBA class.

Quaternary drainage region

Name Class Ecoregion II State of river / streams

Category

A23A Pienaars Non-Perennial Bushveld Basin

Class D: Largely Modified

Critically Endangered


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Figure 4. Terrestrial CBA areas of the study area (2014)


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3. METHODS

3.1 WETLAND DELINEATION AND CLASSIFICATION

The National Water Act, Act 36 of 1998, defines wetlands as follows:

“Land which is transitional between terrestrial and aquatic systems where the water table is usually at

or near the surface, or the land is periodically covered with shallow water, and which land in normal

circumstances supports or would support vegetation typically adapted to life in saturated soil.”

Wetlands were delineated according to the delineation procedure given in “A Practical Field

Procedure for the Identification and Delineation of Wetlands and Riparian Areas” (DWAF, 2003).

Wetland indicators are divided into different unit indicators which need to be given consideration in

the delineation of wetlands (Figure 5). The outer edge of the temporary zone requires the delineator

to take the following specific indicators into account:

The terrain unit indicator helps to identify those parts of the landscape where wetlands are

more likely to occur.

The Soil Form Indicator identifies the soil forms, as defined by Macvicar (1991), which are

associated with prolonged and frequent saturation.

The Soil Wetness Indicator identifies the morphological "signatures" developed in the soil

profile as a result of prolonged and frequent saturation.

The Vegetation Indicator identifies hydrophilic vegetation associated with frequently

saturated soils.

Figure 5. A cross section through a wetland showing how the soil form indicators and vegetation

changes from the centre to the edge of the wetland (adapted from Kotze, 1996)


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3.2 WETLAND CLASSIFICATION

The study area was sub-divided into transects and the soil profile was examined for signs of wetness

within 50 cm of the surface using a hand auger along transects. The wetland boundaries were then

determined by the positions of augered holes that showed signs of wetness as well as by the presence

or absence of hydrophilic vegetation. The wetlands were subsequently classified according to their

hydro-geomorphic setting based on the system proposed in the National Wetland Classification

System (Table 3) (SANBI, 2009).

Furthermore, as a result of alluvial deposits being visible from the air, aerial photography was also

used to assist in determining the extent of deposits, as well as the vegetation line indicating a

difference in species composition or more vigorous growth. The aerial photographs were used to

guide on-screen delineation of wetlands in ArcView GIS 3.3.

Table 3. Wetland Unit types based on hydrogeomorphic characteristics (Adapted from Kotze et

al. 2005).


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3.3 RIPARIAN DELINEATION AND CLASSIFICATION

Riparian areas often associated with streams or drainage lines are also important to protect due to

the followings ecological and hydrological functions that it performs

(DWAF, 2003):

Stabilize stream banks;

Store water and aid in flood attenuation;

Improve water quality by trapping nutrients and sediment;

Maintain natural water temperature for aquatic species;

Provide shelter and food for avifauna and other animals;

Provide corridors for movement and migration of different species; and

Act as a buffer between aquatic ecosystems and adjacent land uses.

The riparian areas have their own unique set of indicators. DWAF (2003) states that in order to

classify an area as a riparian area it must have one or more of the following attributes:

Are associated with a watercourse;

Contain distinctively different plant species than adjacent areas; and contain species similar

to adjacent areas but exhibiting more vigorous or robust growth forms; and

May have alluvial soils.

The delineation process requires that the following be taken into account:

Topography associated with the watercourse (figure 7);

Vegetation (figure 8); and

Alluvial soils and deposited material.

Many riparian areas display wetland indicators and should be classified as wetlands. However, other

riparian areas are not saturated long enough or often enough to develop wetland characteristics, but

also perform a number of important functions, which need to be safeguarded. In these areas alluvial

deposits can predominate and/or the water table is too deep for most of the year to produce

hydromorphic features in the top 50cm of the soil profile. These conditions do not support vegetation

typically adapted to life in saturated soil and it is therefore important to delineate these riparian areas

in addition to wetlands. Riparian areas commonly reflect the high-energy conditions associated with

the water flowing in a water channel, whereas wetlands generally display more diffuse flow and are

lower energy environments.


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The general approach for delineating riparian areas in the field is to identify the active channel or the

lowest part of the river course. Most likely cues like water with associated emergent vegetation,

sedges and reeds or alluvial soil and bedrock will be visible. From this point some topographic units

like sandbars, active channel bank, flood benches and macro-channel bank with associated riparian

vegetation will be identifiable. The next step would be to proceed upwards towards the macro-

channel bank, taking note of alluvial soil, topographic units and vegetation indicators. The outer

boundary will be the point on the edge of the macro channel bank where there is a distinct difference

between the riparian and terrestrial vegetation. In some cases where riparian vegetation is

unrecognisable, because of land-use activities, indicators like alluvial material and topographical units

can still be used to visualize the edge of a riparian area. If you are adjacent to a watercourse, it is also

important to check for the presence of riparian indicators. The riparian areas were identified using the

following information:

Topographical maps: Riparian areas normally occur within the flood area of a river or stream.

Aerial photographs: As a result of alluvial deposits being visible from the air, aerial

photography can assist in determining the extent of deposits, as well as the vegetation line

indicating a difference in species composition or more vigorous growth.

A combination of the abovementioned indicators were used during the field survey that was

conducted during July 2015 to identify the indicator plant species, soil types and specific topography

related to the wetland areas. The outer boundaries were then recorded using a Global Positioning

System (GPS). Riparian areas were mapped by means of the computer programme Arcview 3.3.

Figure 6. Cross section of topography associated with a channel and floodplains


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Figure 7. Typical cross section of a river channel displaying riparian habitat (DWA, 2003)

3.4 WETLAND INTEGRITY ASSESSMENTS

3.4.1 Present Ecological Status (PES) of wetlands

The Present Ecological State (PES) assessment of the wetlands within the study area was undertaken

to determine the extent of departure of the wetlands from a natural state or reference condition. This

method is based on the modified Habitat Integrity approach (Table 4) developed by Kleynhans (1999).

Anthropogenic modification of the criteria and its attributes can have an impact on the ecological

integrity of a wetland.


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Table 4. Habitat integrity assessment criteria for wetlands (Adapted from DWAF, 2003)

For the purpose of this study, the scoring system as described in the document “Resource Directed

Measures for Protection of Water Resources, Volume 4. Wetland Ecosystems” (DWAF, 1999) was

applied for the determination of the PES (Table 5).

Two tools have recently been developed to facilitate the derivation of scores to reflect the present

ecological sate, namely the Index of Habitat Integrity (IHI) DWA, 2007, and Wet-Health, developed by

Macfarlane et al., 2008. Both these tools have limitations in that they were developed primarily to

assess conditions of floodplain and valley bottom wetlands and Hill slope seepage wetlands linked to

drainage lines. The former tool was developed to provide a rapid assessment of the PES specifically

for application in reserve studies, while the latter tool was developed to support the Working for

Wetlands program. The objective of the latter tool was to provide a semi quantitative assessment of

the state of wetland prior to rehabilitation, and one post rehabilitation to demonstrate

“improvement”. The intention in defining the health category (PES) of a wetland is to provide an


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indication of the current “condition” of a wetland in order to inform a management class. The latter

provides the guidelines against that inform water quality and quantity required to maintain or

improve the quality of the water resource.

The PES or health of wetlands has only been applied to the “natural” wetlands, i.e. those that have

developed naturally as a consequence of the presence of water. Wetlands are rated on a scale of A to

F, with A being a natural wetland and F being a completely modified and disturbed wetland (Table 5).

The Wet-Health assesses the following four factors that influence the “health” or condition of

wetlands and in this particular application floodplains and river channels associated with the site:

Hydrology;

Geomorphology

Vegetation, and ideally

Water quality.

The Present Ecological Status Class (PESC) of the wetlands was based on the available information for

each of the criteria listed in Table 3 and the mean score determined for each wetland (Table 5). This

approach is based on the assumption that extensive degradation of any of the wetland attributes may

determine the PESC (DWAF, 2003).

Table 5. Present Ecological Status Class Descriptions

CLASS CLASS

BOUNDARY CLASS DESCRIPTION

A >4

Unmodified, natural;

The resource base reserve has not been decreased;

The resource capability has not been exploited

B >3 and <=4

Largely natural with few modification;

The resource base reserve has been decreased to a small extent;

A small change in natural habitats and biota may have taken place but the

ecosystem functions are essentially unchanged.

C >2 and <=3

Moderately modified;

The resource base reserve has been decreased to a moderate extent.

A change of natural habitat and biota have occurred, but the basic

ecosystem functions are still predominantly unchanged.

D 2

Largely modified;

The resource base reserve has been decreased to a large extent.

Large changes in natural habitat, biota and basic ecosystem functions have

occurred.


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CLASS CLASS

BOUNDARY CLASS DESCRIPTION

E >0 and <2

Seriously modified;

The resource base reserve has been seriously decreased and regularly

exceeds the resource base;

The loss of natural habitat, biota and basic ecosystem functions is

extensive.

F 0

Critically modified;

The resource base reserve has been critically decreased and permanently

exceeds the resource base;

Modifications have reached a critical level and the resource has been

modified completely with an almost total loss of natural habitat and biota. In

the worst instances the basic ecosystem functions have been destroyed and

the changes are irreversible.

