CITY OF CAPE TOWN

SURFACE STORMWATER SYSTEMS

ENVIRONMENTAL AUTHORISATION FOR MAINTENANCE AND MANAGEMENT

INTERVENTIONS UNDERTAKEN BY THE CITY IN ITS SURFACE STORMWATER SYSTEMS:

TECHNICAL ASSESSMENT REPORT (Appendix J of the Basic Assessment Report)

FINAL

Compiled with contributions from:

Coastec Coastal & Freshwater Consulting Group Environmental Consultants

October 2014 J31110

ENVIRONMENTAL AUTHORISATION FOR STORMWATER MAINTENANCE AND MANAGEMENT MEASURES UNDERTAKEN BY THE CITY IN ITS SURFACE STORMWATER SYSTEMS:

TECHNICAL ASSESSMENT REPORT

CONTENTS

Chapter Description Page

1 INTRODUCTION 1

1.1 Background 1

1.2 Legislative Context 2

1.3 Overview of the Project 2 1.3.1 Scope of the Project 2 1.3.2 Authorisation in terms of NEMA (107 of 1998) and the EIA Process 4 1.3.3 Authorisation in terms of National Water Act (36 of 1998) section 21 (c) and (i) 5 1.3.4 Authorisation in terms of National Environmental Management: Waste Act (59 of 2008) 5

1.4 Purpose of this Report 6

1.5 Work Completed to Date 6

2 APPROACH AND METHODOLOGY 7

2.1 Approach 7

2.2 Methodology 7 2.2.1 Maintenance or management measures 7 2.2.2 The Receiving Environment 9 (a) Defining the Receiving Environment 9 (b) Categorising the Receiving Environment (Watercourses) 10 2.2.3 Impact Assessment System 10 (a) Determining Significance 11 (b) Defining Significance 13 (c) Status of Impacts 13 (d) Post-Mitigation 13 2.2.4 Other Considerations 14 (a) Alternatives 14 (b) Cumulative impacts 14 (c) Knowledge gaps and uncertainties 14

3 THE RECEIVING ENVIRONMENT 15

3.1 Overview 15 3.1.1 Major River Catchments 15

3.2 Classification of the Receiving Environment for the Purposes of Stormwater Maintenance Measures 15 3.2.1 Rivers and Streams 16 3.2.2 Wetlands 16

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3.2.3 River and Wetland Groupings (Watercourse Types) 17 3.2.4 Ecological Priority (Watercourse Importance) 21 3.2.5 Topography 24 3.2.6 Geology 24 3.2.7 Soils 24 3.2.8 Climate 24 3.2.9 Population 24 3.2.10 Socio-Economic 24 3.2.11 Tourism 25 3.2.12 Land Use 25 3.2.13 Floral Biodiversity 25 (a) Endemic flora 27 (b) Endangered flora 27 3.2.14 Faunal Biodiversity 27 (a) Endemic fauna 27 (b) Endangered fauna 27 (c) Fauna Listed in the National Environmental Management Biodiversity Act 29

4 DESCRIPTION AND ASSESSMENT OF IMPACTS 33

4.1 Routine stormwater Maintenance / Management Measures included in this Application 33 4.1.1 Thresholds 33

4.2 Description of the Impacts of Stormwater Management / Maintenance Measures 35 4.2.1 Vegetation Management 35 (a) Removal or control of submerged / floating aquatic alien invasive, cosmopolitan or indigenous vegetation 35 (b) Removal or control of indigenous reedbed and emergent vegetation 37 (c) Removal of vegetation from riparian areas and wetland margins 39 4.2.2 Erosion Control 42 (a) River channel profile enhancement 42 (b) Construction, maintenance and expansion of Erosion Control Structures 43 4.2.3 Sediment Management 45 (a) Construction, maintenance and expansion of sediment traps / retention areas 46 (b) Removal of sediment from sediment traps and designated sediment retention areas 48 (c) Manual / mechanical sediment removal from canals, channels and waterbodies 48 4.2.4 Channel Enclosure 49 (a) Conversion of an open channel to an enclosed pipe / culvert system 49 4.2.5 Litter and Debris Management 49 (a) Litter and debris removal 50 (b) Removal of structures to reduce water obstruction 50 (c) Construction, maintenance or expansion of litter management infrastructure 51 4.2.6 Construction Maintenance and Expansion of Minor Stormwater Infrastructure 51 4.2.7 Maintenance of Attenuation Infrastructure 51 4.2.8 Recreational Access 52

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4.2.9 Management of Estuary and River Mouths 52

4.3 Constraints on the Choice of Method for Stormwater Management, in order to Minimise Impacts 55

4.4 Summary Assessment of the Impacts 57

5 CONCLUSION 58

6 REFERENCES 59

LIST OF APPENDICES

APPENDIX A: Listed Activities Triggered by Proposed Maintenance / Management Measures APPENDIX B: Authorisation Matrix APPENDIX C Detailed Descriptions of Maintenance / Management Measures APPENDIX D: Restrictions on Methods Employed for Stormwater Maintenance / Management Depending on the Type and Importance Category of Waterbody. APPENDIX E: Assessment of the Impacts of Stormwater Maintenance / Management Measures on Waterbodies within CCT APPENDIX F: Photographs

LIST OF FIGURES

Figure 1: The City of Cape Town, showing eight Roads and Stormwater management districts showing the location of the co-ordinate points (A-F) used to illustrate the extent of the city. 4 Figure 2: Process used for evaluating impacts 12 Figure 3: Overview map showing location of different watercourse types (as defined for this application). See Section 3.2.3 for further details. 20 Figure 4: Overview map showing location of different watercourses (wetlands and rivers) in terms of Ecological Importance (as defined for this application). See Section 3.2.4 for further details. 23 Figure 5: Top photo: Stepped bank gabion with low-level step for vegetation establishment spread with loose topsoil. Colonisation of the low step by plants will occur but can be promoted by planting. Bottom photo: coir mat-lined gabions with topsoil added to fill the 30 – 40% voids between rockfill promotes vegetation by retaining moisture and soil (note live plant cuttings inserted into face of gabion). 45

LIST OF TABLES

Table 1: Co-ordinates of the extent of the City of Cape area (see Figure 1) 4 Table 2: Approach to the impact assessment used in this project 5 Table 3: Details of the site visits to assess stormwater maintenance measures 8 Table 4: Summary information for each of the major catchments in the City, of the total number of wetlands, natural/semi-natural wetlands, and the numbers of CBA, CESA and OESA wetlands. Note that the concrete reservoirs or WWTW ponds are excluded from the biodiversity prioritisation (from Snaddon and Day 2009). 18 Table 5: Watercourse types: Hydrogeomorphic categories of rivers and wetlands and their allocation to one of six watercourse groups for this assessment. 19 Table 6: Proposed ranking of Ecological Importance to be used specifically for this project. 21 Table 7: Matrix of Watercourse Type x Importance permutations. 22

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Table 8: Critically endangered (red), Endangered (orange), Vulnerable (yellow), and Least threatened (green) vegetation types occurring within the CCT biodiversity network (Information sourced from Mucina & Rutherford, 2006). 26 Table 9: List of species classified as critically endangered, endangered, vulnerable and protected species. 29 Table 10: Typical scale of stormwater maintenance / management measures in the CCT. 34

ABBREVIATIONS

BAR Basic Assessment Report CBA Critical Biodiversity Area CFR Cape Floristic Region CCT City of Cape Town CMA Cape Town Metropolitan Area DEA Department of Environmental Affairs DEA&DP Department of Environmental Affairs and Development Planning DWA Department of Water Affairs EIA Environmental Impact Assessment EMPr Environmental Management Programme ERM Environmental Resource Management Department FCB Foothill cobble beds FGB Foothill gravel beds FRR Foothill and rejuvenated rivers FW Floodplain wetlands GDP Gross Domestic Product GDPR Gross Domestic Product by Region GIS Geographic Information System GO Gorge LLRFP Lowland floodplain river LR Lowland rivers MMP Maintenance Management Plan MOU Memorandum of Understanding MS Mountain streams and transitional rivers ECA Environmental Conservation Act (73 of 1989) ND Natural depression NEMA National Environmental Management Act (107 of 1998) NEM:BA National Environmental Management Biodiversity Act (Act No. 10 of 2004) NEM:PAA National Environmental Management Protected Areas Act (Act No. 57 of 2003) NWCS National Wetland Classification System SA-FrOG South African Frog Re-assessment Group SANBI South African National Biodiversity Institute SANParks South African National Parks S Seeps SDP Stormwater depression ponds

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TMNP Table Mountain National Park UFP Upland floodplain river ToPS Threatened or Protected Species VBW Valley bottom wetland WF Wetland flats WT Wetland transitional rivers

DEFINITIONS

The area from which any rainfall will drain into the watercourse through surface flow Catchment to a common point. The geographical area which falls within the jurisdiction of the City of Cape Town City of Cape Town Municipality. The CCT Environmental Team will typically comprise E&HM District Staff with CCT Environmental Team support from a suitably qualified freshwater ecologist and/or botanist where required. Terrestrial and aquatic areas which are critical for conserving biodiversity and Critical Biodiversity Area maintaining ecosystem functioning.

A species which is only found in a given region or location and nowhere else in the Endemic world.

The Environmental Management Programme sets out general instructions that will be included in a contract document for the construction phase of the project. It Environmental Management Programme will ensure the construction activities are conducted and managed in an environmentally sound and responsible manner. The surroundings within which humans exist and that are made up of- (i) the land, water and atmosphere of the earth (ii) micro-organisms, plant and animal life Environment (NEMA, 107 of 1998) (iii) any part of combination of (i) and (ii) and the interrelationships among and between them, and (iv) the physical, chemical, aesthetic and culture properties and conditions of the foregoing that influence human health and well-being. A body of surface water that is part of a water course that is permanently or periodically open to the sea; in which a rise and fall of the water level as a result Estuary (NEM: ICMA, 24 of 2008) of the tides is measurable at spring tides when the water course is open to the sea; or in respect of which the salinity is measurably higher as a result of the influence of the sea. Land adjoining a watercourse which is susceptible to inundation by floods up to the Floodplain (CCT Storm Water By-Law) one hundred year recurrence interval. Species which outcompete other species leading to environmental degradation. The Invasive term invasive covers native and alien species. Indigenous/ native vegetation Vegetation consisting of plant species occurring naturally in an area. A species that occurs, or has historically occurred naturally in a free state in nature Indigenous Species within the borders of the Republic, but excludes a species that has been introduced in the Republic as a result of human activity. The Red Data list assigns species with one of the following ratings: critically Red Data Species endangered, endangered, vulnerable, least concern. The recovery of ecosystem functions and processes in a degraded habitat. Rehabilitation addresses disturbed habitats and involves establishing geological Rehabilitation and hydrological stable environments. Rehabilitation does not necessarily return an environment to the pre-disturbed condition. Riparian vegetation A specific band of vegetation of variable width fringing a watercourse. A natural channel which moves water across the landscape from higher to lower River elevations. Threatened or Protected Species (ToPs) Species listed in terms of the National Environmental Management: Biodiversity Act as

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being critically endangered, endangered .vulnerable or protected species. “Watercourse” means- (a) a river or spring; (b) a natural channel or depression in which water flows regularly or intermittently; (c) a wetland, lake or dam into which, or from which water flows; and Watercourse (NEMA, 107 of 1998) (d) any collection of water which the Minister may, by notice in the Gazette declare to be a watercourse as defined in the National Water Act, 1998 (Act No. 36 of 1998) and a reference to a watercourse includes, where relevant its bed and banks. 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 Wetland (NEMA, 107 of 1998) shallow water, and which land in normal circumstances supports or would support vegetation typically adapted to life in saturated soil.

Note all changes made to the draft basic assessment report are shown in underlined and italic text.

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1 INTRODUCTION

1.1 Background

The City of Cape Town‟s Stormwater Sustainability Branch of the Roads and Stormwater Department (Directorate: Transport for Cape Town), plays a strategic policy and planning role and in addition is responsible for co-ordination of the management of Cape Town‟s numerous rivers, canals, vleis, wetlands, estuaries and constructed stormwater systems to ensure public safety, manage flood risk, promote habitat and biotic diversity, and prevent or minimise infrastructure damage. It has been estimated that there are over 7,000 natural, semi-natural and artificial “wetlands”, 1,200km of rivers and streams, 7,500km of below ground pipes and culverts, and countless gullies and kerb inlets in Cape Town. These systems are collectively regarded as the urban stormwater management system, and as such are managed in an integrated manner. Whilst some components of the city‟s stormwater management system comprise engineered infrastructure and artificial (“man-made”) aquatic features, much of the naturally-occurring river and wetland habitat within the built-up areas has also been unavoidably used for stormwater storage, conveyance or treatment, and consequently many are moderately or substantially altered from their natural condition. Operational work which is generally undertaken by the Roads and Stormwater Department‟s Operations and Assets Branch district offices involves fairly routine, often repetitive maintenance and minor construction of stormwater infrastructure as well as other management measures that do not involve stormwater structures per se but management of components of the „natural‟ stormwater system. All of these measures are intended to keep the City‟s stormwater system functioning at an optimal level whilst maintaining and, where feasible, in some cases even improving ecosystem condition through rehabilitation of degraded systems. In addition, other departments such as Environmental Resource Management (Environment and Heritage Management and Biodiversity Management Branches, and the Invasive Species Unit), City Parks, and Sports and Recreation also occasionally work near watercourses or within the floodplain either in partnership with Roads and Stormwater, or individually e.g. maintenance of walkways, park furniture and footbridges, mowing of open space areas, invasive plant control, rehabilitation projects, and nature reserve management. The above mentioned routine “stormwater maintenance and management measures” are usually undertaken by CCT in-house staff or contractors, and include, but are not limited to measures such as:  Management of aquatic and terrestrial invasive vegetation;  Removal of sediment from river channels, water bodies and structures such as detention dams, silt traps, stormwater outlets, canals etc.;  Removal of litter and flood debris;  Construction, repair and maintenance of minor stormwater management infrastructure such as gabions, bank stabilisation, silt and litter traps, stormwater outlets, headwalls, canal walls (maintenance), footbridges and boardwalks. These fairly routine low level activities exclude construction of new canals, detention ponds, or other major stormwater infrastructure;  Maintenance of dams – particularly those registered as dams with a safety risk in terms of Chapter 12 of the National Water Act;  Estuary mouth management;  Rehabilitation of degraded stream channels (e.g. bank re-shaping and planting of indigenous vegetation).

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In addition, less frequent interventions requiring significant capital works include for example construction of stormwater detention and retention facilities, major gabion reinforcements, flood protection measures, sustainable urban drainage system structural controls, river widening and bank reshaping etc. These are usually undertaken by external engineering contractors, with input from aquatic ecologists where required.