3.4.2 Ecological Importance and Sensitivity (EIS)

The Ecological Importance and Sensitivity (EIS) assessment was conducted according to the guidelines

as discussed by DWAF (1999). Here DWAF defines “ecological importance” of a water resource as an

expression of its importance to the maintenance of ecological diversity and function on local and

wider scales. “Ecological sensitivity”, according to DWAF (1999), is the system’s ability to resist

disturbance and its capability to recover from disturbance once it has occurred.

In the method outlined by DWAF a series of determinants for EIS (Table 6) are assessed for the

wetlands on a scale of 0 to 4 (Table 7). The median of the determinants is used to determine the EIS

of the wetland unit (Table 7).

Table 6. Criteria for assessing the Ecological Importance and Sensitivity of Wetlands

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. Sensitivity to Changes in the Natural Hydrological Regime

7. Sensitivity to Water Quality Changes

8. Flood Storage, Energy Dissipation & Particulate/Element Removal

MODIFYING DETERMINANTS

9. Protected Status

10. Ecological Integrity

Score guideline Very high = 4; High = 3, Moderate = 2; Marginal/Low = 1; None = 0

Confidence rating Very high confidence = 4; High confidence = 3; Moderate confidence = 2; Marginal/low confidence = 1


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Table 7. Ecological Importance and Sensitivity Classes

Ecological Importance and Sensitivity Category (EIS) 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. They play a major role in moderating the quantity and quality of water of major rivers.

>3 and <=4

High

Wetlands that are considered to be ecologically important and sensitive. The biodiversity of these wetlands may be sensitive to flow and habitat modifications. They play a role in moderating the quantity and quality of water of major rivers.

>2 and <=3

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. They play a small role in moderating the quantity and quality of water of major rivers.

>1 and <=2

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. They play an insignificant role in moderating the quantity and quality of water of major rivers.

>0 and <=1

3.5 GDARD RULES FOR SENSITIVITY MAPPING

GDARD (2012) states specific rules for sensitivity mapping during biodiversity assessments inside the

boundaries of the Gauteng Province. The rules that apply for wetland studies are as follows:

3.5.1 Wetland Zones

The wetland and a protective buffer zone, beginning from the outer edge of the wetland temporary

zone, must be designated as sensitive. Rules for buffer zone widths are as follows:

30m for wetlands occurring inside the urban edge;

50m for wetlands occurring outside the urban edge.

Note that these buffer zones are essential to ensure healthy functioning and maintenance of wetland

ecosystems. Larger buffer zones may be required for wetlands supporting sensitive species (refer to

mapping rules in species-specific sections)

3.5.2 Rivers (non-perennial / perennial)

Riparian zones and buffer zones must be designated as sensitive according to the following mapping

rules.

The riparian zone must be delineated according to “DWAF, 2003: A Practical Guideline

Procedure for the Identification and Delineation of Wetlands and Riparian Zones”;

A 100m buffer zone from the edge of the riparian zone for rivers/streams outside the urban

edge;


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A 32m buffer zone from the edge of the riparian zone for rivers/streams within the urban

edge.

Note that these buffer zones are essential to ensure healthy functioning and maintenance of aquatic

ecosystems. Larger buffer zones may be required for aquatic ecosystems supporting sensitive species

(refer to mapping rules in species-specific sections.


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4. RESULTS

DWAF (2003) states that in order to classify an area as a wetland it must have one or more of the

following attributes:

Hydromorphic soils that exhibit features characteristic of prolonged saturation;

The presence of hydrophytes (even if only infrequently);

A shallow water table that results in saturation at or near the surface, leading to the

development of anaerobic conditions in the top 50cm of the soil.

Two wetland types were identified on site namely:

Unchannelled valley bottom wetland;

Artificial depressions (dams)

The smaller stormwater canals represent water courses and riparian woodland. The identification of

the water courses was done according to the aerial photograph and a field survey where the

topography of the landscape and vegetation were used to delineate the water course or riparian

zone.

A buffer zone of 32 meter is needed around the wetlands, although the water courses represent

stormwater canals and are not natural features. Where road crossings will cause unavoidable impact

on the wetlands and water courses on site, a Water Use Licence should be obtained from DWS.

The wetland delineation map is presented in Figure 8.


-28-

Figure 8. Wetland / riparian map for the proposed development with buffer zones as recommended by GDARD regulations (2014)


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4.1 WETLAND / RIPARIAN CLASSIFICATION

4.1.1 Unchannelled valley-bottom (vb) wetlands

The area in the southern section of the site represents an unchannelled valley-bottom wetland

(Photograph 1). An unchannelled valley-bottom wetland is a mostly flat valley-bottom wetland

area without a major channel running through it, characterised by an absence of distinct channel

banks and the prevalence of diffuse flows, even during and after high rainfall events. Water inputs

are typically from an upstream channel, as the flow becomes dispersed, and from adjacent slopes

(if present) or groundwater. Water generally moves through the wetland in the form of diffuse

surface flow and/or interflow (with some temporary containment of water in depressional areas),

but the outflow can be in the form of diffuse or concentrated surface flow. Infiltration and

evaporation from unchannelled valley-bottom wetlands can be significant, particularly if there are

a number of small depressions within the wetland area. Horizontal, unidirectional diffuse surface-

flow tends to dominate in terms of the hydrodynamics.

In terms of plant species composition the wetland represents moist grassland dominated by

grasses such as Setaria sphacelata, Sorghum bicolor and Sporobolus africanus, although sedges

also occur in the HGM.

Unfortunately, the valley bottom wetland provides a distribution route for weeds and invading

trees. Many of the usual weeds were recorded together with Eucalyptus camaldulensis (Red river

gum), Xanthium strumarium (Large cocklebur) Datura stramonium and Flaveria bidentis. Weeds

and invaders should be removed, as well as destruction of such plants in a safe place and manner.

Photograph 1. Unchannelled valley bottom wetland vegetation unit in the project area


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4.1.2 Artificial depressions (man-made dams)

These features represent man-made features and represent the dams in the valley bottom

wetland (Photograph 2) as well as the area adjacent to the border fence to the west of the site

where water collect in a depression (Photograph 3). These areas are considered as artificial

wetlands.

A depression is classified as 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. Dominant water sources are precipitation, ground water discharge, interflow and

(diffuse or concentrated) overland flow. For ‘depressions with channelled inflow’, concentrated

overland flow is typically a major source of water for the wetland, whereas this is not the case for

‘depressions without channelled inflow’. Dominant hydrodynamics are (primarily seasonal)

vertical fluctuations. Depressions may be flat-bottomed (in which case they are often referred to

as ‘pans’) or round-bottomed (in which case they are often referred to as ‘basins’), and may have

any combination of inlets and outlets or lack them completely.

The two types of depressions that occur in the project area are characterised by the way water

exits the systems. Water exits by means of evaporation and infiltration for endorheic depressions

(area next to wall in eastern section of site); and as concentrated surface flow in channels for

exorheic depressions (dams in wetland area), although the primary means of water still exits as

evaporation.

The vegetation associated with depressions is mostly sedges and bulrushes depending on the

depth of the water and the substrate. Species such as Persicaria serullata, Typha capensis,

Schoenoplectus corymbosus, Ludwigia stolonifer and Phragmites australis mostly grow along the

shallow edges of dams in the project area on a muddy substrate.


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Photograph 2. Edge of dam inside the unchannelled valley bottom wetland

Photograph 3. Small artificial depression adjacent to border wall of adjacent development

4.1.3 Water course and riparian woodland

The non-perennial channels or stormwater canals that occur throughout the project area can be

described as water courses or channels. (SANBI, 2009). The channels are mostly defined with

riparian woodland along its edges dominated by species such as Acacia karroo, Ziziphus

mucronata and Searsia lancea (Photograph 8). The more defined water courses are classified as


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channels. A Channel (river, including the banks) is classified as an open conduit with clearly

defined margins that (i) continuously or periodically contains flowing water, or (ii) forms a

connecting link between two water bodies. Dominant water sources include concentrated surface

flow from upstream channels and tributaries, diffuse surface flow or interflow, and/or

groundwater flow. Water moves through the system as concentrated flow and usually exits as

such but can exit as diffuse surface flow because of a sudden change in gradient. Unidirectional

channel-contained horizontal flow characterises the hydrodynamic nature of these units. As a

result of the erosive forces associated with concentrated flow, channels characteristically have

relatively obvious active channel banks.

Section 1.1 (xi) of the National Water Act (1998) described “instream habitat'' as the area which

includes the physical structure of a watercourse and the associated vegetation in relation to the

bed of the watercourse (Photograph 10). Riparian Habitat are described by the National Water Act

(1998) Section 1.1 (xxi) as follows: “riparian habitat'' includes the physical structure and associated

vegetation of the areas associated with a watercourse which are commonly characterised 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 land areas”.

Riparian zones are particularly vulnerable to invasion by alien vegetation (because they are good

dispersal routes for seeds) and this is becoming a huge ecological problem in South Africa. Large

section of the riparian woodland next to the water courses has been invaded by various aliens

such as Melia azedarach and Cestrum laevigatum.

Although alien species have invaded large section of the riparian woodland it still plays many

essential roles in the functioning of the ecosystem,


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Photograph 4. Small non-perennial water courses in the project area


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4.2 WETLAND INTEGRITY ASSESSMENTS

In determining the integrity of the wetland the condition of the site and the indirect and direct

disturbances is taken into account. Dumping, roads, overgrazing, alien invasive vegetation species,

etc. was taken into account in determining the Present Ecological Status and Ecological

Importance & Sensitivity of these wetland units (Table 8). The valley bottom wetland and dams

inside this wetland type was assessed as one unit. Appendix A and B indicate the scores for the

PES and EIS respectively.

Table 8. Present Ecological State (PES) and Ecological Importance & Sensitivity (EIS) of the

wetlands and riparian zones of the proposed development site

Wetland / Water course PES EIS

Unchannelled VB wetland, riparian zone & dams inside wetland Class C: Moderately

Modified Low

Evidence was observed on site of transformation of the floristic characteristics of the valley

bottom wetlands. Impacting activities which have altered the expected floristic composition

include canalisation, alien infestation, impoundments (dams) and road crossings. All of the above

impacts have resulted in the current condition of the wetlands on site departing significantly from

the reference or unimpacted condition of the wetland.

The impacts associated with the site is reflected in the results of the PES assessment which

indicates that the ‘Unchannelled Valley bottom Wetland is in a ‘Moderately Modified’ condition

due to the factors noted above.

The Ecological Importance and Sensitivity of this HGM unit on site are considered to be Low due

to the impoundments, stands of alien invasive species, sedimentation and overgrazing that

modified the area. These wetlands are not ecologically important and sensitive at any scale. The

biodiversity of these Wetlands is ubiquitous and not sensitive to flow and habitat modifications.

They play an insignificant role in moderating the quantity and quality of water that feeds the

larger rivers of the area.


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5. POTENTIAL IMPACTS OF THE PROPOSED DEVELOPMENT ON THE WETLANDS AND RIPARIAN ZONES

The proposed development will have a definite and direct impact on the wetland areas as well as

the riparian woodland. Subsequently the use of buffer zones is considered very important to

ensure the healthy functioning of the wetland ecosystem.

Indirect impacts could also occur as a result of construction activities (dust, spillages etc.). The

following section deals with the anticipated impacts of the proposed power line on the wetland of

the site.

5.1 PERMANENT LOSS OF WETLAND AND THEIR ASSOCIATED FUNCTIONS

5.1.3 Description of impact:

The construction activities will have an impact on the wetlands and riparian woodland on site,

whether it be through direct or indirect impacts. Clearance of vegetation will currently occur

through large section of the wetlands for the road crossings, and this will also be necessary for

some areas of the developments.

Loss of the riparian habitat will also result in permanent loss or displacement of the invertebrates,

birds and small mammals dependant on the wetland vegetation for feeding, shelter and breeding

purposes. All functions associated with the wetlands and the surrounding landscape will be

compromised.

Certain natural and anthropogenic activities, e.g. floods, development activities and the

development and construction of the access road in the wetland area, will cause immense

damage to the structure of the wetland, and therefore the flow path. The physical wetland

structure forms the template for instream habitat, and is essential for maintaining habitat quality.

Any changes in channel condition and structure would have a cumulative effect, and if sufficiently

extreme, may result in a shift in population structure and possibly biotic diversity at a site.

5.1.3.1 Destruction or loss of riparian floral diversity or riparian communities

The following major impacts of the development will potentially impact on the flora of the site:

Loss of threatened, “near-threatened” and endemic taxa: The anticipated loss of some of

the riparian and instream habitats that support endemic species will result in the local

displacement of endemic listed flora;

The construction activities and associated impacts will lead to the loss of individual plants

associated with riparian zones and in-channel zones;

The construction activities can impact on surrounding riparian vegetation by dust and

altered surface run-off patterns;


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The disturbance of the area could lead to an increase in the growth of alien vegetation;

5.1.3.2 Loss of riparian and water dependant faunal diversity through migration and

decline in animal numbers

The following major impacts of the development will potentially impact on the faunal habitats of

the site:

Habitat modification by construction activities will force riparian-dependant fauna out of

the area and animal numbers will decrease. This impact could also take place because of

hunting and snaring of animals in and around the riparian zones and water courses.

Loss of threatened, “near-threatened” and conservation important taxa: The anticipated

loss of the areas adjacent to the riparian zones will ultimately also result in the local

displacement of some fauna species that occur in the water courses.

Changes in the community structure: It is expected that the faunal species composition

will shift, due to an anticipated loss in habitat surface area. In addition, it is predicted

that more generalist species (and a loss of functional guilds) will dominate the study area.

Attempts to rehabilitate will attract taxa with unspecialised and generalist life-histories. It

is predicted that such taxa will persist for many years before conditions become suitable

for succession to progress.

5.1.4 Mitigation measures:

The overall alluvial characteristics of the proposed stormwater canals (balance between

sand, gravel and stone) must be similar to before construction to ensure natural systems

of flooding and sedimentation deportation and conveyance occur. The stormwater for

the crossings should be addressed by the developers of the development;

The use of cement lined channels as stormwater features must be avoided at all costs

and lining must be done with Loffel stones (or Amourflex stones) or similar products. This

is to prevent the loss of habitat to aquatic organisms living in the system;

The ramps for the in- and out flows from the construction site must be lined with Reno

mattresses and or gabions to prevent structure undermining and to ensure flow is

dispersed and mitigated. Vertical steps should not exceed 500 mm, to ensure aquatic

fauna movement and migration.

The use of gabion structures, well keyed into the surrounding bank walls and secured to

the ground is recommended.

If any construction activity must occur within the riparian areas then it must commence


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from upstream proceeding downstream with proper sedimentation barriers in place to

prevent sediments and pollution moving downstream from the site. This includes non-

perennial systems.

The velocity of storm water must be attenuated and spread. As far as possible the link

between the wetland and the local environment must be maintained. This is to ensure

water movement into the soils and ensuring the survival of associated vegetation.

Clearing of vegetation should be scheduled for the drier winter months and limited to

areas immediately needed for construction. Vegetation stripping should occur in parallel

with the progress of construction to minimise erosion and/or run-off. Large tracts of bare

soil will either cause dust pollution or quickly erode and then cause sedimentation in the

lower portions of the catchment. Only selected plant species must be used in the re-

vegetation process.

All development activities should be restricted to the footprint areas of the proposed

development. The Environment Site Officer (ESO) should demarcate and control these

areas. Storage of road-building equipment, fuel and other materials should be limited to

demarcated areas. Layouts should be adapted to fit natural patterns rather than

imposing rigid geometries.

The Environment Control Officer (ECO) should advise the construction team in all

relevant matters to ensure minimum destruction and damage to the environment and

specifically riparian zones. The ECO should enforce any measures that he/she deem

necessary. Regular environmental training should be provided to construction workers to

ensure the protection of the habitat, fauna and flora and their sensitivity to conservation.

The removal of indigenous trees and shrubs associated with the riparian areas should be

limited to the footprint areas;

Should the development be approved by authorities, environmental monitoring of

environmental aspects should be implemented during the construction phase of the

development to ensure that minimal impact is caused to the riparian zones of the area.

5.2 SOIL COMPACTION AND INCREASED RISK OF SEDIMENT TRANSPORT AND EROSION

5.2.1 DESCRIPTION OF IMPACT:

The use of heavy machinery during the construction process will result in the compaction of soil,

resulting in decreased infiltration of rain water and increased surface run-off volumes and

velocities leading to a greater erosion risk. The hardened surfaces of the paved road and

compacted soils of the proposed road development area will also lead to an increase in surface


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run-off during storm events which will likely be discharged via stormwater outlet points,

concentrating flows leaving the paved areas. This can lead to erosion and channel incision in the

water courses and change the in-stream habitat. This could result in higher velocity flows with

greater erosive energy which can result in channel incision and gully erosion downstream within

the channel riparian zones.

Hard engineered surfaces also reduce the amount of permeable surfaces for water to

penetrate the soils and maintain the local groundwater systems. Due to the linear nature

of the proposed project and cumulative impacts, the environmental significance on the

vegetation could be significant without mitigation as water is then diverted and the soils

then dry out and later erode due to the lack of plant cover.

Soil erosion also promotes a variety of terrestrial ecological changes associated with

disturbed areas, including the establishment of alien invasive plant species, altered plant

community species composition and loss of habitat for indigenous fauna and flora.

5.2.2 MITIGATION MEASURES

The following mitigation measures should be implemented to prevent erosion along slopes and

drainage channels during road construction:

Increased runoff due to removal of vegetation and increased soil compaction must be

managed to ensure the prevention of siltation and the maximum stream bank stability.

Storm water leaving the site downstream must be clean and of the same quality as in situ

before it enters the construction site (upstream). Preconstruction measures must be in

place to ensure sediments are trapped.

The project should be divided into as many phases as possible, to ensure that the

exposed areas prone to erosion are minimal at any specific time;

Cover disturbed soils as completely as possible, using vegetation or other materials;

Minimize the amount of land disturbance and develop and implement stringent erosion

and dust control practices.