1.2 Legislative Context

Many of these above-mentioned stormwater maintenance and management measures require authorisation in terms of the National Environmental Management Act (107 of 1998) (NEMA) and its subsequent Environmental Impact Assessment (EIA) Regulations (GN 544 and GN 546, 18 June 2010), hereafter referred to as the “EIA Regulations”. In the early 2000s environmental authorisation was obtained under the Environmental Conservation Act (73 of 1989) for undertaking these interventions however the Department of Environmental Affairs and Development Planning (DEA&DP) has advised the City of Cape Town that the original authorisation is now invalid due to the NEMA and 2010 EIA Regulations having come into effect, and superseding the Environmental Conservation Act. The Regulations which relate specifically to activities taking place in or near “watercourses” and “estuaries” are pertinent mainly to the City‟s stormwater operational management interventions. DEA&DP has advised the City of Cape Town that in order to demonstrate due diligence, duty of care and to be compliant with the new legislation, the City must rectify the situation by applying for the appropriate authorisations under the new legislation. Consequently, the City has embarked on a project to obtain this required authorization. The City also wishes to engage with the Department of Water Affairs (DWA) regarding their requirements in terms of the National Water Act. It is desired that the process of engaging with these two authorities will be aligned and that congruence between their requirements and approval processes can be achieved.

1.3 Overview of the Project

GIBB has been appointed as the Environmental Assessment Practitioner for the undertaking of the above-mentioned authorisation project. GIBB is assisted by Dr Geordie Ractliffe of The Freshwater Consulting Group (aquatic ecologist) and Barrie Low from COASTEC (botanist).

1.3.1 Scope of the Project The project involves an application for authorisation for all routine maintenance and management measures undertaken by the City in its surface stormwater system (as described in 1.1 above, but excluding gullies, kerb inlets, underground pipes) and is applicable to the entire jurisdictional area of the CCT shown in Figure 1. Large scale, once-off interventions that typically require significant capital works and detailed input from engineering, hydrological and environmental consultants are not included in this application. These would be subject to individual applications for authorisation from the relevant authorities.

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Figure 1: The City of Cape Town, showing eight Roads and Stormwater management districts showing the location of the co-ordinate points (A-F) used to illustrate the extent of the city.

Table 1: Co-ordinates of the extent of the City of Cape area (see Figure 1)

Co-ordinate point Longitude Latitude A 18°27'19.9" E -33°28'16.5" S B 18°49'18.8" E -33°38'30.4" S C 19°00'16.9" E -34°04'29.4" S D 18°50'43.9" E -34°16'10.5" S E 18°28'13.3" E -34°21'30.4" S F 18°18'39.4" E -34°01'39.1" S

1.3.2 Authorisation in terms of NEMA (107 of 1998) and the EIA Process The EIA Regulations (2010) require that, depending on the scope of the activity proposed, one of two types of assessment processes are to be undertaken; either a) a Basic Assessment or b), a more extensive Scoping and EIA process. While a number of the City‟s proposed routine stormwater management and maintenance measures trigger the need for a Basic Assessment a requirement of Listing Notice 1 (GN 544) and Listing Notice 3 (GN 546), none of them trigger authorisation in term of Listing Notice2 (GN 545) i.e. requiring the full Scoping and EIA process. The project is therefore following the Basic Assessment process as defined in the EIA Regulations. Some of the main components of this Basic Assessment process are: a) Application: A formal application was made to the competent authority, in this case DEA&DP, on 13 June 2012. The DEA&DP responded and accepted the application on 3 July 2012. The application reference number is 16/3/1/3/1/A7/4/2031/12. b) Assessment: The impacts of the proposed measures must be determined. This has been described in the Basic Assessment Report of which this “Technical Assessment Report” forms an integral component. c) Public participation: An appropriate Public Participation Process (PPP) is to be undertaken. This includes advertising the activity and making the documents available to the public for their scrutiny. d) Report: A Basic Assessment Report, as well as an Environmental Management Programme (EMPr), is to be submitted to the competent authority for their evaluation. The majority of the measures addressed in this EMPr are repair or maintenance-type activities, and this EMPr provides limitations and guidelines to be followed when executing these. This EMPr therefore also meets the requirements of a Maintenance Management Plan (MMP) for maintenance activities as described in activity 18 of the Listing Notice 1 of the EIA Regulations. e) WULA: a Water Use License Application may be required in terms of section 21 of the National Water Act (36 of 1998) for management and maintenance interventions that will be “impeding or diverting the flow of water in a watercourse” (section 21(c)) and/or “altering the bed, banks course or characteristics of a watercourse” (section 21(i)). Given the numerous types of stormwater maintenance / management measures undertaken by the CCT, this application and the supporting documents have been prepared to obtain EIA authorisation for ALL of these measures, where the EIA legislation is relevant. This application for authorisation therefore covers a number of “listed activities”, as described in the EIA regulations GN R545 and R546. It is noted that Section 14 of the EIA Regulations makes provision for issuing a consolidated authorisation such as is desired in this case for the reasons described in more detail below.

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This project involves numerous interventions in different locations as the City‟s drainage network naturally extends across the entire metropolitan landscape and, conceivably, any part of this network could be subject to deterioration and thus require management in the future. Thus the nature of the application is such that it covers the entire drainage network. The following approach for assessing impacts was therefore adopted for this project (elaborated on in Table 2).  Identify the types of stormwater maintenance / management measures which require authorisation;  Understand the nature of the receiving environments in which they do or could occur: here the receiving environments are categorised according to type and conservation importance;  Assess the nature and significance of potential impacts of each of the measures within each receiving environment (type and importance);  Identify mitigation measures to address negative impacts. This methodology was presented in a Methodology Report (J31110), dated 23 February 2012, at a meeting with DEA&DP, dated 30 November 2012, and accepted.

1.3.3 Authorisation in terms of National Water Act (36 of 1998) section 21 (c) and (i) Section 21 of the National Water Act identifies eleven water use types that may require a WULA. Of the identified water uses only the “impeding or diverting the flow of water in a watercourse” (section 21(c)) and “altering the bed, banks, course or characteristics of a watercourse” (section 21(i))are deemed applicable to this application since some of the City‟s routine management and maintenance measures may include aspects of these water uses. The Department of Water Affairs will assess the proposed interventions and advise on their requirements and the form of the WULA accordingly in due course.

1.3.4 Authorisation in terms of National Environmental Management: Waste Act (59 of 2008) The National Environmental Management: Waste Act (59 of 2008) lists a number of waste management related activities which may not be undertaken without obtaining a Waste License. The Waste Management Licensing section of DEA&DP confirmed on 26 April 2012 that the stormwater management activities as presented in this assessment do not trigger the need for a Waste License.

Table 2: Approach to the impact assessment used in this project

Phase Explanation Detailed Tasks Output

Identification of While many of the routine  Identify stormwater  “Authorisation Matrix” (see Listed Activities maintenance and management measures Appendix B) which includes a measures trigger authorisation  Classify the measures in list of all interventions and requirements, some do not. Hence terms of authorisation whether or not they trigger the the triggering activities have to be requirements. EIA regulations. defined and the authorisation requirements understood. These may be either “none”, Maintenance Management Plan”, or “Basic Assessment”. Classification and The proposed interventions occur in  Define and agree on  Agreed grouped classification description of or adjacent to watercourses, (e.g. appropriate new “grouped” and maps showing the receiving rivers, estuaries and wetlands). The classifications so as to distribution of groups (see Table environment CCT has previously undertaken make the assessment 5 and Table 6 and Figure 3 and classification of its rivers (Harding et manageable (seven Figure 4 of this report). al, 2002) and wetlands (Freshwater watercourse groups Consulting Group, 2009). defined).  Prepare maps

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Importance The impact of an activity will differ  Rationalise the importance  Maps updated with high (H), ranking of the not only according to the type of classes of rivers and medium (M), or low (L) receiving system, but also according to how wetlands. High, Medium or ecological importance classes. environment important it is in terms of biodiversity Low classes. or ecological function. The City’s rivers and wetlands have been ranked or categorised according to their importance, with five river priority classes (Harding et al 2002) and three wetland priority classes (FCG 2009) identified. Assessment of Due to the large number of  Undertake site visits to  Assessment matrix (see impacts stormwater measures and the many selected typical stormwater Appendix E) resulting permutations of management locations in 8 assessments, a matrix approach districts to evaluate was deemed the most appropriate interventions and impacts form for rating impacts.  Assess impacts

1.4 Purpose of this Report

The application for authorisation of the City‟s routine stormwater maintenance and management measures is in the form of a Basic Assessment, which is normally a form-bound report. However due to the complexity of the activities, it was deemed appropriate to compile a separate Technical Assessment Report to append to the form-bound Basic Assessment Report (BAR), in which the details of the assessment would be presented. This Technical Assessment Report is therefore presented as an appendix to the BAR and does not replace it. The BAR will make reference to this Technical Assessment Report.

1.5 Work Completed to Date

Much effort has been expended in planning the project, defining and understanding the routine stormwater maintenance / management measures, and assessing the impacts. Prior to this report, the following reports have been generated to date:  Inception Report (September 2011)  Proposed Methodology Report (February 2012).

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2 APPROACH AND METHODOLOGY

2.1 Approach

This report aims to answer the following basic questions:  What are the routine stormwater maintenance / management measures requiring authorisation?  Where do they occur and what is the nature of the receiving environment?  What is the significance of the anticipated impact resulting from each measure, and  How can these impacts be mitigated?

The report is structured in the same chronological order as these questions and consists of the following sections:  Maintenance / management measures  The receiving environment  Impact assessment  Mitigation

2.2 Methodology

2.2.1 Maintenance or management measures Determining the routine stormwater maintenance / management measures requiring authorisation began early in this process and involved the following tasks:  Review of the CCT‟s existing documentation. These include: o River Maintenance Guidelines; a Practical Guide to Good Practice (CCT, December 2002); o Ecological Guidelines for River/ Wetland Upgrading Projects (CSRM Vol 1, References Manual, 2003); o Ecological Guidelines for River/ Wetland Upgrading Projects (CSRM Vol 2, Assessment of Strategies, 2003); o Ecological Guidelines for River/ Wetland Upgrading Projects (CSRM Vol 3, Project Catalogued, 2003); o River Maintenance Activities in the CMA (CCT, 2002); o River and Vlei Assessment and Monitoring in the CMA (Southern Waters, 2002); o Practitioner‟s Manual for Urban River Maintenance (Southern Waters, 2000); o Prioritization of City Wetlands (Freshwater Consulting Group, 2009); o Further Development of a Proposed National Wetland Classification System for South Africa. (Freshwater Consulting Group / SANBI, 2009).  Workshops with CCT and the appointed specialists.  Site visits. The eight Roads and Stormwater districts within the CCT (Figure 1) were visited for a day each by the project team including CCT Catchment, Stormwater and River Management, Roads and Stormwater districts, Environment and Heritage Management, GIBB and the two appointed specialists. The aim of the site visits was to examine and discuss examples of the different sorts of routine stormwater maintenance / management measures undertaken by the City, as the basis for the assessment of the generic impacts of each. The table below presents further details of the site visits:

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Table 3: Details of the site visits to assess stormwater maintenance measures

No. District Date Areas Inspected

 Zoarvlei Canal: Vrystaat Road Outlet  Zoarvlei Canal: south-west inlet from Paarden Eiland  Diep River mouth (Lagoon Beach)  Dieprivier: Milnerton High School outlet  Theo Marais Outfall  Duikersvlei Canal 1 Blaauwberg 2011.12.13  Parklands Open Spaces, which include the Avon Mouth Detention Pond (Gie Road extn)  Sout River Mouth (Otto Du Plessis Rd Bridge, Melkbosstrand)  Table View Beach Front stormwater outlet (Beach Road)  Table View Beach Front stormwater outlet (Foam Road)  Bayside Canal  Canal opposite Kraaifontein Wastewater Treatment Plant  Detention pond opposite Kraaifontein Wastewater Treatment Plant  Doordekraal Dam  Klapmuts River 2 Kraaifontein, 2011.11.25  Mosselbank River canal at Kraaifontein Sports Council  Sonstraal Dam  Stormwater detention pond near Cobble Walk Shopping Mall  Uitkamp wetland  Friesland Park  Elsieskraal River Elizabeth Park (behind Bellville Library)  Francie van Zyl Canal – along railway line Bellville South of 3 2011.12.14  Kuilsrivier (Frans Conradie Drive) N1  Kuilsrivier (Kuils River Hospital) intersection of R300 and Strand Road  Kuilsrivier (Nooiensfontein Vlei)  Delft Detention Pond c/o Delft Main Road and Hindle Road  Radloff Road (Geelsloot)  Somerset Ridge Detention Pond (Somerset Mall)  Somerset Ridge Lower Pond  Sanctuary Pond  Strand Beachfront – stormwater outlets 4 Somerset West 2011.12.12  Soetvlei (Soetrivier wetland)  Broadlands Canal Outlet  Sir Lowry’s Pass Diversion Canal Detention Pond  Lower Sir Lowry’s Pass River (Lancaster Rd)  Sir Lowry’s Pass (Rhine Stream and River)  Lourens River Park  Liesbeek River Canal, River Club  Malta Canal, River Club  Jakkalsvlei Canal Silt Trap Cape Town  Washington Road Culvert 5 Central & Atlantic 2011.12.09  Viking Way Canal, Epping Seaboard  Elsieskraal Canal (Ringwood Drive, Pinelands)  Salt River Canal  N1 Detention Pond BRT Route and railway line  Vygekraal River (opposite Rondebosch Golf Course)  Jakkalsvlei Canal (confluence with Vygekraal Canal)  Vygekraal (Nantes Park) Blossom Road  Blomvlei Canal 6 Athlone 2011.12.05  Little Lotus River  Madeira Drive Retention Ponds  Zeekoevlei Outlet  Zeekoevlei inlet (Pelikan Park) channel  Kuilsrivier (south of N2) upper Khayelitsha wetland  Kuilsrivier - Spine Rd/ Khayelitsha wetland Culverts  Silvertown Stormwater Outlet 7 Khayelitsha 2011.12.06  Kleinvlei Pylon Access Weir  Baden Powell Drive Culverts  Macassar south-west detention pond (near Monwabisi) and outlet

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No. District Date Areas Inspected

 Sand River Canal litter trap  Silvermine River mouth  Westlake River, Kirstenhof Plumstead and  Westlake River, Orange Road 8 2011.11.28 South Peninsula  Westlake River, Duck Pond  Grootboschkloof Stream, Constantia  Wynberg Stream box culvert and Maynardville Detention Pond, Wynberg  Lower Dieprivier canal

A total of nine broad stormwater maintenance and management measures were identified through the site visits and workshops with the various CCT staff in different districts. These were deemed to encompass all the maintenance activities regularly undertaken by the CCT and were reviewed and reworked a number of times by the project team. The final list is presented in Table 10 of this report and described further in Section 4 and Appendix C.