Sediment trapping, erosion and stormwater control should be addressed by a

hydrological engineer in a detailed stormwater management plan;

Protect sloping areas and drainage channel banks that are susceptible to erosion and

ensure that there is no undue soil erosion resultant from activities within and adjacent to

the construction camp and Work Areas;


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Repair all erosion damage as soon as possible to allow for sufficient rehabilitation

growth;

Gravel roads must be well drained in order to limit soil erosion;

Control the flow of runoff to move the water safely off the site without destructive gully

formation;

5.3 SOIL AND WATER POLLUTION


Construction work will also carry a risk of soil and water pollution, with large construction

vehicles contributing substantially due to oil and fuel spillages. If not promptly dealt with,

spillages or accumulation of waste matter can contaminate the soil and surface or

ground water, leading to potential medium/long-term impacts on fauna and flora. During

the operational phase vehicles would be the main contributors to potential pollution

problems.

5.3.2 MITIGATION MEASURES:

Any excess or waste material or chemicals should be removed from the site and

discarded in an environmental friendly way. The ECO should enforce this rule rigorously;

Hazardous chemicals to be stored on an impervious surface protected from rainfall and

storm water run-off;

Spill kits should be on-hand to deal with spills immediately;

All vehicles should be inspected for oil and fuel leaks on a regular basis. Vehicle

maintenance yards on site should make provision for drip trays that will be used to

capture any spills. Drip trays should be emptied into a holding tank and returned to the

supplier.

5.4 SPREAD AND ESTABLISHMENT OF ALIEN INVASIVE SPECIES


The construction almost certainly carries by far the greatest risk of alien invasive species being

imported to the site, and the high levels of habitat disturbance also provide the greatest

opportunities for such species to establish themselves, since most indigenous species are less

tolerant of disturbance. The biggest risk is that seeds of noxious plants may be carried onto the

site along with materials that have been stockpiled elsewhere at already invaded sites.

Continued movement of personnel and vehicles on and off the site, as well as occasional delivery

of materials required for maintenance, will result in a risk of importation of alien species


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throughout the life of the project.

Furthermore, the spread of the alien invasive species through the area will be accelerated when

seeds are carried by storm water into the drainage features and riparian zones on the site that will

cause environmental degradation and indigenous species to be displaced.

5.4.2 MITIGATION MEASURES:

The use of indigenous plants must be encouraged in the rehabilitated areas (stormwater

canals), and stockpiles containing mostly exotic or weedy species should receive

specialised handling and should be covered for extended periods to inhibit seedling

germination of these species. Active management and eradication of exotic / alien plant

species should also occur when seedlings are found.

Institute strict control over materials brought onto site, which should be inspected for

potential invasive invertebrate species and steps taken to eradicate these before

transport to the site. Routinely fumigate or spray all materials with appropriate low-

residual insecticides prior to transport to or in a quarantine area on site. The contractor is

responsible for the control of weeds and invader plants within the construction site for

the duration of the construction phase.

Control involves killing the plants present, killing the seedlings which emerge, and

establishing and managing an alternative plant cover to limit re-growth and re-invasion.

Weeds and invader plants will be controlled in the manner prescribed for that category

by the Conservation of Agricultural Resources Act or in terms of Working for Water

guidelines.

Rehabilitate disturbed areas as quickly as possible to reduce the area where invasive

species would be at a strong advantage and most easily able to establish.

Institute a monitoring programme to detect alien invasive species early, before they

become established and, in the case of weeds, before the release of seeds.

Institute an eradication/control programme for early intervention if invasive species are

detected, so that their spread to surrounding natural ecosystems can be prevented.

A plan should be developed for control of noxious weeds and invasive plants that could

occur as a result of new surface disturbance activities at the site. The plan should address

monitoring, weed identification, the manner in which weeds spread, and methods for

treating infestations. Require the use of certified weed-free mulching. Prohibit the use of

fill materials from areas with known invasive vegetation problems. The spread of invasive

plants should be avoided by keeping vehicles and equipment clean and reseeding


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disturbed areas with native plants.

5.5 IMPACT ASSESSMENT MATRIX FOR THE CONSTRUCTION PHASE OF THE

DEVELOPMENT

Table 9 indicates the impacts described above and specific ratings of significance the impact

during construction will potentially have on the drainage features of the area. The most significant

impacts are erosion and soil compaction, although impacts such as alien species invasion and

spillages are limited during the construction phase or can be successfully mitigated.


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Table 9. Impact assessment matrix for the proposed Erasmuspark Mixed Use Development

Nr Activity Impact P D S M Significance Before

Mitigation

Mitigation Measures

P D S M Significance

Construction Phase Pre-Construction and Construction Phase

1 Construction of roads / infrastructure in wetland or in close proximity

Loss of wetland and riparian habitat

5 5 1 8 80 High

See section 6.1.2

5 5 1 6 60 Moderate-High

2

The increased hardened surfaces around infrastructure and exposed areas created, as well as the roads and additional surface areas created during construction

Soil compaction and erosion leading to sedimentation

5 5 3 8 80 High

See section 7.2.2

4 2 2 6 40 Moderate-Low

3

Large construction vehicles contributing substantially due to oil and fuel spillages; building waste, batching plants, sewage and domestic waste; stripping of topsoil

Water pollution from spillages and dust 4 4 3 6 52 Moderate

See section 7.1.4.2 4 3 2 2 28 Low

4

Continued movement of personnel and vehicles on and off the site during the construction phase, as well as occasional delivery of materials required for maintenance

Spread of alien invasive species in wetland systems

4 5 2 6 52 Moderate

See section 6.6.2

2 3 2 2 14 Negligible


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6. MANAGEMENT STRATEGY FOR THE DEGRADED WETLANDS

6.1 CONSTRAINTS AND OPPORTUNITIES OF THE EXISTING ENVIRONMENT

The existing environment presents a number of constraints and opportunities which have been

considered in the development of the recommendations for the site as part of the proposed

development.

6.1.1 Constraints

Loss of stream or wetland habitat

Pollution of the streams, wetlands and groundwater. Stormwater runoff contains a

number of potentially harmful pollutants, including fuels and oils, lead, etc.

Increased stormwater runoff: The construction of hardened surfaces on the property will

lead to an increase in the quantity of runoff flowing across the site.

Loss of surface and subsurface water recharge to groundwater: Any loss of seep or

stream habitat, or condition, could interfere with the natural recharge of subsurface

water resources. In addition, if natural surface runoff is diverted away from houses on

the site, this might interfere with subsurface drainage across the site.

Increased erosion and sedimentation: Runoff from residential areas can lead to increased

mobilisation of fine sediments during rain and storm events.

Increased disturbance of aquatic fauna and flora: The proximity of homes to the wetland

corridor will lead to an increase in disturbance in the form of noise, light, pets and

physical disturbance from trampling.

Introduction of alien invasives.

6.1.2 Opportunities

Opportunity to manage and monitor the wetland effectively and thereby increasing

knowledge base on the specific wetlands of the area;

6.2 MANAGEMENT STRATEGIES

The following strategies are proposed for the management of the wetland environment:

Edge effects of pre-construction and construction activities, including erosion,

sedimentation and alien/weed control, need to be strictly managed in the artificial

created wetland areas (grass canals);

Implement appropriate silt traps and filters to ensure optimal water quality to the canals

from stormwater run-off. Stormwater should be conveyed into detention ponds that are

earth-lined, thereby allowing settling out of sediments.


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Ensure that the wetlands and stormwater canals are adequate to carry floodwaters

(1:100 year floodline) is provided around the wetlands that lie outside the layout

footprint area.

Unnecessary excavation and infilling of the stream corridors and wetland areas (unless

associated with rehabilitation) must be avoided or, where unavoidable, kept to a

minimum;

Construction of infrastructure should take place during the dry season, to reduce the

risks of contamination of the streams and wetlands through rainfall, runoff and erosion.

6.2.1 Stormwater Management: The Sustainable Drainage System (SuDS)

Township and road developments reduces the natural permeability characteristics of land by

replacing free draining surfaces with impermeable surfaces, typically drained by pipes and/or

canals. This also results in the general loss of vegetation, biodiversity and amenity.

It is widely recognised that developments impact negatively on natural drainage systems in

several ways, including:

Reduced permeability of catchment areas by introduction of impervious surfaces such as

streets and buildings. This results in increased catchment runoff volumes.

The introduction of efficient stormwater drainage results in reduced catchment response

times with concomitant increased downstream flow peaks.

Manipulation of groundwater tables, which can have severe effects on wetland

functioning and the survival of many terrestrial plant communities.

Alteration to the natural flow regimes in river systems resulting in both geomorphologic

(e.g. channel / bank erosion) and aquatic ecosystem changes over time.

Deteriorating water quality as a result of industrial fallout, fertilisers and other pollutants

that are conveyed by stormwater systems directly to receiving water bodies, without any

attempt to ameliorate enroute.

These guidelines require greater cognisance to be taken of natural hydrological patterns and

systems in the development of stormwater management systems and that the potential negative

impacts highlighted above are reduced as far as is practically possible. This is illustrated by means

of Figures 9 to 11 below, depicting both the traditional and recommended approaches to

stormwater management within the urban context.