2.2.2 The Receiving Environment (a) Defining the Receiving Environment This application applies to the entire jurisdictional area of the CCT (see Figure 1) but because of the stormwater focus, the following key points regarding the receiving environment are noted within the context of this application:  Both natural and constructed surface stormwater facilities are considered. The City defines its urban stormwater system as including both the constructed and natural facilities, including pipes, culverts, watercourses and their associated floodplains, used or required for the management, collection, conveyance, temporary storage, control, monitoring, treatment, use and disposal of stormwater (City of Cape Town By-Law Relating to Stormwater Management, PG 6300; LA 31420 2005). This project however does not include proactive maintenance (mostly cleaning) of underground infrastructure such as pipes, culverts, and also excludes roadside gullies and kerb inlets. The latter activities are undertaken in terms of best practise guidelines detailed in the City‟s “Stormwater Cleaning Manual” (Vela VKE Report C1276-W-I [REPORT]-001, 2011).  Within the urban stormwater management context, the aquatic receiving environment and types of systems in which work is undertaken are referred to in very simple, generalised terms by operational staff. For example:- o Linear systems may be recognised and known as rivers, streams, engineered stormwater channels / swales, canals (concrete lined). o Wetlands, vleis, estuaries and possibly some dams would be viewed as waterbodies that are natural or semi-natural. o Artificial and engineered systems would include some dams, detention dams / ponds (dry), retention dams / ponds (wet), constructed treatment wetlands, etc.  The term “watercourse”, for the purposes of this report, is defined broadly and is complimentary to national and local government terminology. Watercourses should be considered in view of the following national (NEMA) and municipal (City of Cape Town Stormwater By-law) definitions.

Appendix J. Technical Assessment Report Page 9

NEMA EIA 2010 regulations:  A river, spring natural channel or depression in which water flows regularly or intermittently, or  A wetland, lake or dam into which, or from which, water flows; and  Any collection of water which the Minister may, by notice in the Gazette, declare to be a watercourse as defined in the National Water Act, 1998 (Act No. 36 of 1998) City of Cape Town Stormwater By-law (PG 6300; LA 31420 2005):  A river, spring, stream, channel or canal in which water flows regularly or intermittently, and  A vlei, wetland, dam or lake into which or from which water flows, and includes, where relevant, the bed and the banks of such watercourse.

 The term “wetlands” included de facto in the above watercourse definition is understood to include bodies of water further defined by the National Water Act (36 of 1998) as “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”. This definition is acknowledged in Council approved policies (“Management of Urban Stormwater Impacts” and “Floodplain and River Corridor Management” C 58/05/09).  The location of interventions affecting the receiving environment is not fixed. The maintenance of the surface stormwater systems is a dynamic process and while every effort is made to be proactive, some reactive interventions are necessary when and where a problem arises. Therefore, whilst the locations of present maintenance interventions are known, these may change / expand in the future due, primarily, to the duration and type of rainfall intensity, catchment development, and as the City‟s footprint expands and new areas require urban stormwater infrastructure and management.

(b) Categorising the Receiving Environment (Watercourses) Due to the large number of aquatic systems requiring maintenance and management measures and the fact that the locations of the measures vary from time to time, it would not be possible or practical to assess the potential impacts of each measure by specific locations. Rather, the City‟s surface water systems have been categorised where appropriate according to (i) their “watercourse/ hydrogeomorphic” type, and (ii) their ecological importance. The impacts of the routine maintenance and management measures have been generally assessed per watercourse category and importance.

2.2.3 Impact Assessment System Not all interventions undertaken by CCT trigger the need for authorisation in terms of the EIA Regulations. However, as best practice, the impacts of all interventions have been assessed and mitigation measures developed and proposed in the EMPr. A system of tables (as shown in Figure 2) has been employed to select, describe and assess the relevant interventions. All impacts should be evaluated for their full life cycle for the proposed works. The simple, standard system for judging impact significance in this assessment is explained below.

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(a) Determining Significance The following factors are considered in the determining of impact significance: i. Spatial extent: The geographical area in which the impact will be experienced. This can be limited to being site specific (i.e. extending to<500 m reach of river or <10% of the area of a wetland, local (extending up to < 3 km from site or up to 50% of wetland), regional (extending over a full river reach / wetland, which is considered to have implications for biodiversity within the CCT Municipality) or national (affecting a whole category of waterbodies, which is deemed to have implications for national biodiversity). ii. Magnitude of impact: The severity or size of the impact. The magnitude in terms of its potential for causing either negative or positive effects can be expressed as high (natural and/or social functions and/or processes are severely altered), medium (natural and/or social functions and/or processes are notably altered) or low (natural and/or social functions and/or processes are negligibly altered). This assessment is considered relative to the pre-disturbance state rather than the pristine condition1. iii. Duration: Most of the stormwater management measures are implemented over a period of days or weeks at the most, but may be performed on an annual to once every 2 to 5 years basis. For repeated impacts, therefore, the duration of the impact is expressed relative to recovery times of the watercourse (and thus at least partially related to both the magnitude of an impact but also the resilience of the watercourse). The expected timeframe of an impact can be expressed as: o temporary (TEMP) - the management measure is a once-off occurrence and implemented over a discrete period, in the order of weeks (e.g. gabion installation); o short term (ST) – the management measure can be expected to be repeated at some interval (e.g. annually), but the impact is considerably shorter-lived than the period required for recovery, such that the ecosystem remains in its pre- disturbance state >80% of the time; o medium term (MT) - the impact of the management measure is shorter-lived than the period required for recovery, such that the ecosystem remains in its pre- disturbance state for 40 - 80% of the time and in some partially-recovered state for some of the time; o long term (LT) - the impact of the management measure persists>60% of the time between impacts, such that the ecosystem exists in its pre-disturbance state for <40% of the time and in some only partially-recovered state for the majority of the time, o permanent (PERM) - the impact of the management measure is such that the ecosystem cannot recover between the implementation of maintenance measures, and persists in some modified form (depending on the magnitude of the impact). iv. Probability: This considers the likelihood of the impact occurring and is described as follows:

o Improbable (IMP): little or no chance of occurring (< 10% chance of occurring) o Possible (POSS): 10 – 39 % chance of occurring o Probable (PRO): 40 - 59% chance of occurring o Highly probable (HPRO): 60 – 95% chance of occurring o Definite (DEF) :> 95% chance of occurring.

1“pre-disturbance” refers to the state prior to the implementation of the management measure. Most of the watercourses in the CCT have long been disturbed relative to some pristine state.

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All measures initially considered Those measures requiring no authorisation or MMP not assessed further in this report. They are however addressed in terms of best practise with in the EMPr. Authorisation Matrix (Appendix B)

Environmental Determines which of the measures have Management Programme authorisation requirements Report (EMPr)

Only those interventions requiring authorisation are Those measures considered further in this requiring an MMP are Technical Assessment not assessed further in report this report. They are addressed in the EMPr.

Detailed Description of Measures (Appendix C)

Detailed description of the relevant measures (only those requiring authorisation) is provided.

Restrictions on the use of various measures in certain waterbodies of importance (Appendix D)

Lists measures which should not be undertaken in certain waterbodies because of their ecological importance.

Assessment of the impact of the relevant Intervention Impact interventions Assessment (Appendix E)

Evaluation of the impact significance per measure for different waterbody types.

Figure 2: Process used for evaluating impacts

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(b) Defining Significance Based on spatial extent, magnitude and duration, the following levels of significance are defined: High: o Permanent impacts of medium or high magnitude, on a local to national scale, o Long-term impacts of medium or high magnitude, on a regional to national scale, o Medium-term impacts of medium magnitude on a national scale o Medium-term impacts of high magnitude on a regional to national scale

Medium: o Permanent impacts of medium or high magnitude on a site-specific scale. o Long-term impacts of medium magnitude on a local scale. o Medium-term impacts of medium magnitude on a regional scale o Medium-term impacts of high magnitude on local scale o Short-term impacts of high magnitude on regional to national scale

Low: o Medium-term to permanent impacts, with low magnitude on a site-specific scale. o Temporary to permanent impacts, with low magnitude on a local scale. o Temporary to short-term impacts, with medium magnitude on a local to regional scale. o Medium-term impacts of medium magnitude on a local or smaller scale

Very Low: o Temporary or Short-term impacts of low magnitude on site specific scale

No impact: a potential concern or impact, which, upon evaluation, is found to have no impact.

(c) Status of Impacts The status is the overall effect on the environment and should be stated as positive (a benefit) negative (a cost) or neutral.

(d) Post-Mitigation In this case, the assessment of the significance of the impact is made on the assumption that mitigation measures have been implemented. The majority of the stormwater measures addressed in this application are routine activities undertaken on numerous occasions and best practice techniques are well understood. These mitigation measures are broadly outlined in this report (Section 4) and the methods for mitigation are presented in detail in the Environmental Management Programme (EMPr). They are however cross-referenced in this report (refer to Appendix E).

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2.2.4 Other Considerations Other aspects that should be taken into consideration are: (a) Alternatives Alternatives as defined in the EIA context have not been specifically considered in this assessment for the following reasons:  The measures in question have been developed over time, and refined with experience. They are considered the most practical and effective means for achieving the desired result and hence considering other alternatives is not considered worthwhile.  On the other hand the assessment considers numerous alternative methods for achieving a particular result. For example, sediment removal may be achieved by manual or mechanical means. These different methods will be used in different areas as dictated by the physical and environmental constraints of the area.

(b) Cumulative impacts The impact evaluation should take into account the cumulative impacts of other activities which have occurred or are simultaneously in the process of occurring within the study area. In most instances the watercourses utilised for stormwater conveyance are already modified from the natural condition, with a loss of biodiversity as a result of existing levels of pollution, alien invasion and historical physical impacts such as infilling, catchment deterioration, erosion and so on. On largely modified systems cumulative impacts will be low as the systems are already transformed. The negative impacts associated with some stormwater measures, where these are felt, may be more or less permanent, because the recovery period may be longer than the interval between the actions taken – for example where it is necessary to remove sediments more frequently than the recovery period. On the other hand, some maintenance tasks may be temporary and negligible especially if these tasks are undertaken only once or very infrequently, such as once every 5 years.

(c) Knowledge gaps and uncertainties The following knowledge gaps and uncertainties are noted:  Scale of the study site: Due to the large size of the application area, the exact receiving environment for all stormwater measures could not be assessed individually. It has been considered using “type of watercourse” and “watercourse importance” classifications which were determined using existing data for watercourses in the CCT.  Scale of the interventions: The interventions proposed are future interventions the scale of which cannot be pre-defined on a site by site basis. The scale of the interventions is presumed to be in line with that which CCT has undertaken to date as presented in Section 4.  The number of interventions: This application has not quantified the number of interventions which may be undertaken on a particular watercourse, and again, it will be the responsibility of the City to limit this as appropriate, and is dependent upon the need to attain hydraulic capacity in order to prevent consequential flooding and damage. This means that there remains some uncertainty regarding the significance of potential cumulative impacts on a watercourse.

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3 THE RECEIVING ENVIRONMENT

3.1 Overview

The jurisdictional area of CCT covers approximately 2,467 km2. Cape Town‟s stormwater management system comprises an extensive network of underground pipes and surface features. These include approximately 1,200 km of rivers and streams of which 300 km are maintained annually, roughly 650 detention and retention ponds, close to 150,000 gullies and intakes, and a large network of informal or private channels and ponds. Although there are over 7,000 wetlands that have been mapped in the City, not all of these require stormwater management interventions. This application is however only concerned with surface features such as rivers, wetlands, canals, dams and ponds. Since it is not possible to describe all these features in great detail, this section merely presents an overview of the receiving environment.

3.1.1 Major River Catchments The greater Cape Town metropolitan area contains 20 major river catchments that include the Atlantis, Chapman's Peak, City, Diep River, Eerste/ Kuils River, Hout Bay, Llandudno, Lourens River, Mitchell's Plain/ Khayelitsha, Muizenberg, Noordhoek, Salt River, Sand River, Silvermine, Sir Lowry's Pass, Sout River, South Peninsula, Steenbras River, West Coast, and Zeekoe catchments.

3.2 Classification of the Receiving Environment for the Purposes of Stormwater Maintenance Measures

Within the urban stormwater management context, the aquatic receiving environment and types of systems in which work is undertaken are referred to in very simple, generalised terms by operational staff. For example:-  Linear systems may be recognised and known as rivers, streams, engineered stormwater channels / swales, canals (concrete lined).  Wetlands, vleis, estuaries and possibly some dams would be viewed as waterbodies that are natural or semi-natural.  Artificial and engineered systems would include some dams, detention dams / ponds (dry), retention dams / ponds (wet), and constructed treatment wetlands.

Since the above is part of an integrated aquatic landscape, which in environmental terms could have some intrinsic ecological value, it is necessary to also understand and evaluate the stormwater management environment in terms of accepted ecological principles and assessment methodologies. In order to simplify the application of best practices for carrying out stormwater maintenance activities on different sorts of waterbodies within the City‟s jurisdiction, the watercourses previously categorised according to (i) their “hydrogeomorphic” type, and (ii) their ecological importance, are further simplified into six watercourse groups and three importance ranks, as described below. The impacts of the maintenance and management interventions have thus been assessed according to each of these watercourse groups and importance rankings.

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3.2.1 Rivers and Streams In a river classification exercise for the Cape Metropolitan Area (Harding et al. 2002), the major rivers and tributaries in the city were mapped at a 1:50 000 scale. Based on a geomorphological reach analysis, the rivers were sub-divided into up to eight geomorphological zones and reaches. In total there are 227 mountain stream river reaches, 109 foothill-cobble bed rivers, 75 foothill-gravel bed rivers, 54 wetland transitional rivers2, 32 lowland floodplain rivers, two gorges and two upland floodplain river reaches. The City‟s rivers layer thus developed was also subjected to a prioritisation exercise (Harding et al. 2002). This process identified the priority river reaches within each river type, based on a number of factors such as condition, contribution to important downstream ecosystems, unique features, and rehabilitation potential. The river reaches were then prioritised by ranking the scores and grouping into five categories, from 1 (highest priority: either because they were the best examples of their river type or because they were in good ecological condition) to 5 (highly modified systems with extremely limited potential to undertake any rehabilitation). Recommendations regarding ecological buffers for the assessed rivers were also provided in the report. A large proportion of the mountain and foothill streams draining the Peninsula chain, and the upper portions of the Lourens and Sir Lowry‟s catchments, are relatively undisturbed and regarded as important refuge and repositories of the biodiversity remnants of these system types. Based on their condition alone, many of these were accorded a high priority rank in the abovementioned studies. The ecological condition of river reaches in the CMA was found to decline with distance downstream, as a result of the cumulative impacts that are associated with urban areas. As a consequence, fewer of these river reaches were accorded high priority. The Category 1 Priority lowland rivers that were accorded the most natural ecological condition were the Schusters, Silvermine and Sir Lowry‟s Pass Rivers, whilst other Category 1 and 2 lowland rivers were portions of the Kuils, Eerste, Mosselbank, Lourens, Hout Bay, Diep and Moddergat Rivers, often because of the potential for rehabilitation in these systems. The Diep River (north) and the Kuils River, although subject to some urban derived impacts, nevertheless support important wetlands (Rietvlei and Nooiensfonteinvlei, respectively), which affords these two rivers higher than would be expected ecological importance. Similarly, despite the poor state of the Sand River Canal and the Langevlei Canal, which are both concrete canalised, the two canals enjoy high “ecological importance” as they drain into Zandvlei, an important estuary in Cape Town (Harding et. al. 2002). Rivers draining the Cape Flats are not regarded as unique at any scale, their habitat is almost completely altered (either by concrete canalisation or channelised within earthen embankments). These systems are no longer particularly sensitive to flow modifications because their flow regimes are completely altered from their natural state (Harding et. al. 2002).