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Figure 9. Natural hydrological system

Figure 10. Stormwater management approach with little concern for natural environment


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Figure 11. Responsible approach to stormwater management

Stormwater management objectives should include the following:

Minimise the Threat of Flooding: This remains a key objective of any stormwater

management system. However the challenge when contemplating design of stormwater

management systems is to consider the following:

o To mimic pre-development responses to storms

o To reduce the volume of runoff by promoting infiltration

o To reduce the peak flows and increase the time-to-peak through detaining the

runoff and releasing it at a gradual rate

o Where necessary, to construct means to contain flood waters and safely convey

them out of the urban area

Protection of Receiving Water Bodies: Receiving water bodies include the following:

o Rivers / streams;

o Groundwater;

o Wetlands;

It should be noted that the “receiving water body” is not necessarily the system into which

stormwater is discharged directly, but can also be a natural system located further downstream in

the catchment. Every endeavour should be made to achieve the following as far as possible:


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Maintain natural flow regimes and seasonality

Prevent deterioration in water quality

Prevent erosion or sedimentation of natural wetlands or rivers

Preserve natural river channels, wetlands and vegetation, and preclude engineering

interventions that may alter their physical and ecological characteristics.

The need to design appropriate stormwater management systems for new developments should

be seen as an opportunity to preserve or, if possible, improve natural freshwater ecosystems that

have suffered degradation as a result of past activities, and in some cases, to create additional

freshwater habitats that will contribute to the availability of appropriate, high quality river and

wetland habitat that mimics the natural condition.

Promote Multi-Functional Use of Stormwater Management Systems: Resources such as

land and water are becoming increasingly scarce and multiple use of these must be

strived for. Stormwater systems provide a wide range of opportunities for multi-

functionality.

Development of Sustainable Environments: Developers should think beyond their short-

term involvement with the project and consider the sustainability of the stormwater

management system that is to be implemented. All relevant factors that will impact on

future operation and maintenance should be taken into account. Maintenance

requirements should be minimised as far as possible in order to maximise the available

local authority funding, personnel and equipment. Responsibilities for maintenance must

be resolved with the relevant local authority department at an early stage of the design.

The possibility of developing public/private partnerships should be explored with local

authorities (e.g. division of funding of capital versus maintenance costs between public

and private sectors). Environmental policies such as promoting the use of locally

indigenous vegetation in planting programmes will also reduce the long-term

maintenance requirements of the development.

Conventional drainage systems are generally focused on eliminating local flood nuisances and

ignore the water quality, amenity, and biodiversity. Sustainable drainage systems (SuDS) aim to

mimic the natural hydrological cycle thereby improving water quality, preserving biodiversity, and

enhancing amenity. The result is a more sustainable and liveable city.

The key objectives of the SuDS approach are the effective management of: stormwater runoff

quantity, quality and the associated amenity and biodiversity as described by the hierarchy below

(Figure 12) where each level contributes to an improved, more sustainable drainage system.


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Figure 12. Stormwater design hierarchy of the SuDS

Treatment trains are critical in designing an effective SuDS scheme. The SuDS Treatment Train

starts with good housekeeping before moving on to source controls, local controls and regional

controls. SuDS controls should be used sequentially in order to optimally treat stormwater runoff.

Good Housekeeping ensures that as much as possible is done to minimise the release of pollutants

– such as solid waste – into the environment where it may subsequently be transported by

stormwater.

Source controls manage stormwater runoff as close to its source as possible, usually on site.

Typical SuDS options include: green roofs, rainwater harvesting, permeable pavements and

soakaways.

Local Controls manage stormwater runoff in the local area, typically within the road reserves and

around infrastructure. Typical SuDS options include: bio-retention areas, filter strips, infiltration

trenches, sand filters and swales.

Regional Controls manage the combined stormwater runoff from several developments. Typical

SuDS options include: constructed wetlands, detention ponds and retention ponds.

These aspects and specific management practices that can be considered for implementation for

the developments is indicated in Table 10.


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Table 10 SuDS conceptual design matrix

There are circumstances where SuDS may be unsafe; for example where there is a serious risk of

contamination resulting from point or non-point sources. These risks should be taken into

consideration in the design and precautions taken. Table 11 highlights pollutants that may be

found in stormwater. The potential risks of each pollutant on a site need to be assessed. This is

especially important in the case of pathogens where stormwater facilities are open to the general

public.


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Table 11. Potential stormwater pollutants and impacts that needs to be assessed and monitored

during the development phases

6.2.2 Erosion control and rehabilitation

Erosion control will need to be undertaken to ensure the successful landscape and rehabilitation

of the surrounding areas and wetlands of the larger area. Specific soil management practices

needs to be implemented to prevent erosion and sedimentation as stipulated below:

6.2.2.1 Disturbance to wetland soil

Stringent controls must be put in place to prevent any unnecessary disturbance or compaction of

wetland soils. Compaction of soils should be limited and / or avoided as far as possible.

Compaction will reduce water infiltration and will result in increased runoff and erosion. Where

any disturbance of the soil takes place (have taken place in the past), these areas must be

stabilized and any alien plants which establish should be cleared and follow up undertaken for at

least 2 years thereafter and preferably longer. Where compaction results, remedial measures

must be taken (e.g. “ripping” the affected area). Topsoil should preferably be separated from the

subsoil, and topsoil sections should be kept intact as deep as possible.


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6.2.2.2 Erosion prevention

During the construction phase the clearing of the site will leave the soil exposed and this can

cause erosion. The following list provides a guide to preventing erosion on construction sites:

Programming: Install erosion control measures before construction commences.

Schedule construction activities to minimize land disturbance.

Land clearing: minimize the extent and duration of land clearing.

Stormwater and run-off systems: install temporary drains and minimize concentrated

water flows. Control stormwater velocity where necessary with temporary energy

dissipater structures. Divert run-off around trench excavations or disturbed areas.

Rehabilitation: revegetate or stabilize all disturbed areas as soon as possible. Indigenous

trees can be planted in the buffer zone of the proposed development to enhance the

aesthetic value of the site and stabilize soil conditions.

Services: coordinate the provision of site services to minimize disturbance.

Stockpiles: locate stockpiles away from concentrated flows and divert run-off around

them.

6.2.2.3 Prevention of sedimentation

Erosion is likely to occur on site, with sediment export being an inevitable risk. Measures must be

employed to capture sediment and reduce the amount of sediment that leaves the site. The

generation of dust, litter and debris need to be minimized. A regular site maintenance schedule

needs to be introduced. Sediment control devices need to be installed to capture mobilized

sediment. The following sediment control devices are suggested:

Grass filter strips: it encourages sediment to settle as water passes over a vegetated area.

Sediment filters: use materials such as fine mesh or geofabric to filter run-off prior to

discharge.

Sediment traps: temporary sedimentation basins.

Drop inlet filters: e.g. hay bales and silt fences, which prevent sediment entry into the

drainage system.

6.2.2.4 Pollution prevention

Stored material that has been poorly located or left unprotected can be a source of pollutants.

The following measures need to be taken to prevent pollution to the wetland:

Stockpile location: locate stockpiles and material storage 30m or more away from

drainage lines and identified wetland habitat.


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Stockpile construction: minimize the number and size of stockpiles. Construct stockpiles

with a height to width ratio of less than 2:1. Surround unstabilised stockpiles and batters

with silt fences or drainage systems that will collect and treat uncontaminated water.

Stockpile maintenance: cover any stored material to protect it from rainfall. Mulch,

roughen and grass seeding can be used on any batter or topsoil stockpile that is to be

maintained for longer than 28 days.

6.2.2.5 Littering prevention

Uncontrolled littering can be a source of pollution to the wetland. The following measures need to

be taken in order to mitigate against littering in wetlands:

Litter storage and housekeeping: maintain a high standard of housekeeping. Store all

litter carefully so it cannot be washed or blown into the stormwater drainage systems.

Rubbish bins: provide bins for construction workers and staff at appropriate location,

particularly where food is consumed.

Daily site clean-up: cleanup site of all litter daily.

Rubbish disposal: dispose of scrap materials (e.g. off-cuts and scrap machinery

components) in a responsible manner.

6.2.2.6 Building activity associated impacts

Dust concrete, solvents, steel fillings, fuel and other wastes are all produced during building

construction and can cause impacts to the wetlands. Take the following mitigation measures:

Materials storage: store building materials under cover or in contained areas.

Site cleaning: clean the repair or construction site daily. Do not use water for cleaning the

site.

Leakage containment and treatment: ensure that oil, fuel or solvent leakages cannot

enter the stormwater system.

Temporary filters: fit temporary inlet pit filters near wash-down areas to prevent

pollutant entry into the drainage system.

6.3 IMPLEMENTATION

The cost of implementation of the Wetlands Management Plan includes initial costs of

environmental works, plus the capital costs associated with infrastructure development as well as

an ongoing maintenance cost. Implementation of the plan needs to be balanced with the likely

use the site will receive and the benefits to the community of the improved amenity.

The proposed staging of works is based on the criteria of:


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Improved environment – the canal area is enhanced by the rehabilitation and alien

clearing program;

Community value – The local people are better able to use or appreciate the site

This project will require a commitment to ongoing maintenance.


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7. REHABILITATION PLAN FOR DEGRADED WETLANDS / STORMWATER CANALS

This rehabilitation plan is applicable to the activities directly associated with the construction of the

proposed development in the vicinity of the degraded wetlands and riparian zones.