3.2.2 Wetlands The City‟s comprehensive project involving desktop GIS mapping and classification of wetlands in the entire Cape Town metropolitan area using a multi-year series of aerial photographs (Ewart-Smith et. al., 2008) revealed a total of 7,677 polygons classified as “wetlands” in terms of the NWCS. Of these, 3,503 wetlands were described as having anthropogenic features3, while 4,174 wetlands are considered to be in a natural or semi- natural state (Snaddon and Day, 2009).Note that only a small percentage of these wetlands

2The “Wetland Transitional River” is not a wetland type included in the NWCS, but was used in the City‟s rivers GIS layer. It usually describes what is now referred to as a channelled valley bottom. Since the City‟s rivers layer has not yet been updated, we have retained this category. 3Wetlands considered to be artificial – i.e. those that have been categorised as such in any City database, or which clearly appear to be man-made – are included in the classification and biodiversity ranking because many of these support biodiversity notwithstanding their origins. The water bodies defined as having anthropogenic alteration however, exclude concrete reservoirs and WWTWs.

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require active management. This classification distinguished 54 wetland types based on a set of criteria, which included the differentiation between isolated and inter-connected wetlands which are believed to function in different ways. In a subsequent phase to the abovementioned mapping project these wetlands were prioritised based on factors such as condition, size, connectivity, biodiversity, surrounding land use and rehabilitation potential (Snaddon and Day, 2009). Three categories of importance were derived based on overall ranked scores. These were Critical Biodiversity Areas (high ranking “natural or semi-natural” wetlands; all estuaries), Critical Ecological Support Areas (High ranking artificial wetlands; middle ranking natural or semi-natural wetlands); and Other Ecological Support Areas (Lower ranking artificial wetlands; lowest ranking natural or semi- natural wetlands). The distribution of wetlands in these three priority categories, within each major catchment, is provided in Table 4 (from Snaddon and Day, 2009)

3.2.3 River and Wetland Groupings (Watercourse Types) Notwithstanding the extent of detail provided in the aforementioned studies, for the purposes of this application, different hydrogeomorphic types of river and wetlands were combined so as to make the assessment manageable (see Table 5). It is the opinion of the project team that this „simplification‟ does not detract from accuracy or the intention of providing an ecologically defendable level of screening / separation of systems by type and sensitivity. The practical and operational aspects of the City‟s stormwater management and maintenance programme contemplated herein necessitate the formulation of an operating system that is both feasible and manageable, while being complimentary and compliant with legislative requirements. The NWCS defined classification of inland systems4 is shown in, along with this project‟s rationalisation into six groups of watercourses, with estuaries comprising a seventh group. Figure 3 illustrates the locations of the seven watercourse types. This grouping of hydrogeomorphic types was based on the conviction that similar approaches to stormwater maintenance, similar challenges, and similar sorts of impacts will characterise the ecosystems within each of the seven groups. For example, the need for and method of removal of sediment from a floodplain river will be very different from that of a foothill river – each could have vastly different consequences, and different methods may therefore be warranted.

4Estuaries and marine systems are differentiated from inland systems at a higher level of the classification.

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Table 4: Summary information for each of the major catchments in the City, of the total number of wetlands, natural/semi-natural wetlands, and the numbers of CBA, CESA and OESA wetlands. Note that the concrete reservoirs or WWTW ponds are excluded from the biodiversity prioritisation (from Snaddon and Day 2009).

Number of “natural/semi- Number of Number of Number of Catchment Total number Total area of Catchment natural” wetlands CBA CESA OESA area (ha) of wetlands wetlands (ha) (% of total number wetlands wetlands wetlands of wetlands)

Atlantis 35 651 149 226 115 (77%) 101 16 27

Chapman’s Peak 653 25 12 25 (100%) 25 0 0

City 5 296 69 29 44 (64%) 38 9 16

Diep River 153 791 1493 2518 507 (33%)* 171 259 953

Eerste/Kuils River 66 680 1183 2383 802 (68%) 413 299 412

Hout Bay 3 787 181 155 146 (81%) 125 24 32

Llandudno 1 086 13 9 13 (100%) 12 1 0

Lourens River 12 455 394 736 248 (63%) 180 84 114

Mitchells Plain / 7 552 286 236 95 (33%) 47 81 138 Khayelitsha

Muizenberg 556 5 2 5 (100%) 5 0 0

Noordhoek 3 516 146 352 62 (42%) 41 16 76

Salt River 25 034 798 655 342 (43%) 132 90 444

Sand River 9 655 338 478 226 (67%) 107 103 123

Silvermine 2 156 100 99 84 (84%) 84 3 13

Sir Lowry’s Pass 7 576 336 287 158 (47%) 79 89 155

Sout River 14 192 343 241 179 (52%) 77 119 125

South Peninsula 16 798 619 773 557 (90%) 546 20 32

Steenbras River 7 184 194 996 191 (98%) 184 8 2

West Coast 1 707 17 7 3 (18%) 2 1 14

Zeekoe 7 812 652 1277 204 (31%) 65 218 369

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Table 5: Watercourse types: Hydrogeomorphic categories of rivers and wetlands and their allocation to one of six watercourse groups for this assessment.

Type grouping for Stormwater System type River / Wetland Hydrogeomorphic Type Classification Maintenance Assessment

 Gorge (GO)  Mountain streams and transitional rivers (MS)  Upland floodplain rivers (UFP) Group 1 – Gorges, mountain and foothill  Foothill cobble bed (FCB) rivers  Foothill gravel bed (FGB)

Rivers  Lowland rivers (LR)  Lowland floodplain river (LLFP) Group 2 – Lowland and lowland floodplain rivers  Wetland transitional rivers(WT)

Inland systems Group 3 - Valley bottom and floodplain  Valley-bottom wetlands (VBW) and wetlands; wetland transitional rivers including floodplain wetlands

 Seeps (S) Group 4 - Seeps

 Flats & Depressions (FD) Wetland Group 5 - Flats and depressions

 Depressions Dams (D)  Note: these include natural and semi- natural features, but exclude features Group 6 - Dams associated with Waste Water Treatment Works (WWTW).  River mouth (RM)  Permanently Open (PO) Estuaries Estuaries Group 7 - Estuaries  Temporary Open/Closed (TOC)  Including marinas.

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Figure 3: Overview map showing location of different watercourse types (as defined for this application). See Section 3.2.3 for further details.

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3.2.4 Ecological Priority (Watercourse Importance) For this project, the “ecological priority” ratings of the different watercourses recommended by Harding et al. (2002) have been grouped into a simpler three tier system of “high”, “medium” and “low” “watercourse importance” as shown in Table 6. Since the term ecological priority may be misconstrued by operational staff to have a timing element to it (e.g. those of highest priority are to be addressed first) it has been replaced with the term watercourse importance. Figure 4 illustrates the locations along with the project importance rating of watercourses in the CCT area.

Table 6: Proposed ranking of Ecological Importance to be used specifically for this project.

Ranking of Watercourse Importance for Type Existing Ecological Priority ranking of systems maintenance and management measures

Rivers Category 1 High

Category 2 High

Category 3 Medium

Category 4 Low

Category 5 Low

Wetlands (excl. rivers) Critical Biodiversity Area High

Critical Ecological Support Area Medium

Other Ecological Support Areas Low

Estuaries Critical Biodiversity Area High

Critical Ecological Support Area Medium

Other Ecological Support Areas Low

Combining the systems in Table 5 and Table 6, a matrix of Watercourse Type and Importance permutations has been defined as presented in Table 7 below.

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Table 7: Matrix of Watercourse Type x Importance permutations.

Watercourse Importance ranking for stormwater maintenance Watercourse Type and management interventions

Group 1: HIGH (Category 1 or 2)

Mountain streams MEDIUM (Category 3) Gorges Foothill rivers LOW (Category 4 or 5)

Group 2: HIGH (Category 1 or 2)

Lowland rivers MEDIUM (Category 3) Lowland floodplain rivers LOW (Category 4 or 5)

Group 3: HIGH (Critical Biodiversity Area)

Wetland transitional rivers MEDIUM (Critical Ecological Support Area / Category 3) Valley-bottom wetlands LOW (Other Ecological Support Areas / Category 4 & 5 Wetland- Floodplain wetlands Transitional channels))

Group 4: HIGH (Critical Biodiversity Area)

Seeps MEDIUM (Critical Ecological Support Area) LOW (Other Ecological Support Areas)

Group 5: HIGH (Critical Biodiversity Area)

Flat & depressions MEDIUM (Critical Ecological Support Area) LOW (Other Ecological Support Areas)

Group 6: HIGH (Critical Biodiversity Area)

Dams MEDIUM (Critical Ecological Support Area) LOW (Other Ecological Support Areas)

Group 7: HIGH (Critical Biodiversity Area)

Estuaries MEDIUM (Critical Ecological Support Area) LOW (Other Ecological Support Areas)

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Figure 4: Overview map showing location of different watercourses (wetlands and rivers) in terms of Ecological Importance (as defined for this application). See Section 3.2.4 for further details.

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3.2.5 Topography The topography of the CCT area varies significantly and includes the Cape Flats in the south which are characterised by low lying extensive vleis and wetland areas while the Cape Peninsula is a mountainous region with over 70 peaks reaching over 300 m. The topography in the city is dominated by Table Mountain, a 3 km long level plateau. Low to moderate elevation hills characterise portions of the north-eastern metropole e.g. Platteklip, Durbanville, while high peaks occur above Somerset West and Gordons Bay.

3.2.6 Geology The CCT consists of four dominant geological formations:  Malmesbury Group (shales) – sedimentary rocks, mudstones and sandstones.  Cape Granite – metamorphic rocks containing feldspar, black mica and quartz.  Table Mountain Group – weather resistant sandstone and sedimentary rocks.  Sandveld Group- aoelian quartzose sand (CCT District Plans, 2011).

3.2.7 Soils The soil types in the CCT are predominantly sandy soils of varying depths. The soils on the slopes and plateau of Table Mountain and the Cape Peninsula are generally Red and Yellow apedal soils, shallow, acidic, sandy soils which present harsh growing conditions for plants. The Cape Flats generally have deeper sandy or loamy soils with a higher nutrient value than the Red and Yellow apedal soils. Deeper soils are found within the Eerste River Valley; these soils covering the river banks and floodplain have a higher fertility and contain silt, clay and peat in some wetland areas (CCT District Plans, 2011).

3.2.8 Climate The CCT has a Mediterranean type climate with pronounced seasons. Rainfall can occur throughout the year with the majority of rainfall in the winter months. Rainfall in the winter between May and August is a result of cold fronts originating in the Atlantic. The rainfall across the CCT area is however not consistent, with an average of 500 mm of rainfall per annum in the valleys and coastal plains and an average of 1,500 mm falling in the mountainous regions each year. Temperatures range from 15-27°C in the summer months (December to February) to 7-20°C in the winter months (June to August).

3.2.9 Population The population of the CCT has increased by 28.7% from 4,524,335 in 2001 to 5,822,734 in 2011 (Figure from STATS SA 2012). There has been a large migration of people from other provinces in South Africa into Cape Town, particularly from the Eastern Cape.

3.2.10 Socio-Economic The average household size in the CCT in 2007 has decreased from 3.7 in 2001 to 3.5 in 2011. The number of households in the CCT which own and have fully paid off their property decreased from 60.7 % in 2001 to 54.2 % in 2011. The percentage of households with access to services in the CCT is very similar to that of the Western Cape as a whole and households in the CCT have a significantly better level of access to services compared to South Africa as a whole. Households in the CCT that have access to a waste removal service through the local authority or a private company remained constant (94.3 %) from 2001 to 2011. This is significantly higher than South Africa as a whole (63.6 %, 2011). In 2011, a total of 99.1 % of households in the Western Cape have access to piped water. Again this is above the national average of 91.3 % (2011).

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Access to electricity in the CCT, Western Cape and South Africa based on the 2011 Census results is as follows (STATS SA, 2012):  electricity for lighting: CCT (94%), Western Cape (93.4 %), National (84.7 %),  electricity for cooking: CCT (89.5%, 2007), Western Cape (86.9 %), National (73.9 %)  electricity for heating: CCT (80.4%, 2007), Western Cape (63.1 %), National (58.8%)

The CCT contributed 76.5% of the Gross Domestic Product by region (GDPR) of the Western Cape and 11.2% of the national Gross Domestic Product (GDP) in 2004. The major economic drivers in the CCT are the finance and business sector (31.7%), manufacturing (17.9%) and wholesale and retail trade (17.3%). Unemployment rose from 17.3% in 1995 to 23.4% in 2005(Western Cape, 2006). Tourism is also noted as a key driver of Cape Town‟s economy.

3.2.11 Tourism In 2008 tourism in the CCT had an economic value of R13.6 billion to Cape Town, a 20% increase from 2007 according to the City of Cape Town Report on Economic Value of Tourism (Grant Thornton, 2009). The review by GAB Consulting (2010), valued the 2009 contribution by tourism at R17.3 billion. Tourism employs 20,062 people in permanent positions and a further 12,216 people in temporary positions annually in the CCT (GAB Consulting, 2010).

3.2.12 Land Use The Cape Town District is the central business district of Cape Town, contains the Port of Cape Town and is also the tourism centre of Cape Town. The Tygerberg region is also of economic importance as it contains the greatest amount of industrial property within the CCT. Land use in the Blaauwberg District consists of large areas of agriculture and conservation areas and also includes some of the fastest growing new development in the City. Wine farms are found in the Constantia Valley and forestry and agriculture are features of the Helderberg area. Residential areas in the CCT range from dense urban suburbs to small outlying towns. The Cape Flats and Khayelitsha areas are residential areas with very little economic activity. Two of the most densely populated suburbs, Green Point and Sea Point, are found within the Table Bay District. Twenty two nature reserves and conservation areas are found within the CCT area, including the Table Mountain National Park (Information sourced from City of Cape Town 2011 District Plans).

3.2.13 Floral Biodiversity The City of Cape Town is located in the Cape Floristic Region (CFR). The CFR is the world‟s smallest but most diverse floral kingdom and has one of the highest proportions of endemic species in the world, with over 70% of its approximately 9,600 species found nowhere else in the world. The CCT municipal area contains a number of endangered and critically endangered vegetation types; 12% of South Africa‟s plant species are found within the city which covers 0.1% of the country (Table 8). The CCT Biodiversity Network is a municipal defined network of habitats of biodiversity value and includes numerous features such as Critical Biodiversity Areas (CBAs). Table 8 indicates to what extent the different vegetation types occur within the Biodiversity Network. Estimates (determined through GIS) of the extent of these vegetation types occurring in close proximity to wetlands have also been included in the table.

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Table 8: Critically endangered (red), Endangered (orange), Vulnerable (yellow), and Least threatened (green) vegetation types occurring within the CCT biodiversity network (Information sourced from Mucina & Rutherford, 2006).

Occurrence within Occurrence in CCT % vegetation type occurring in Vegetation type CCT Biodiversity Biodiversity Network within the CCT Biodiversity Network Network (km2) 500 m from wetland (km2) within 500 m from a wetland

Cape Flats Sand Fynbos 88.227 58.415 66 Elgin Shale Fynbos 2.945 2.945 100 Lourensford Alluvium Fynbos 4.448 4.304 97 Peninsula Shale Renosterveld 6.146 2.079 34 Swartland Alluvium Fynbos 1.775 1.331 75 Swartland Granite Renosterveld 27.469 19.998 73 Swartland Shale Renosterveld 53.865 35.093 65 Swartland Silcrete Renosterveld 4.496 3.599 80 Boland Granite Fynbos 59.706 54.604 91 Cape Flats Dune Strandveld 192.124 114.842 60 Cape Winelands Shale Fynbos 26.486 14.296 54 Peninsula Granite Fynbos 40.096 26.620 66 Atlantis Sand Fynbos 173.152 77.502 45 Cape Inland Salt Pans 2.174 2.174 100 Hangklip Sand Fynbos 13.194 11.371 86 Langebaan Dune Strandveld 0.001 0.001 100 Cape Lowland Freshwater Wetlands 8.836 8.366 95 Cape Seashore Vegetation 2.366 0.753 32 Kogelberg Sandstone Fynbos 93.091 78.339 84 Peninsula Sandstone Fynbos 219.281 184.602 84 Southern Afrotemperate Forest 3.267 1.310 40 Southern Coastal Forest 0.082 0.027 33 Western Coastal Shale Band Vegetation 3.362 2.918 87

The most endangered systems within the City are generally the Renosterveld and Fynbos vegetation types. Critically endangered and endangered vegetation types occurring within the city‟s Biodiversity Network include: Cape Flats Sand Fynbos, Elgin Shale Fynbos, Lourensford Alluvium Fynbos, Swartland Alluvium Fynbos, Swartland Granite Renosterveld, Swartland Shale Renosterveld, Swartland Silcrete Renosterveld, and Peninsula Shale Renosterveld, Peninsula Granite Fynbos and Kogelberg Sandstone Fynbos. Elgin Shale Fynbos and Lourensford Alluvium Fynbos occurs almost exclusively within 500 m of wetlands in the Biodiversity Network, whereas the majority (65 – 80%) of the remaining critically endangered vegetation types occur within 500 m from a wetland, with the exception of Peninsula Shale-Renosterveld (34%). Of the critically endangered vegetation types, Cape Flats Sand Fynbos and Swartland Shale Renosterveld cover the largest area (approximately 58.4 and 35.1 km2, respectively) within 500 m from a wetland (SANBI 2006). The Cape Town Lowlands have the highest concentration of threatened plants species per area of remaining vegetation in the world. The Cape Town Lowlands support more than 1466 plant species in 1874 km2, of which 76 are endemic and 319 are Red Data Book species with a further 120 of conservation concern. The Cape Peninsula mountain chain supports 2285 plant species in 471 km2, of which 90 species are endemic. Only 3 percent remains of the original extent of the threatened Renosterveld vegetation.

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(a) Endemic flora There are 190 known species of vegetation which are endemic to Cape Town (CCT, 2006). The Cape Peninsula has a high level of plant endemism; endemic species (158 species and 3 subspecies) constitute 7 % of the flora species, and 62 % of the endemic species are shrubs or dwarf shrubs. The majority of endemic species (76 %) belong to ten families; the genus Erica contains 39 of the Cape Peninsulas endemic species. The genus‟s Roella, Tetraria, Serruria and Muraltia also contain species endemic to the area. Of the 161 endemic species 41 % are Red Book listed (Helme & Trindle-Smith, 2006). Passerina paludosa thoday is a wetland species endemic to the Cape Flats and the Agulhas Plain, it is typically found in lowland coastal marshes and seeps. The greatest threats to the Cape Flats population are continued habitat loss due to development and draining of marshes (Helme et al, 2012). Serruria foeniculacea, a terrestrial species, occurs in moist conditions on the Cape Flats. The population has decreased due to overgrazing, urban expansion and too infrequent fires. A small population of plants occurs on the Cape Flats which continues to decline (Rebelo et al, 2012).

(b) Endangered flora The City of Cape Town owns and operates 24 nature reserves, however over two thirds of the city‟s natural vegetation largely occurs outside of formal reserves and is classified as „endangered‟ or „critically endangered‟. Contrasting the high endemism of Cape Town‟s biodiversity, the city also has the world‟s highest rate of plant extinctions in an urban area (CCT, 2003).According to the 2006 CCT Local Biodiversity Strategy and Action Plan, 84 plant species within the CCT are critically endangered, four species are extinct in the wild and a further nine species are extinct.

3.2.14 Faunal Biodiversity (a) Endemic fauna There are only two species of vertebrates known to be endemic to the CCT, the Table Mountain Ghost Frog (Heleophryne rosei) and the Cape Peninsula Moss frog (Arthroleptella lightfooti) also known as Lightfoot‟s Moss Frog. The Table Mountain Ghost Frog is only found on the slopes of Table Mountain in an area covering 9 km2.The Cape Peninsula Moss Frog occurs over a range of 134 km2 on Table Mountain and other peaks of the Cape Peninsula (SA-Frog, 2010).There are 136 species of invertebrates known to be endemic to the CCT but because no comprehensive study has been completed the actual number of endemic invertebrates in Cape Town is anticipated to be significantly higher (CCT undated publication).There are approximately 111 endemic invertebrate species on the Cape Peninsula mountain chain alone.

(b) Endangered fauna Forty-one mammal species reside in Cape Town, with six recently becoming extinct. Furthermore, the Cape Town area is home to approximately 250 bird species, of which ten are endangered, and with at least three becoming extinct in recent years. Eighteen amphibian species occur in Cape Town, of which four are listed in the Red Data Book, while forty-eight reptile species are found in Cape Town, of which four are endangered and two locally extinct. Twenty-four fish species have been found to be dependent on the estuaries in the broader Cape Town area. Faunal species of special concern include:

(i) Western Leopard Toad (Amietophrynus pantherinus)

The Western Leopard Toad has been classified as Endangered with a looming threat of becoming extinct. Main threats include habitat loss due to urbanization, alien fish and

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infestation of aquatic weeds in breeding sites, obstacles to movement (such as road gutters, boundary walls, large buildings, canals, storm water drains), and road mortality during breeding migrations. Most of its range is concentrated around the Cape Flats in Hangklip Sand Fynbos and the Cape Flats Dune Strandveld. It is also common in gardens of residential areas in the southern suburbs. The Toad‟s distribution is generally limited to 5 km around breeding sites. This species is of relevance to stormwater and public open space maintenance activities because of its habitat requirements. The CCT Environmental Resource Management Department monitors toad habitats and has signed a Memorandum of Understanding (MOU) with operational divisions of the City‟s Road and Stormwater and Parks Departments to ensure impacts on the species are not compromised through stormwater management and public open space mowing activities. `The construction of enclosed pipe systems and canals may negatively affect the movement of toads and it is therefore important that canals and pipeline are fitted with toad escape routes.

(ii) Micro Frog (Microbatrachella capensis)

The Micro Frog has been classified as Critically Endangered due to its limited distribution. Main threats include habitat loss and fragmentation of habitat due to urbanization. The distribution of the species is fragmented and it can be found in high concentrations around a limited number of breeding sites. The Micro Frog is found in sandy, coastal Fynbos and is generally not found in anthropogenic / altered habitats. This species is of potential relevance to stormwater and public open space maintenance activities because of it can only tolerate very limited habitat disturbance (SA-FrOG, 2013). The only known population within the CCT is at Kenilworth Race Course which will not generally be subjected to any stormwater maintenance activities by the municipality i.e. potential impact as a result of this project are likely to be absent / negligable.

(iii) Table Mountain Ghost Frog (Heleophryne rosei)

The Table Mountain Ghost Frog has been classified as Critically Endangered due to its extremely restricted distribution. The frogs’ range is restricted to an area of approximately 9 km2 on the southern and eastern slopes of Table Mountain. The Table Mountain Ghost Frog lives in forest and Fynbos heathland and breeds in clear perennial streams in gorges, valleys and ravines. Main threats include habitat loss, frequent fires, alien vegetation and storage of water in reservoirs on Table Mountain which can affect the consistency of stream flow (SA- FrOG, 2010). Due to its distribution it is unlikely that it would be subjected to disturbance from this project as it is seldom, if ever, that the municipality will undertake stormwater maintenance activities at these locations.

(iv) Cape Platanna (Xenopus gilli)

The Cape Platanna has been classified as Endangered due to its declining extent of occurrence. The Cape Platanna is known to occur on the Cape Peninsula, and is found only in black acid water in Cape Fynbos heathland. Known populations of Cape Platanna are found within 10 km of the coast. Main threats include habitat loss due to urbanization, agricultural run-off and infestation of alien plants (SA-FrOG, 2010).

(v) Rose’s Mountain Toad (Capensibufo rosei)

The Rose’s Mountain Toad is classified as Vulnerable due to its limited distribution. The toad is only know to occur in eight locations including on the Cape Peninsula. Main threats include loss of fynbos habitat due to burning and colonisation by invasive vegetation. Rose’s Mountain Toad’s habitat is mountain Fynbos heathland and the species does not survive in altered habitats (SA-FrOG, 2010).

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(c) Fauna Listed in the National Environmental Management Biodiversity Act The following list of species is taken from the National Environmental Management Biodiversity Act, 2004 (Act 10 of 2004): Publication of Lists of Critically Endangered, Endangered, Vulnerable and Protected Species.

Table 9: List of species classified as critically endangered, endangered, vulnerable and protected species.

Critically Endangered Species Scientific Name Common Name Distribution within CCT PISCES Labeo seeberi Clanwilliam Sandfish No REPTILIA Caretta caretta Loggerhead Sea Turtle Possible (unlikely) Dermochelys coriacea Leatherback Sea Turtle Possible (unlikely) Eretmochelys imbricate Hawksbill Sea Turtle Possible (unlikely) AVES Grus carunculatus Wattled Crane No Hirundo atrocaerulea Blue Swallow No Neophron percnopterus Egyptian Vulture No Poicephalus robustus Cape Parrot No MAMMALIA Bunolagus monticularis Riverine Rabbit No Chrysospalax villosus Rough-haired Golden Mole No FLORA Adenium swazicum Swaziland Impala Lily No Aloe pillansii False Quiver Tree No Diaphananthe millarii Tree Orchid No Dioscorea ebutsiniorum Wild Yam No Data Encephalartos aemulans Ngotshe Cycad No Encephalartos brevifoliolatus Escarpment Cycad No Encephalartos cerinus Waxen Cycad No Encephalartos dolomiticus Wolkberg Cycad No Encephalartos heenanii Woolly Cycad No Encephalartos hirsutus Venda Cycad No Encephalartos inopinus Lydenburg Cycad No Encephalartos latifrons Albany Cycad No Encephalartos middelburgensis Middelburg Cycad No Encephalartos nubirnontanus Blue Cycad No Data Encephalartos woodii Wood’s Cycad No Endangered Species Scientific Name Scientific Name Distribution within CCT INVERTEBRATA Possible (No conclusive data – Distribution Colophon spp - All species Stag Beetles possible throughout South Africa) PISCES Barbus andrewi Whitefish No Barbus serra Sawfin No Pristis microdon Largetooth Sawfish No REPTILIA Chelonia mydas Green Turtle No Possible (No conclusive data – Cordylus giganteus Giant Girdled Lizard Distribution possible throughout South Africa) Lepidochelys olivacea Olive Ridley Turtle No

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Psarnrnobates geornetricus Geometric Tortoise Possible (Unlikely) AVES Anthropoides paradiseus Blue Crane Yes Balearica regulorum Grey Crowned Crane No Ephippiorhynchus senegalensis Saddle-billed Stork No Gypaetus barbatus Bearded Vulture No Gyps africanus White-backed Vulture No Gyps coprotheres Cape Vulture Yes Necrosyrtes rnonachus Hooded Vulture No Pelecanus rufescens Pink-backed Pelican No Scotopelia peli Pel’s Fishing Owl No Torgos tracheliotus Lappet-faced Vulture No MAMMALIA Amblysomus robustus Robust Golden Mole No Damaliscus lunatus Tsessebe No Diceros bicornis Black Rhinoceros No Equus zebra Mountain Zebra Yes Lycaon pictus African Wild Dog No Neamblysomus gunningi Gunning's Golden Mole No Ourebia ourebi Oribi No Paraxerus palliatus Red Squirrel No Petrodromus tetradactylus Four-toed Elephant-shrew No FLORA Angraecum africana Tree Orchid No Encephalartos arenarius Dune Cycad No Encephalartos cupidus Blyde River Cycad No Encephalartos horridus Eastern Cape Blue Cycad No Encephalartos laevifolius Kaapsehoop Cycad No Encephalartos lebomboensis Lebombo Cycad No Encephalartos msinganus Msinga, Cycad No Jubaeopsis caffra Pondoland Coconut No Siphonochilus aethiopicus Wild Ginger No Warburgia salutaris Pepper-bark Tree No Newtonia hilderbrandii Lebombo Wattle No Vulnerable Species Scientific Name Scientific Name Distribution within CCT ONYCHOPHORA Peripatopsis alba White Cave Velvet Worm Yes PISCES Epinephelus andersoni Catface Rockcod No Labeobarbus capensis Clanwilliam Yellowfish No Labeobarbus kimberleyensis Vaal-Orange Largemouth Yellowfish No Myxus capensis Freshwater Mullet Possible Oreochromis placidus Black Tilapia No Serranochromis meridianus Lowveld Largemouth No AVES Trigonoceps occipitalis White-headed Vulture No Aquila rapax Tawny Eagle No Ardeotis kori Kori Bustard No Ciconia nigra Black Stork Yes Circaetus fasciolatus Southern Banded Snake Eagle No Eupodotis caerulescens Blue Korhaan No Falco fasciinucha Taita Falcon No Falco naumanni Lesser Kestrel Yes Falco peregrinus Peregrine Falcon Yes Geronticus calvus Bald Ibis No Neotis ludwigii Ludwig’s Bustard No Polemaetus bellicosus Martial Eagle Yes Terathopius ecaudatus Bateleur No Tyto capensis Grass Owl No