7.1 WETLAND REHABILITATION PROBLEMS

The ecological integrity of the wetlands on site (especially the channelled VB wetlands) has been

impacted by several factors including:

Flow impediment through dam construction in wetlands;

Transformation of natural vegetation by alien plant infestation.

Habitat transformation and alteration of natural hydrological processes by roads.

7.2 WETLAND REHABILITATION OBJECTIVES

In order to address the problems identified, a number of objectives were established to guide

rehabilitation planning for the impacted wetland units identified. In order to achieve the

rehabilitation objective defined, a number of wetland interventions have been proposed. These have

been prioritized from a wetland rehabilitation perspective but implementation may need to be re-

ordered due to practical or financial constraints. The proposed interventions aim to:

Control alien invasive species in wetland areas;

Stabilization of sloped banks to reduce erosion hazard;

Support upstream intervention to reduce risk of failure;

Re-direct flows out of downstream drain;

Divert moderate summer flows and high flows out of downstream drain and into adjacent

wetland area.

7.3 REHABILITATION WORKS / METHODS

The Environmental Rehabilitation process at the construction site should form an integral part of site

development, operation and post-construction activities. A Rehabilitation Specialist and/or

Environmental Control Officer (ECO) should therefore be appointed, and be available on-site as part

of the rehabilitation management / construction team. The ECO should form an integral part of the

management team, attending regular site meetings, receiving Project Meeting Minutes and being

kept fully updated regarding the closure plan and site rehabilitation process.

This information is vital in ensuring that the necessary preventative measures and Search and Rescue

activities are affected timeously.

Rehabilitation measures that may be affected on site include systems such as soil terracing, berm

creation, grass blocks, fascine work, gabion basket work, reno mattresses, retaining block


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mechanisms, sand bags, boulder and rock placement, stone pitching, and grading. Decisions

pertaining to plant material choices and specific vegetation utilisation for specific areas from an

integral part of the process, as the hard landscape components work in conjunction with the soft

landscape components. For example, the utilisation of plants with substantial roots for bank

stabilisation purposes.

7.3.1 Identification and protection of environmentally sensitive areas

The on-site Environmental Control Officer and/or Rehabilitation Specialist should be fully aware of the

scale and extent of the rehabilitation operations. No further vegetation clearing, levelling, excavation,

topsoil removal or plant material removal is to be permitted without prior consent from the ECO and

Rehabilitation Specialist based on the rehabilitation plan for the site unless instructed by them. Care

must be taken during rehabilitation to avoid the natural drainage areas adjacent to the construction

site. No vegetation clearance, topsoil collection or movement of machinery and vehicles should be

allowed here as to keep the ecological integrity of the drainage areas and banks intact.

7.3.2 Comprehensive Photographic Record

In order for practical and attainable rehabilitation goals to be defined, it is recommended that a

comprehensive photographic record of the entire property be created. Video footage may also be

useful in compiling such a record. A photographic record of the entire property should be kept as it

could become a very valuable tool for the Rehabilitation Works in future. It would serve as the basis

for rehabilitation requirements, informing decisions on drainage, soil shaping, levels, plant choices

and rehabilitation in general. It can also serve as a verification report to authorities and land

administrators regarding the legislative processes, sustainable approach and progressive

improvement.

7.3.3 Search and Rescue Activities

Search and Rescue activities could be initiated as part of the Rehabilitation process. Where

rehabilitation actions will commence, viable, transplantable plant species could be identified by the

ECO / Rehabilitation Specialist, removed and stored in a potential ‘on-site’, self-sustaining nursery, to

be re-used in rehabilitation activities in future.

Plant material that is to be “rescued” must be potted up into bags utilising local soil obtained from

the previously stored topsoil heap. Adequate root systems per plant material type must be carefully

excavated and retained in order for plant material to remain viable. Search and Rescue activities

would include the removal of grass clumps, smaller transplantable shrubs and trees and endangered

species such as geophytes and succulents should be placed into bags using local soil.

Animals like small mammals, reptiles and birds encountered during rehabilitation operations should

be captured or moved by a specialist and released in a safe area. No animals may be poached at the


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property or adjacent areas. Many animals are protected by law and poaching or other interference

could result in a fine or jail term.

7.3.4 Cleared Indigenous Plant Material

Where construction or rehabilitation activities are to commence in a specific area, certain indigenous

plant material from the construction footprint area could be collected and bagged to be used in re-

vegetation or as mulch during rehabilitation. To protect drainage areas and small streams as well as

erosion prone areas, encroachers such as sickle bush could be cut and used to “brush pack” these

problem areas to protect it. This will also restrict movement of animals and humans over sensitive

erosion probe areas until pioneer vegetation has established.

7.3.5 Removal of Overburden

Removal of Overburden (or spoil material) means the total removal of soil and rock material from the

site up to natural surrounding ground level. Overburden may be used to backfill excavated areas.

Where overburden remains after backfilling excavated areas to natural ground level, this needs to be

transported off-site by the contractor to a location approved by the Engineers.

In addition to the removal of excess rock and soil from the site, all other construction-related

materials (bricks, concrete, steel rods, machinery etc.) also have to be taken off-site after cessation of

construction activities.

7.3.6 Compaction Rehabilitation Measures (ripping and / or scarifying)

Soil compaction is often an effect of high traffic areas on development sites. It can become a major

problem and can be recognized by:

Excess surface moisture and slow drying soils due to deeper compaction preventing the

percolation of water through the soil profile;

Water runoff due to surface compaction preventing penetration and absorption (ponding of

water), especially on banks and sloping surfaces;

Large clear or sparsely covered areas devoid of a good vegetative cover due to hardened

topsoil layers.

Ripping and / or Scarifying means the loosening of compacted soils by hand or appropriate

machinery. The removal of overburden by excavator will loosen some of the upper compacted soils to

some degree. Soils are to be loosened to a depth not less than 500mm. Slope angles should not

exceed 18º incline angles (unless where specifically required in which case slope stabilization methods

have to be implemented). Re-shaped land must resemble the pre-construction landscape as closely as

possible. Ripping/Scarifying should preferably be done before the rainy season. Do not rip and/or

scarify areas under wet conditions, as the soil will not loosen.


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Compacted soil can also be decompacted by “Rotary Decompactors” to effectively aerate soils for

vegetation establishment.

7.3.7 Erosion Rehabilitation Measures

Water has the gift to sustain life, but also the potential to maim, damage and destroy if not managed

correctly. Remedial actions must be established to ensure that potential erosion on site is addressed

with an erosion control strategy towards rehabilitation. The following management measures are

proposed for the rehabilitation process:

Reprofiling of the banks of disturbed drainage areas to a maximum gradient of 1:3 to ensure

bank stability;

Reinforce banks and drainage features where necessary with gabions, reno mattresses and

geotextiles. This is especially relevant for the stormwater outlet area;

Reseed any areas where earthworks have taken place with indigenous grasses to prevent

further erosion;

Erosion control mechanisms must be established as soon as possible. Further financial

provision should be continued over the subsequent years to allow for maintenance of the

gabions, reno mattresses, and associated structures;

A stormwater plan must be developed with the aid of an engineer to ensure that water

runoff is diverted off the site without pooling and stagnation or erosion. Financial provision

for closure will include the estimated costs for erosion control post-construction;

Topsoil stockpiles should be vegetated to control loss from erosion and should have berms

on top to reduce erosion from surface runoff. In areas where soil stockpiles are greater than

2 m high, soils should be ameliorated during closure to ensure their suitability for use in

rehabilitation;

If compaction occurs, rectification can be done by application and mixing of manure,

vegetation mulch or any other organic material into the area. Use of well cured manure is

preferable as it will not be associated with the nitrogen negative period associated with

organic material that is not composted;

Vehicle traffic should not be allowed on the rehabilitated areas, except on allocated roads,

must not be allowed. It will have a negative impact due to the dispersive/compaction

characteristics of soils and its implications on the long term;

Foot action should be prevented by brush-packing the area during the establishment phase

of vegetation on the rehabilitated areas, especially the first two seasons.


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7.3.8 Reinstatement of Topsoil

Topsoil is the most important factor in re-vegetation and should receive substantial attention in

rehabilitation strategies at the construction site during re-vegetation of areas. When the topsoil was

previously stripped at the site, it contained large amounts of seed from the natural environment and

considering the short-term nature of the construction, this soil will still be available for reinstatement.

The manner in which topsoil and stockpiles are created and maintained is important with regards to

the implementation of a successful rehabilitation process. Soil management practices must be

adhered to in order to reduce soil loss and to encourage rehabilitation post-construction. The two

most important aspects to consider when removing topsoil are the depth of soil to be removed and

the conditions of storage.

The topsoil layer (0-25 cm) is important as it contains nutrients, organic material, seed, and

communities of micro-organisms, fungi and soil fauna. The biologically active upper layer of soil is

fundamental in the development of soils and the sustainability of the entire ecosystem.