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MAMMALIA Acinonyx jubatus Cheetah No Chrysospalax trevelyani Giant Golden Mole No Cricetomys gambianus Giant Rat No Damaliscus pygargus Bontebok No Dendrohyrax arboreus Tree Hyrax No Hippotragus equinus Roan Antelope No Manis temminckii Pangolin No Neamblysomus julianae Juliana’s Golden Mole No Neotragus moschatus Suni No Otomops martiensseni Large-eared Free-tailed Bat No Panthera leo Lion No Panthera pardus Leopard No Philantomba monticola Blue Duiker No Protected Species Scientific Name Scientific Name Distribution within CCT INVERTEBRATA Aloeides clarki Coega Copper Butterfly No Ceratogyrus spp - All species Horned Baboon Spiders Yes Echinodiscus bisperforatus Pansy Shell No Dromica spp - All species Tiger Beetles Yes Graphipterus assimilis Velvet Ground Beetle Possible Xadogenes spp - All species Flat Rock Scorpions No Haliotis midae South African Abalone No Xarpactira spp - All species Common Baboon Spiders Yes Ichnestoma spp - All species Fruit Chafer Beetles Yes Manticora spp - All species Monster Tiger Beetles Yes Megacephala asperata Tiger Beetle Possible (No data) Megacephala regalis Tiger Beetle Possible (No data) Nigidius auriculatus Stag Beetle Possible (No data) Oonotus adspersus Stag Beetle Possible (No data) Oonotus interioris Stag Beetle Possible (No data) Oonotus rex Stag Beetle Possible (No data) Oonotus sericeus Stag Beetle Possible (No data) Opisthacanthus spp - All species Creeping Scorpions No Opistophthalmus spp - All species Burrowing Scorpions No Platychile pallida Tiger Beetle Possible (No data) Prosopocoilus petitclerci Stag Beetle Possible (No data) Prothyma guttipennis Tiger Beetle Possible (No data) Pterinochilus spp - All species Golden Baboon Spiders Yes AMPHIBIA Pyxicephalus adspersus Giant Bullfrog No Pyxicephalus edulis African Bullfrog No PISCES Anchichoerops natalensis Natal Wrasse No Biycinus lateralis Striped Robber No Carcharodon carcharius Great White Shark No Epinephelus lanceolatus Brindle Bass No Epinephelus tukula Potato Bass No Hydrocynus vittatus Tigerfish No Latimeria chalumnae Coelacanth No Lithognathus lithognathus White Steenbras No Nothobranchius orthonotus Spotted Killifish No Nothobranchius rachovii Rainbow Killifish No Polysteganus undulosus Seventy-four Seabream No Pristis zijsron Longcomb Sawfish No Varicorhinus nelspruitensis Incomati Chiselmouth No REPTILIA Bitis gabonica Gaboon Adder No Bitis schneideri Namaqua Dwarf Adder No

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Bradypodion taeniabronchum Smith’s Dwarf Chameleon No Cordylus cataphractus Armidillo Girdled Lizard No Crocodylus niloticus Nile crocodile No Python natalensis African Rock Python No AVES Bucowus leadeateri Southern Ground-Hornbill No Circus ranivorus African Marsh Harrier Possible Neotis denhami Denham’s Bustard Yes Spheniscus demersus Jackass Penguin Yes (Marine) MAMMALIA Atelerix frontalis South African Hedgehog No Ceratotherium simum White Rhinoceros No Connochaetes gnou Black Wildebeest No Crocuta crocuta Spotted Hyaena No Felis nigripes Black-footed Cat No Parahyaena brunnea Brown Hyaena No Leptailurus serval Serval No Loxodonta africana African elephant No Lutra maculicollis Spotted-necked Otter No Mellivora capensis Honey Badger Yes Raphicerus sharpei Sharpe’s Grysbok No Redunca arundinum Reedbuck No Vulpes chama Cape Fox Yes FLORA Adenia wilmsii No common name No Aloe simii No common name No Clivia mirabilis “Oorlogskloof‘ Bush Lily No Disa macrostachya No common name No Disa nubigena No common name Yes Disa physodes No common name Yes Disa procera No common name No Disa sabulosa No common name Yes Encephalartos altensteinii Bread Palm No Encephalartos caffer Breadfruit Tree No Encephalartos dyerianus Lowveld Cycad No Encephalartos friderici-guilielmi White-haired Cycad No Encephalartos ghellinckii Drakensberg Cycad No Encephalartos humilis Dwarf Cycad No Encephalartos lanatus Olifants River Cycad No Encephalartos lehmannii Karoo Cycad No Encephalartos longifolius Thunberg's Cycad No Encephalartos natalensis Natal Giant Cycad No Encephalartos paucidentatus Barberton Cycad No Encephalartos princeps Kei Cycad No Encephalartos senticosus Jozini Cycad No Encephalartos transvenosus Modjadje Cycad No Encephalartos trispinosus Bushman's River Cycad No Euphorbia clivicola No common name No Euphorbia meloformis No common name No Euphorbia obesa No common name No Harpagophytum procumbens Devil’s Claw No Harpagophytum zeyheri Devil’s Claw No Hoodia gordonii Ghaap No Hoodia currorii Ghaap No Protea odorata Swartland Sugarbush Possible Stangeria eriopus Natal Grass Cycad No

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4 DESCRIPTION AND ASSESSMENT OF IMPACTS

4.1 Routine stormwater Maintenance / Management Measures included in this Application

Nine categories of stormwater maintenance / management measures are listed in Table 10 as the basis for this application, and are further described in two stages.  Evaluation in terms of whether or not they trigger the EIA regulations, and if so5, what the authorisation requirements are (i.e. a Basic Assessment and EMPr, or in the case of some maintenance activities, simply a “management plan” suffices. In such cases, the EMPr fulfils this requirement for a management plan). The applicable activity triggers listed in the EIA Regulations are summarised in Appendix A, and the evaluation of the proposed interventions in terms of these triggers is provided in Appendix B.  A more detailed description of the impacts of these measures, along with a description of where and when the various methods are used in different types of watercourse, is provided in Section 4.2 and Appendix C, which should be read together.

4.1.1 Thresholds The significance of impacts cannot be evaluated with any meaning without an understanding of the scale of the proposed activity. This application is unique in that it includes a wide range of types of activities, and that the scale of these activities will vary from location to location. For example, the intervention “erosion control” could include construction of gabions on a river bank to prevent erosion, but the extent of the gabion works may vary significantly from site to site. The table below presents the likely range of scales of these interventions, based on historical knowledge of interventions undertaken by CCT in the past.

5Many of the activities undertaken as a part of stormwater management (e.g. removal of alien aquatic vegetation) do not trigger the EIA regulations but are nevertheless included here in the evaluation of (positive and negative) impacts, and addressed in terms of best practices in the EMPr document.

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Table 10: Typical scale of stormwater maintenance / management measures in the CCT.

Maintenance/management Typical Extent No. Intervention sub-type measure (footprint in m2) 1 Vegetation management 1.1.1 Manual removal 1 – 500 m2 1.1. Aquatic (submerged and 1.1.2 Mechanical removal 1 – 10 000 m2 floating) vegetation 2 management 1.1.3 Biocontrol 1 – 10 000 m 1.1.4 Chemical control 1 – 10 000 m2 1.1.5 Manipulation of water levels 1 – 5000 m2 1.2. Reedbed and indigenous 1.2.1 Manual removal 1 – 500 m2 emergent vegetation 1.2.2 Mechanical removal 1 – 1000 m2 management 1.2.3 Chemical control 1 – 10 000 m2 1.2.4 Burning 1 – 100 000 m2 1.2.5 Manipulation of water levels 1 – 5000 m2 1.3.Riparian / marginal 1.3.1 Manual removal 1 – 500 m2 vegetation management 1.3.2 Mechanical removal 1 – 1000 m2 1.3.3 Biocontrol, 1 – 5000 m2 1.3.4 Chemical control 1 – 5000 m2 1.3.5 Burning 1 – 5000 m2 2 Erosion control 2.1 River channel profile enhancement 1 – 2000 m2 2.2 Construction, maintenance and expansion of erosion 1 – 400 m2 control structures 3 3.1 Construction, maintenance and expansion of sediment Sediment Management 1 – 500 m2 traps/retention areas 3.2 Manual/mechanical sediment removal from sediment 1 – 500 m2 traps/retention areas 3.3 Manual/mechanical sediment removal from canals, 1 – 10 000 m2 channels and waterbodies 4.1 Conversion of an open channel to an enclosed pipe / 4 Channel Enclosure 1 – 1000 m2 culvert system 5.1 Litter and debris removal using either mechanical or 5 Litter and debris management 1 – 1000 m2 manual methods

5.2 Removal of structures to reduce water obstruction 1 – 100 m2

5.3 Construction, maintenance and expansion of litter 1 – 1000 m2 management infrastructure Construction, maintenance and 6.1 Stormwater outlets, dam scour valves, headwalls and 6 expansion of minor stormwater 1 – 100 m2 culverts infrastructure 7 Maintenance of attenuation 7.1 Weirs 1 – 50 m2 infrastructure 7.2 Retention / detention ponds and dams registered in terms 1 – 2000 m2 of the National Water Act as dams with a Safety Risk

7.3 Flood protection embankments / berms 1 – 1000 m2 7.4 SUDS facilities 1 – 2000 m2 7.5 Other dams / ponds 1 – 2000 m2 8.1 Construction, maintenance and expansion of footbridges, 8 Recreational access 1 – 200 m2 boardwalks or bird hides

9.1 Breaching: removal of sand bars deposited in mouth 9 Management of river / estuary 9.2 Straightening: redirecting meandering mouth across the 1 – 4000 m2 mouth shortest route directly towards the sea

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4.2 Description of the Impacts of Stormwater Management / Maintenance Measures

The typical stormwater management / maintenance measures, their ecological impacts and the mitigation proposed as the basis for this application, are described below, which should be read in conjunction with the detailed descriptions of these measures in Appendix C. The required mitigation of the impacts differ according to watercourse type and importance category. Appendix D outlines the level of mitigation required depending on the watercourse type and importance. For each stormwater management / maintenance measure, detailed specification of best practice methods is included in Part 2 of the EMPr. The evaluation of these impacts, based on their effects on different watercourse categories of differing ecological importance, and assuming mitigation is in effect, is then presented in Appendix E and summarised in Section 4.4.

4.2.1 Vegetation Management (a) Removal or control of submerged / floating aquatic alien invasive, cosmopolitan or indigenous vegetation All alien invasive aquatic plants, to a greater or lesser extent impact on streams and wetlands by:  promoting stagnation during low flow conditions;  promoting evapotranspiration losses from water surfaces;  forming dense mats (floating macrophytes), which reduce light penetration, reduce oxygen levels, alter water quality, increase detritus loads and contribute to eutrophication;  replacement of indigenous species and loss of biodiversity (e.g. parrot‟s feather replacement of pond weed). Typical floating / submerged alien invasive species that are found in Cape Town‟s watercourses include water hyacinth (Eichhornia crassipes), parrot‟s feather (Myriophyllum aquaticum), kariba weed (Salvinia molesta), water lettuce (Pistia stratiotes) and south American water fern (Azolla filiculoides) Submerged aquatic angiosperms (e.g. pondweed Potamogeton pectinatus and water hornwort Ceratophyllum demersum) are important feeding and rearing habitats for water birds, fish, and many other organisms, for example zooplankton. Although rooted, these hydrophytes absorb a greater proportion of their nutrient requirements from the water column than from the bottom substratum. Potamogeton also increases water clarity and oxygenates the water, producing excellent habitat for a range of invertebrate taxa. Removal of this plant is largely undertaken to enhance recreational access to waterbodies e.g. boating and swimming.

(i) Positive ecological impacts

i. The ongoing eradication or control of aquatic alien vegetation has a potentially highly positive impact on ecosystem function, through removing the stresses on water and habitat quality. ii. Selective or controlled removal of indigenous submerged aquatic vegetation (Potamogeton) may contribute to improved water quality as the nutrients taken from the water column are stored in biomass.

(ii) Negative impacts

i. Damage to riparian vegetation through stockpiling of material too close or on the bank. ii. Damage to riparian vegetation from heavy machinery access points may leave banks bare, increasing erosion potential.

Appendix J. Technical Assessment Report Page 35

iii. Chemical sprays on floating plants enter the water column and depending on the chemical can be harmful to non-target species of plants and animals. iv. Dead material left rotting within the waterbody after chemical spraying will reduce water quality, through a reduction in oxygen from biological breakdown of the organic load. v. A major social problem in some areas is associated with the smell of rotting plant matter piled along the banks as it dries out – this drying out period is a necessary step in the removal of the material. vi. Mechanical removal results in fragmentation of plants, e.g., Parrot‟s feather, Myriophyllum. Plant fragments may easily regrow or be carried downstream to create new infestations. vii. Disturbance of river bed sediments during excavation of vegetation (especially by mechanical means) causes nutrient release and can promote rapid re-growth of the plants. viii. Loss of cover for aquatic species e.g. fish, frogs, may cause increased predation. ix. Loss of Potamogeton habitat in particular for invertebrate life. The Zandvlei estuary has a Pondweed Management Plan supported by a technical working group convened in terms of the Zandvlei Estuary Management Forum. This plan provides guidance on balancing pondweed removal for recreational purposes with ecological benefits of maintaining healthy pondweed beds. x. Water-level manipulation (draw-down) to control alien aquatic vegetation, although only possible in the case of reservoirs, man-made lakes, and regulated rivers, will result in stranded rotting biomass, may have other implications for water quality, and also may have downstream implications as a result of flow modification. xi. Disturbance of river bed sediments and resulting increased turbidity is the most common cause of a reduction in Potamogeton. Knock-on impacts include a reduction in zooplankton grazers from habitat loss, elevated nutrients, an increase in the biomass of phytoplankton and the possibility of algal blooms which further decreases water clarity and inhibits Potamogeton. This chain of events is the common reason for the absence of Potamogeton from many from wetlands and watercourses. Furthermore, disturbed sediment can degrade fish habitat for the medium term e.g. fish eggs laid on gravel can be smothered by sediment.

(iii) Mitigation

The bulk of the negative impacts of aquatic alien vegetation removal stem from the manner rather than the fact of its removal, particularly the use of mechanical versus manual methods. In some systems, e.g. those with low biodiversity value or no natural riparian zones, the significance of the removal processes is low, although access routes may harm adjacent ecosystems. Elsewhere, restrictions on the removal practices can effectively mitigate many of the impacts. For example, manual removal of aquatic weeds has far less impact on the structure of the channel bottom than mechanical means, and the deployment of a loader with a long boom to retrieve the collected material as it is brought close to the bank would minimise riparian degradation / bank erosion. Special attention should be paid to access routes for all systems being cleared of aquatic weeds.6 These should be located at right angles to the channel, especially when working in a valley bottom or floodplain wetland, or to minimise the footprint when working in a depressional wetland with a wide littoral fringe (e.g. Princess Vlei). Access routes must ensure that drainage patterns are not altered, in particular during high flows and that culverts of adequate size are installed in any permanent access route. Details and guidance on these mitigation measures and restrictions are provided in Table D1, Appendix D depending on the watercourse type and importance. Detailed information regarding aquatic alien removal is addressed in the EMPr (City of Cape Town, 2013).

6Many sites requiring vegetation removal are not visited frequently enough because of access constraints, where track machines are unable to cross the marshy terrain of floodplain / valley bottom wetlands in systems like the Kuils River floodplain, indicating the real need to attend to the detail of access in planning maintenance tasks.

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In addition, mitigation of impacts in areas where manual removal is exercised can be achieved through more frequent maintenance of clear conditions following the initial removal of floating mats, using work teams dedicated for this purpose. This approach not only maximises ecosystem benefits but also provides employment, for example though the use of EPWP personnel. It is not cost effective or supportive of personnel morale to wait until the water surface of a river has all but disappeared beneath water hyacinth before initiating removal. Biocontrol is preferred where these agents can be effectively introduced. Finally, maximum periods for stockpiling of material should pertain to all works, to minimize the impacts associated with piles of rotting vegetation. This should be a maximum of two weeks irrespective of the ecological importance of the system. Removal of indigenous aquatic vegetation such as indigenous water lilies requires planning appropriate to the specific characteristics of the target watercourse. The “CCT Environmental Team” (see Definitions list) will advise and provide planning guidance in such cases. (b) Removal or control of indigenous reedbed and emergent vegetation Emergent vegetation like reeds, but also including sedges, restios, and grasses is most often limited to the margins of fast-flowing rivers, but in channelled valley bottom wetlands and low- gradient artificial or altered channels reedbeds may extend across the channel. Many detention ponds and several of the highly altered waterbodies such as Zeekoevlei, Princessvlei, Rondevlei etc are vegetated with reeds, either intentionally or as a result of invasion. In the rivers of the CCT nutrient enrichment is an almost inevitable consequence of their use as stormwater conduits. The inevitable consequences of eutrophication are that plants grow better, faster and often become larger, clogging river channels, exacerbating sediment deposition and hampering the passage of floodwaters. In many systems therefore, removal of the vegetation (and the deposited sediments – see section 4.2.3) is required:  to increase conveyance capacity or retention volume for stormwater management;  occasionally only at culvert inlets / outlets to prevent their acting as bottlenecks to the movement of flood waters;  to improve biodiversity value.

(i) Positive ecological impacts

i. Management of reeds like Typha capensis in wetlands improves floral biodiversity and wetland structure in instances where it allows for re-establishment of a more diverse habitat and flora7. The biodiversity benefits of reedbed management include:  To slow, or reverse, the natural succession of reedbeds to scrub and woodland , primarily by reducing the rate of plant litter and sediment accumulation, and at the same time stimulating the production of new reed;  To provide ideal conditions for wildlife through the creation of structure, including open, wet habitat, pools, glades, reed edge etc. Many reedbed birds favour „edges‟ or younger, more open reedbeds, either for feeding or breeding. Reed management can create such structural variations. ii. Water quality improvement of stormwater passing through filtration reedbeds and vegetated channels / swales (Typha capensis and Phragmites australis) is maximised by optimal reed management (harvesting or burning of biomass and removal of senescent reed material) which stimulates new shoot formation, retains root function and regenerates the water quality improvement capacity of reedbeds if implemented correctly.

7 Many wetlands in their natural condition support a diversity of vegetation species with a variety of structural forms and densities, thus providing a heterogeneous habitat and diverse faunal community. However, where reed beds are constructed primarily for filtration and water quality amelioration, structural diversity, including topographical heterogeneity is avoided – a uniform bed being desirable. In these circumstances and where nutrient levels are very high, reedbed clearing is not expected to result in the re-establishment of greater diversity because their characteristics favour the re- establishment of the same reed species.

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iii. Prevention of flood damage has not only positive social impacts but also prevents channel degradation through lateral erosion and bank slumping, which occurs often where flood waters bypass stands of dense instream vegetation.

(ii) Negative impacts

i. Indiscriminate and frequent clearing of conservation-worthy vegetated channels and reedbeds destroys habitat and biota:  Mechanical, and manual, disturbance can kill and/or stress animals, such as fish, frogs, small mammals and birds, living in the reedbeds. This is particularly true when maintenance activities coincide with breeding periods.  Recovery from undisturbed areas has been shown to be rapid, and mitigates against the impacts on flora of clearing. However, frequent (e.g. annual) clearing of the full extent of reedbeds reduces the chances of recovery. In a number of instances, complete clearing of channels is unwarranted where conveyance / capacity is adequate, for example where the channel is not likely to become choked with Typha. ii. Negative impacts of burning include the loss of reedbed invertebrates and reduced bird breeding habitat, but this has not been shown to be worse than cutting if the burn is carefully controlled. Burning reed is also known to increase early shoot emergence and density and has been shown to increase plant diversity (see White 2009). iii. Mechanical removal of reeds / emergent vegetation by excavation alters the physical shape of the watercourse and exposes in most instances anoxic sediments underlying the vegetation. iv. Deepening of channels through over-extraction, in an attempt to recover all root material. Deepening is associated with an increased tendency for bank failure because the roots of the remaining vegetation are less and less likely to extend below the failure plane of a radial slide as accretion elevates the bank height. v. Disturbance of the sediments associated with mechanical removal of vegetation and with burning releases nutrients into the water column, thereby promoting re-growth of the vegetation. vi. The stockpiling of reeds and emergent plant material too close to or on the banks of channels or wetland margins causes damage to riparian vegetation. This is exacerbated where anoxic sediments are included with the removed vegetation. vii. Damage to riparian vegetation from heavy machinery access points may leave banks bare. In extreme cases, where machinery traverses the length of the bank, the entire riparian zone may become devoid of vegetation and compacted, leading to erosion and invasion by alien weeds. viii. Denuded banks significantly degrade the riparian zones alongside reedbed rivers, with a loss of the buffering that these provide to instream water quality. ix. Clearing from both banks destroys the corridor that riparian vegetation provides. x. Extensive damage to wetlands is likely during the construction of access routes to the conveyance channel. This may result from:  Placement of fill over wetland / floodplain areas to construct access roads – either as a permanent feature or exacerbated further by excavation of wetland during removal of temporary fill;  Alteration of flow patterns between a channelled section and its adjacent valley- bottom) wetland or floodplain, in the case where access for machinery runs parallel to a channel. xi. Water-level manipulation (draw-down) to control growth of emergent / littoral vegetation, although only possible in the case of reservoirs, man-made lakes, and regulated rivers, may have other implications for water quality, and also may have downstream implications as a result of flow modification. xii. Spillages of hydraulic fluids and or diesel into the rivers from mechanical plant can pollute river and wetland systems, killing resident organisms.

(iii) Mitigation

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Mitigation of these impacts is not possible in all cases, given the overriding need to prevent flooding as a result of choked watercourses. However, restrictions on these activities, through stipulation of appropriate methods, or the preclusion of one or other method, are provided in Table D2, Appendix D, depending on the watercourse type and importance. In addition best practice guidelines in Section 5.2 of the EMPr (City of Cape Town, 2013) should be implemented, including:  Where clearing involves indigenous “non-reedbed” emergent wetland vegetation within a channel or floodplain (i.e. wetland species that are not monospecific stands of Typha capensis and Phragmites australis: typical species may include Schinoplectis littoralis, Bulboschoenus maritimus, Ficinia nodosa, Juncus kraussii, Psoralea spp., Isolepis prolifer, restias etc.), the need for clearing should be confirmed by the CCT Environmental Team. Clearing of indigenous non-reed vegetation should only be allowed where: o There is a real threat of flooding associated with the capacity of the channel relative to the stormwater flows. o There is no alternative to enhance channel capacity, for example widening of the channel (see section 4.2.2 channel profile enhancement)  Clearing of unchannelled portions of reedbed with high conservation importance shall be planned under the guidance of the CCT Environmental Team.  Clearing should take place no more frequently that every two years, to allow for recovery of the disturbed footprint between disturbances.  Clearing should avoid breeding periods of especially birds and amphibians.  A cutting regime that creates different age mosaics of reed with a high degree of reed/water interface should be aimed for, even in reedbeds whose function is primarily filtration and water quality management.  For reedbeds whose function is primarily filtration and water quality management, the maintenance programme should maintain as far as possible an even shallow flow of water across the full extent of the reedbed, to maximise the water-soil-microbial interaction and decrease velocity.  Reed removal from channels should only take place from already channelled watercourses i.e. this application precludes the excavation of conduits for drainage within unchannelled wetlands, including creating new drainage through floodplains. Such an activity would require more detailed and specific ecological assessment and be part of a separate application for authorisation. A maximum 2 week period for stockpiling of material should pertain to all works, irrespective of the ecological importance of the system, to minimize the impacts associated with piles of rotting vegetation. (c) Removal of vegetation from riparian areas and wetland margins Many urban river systems are infested with alien riparian species as a result of past physical disturbances that open up space for the establishment of aliens, such as bank clearing and channel modification, infilling and fires. These include the woody species such as Acacia spp. Sesbania punicea, pines and gums, as well as reeds like Arundo donax and herbaceous species like the castor-oil plant Ricinus communis or bugweed, Solanum mauritianum. Woody alien species also establish a toe-hold in the drier (e.g. seasonally saturated) patches of seeps, valley bottom and floodplain wetlands often in response to anthropogenic disturbance. Detention ponds, dams and other depression wetlands used in the stormwater system for the most part are either artificial systems constructed for this purpose or heavily modified naturally-occurring systems: both categories are also prone to the establishment of aliens on disturbed margins and the gradual creep of these over the drier area of the depression. Removal of dense riparian / marginal vegetation is required:  to increase conveyance capacity or retention volume for stormwater management;  in artificial, grassed dry detention ponds, to facilitate recreational use;

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 for aesthetic requirements (neatness) in terms of the requirements of the Alien and Invasive Species Regulations of the National Environmental Management: Biodiversity Act, 2004 (Act No.10 of 2004);  from areas where dense vegetation has been found to pose a serious risk to public safety due to vagrants or criminals using the vegetation for cover;  most vegetation, including indigenous species, with the possible exception of low grasses is removed from dam walls to ensure structural integrity of the wall and public safety.

(i) Positive ecological impacts

The positive impacts associated with the permanent removal of woody and herbaceous alien species from rivers and those that invade the edges of, or drier patches within, wetlands include: i. Improvement in dry-season baseflows in channels because of the high water use by alien woody species, or increased moisture levels in subsurface soils and longer hydroperiod; ii. Improvement in channel geometry: extensive sediment trapped by dense stands of woody vegetation generally has the effect of reducing the channel width and also may raise the height of the river bank relative to the water table. Channel narrowing results in reduced channel capacity and more frequent over-bank flooding, whilst channel deepening is associated with an increased tendency for bank failure because the roots are less and less likely to extend below the failure plane of a radial slide as accretion elevates the bank height. Woody riparian vegetation in headwaters in largely open- canopied headwater streams could lead to local channel widening associated with lateral erosion of the channel banks. iii. Improved biodiversity value: Many alien species are competitively superior to their indigenous counterparts in many aspects, particularly through:  their ability to tap groundwater resources more efficiently than indigenous vegetation, often leading to “droughting” of seasonal wetlands and loss of flora;  the release of allelopathic substances which impair the growth rate or survival of indigenous vegetation;  their ability to grow rapidly and proliferate, which is often implicated as the major mechanisms for competitive displacement of indigenous plants by aliens - for example vegetative post-flood establishment of Arundo donax from rhizome and stem fragments;  shading by aliens is also likely to inhibit many indigenous riparian or wetland plant species;  and finally, different fire regimes associated with alien as opposed to indigenous riparian vegetation have been associated indirectly with broad changes in riparian community structure. iv. Reduction in nutrients: Acacia spp. with their high nitrogen concentrations have been shown to contribute significantly to the natural level of nitrate concentrations in groundwater that supports ephemeral wetlands on the west coast.

(ii) Negative impacts

i. Lateral erosion as a result of felled woody debris not being removed from the channel, and / or bank erosion as a result of slope clearing without replanting or stabilization. ii. Loss of bank stability, with the result that wash-aways and other erosion occur more frequently than would be the case if banks were vegetated with indigenous species. iii. Loss of habitat where felled vegetation is stockpiled within a wetland. iv. Short-medium term increase in in-stream sediment transport as accumulated sediments associated with dense invasions on channel features such as the channel shelf or channel bars, are exposed to the natural disturbance forces of floods (mid reaches).

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v. Disturbance as a result of access roads or paths and camps, especially in densely vegetated wetlands where alien species are interspersed among natural plants vi. Impacts associated with burning stockpiled vegetation, chiefly heat scars that re- vegetate slowly and are prone to erosion. vii. Indiscriminate removal of vegetation, when the most likely recolonizing species will be invasive, will reduce biodiversity value. viii. In many instances the removal of vegetation may serve only to ensure some subjectively-defined aesthetic or public safety purpose, i.e. where it does not contribute to biodiversity or where there is no capacity / conveyance requirement to be met by clearing. There are numerous examples of this category of stormwater management action, often with dubious merit as to the strategic use of resources. For example the margins of many detention ponds are left barren through indiscriminate clearing, which further promotes the regrowth of weeds. Other examples include the mowing of all vegetation to the edge of the watercourse, preventing the establishment of a natural riparian corridor, which, even in somewhat degraded systems, has ecological value.

(iii) Mitigation

In many systems the re-establishment of natural riparian vegetation requires a greater level of input than simply removing alien invasive plants on an annual basis. In densely infested areas with little remaining natural vegetation, stabilisation of one or both slopes and an indigenous replanting programme may be required to realise the gains of alien clearing. Thus the positive impacts for ecosystem function are only significant where combined with an intentional biodiversity improvement programme on systems selected for their importance. In waterbodies of lower biodiversity importance the control of woody alien vegetation is more strategically geared to ensuring conveyance capacity, and the ecological benefits are not primary. Best practice guidelines for the removal of alien vegetation have received considerable attention from the Working for Water / Working for Wetlands programmes. These form the basis of the methods compiled in Section 5 of the EMPr (City of Cape Town, 2013), and should be followed in all the watercourses within the City of Cape Town, with the exception of artificial systems and those of very low importance, where investing these rehabilitation aspects would provide insufficient ecological benefit to warrant the resource allocation. Where removal of vegetation is undertaken for recreational or aesthetic motives, the following guidelines should apply:  Recreational use of dry detention areas (i.e. during summer) may be facilitated by design of the low-flow portion of the pond being routed to the side of the used area that best facilitates the desired use (e.g. playing field vs. play-park with equipment). The low-flow channel could comprise grass blocks for easy maintenance and infiltration where feasible in local soil conditions. The low-flow channel should remain un-mowed and the establishment of short indigenous species (e.g. sedges) should be promoted. This may be permanently wet, depending on the catchment characteristics, and could enhance recreation (play-park) uses. These low flow design considerations may be retrofitted to existing detention areas.  Mowing of green open space adjacent to stream channels must preclude any mowing in the riparian zone, to encourage both the buffering of stream water by riparian vegetation and the establishment of a corridor function. Manual cutting of tall vegetation is acceptable where this constitutes a safety hazard.