The correct handling of topsoil is vital in conserving the seed bank and nutrients which occur within

this layer thereby ensuring successful rehabilitation:

Topsoil must only be used for rehabilitation purposes and not for any other use example i.e.

construction of roads;

Previously excavated areas on the site should be backfilled with suitable topsoil, levelled to

resemble the surrounding topography and slopes and scarified for re-vegetation/re-seeding;

On steeper slopes rehabilitation measures may include systems such as soil terracing, berm

creation, grass blocks, fascine work, gabion basket work, reno mattresses, retaining block

mechanisms, sand bags, boulder and rock placement, stone pitching, and grading;

Erosion control netting or matting (GeoJute or Bio-Jute) may be utilised on steep slopes to

assist with soil retention, weed control and vegetation establishment. The netting material

helps protect the soil from wind and water erosion, and the required rehabilitation plant

material can be installed by making small incisions for planting. The netting is biodegradable

and will eventually break down and form a mulch layer.

7.3.9 Re-vegetation

Revegetation is the process of vegetation establishment and care, as part of the process of

reclamation, rehabilitation or restoration. The biggest challenge of rehabilitation is to establish a

sustainable ecosystem that is self-productive and able to survive without continued anthropogenic

interventions (irrigation, fertilization or re-seeding). After the construction on a landscape has ceased,

processes of self-restoration are often slow (decades) and the final community of plants may not be

the most desirable. Re-vegetation may be achieved by three main techniques, namely planting of


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trees and shrubs, direct seeding, or by self-regeneration.

Topsoil needs to be used wisely to achieve successful re-vegetation. Analysing the chemical

properties of the soil can be helpful in directing possible soil amendments and guiding species

selection. A well-prepared site will provide the most suitable conditions for plant germination,

survival and to promote long-term re-vegetation success.

Plant species that have been rescued or removed and relocated to the temporary nursery could be

used in replanting rehabilitation areas. Additional plant material (indigenous trees) as required should

be sourced from local indigenous nurseries and specifications regarding plant sizes, heights and the

installation process of these plants should be developed by the On Site ECO and Rehabilitation

Specialist. Standard horticultural best practice would apply, with specific reference to the fact that the

plant material would have to be in good condition, free from pests and diseases (any such plant

would have to be removed from the site), well-formed and well rooted, potting materials are weed

free and with sufficient root cover. Groundcovers and sedges are often supplied in trays, and the

same standards would apply.

A plant species specification for the rehabilitated areas is included below. Re-grassing or

planting of wetland species should be undertaken (as far as possible) during the summer

months, as germination and establishment is best at this time of year. Spring rains are

also conducive to good germination results, and as such rehabilitation programmes

should take these factors into consideration;

There are two methods for seeding, hand broadcasting and hydro-seeding. The methods

utilised will be site specific and the On Site ECO and Rehabilitation Specialist will

determine them;

Re-vegetation (grassing) should occur immediately after topsoil reinstatement. Seeding

on the site can in most cases be done by hand. The contractor is to guarantee a success

rate of 80% for all re-seeded areas, and follow up will be conducted monthly until such

time as 80% success of vegetation cover has been achieved.

In certain areas grass runners may be required, and grass sods where instant cover is

necessary;

Indigenous seed tends to germinate much easier going into spring and summer than in

midsummer as temperatures escalate slower. This method has been used the past

several years abroad with great results and in South Africa as well the last three years;

The following hydrophilic plant species are considered suitable to be planted in the pans:

o Cyperus sexangularis


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o Juncus kraussii (sedge);

o Imperata cylindrica (grass);

o Paspalum urvillei (grass)

o Mariscus congestus (sedge);

o Schoenoplectus corymbosus (sedge);

o Stenotaphrum secundatum (grass);

Lightly compact the area mechanically with a Cambridge roller or manually by raking;

Monitor.

7.3.10 Surface Rehabilitation of exposed areas

All areas where material will be removed for backfill and rehabilitation construction

purposes should be graded and shaped in such a way as to resemble the natural surrounding

landscape;

Surfaces will be ripped / scarified, and re-vegetated with indigenous grass species;

As far, as is practical, implement concurrent rehabilitation processes in order to limit

degradation of soil biota.

Terrestrial invasive removal programs must be maintained throughout the proposed

development as well as in the aftercare and maintenance phases;

Use Natural Infiltration and Best Practices for Stormwater Management;

7.3.11 Alien invasive species

Alien plants in the catchment are having a negative impact on the hydrology of the wetland. These

plants should be cleared and controlled by the landowner as part of the rehabilitation strategy of the

wetland. Alien plant control should be implemented as follows (No Kemprin type herbicides to be

used):

Frill all tree type alien plants located within the wetland body by chopping a frill into the bark

near the base of the tree and painting the frill with herbicide. Once dead to selectively cut

down and remove trees.

All shrub type alien plants need to be cut down and the stems treated with herbicide.

All other smaller forb type alien invader plants need to be removed by hand weeding.

7.3.12 Fire management

Based on mean annual precipitation, wetland areas should be burnt every 3 to 4 years.


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Where possible, burning should be undertaken on a rotational basis. If this is impractical, the

entire wetland may be burnt every third year provided there are other un-burnt wetlands

nearby for wetland-dependant species to utilize.

Cool and patchy burns should be promoted where possible by burning when relative

humidity is high and air temperatures are low, preferably after rain.

Preference should be given to burning of areas with abundant dead (moribund) stem and

leaf material that limits new growth.

Autumn/early winter breeding species such as the marsh owl and marsh harrier may be

negatively impacted by early winter burning. If these species are recorded at the site, burn

rotationally through block burning and check before burning by having 'beaters' 10 m apart

walking through the area and then closely examining all localities where these birds are

flushed. Leave areas unburnt where chicks have still not fledged, or, if possible, delay burning

for that year.

7.3.13 River Bank stabilisation’

The operation of heavy equipment and vehicles in and around the pans might cause destruction of

the soil profile or soil compaction, thereby increasing erosion by reducing soil infiltration and

causing overland flow (Hill & Kleynhans, 1999). When stockpiles are too closely located to the

pans might also increase the risk of erosion. If riparian land is not well-vegetated with deep-

rooted plants, then flood-outs, stripping of topsoil from the floodplain, and accelerated bank

erosion can occur; all of these can lead to the loss of valuable agricultural land. The following

measurements should be implemented:

Identify activities, which are causing erosion and incision of any of the wetland feature

and mitigate these impacts immediately;

Adequate erosion control and siltation control measures should be put in place;

Care must be taken to ensure that machinery used does not erode the embankments

further. Where embankments along the alignment are severely eroded, the ECO may

request the Contractor to install erosion control measures.

The wetland edges should be sloped according to engineer’s specification. The slopes

must then be stabilized, with a biodegradable matt if necessary, and after re-vegetated

with indigenous grass seed mixtures according to specification;

Where any disturbance of the soil takes place (have taken place in the past), these areas

must be stabilized and any alien plants which establish should be cleared and follow up

undertaken for at least 2 years thereafter and preferably longer. Where compaction


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results, remedial measures must be taken (e.g. “ripping” the affected area);

Reseed any areas where earthworks have taken place with indigenous grasses to prevent

further erosion (where applicable);

The time in which soils are exposed during construction activities should remain as short

as possible;

During the construction of the bridge, erosion berms should be installed to prevent gully

formation and siltation of the riparian resources;

7.4 MAINTENANCE AND MONITORING OF REHABILITATION

Several methods exist to monitor rehabilitated areas to scientifically prove that a self-sustainable

ecosystem has developed or show a positive trend towards successful rehabilitation. This will prove

that environmental degradation and biological diversity have been mitigated and restored where it

has been negatively impacted upon. The important aspect to keep in mind is that it is not only a visual

inspection, but measurable information gathering e.g. soil samples, vegetation diversity, biomass,

basal cover, species composition etc. The monitoring data must be of such a standard that meaningful

conclusions can be made and a trend indicated. Good record keeping is essential. All illegal invader

plants and weeds shall be eradicated as required in terms of Sections 119 to 126 of The

Environmental Management Act.

Throughout the life of the structure, biomonitoring assessments should take place on a quarterly

basis to identify any emerging impacts on the aquatic ecology of the system. The monitoring should

focus on habitat integrity assessment as well as the assessment of impacts on the aquatic macro-

invertebrate and fish communities.

Monitoring should also take place on regular time intervals to establish if the re-vegetation strategy

was successful. The site must be monitored for at least one year in order to observe any possible

invasion by alien species and, if they appear, they must be controlled as is appropriate. Also to

monitor and correct possible erosion, storm water and siltation problems

8. MONITORING PLAN FOR STORMWATER CONTROL STRUCTURES AND WETLANDS

Several methods exist to monitor rehabilitated areas to scientifically prove that a self-sustainable

ecosystem has developed or show a positive trend towards successful rehabilitation. This will

prove that environmental degradation and biological diversity have been mitigated and restored

where it has been negatively impacted upon. The important aspect to keep in mind is that it is not

only a visual inspection, but measurable information gathering e.g. soil samples, vegetation


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diversity, biomass, basal cover, species composition etc. The monitoring data must be of such a

standard that meaningful conclusions can be made and a trend indicated. Good record keeping is

essential. All illegal invader plants and weeds shall be eradicated as required in terms of Sections

119 to 126 of The Environmental Management Act.

Monitoring should also take place on regular time intervals to establish if the re-vegetation

strategy was successful. Table 9 indicate the monitoring strategy and aspects to be monitored at

the crossings:


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Table 12. Monitoring framework for the rehabilitation plan on stormwater structures and canals proposed for the area

VARIABLES METHODS SAMPLING FREQUENCY PERFORMANCE INDICATOR MEASUREMENT

Integrity if structures:

Gabions / weirs / infilling of furrows,

etc.

On-site inspections;

Fix point photography

Field markers at headcuts

Monthly and after rainfall events for first

year and then yearly (1-3 years)

Arresting of erosion / headcut.

Sedimentation behind structure;

Spreading of flow

Stabilising of erosion front;

Filled up to gabian level

Regular overtopping of streambanks on

floodplains or sustained diffuse flow

Vegetation cover Map main vegetation cover (and / or

aerial or fix point photography

Baseline study before project start, then

yearly (1-3 years)

Spreading of distribution of dominant

species in specified wet zones

Identify climax species in specified wet

zones

Plant species composition Fix transects to determine the species

composition by means of the nearest to

the point plant technique

Baseline study before project start, then

yearly (1-3 years)

Presence / absence of species

composition in specified wet zones


zones

Water quality Collect water samples and do inorganic

scan and organic analyses

Monthly for first year, including low and

high flow events, then yearly during

seasons

Levels of heavy metals / pollutants within

acceptable levels

Levels of bacteria counts / pollutants

within acceptable levels

Levels of heavy metals / pollutants /

bacteria count / within specified limits

Water quantity / outflow Measure water level outflow at existing

gabians

Monthly, including low and high flow

levels

Flood attenuation, and baseflow

maintenance

Reduced peak flows, reduced energy flow,

Permanent/ sustainable baseflow

Invertebrate and / or frog survey Compile invertebrate and / or frog study Invertebrate: Yearly during low flow

period

Frogs: Yearly during rainy season

Presence / absence of species

composition in specified wet zones


zones

Catchment and causative factors Monitor catchment condition (GIS) and

causative factors in water courses

3 Monthly Conservation and improvement of natural

resources in catchment

Specific catchment components within set

limits, e.g. grazing.Stabilising of causative

problems in water course / wetlands


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9. DISCUSSION & CONCLUSION

The wetland and riparian delineation for the project was done according to the criteria set by the

Department of Water Affairs and Forestry (2003) and the National Wetland Classification System

for South Africa (SANBI, 2009). The soils, vegetation associated with wetlands and landscape were

all used as parameters in identifying the wetland zones. The wetlands of the proposed

development site can be classified as an unchannelled valley bottom wetland and man-made

depressions (dams) with riparian woodland, while the smaller drainage canals are classified as

water courses.

Baseline soil information, landscape profile and vegetation were used to confirm wetland and

terrestrial properties within the study area. The soils in the wetlands showed signs of wetness

within 50cm of the surface and displayed typical hydromorphic characteristics.

The wetland delineation was done according to the topography, alluvial soils and vegetation along

the clearly defined banks of the valley bottom wetland.

The impacts associated with the site are reflected in the results of the PES assessment which

indicates that the wetlands at the proposed development site are in a ‘Moderately Modified’

condition. The wetlands have been modified through impoundments, alien invasive species,

sedimentation and road crossings. These impacts also play a major part in the LOW EIS of the

unchannelled valley bottom wetlands.

An impact assessment was conducted for the wetlands on site in addition to the buffer zones

recommended to ensure the protection of the wetlands. Impacts relating to the proposed

development on the wetlands are as follows:

Direct wetland destruction;

Soil erosion and sedimentation;

Water pollution from spillages;

Spread and establishment of alien invasive species in wetlands;

Specific mitigation measures need to be implemented in the areas surrounding the wetland zones.

The following was concluded as the most important management aspects for the wetlands

considering the proposed development

The overall alluvial characteristics of the proposed stormwater canals (balance between

sand, gravel and stone) must be similar to before construction to ensure natural systems

of flooding and sedimentation deportation and conveyance occur;

The use of cement lined channels must be avoided at all costs and lining must be done


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with Loffel stones (or Amourflex stones) or similar products. This is to prevent the loss of

habitat to aquatic organisms living in the system;

The use of gabion structures, well keyed into the surrounding bank walls and secured to

the ground is recommended.

The implementation of a Wetland Management -, Rehabilitation and Monitoring Plan should be

considered a priority for the proposed development in combination with the road crossings.

Provided that all recommendations and mitigation measures provided in this report are adhered

to the planned project can be supported.


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10. REFERENCES

ACOCKS, J.P.H. 1988. Veld types of South Africa, 3rd ed. Memoirs of the Botanical Survey of South

Africa. 57: 1–146.

BRADY, N. C. & WEIL, R. R. 1996. The Nature and properties of Soils. Prentice Hall, New Jersey.

LOW, A.B. & REBELO, A.G. (eds) 1996. Vegetation of South Africa, Lesotho and Swaziland, p. 39.

Dept Environmental Affairs & Tourism, Pretoria.

DWAF. 2003. A practical field procedure for identification and delineation of wetlands and riparian

areas. Department of Water Affairs and Forestry, Pretoria.

ENPAT, 2000. Environmental Potential Atlas. Department of Environmental Affairs and Tourism,

Pretoria.

GALAGO ENVIRONMENTAL, 2014. Aquatic ecosystem delineation of The Proposed K54 Road,

Mamelodi on Portions of the Farm Franspoort 332 JR, Pienaarspoort 339 JR and Doornhoek 365 JR

KOTZE, D. C., MARNEWECK, G. C., BATCHELOR, A. L., LINDLEY, D. S. & COLLINS, N. B. 2005. Wet-

ecoServices: A technique for rapidly assessing ecosystem services supplied by wetlands. South

Africa National Biodiversity Institute, Pretoria.

MACVICAR, C. N. 1991. Soil Classification: A Taxonomic system for South Africa. Department of

Agriculture, Pretoria.

MCLEESE, R.L. AND WHITESIDE, E.P. 1977. Ecological effects of highway construction upon

Michigan woodlots and wetlands: soil relationships. Journal of Environmental Quality. v6 n4, 476-

471.

MUCINA, L & RUTHERFORD, M. C. (eds) 2006. The vegetation of South Africa, Lesotho and

Swaziland. . Strelitzia 19. South Africa National Biodiversity Institute, Pretoria.

WINTER, C. 1988. A conceptual framework for assessing cumulative impacts on the hydrology of

nontidal wetlands. Environmental Management. v12, n5, 605-620.


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APPENDIX A PES SCORES OF THE WETLANDS IN THE STUDY AREA

Criteria and Attributes Relevance Valleybottom without channel

Hydrologic

Flow Modification Consequence of abstraction, regulation by impoundments or increased runoff from human settlements or agricultural land. Changes in flow regime (timing, duration, frequency), volumes, velocity which affect inundation of wetland habitats resulting in floristic changes or incorrect cues to biota. Abstraction of groundwater flows to the wetland.

3

Permanent Inundation Consequence of impoundment resulting in destruction of natural wetland habitat and cues for wetland biota. 2

Water Quality Modification From point or diffuse sources. Measure directly by laboratory analysis or assessed indirectly from upstream agricultural activities, human settlements and industrial activities. Aggravated by volumetric decrease in flow delivered to the wetland.

2

Sediment Load Modification Consequence of reduction due to entrapment by impoundments or increase due to land use practices such as overgrazing. Cause of unnatural rates of erosion, accretion or infilling of wetlands and change in habitats.

2

Hydraulic/Geomorphic

Canalisation Results in desiccation or changes to inundation patterns of wetland and thus changes in habitats. River diversions or drainage.

2

Topographic Alteration Consequence of infilling, ploughing, dykes, trampling, bridges, roads, railway lines and other substrate disruptive activities which reduce or changes wetland habitat directly in inundation patterns.

3

Biota

Terrestrial Encroachment Consequence of desiccation of wetland and encroachment of terrestrial plant species due to changes in hydrology or geomorphology. Change from wetland to terrestrial habitat and loss of wetland functions.

2

Indigenous Vegetation Removal Transformation of habitat for farming, grazing or firewood collection affecting wildlife habitat and flow attenuation functions, organic matter inputs and in increases potential for erosion.

3

Invasive Plant Encroachment Affects habitat characteristics through changes in community structure and water quality changes (oxygen reduction and shading).

3

Alien Fauna Presence of alien fauna affecting faunal community structure. 2

Over utilisation of Biota Overgrazing, overfishing, etc. 2

Total 26

Mean 2.4

Category Class C

Ecological Management Class Moderately Modified


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APPENDIX B EIS SCORES OF THE WETLANDS IN THE STUDY AREA

Determinant Valleybottom without channel

PRIMARY DETERMINANTS

1. Rare & Endangered Species 0

2. Populations of Unique Species 0

3. Species/taxon Richness 1

4. Diversity of Habitat Types or Features 1

5. Migration route/breeding and feeding site for wetland species 1

6. Sensitivity to Changes in the Natural Hydrological Regime 1

7. Sensitivity to Water Quality Changes 1

8. Flood Storage, Energy Dissipation & Particulate/Element Removal 3

MODIFYING DETERMINANTS

9. Protected Status 0

10. Ecological Integrity 2

TOTAL* 10

MEDIAN 1

OVERALL ECOLOGICAL SENSITIVITY AND IMPORTANCE LOW

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