Where clearing involves indigenous riparian or marginal vegetation, the need for clearing should be confirmed by the CCT Environmental Team. Clearing of indigenous non-reed vegetation should only be allowed where:  There is a real threat of flooding associated with the capacity of the channel relative to the stormwater flows.  There is no alternative to enhance channel capacity, for example widening of the channel (see section 4.2.2(a) channel profile enhancement).

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4.2.2 Erosion Control Erosion is one of the most common problems affecting the stability of rivers and other water courses within urban areas. Erosion is a natural process, which plays an important role in determining the characteristics of different reaches of a river system. Steep gradients and faster flows will result in high rates of erosion leading to bedrock or boulder habitats, while those reaches experiencing less erosion are characterised by smaller particles – cobbles, to sands and muds. These smaller particles may be carried downstream from the more erosive upper reaches and deposited in less erosive reaches downstream. Erosion of river beds is also a natural process that allows the lateral movement of rivers across their floodplains. Where landscapes are highly developed, however, substantial increases in erosion can become a serious problem. This is usually as a result of one or more of the following impacts:  catchment hardening, resulting in increased rates of runoff and higher peak flood flows;  concentration of flows, as a result of point source inlets, catchment hardening, channel narrowing;  constriction of the river channel – this results in faster flow, through a confined channel, rather than overtopping of flows into a broader flood channel or floodplain. In urban areas, development encroaches into the macrochannel of most rivers, precluding the natural lateral movement of a river across its floodplain. Severe alien infestation can also have this effect;  loss of the protective fringe of riparian vegetation along river courses – this vegetation plays a role in controlling bank stability;  diversion of rivers from their natural courses, resulting in changes to natural vertical gradients;  interference with natural river bed and bank profiles – for example, canalisation of sections of rivers speeds up the flow of water entering downstream reaches, making them vulnerable to erosion;  barriers to flow (e.g. bridges, pipes across rivers, but also dumping and severe littering).

All of the streams passing through the urban areas of the City of Cape Town are subjected to most, if not all, of the above conditions. Given the impracticality of reversing many of these impacts once development has already taken place, addressing their symptoms – i.e. erosion – is a reality of the management of urban rivers. Not only does erosion result in instability in the eroding area, but it frequently also contributes to sedimentation of downstream reaches, resulting in the on-going need for costly and often environmentally damaging, removal of sediment. For the purposes of this application, erosion control measures fall into two categories:  channel profile enhancement  installation of erosion control structures

(a) River channel profile enhancement This refers to the physical alteration of one or more reaches of a river in order to accommodate the flows routed through them in a manner that increases or restores some of the natural functions of the ecosystem, chiefly re-shaping and the addition of roughness elements to reduce runoff rates and limit erosion. The measures may include inter alia:  channel bed widening and / or roughening,  conversion of concrete-lined channels to rock / earth channels with concomitant re- shaping,  installation of snags,  creation of meanders, braids or bars,  installation of cross gabions to reduce longitudinal gradients,

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 flattening and sculpting of banks to reduce erosion and increase structural habitat diversity, and  planting with appropriate instream and / or riparian vegetation. In valley-bottom and other channelled wetlands, this approach may extend beyond the channel to adjacent wetland shaping to maximize the natural features whilst redressing erosion gullies and the like.

(i) Positive ecological impacts

i. Channel profile enhancement is chiefly a rehabilitative approach to dealing with erosion, aimed at restoring habitat, notwithstanding the need to accommodate alterations in the natural hydrology of the target systems. Positive impacts include increased habitat diversity, riparian – instream connectivity, corridor integrity, and reduced erosion or sedimentation.

(ii) Negative impacts

i. There may be a short- term increase in in-stream sediment transport or deposition (depending on the position along the river of the intervention), as the system adjusts to a new equilibrium. ii. The measures that may be used in conjunction with channel profile enhancement could include erosion control structures (b below) - different options having different benefits and drawbacks.

(iii) Mitigation

No mitigation is warranted. However, channel profile enhancement is an activity that requires technical input by specialist freshwater ecologists and engineers. The CCT Environmental Team will provide these inputs. This approach is fairly limited in application, as it presupposes both the availability of space laterally to be incorporated into the channel and riparian area, as well as the budget to undertake the extra measures aimed at improving function, rather than the narrow focus on controlling erosion.

(b) Construction, maintenance and expansion of Erosion Control Structures This refers to measures to address specific points of bed or bank erosion or gulley formation. The typical location of these erosion points are:  Pipe outlets, culverts, weirs, bridges and pipe crossings  Areas of overland / sheet flow  Outsides of river bends  Interface between lined and unlined reaches  Interface between natural hard river inverts and soft inverts  Incised channels / rivers with in-filled macrochannels

(i) Positive ecological impacts

i. Where no other options are available due to space or other physical / geomorphological constraints, these measures assist in preventing the spread of erosion from localised nick-points and consequent loss of habitat and downstream siltation.

(ii) Negative impacts

i. All built erosion control measures result in the loss of riparian or instream habitat and its replacement with hard structures. Whilst a highly localised impact, the size or number of these along a reach may result in significant loss of function, and where the gabion portion of river bank comprises a significant portion of the channel, this effectively

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amounts to “canalisation” of the reach. The following impacts may be significant where the structures are extensive within a reach:  Loss of riparian vegetation and lateral connectivity.  Increased insulation and warming.  Loss of instream / wetland emergent vegetation: cavity sizes in reno mattresses / gabions may not provide sufficient space for root ball formation of some aquatic plants. ii. Construction-related impacts, such as water quality impacts associated with cement works or washing of construction tools / vehicles; disturbance of sediments and downstream sedimentation

(iii) Mitigation

Mitigation of negative impacts lies in the choice of structure, although this is at times constrained by the severity of the erosion problem that dictates specific engineering solutions. For example:  rock-pile weirs should be selected where possible over gabion weirs as they provide better habitat; gabions are in turn better than mass concrete weirs;  rip rap against channel banks provides for stability with cavities for establishment of riparian vegetation if constructed correctly;  all-bank gabions must be constructed with at least a low-level step (see figure below) to facilitate establishment of wetbank vegetation. Coir-mat lining and filling of voids between rocks with topsoil, or the use of “green gabions”, will improve establishment of vegetation and can provide a degree of riparian function. Vertical gabions should be avoided.  Reinforced bank and channel floor sections should not be constructed from mass concrete.

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Figure 5: Top photo: Stepped bank gabion with low-level step for vegetation establishment spread with loose topsoil. Colonisation of the low step by plants will occur but can be promoted by planting. Bottom photo: coir mat- lined gabions with topsoil added to fill the 30 – 40% voids between rockfill promotes vegetation by retaining moisture and soil (note live plant cuttings inserted into face of gabion).

The merits of different approaches are detailed in CSRM 2003 Ecological Guidelines for River / Wetland Upgrading Projects, and this information has been incorporated into the EMPr that accompanies this application. To ensure appropriate mitigation, the erosion control structures should be planned with the guidance and expertise of the Roads and Stormwater Department‟s engineers and with the support of the CCT Environmental Team. Table D3, Appendix D indicates some of the cautionary restrictions applicable to the installation of erosion control structures in watercourses of various types and importance. In Medium and High Importance rivers the installation of reinforced bed and bank sections should only be allowed where:  There is a direct threat to built infrastructure (i.e. excluding gardens and open space areas) from flooding.  There is no alternative to enhance channel capacity, for example widening of the channel (see section 4.2.2(a) channel profile enhancement).

4.2.3 Sediment Management In developed catchments larger than natural quantities of sediment (including clays, silt and soil)are washed into the rivers from unstable areas in the catchment, such as construction sites, agricultural areas or newly-burnt lands. The gradient of many of the man-made canals and the lowland rivers of the CCT is extremely shallow, with the result that this sediment settles out, reducing the depth of the river channels and providing an ideal substrate for plants, thereby reducing the carrying capacity of the channels. Removal of sediment from certain channels is required to maintain conveyance capacity and thus to prevent overbank flooding and bank erosion. Removal of sediment from structures such as culverts which become blocked is also necessary. Excavation is either done from the banks, or by operating within the channel, and manually or by machine, depending on the scale of the problem, the depth of the river, and the conservation importance of the system.

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Descriptions of the mechanical plant used are provided in the EMPr (City of Cape Town, 2013) which examines the pros and cons of different machinery. Manual removal of sediment has extremely limited application compared with mechanical means, because of the significant labour effort required. However, three central approaches to (mostly mechanical) sediment management are differentiated in this impact assessment:  Continuous removal of sediments along a river reach, which is a consequence of heavy sediment deposition and shallow gradients;  Removal of sediments from formally constructed sediment traps or designated restricted areas where sediment accumulation is identified;  Removal of sediment, often with associated reeds or other vegetation, from inlet and outlets of culverts, pipes, points where canals enter detention ponds etc.

(a) Construction, maintenance and expansion of sediment traps / retention areas Any depression, swale, low-lying area, or flattened river reach that receives sediment-laden flows from exposed soil or unstable catchment areas can serve as a sediment trap site, by virtue of the fact that sediment deposition will occur there. In the City of Cape Town, different sorts of sediment traps have been designed and / or constructed, for example:  Brookwood Stream, Noordhoek: an example of a series of in-channel earth ponds constructed along an engineered cobble channel, each node located at a bend in the channel. Access for sediment removal is conveniently on the “elbow” of each river bend, allowing space for temporary stockpiling of sediment.  Many of the sediment removal areas are, similarly, located along concrete canalised sections of watercourses.  Many of the numerous detention ponds require regular cleaning of accumulated sediments to fulfil their attenuation role.  Many of the sediment removal areas are little more than a designated portion of river or waterbody (vlei) where sediment accumulates. Often these are naturally wider sections, or inevitably become wider or deeper, as a result of the excavation of sediments, or need to construct access.

The construction of new traps, upgrading of existing structures, or designation and / or modification of river reaches and inlets on channels and waterbodies is part of this application and assessed below.

(i) Positive ecological impacts

i. Sediment traps situated in appropriate positions along the longitudinal profile of a river have a “positive” impact insofar as they minimize the negative impact of anthropogenically-increased sediment loads being deposited along the full river course. ii. Sediments that are contaminated or heavily enriched with nutrients can contribute to eutrophication of waterbodies, especially in shallow lakes and vleis. Under these conditions, removal of sediment can improve water quality.

(ii) Negative impacts

i. Short-term negative impacts of the installation / construction of sediment traps include: disturbance of bed sediment and water pollution during construction (e.g. washing of vehicles, cement work). ii. Longer term impacts are associated with the loss of stream habitat and potentially riparian wetlands, depending on the size and location of the sediment trap. These impacts are permanent and could be of high significance, but can be mitigated by the appropriate choice of location and design. iii. Where sediment traps are located on channelled valley bottom or floodplains, such that access to the trap is over the wetland, impacts include the damage to riparian and lateral wetland areas by vehicular access tracks or roads; compaction and dredging; and

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diversion of natural flow or seepage pathways as a result of the construction of access to the site. iv. Depending on the sediment load and discharge in a system, the footprint of a sediment trap may result in a loss of habitat. This impact however, is considered to be on a local scale, especially when evaluated against the need to address erosion and deposition: sediment traps are only required where an unnatural sediment load is carried by the river, which itself would constitute an existing impact on natural processes.

(iii) Mitigation

Basic site management and good design and construction planning identified could provide effective mitigation of impacts, with the benefit that an effective sediment trap or designated sediment retention area will protect other portions of river channels. As a minimum the following should apply:  The need and desirability for a sediment trap versus simply utilising designated sediment retention areas for removal of deposited load should be evaluated by the CCT Environmental Team.  Design options for sediment removal should be evaluated against the nature of the problem. A plethora of information is available on the design of small and large traps, some of which suggests:  A well-designed sediment trap is ultimately preferable to ongoing excavation of sediment from waterbodies, albeit more costly in the short-term.  Installing several small traps at strategic locations is often better than building one large basin.  Designing traps with long flow paths between the inlet and outlet also helps to increase sediment removal efficiency by extending the detention time which facilitates settling of sediment particles.  Where space restrictions preclude design of long basin, barriers placed in the trap can lengthen detention times by creating a serpentine flow path between the inlet and outlet.  Sediment removal strategies should be balanced by examining catchment management practices that can address erosion and sediment mobilisation at source.  The most important consideration for any sediment retention / removal structure is its location along the watercourse. Planners should aim to locate sediment traps upstream of valley bottom and floodplain areas, so that a) access impacts are minimised and b) these wetland types are protected from sediment. The downstream end of the sediment retention area may be demarcated with a low gabion weir.  Constructed sediment traps require engineering and ecological input and should be undertaken by appropriately qualified and experienced staff in both of these fields.  In waterbodies with a medium or high importance ranking, the proposed location of sediment traps should be planned under the guidance of the CCT Environmental Team.  Access routes8 should be located at right angles to the channel, especially if locating a sediment trap in a valley bottom or floodplain channel is unavoidable. Access routes must ensure that drainage patterns are not altered, in particular during high flows and that culverts of adequate size are installed in any permanent access route.

8Many sites requiring sediment removal are not visited frequently enough because of access constraints, where track machines are unable to cross the marshy terrain of floodplain / valley bottom wetlands in systems like the Kuils River floodplain, indicating the need to attend to the detail of access in planning maintenance tasks.

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 An alternative, depending on the frequency with which sediment traps are cleared, is the compilation of a standard operating procedure regarding the placement of fill for a temporary access route to the site. Such a procedure would include:  Utilising clean fill material  Maintaining pre-construction ground levels when material is removed from site  Appropriate disposal of the fill  Stabilisation of the disturbed ground surface to prevent erosion, or the establishment of alien / weedy species.

(b) Removal of sediment from sediment traps and designated sediment retention areas

(i) Positive ecological impacts (see above).

(ii) Negative impacts

i. Disturbed / re-suspended sediments and associated nutrient / organic loads (and plants) can be transported to downstream reaches during cleaning of sediment traps, possibly resulting in smothering of habitat and animals, and reducing light penetration and oxygen availability. ii. The operation of heavy plant in and around rivers crushes vegetation and animals, and in some cases creates a permanent „disturbance‟ footprint along the banks of the rivers and adjacent wetlands.

(iii) Mitigation

Given the limited footprint represented by dedicated retention areas / sediment traps, the impacts will be relatively restricted in extent. Mitigation is possible through inter alia the following:  Best practices included in the EMPr (City of Cape Town, 2013) should be followed, regarding the timing of sediment removal, planning and demarcating of access routes, identification of any sensitive features to be avoided and reinstatement.  A maximum two week maximum period for stockpiling of sediment should pertain to all works in all systems irrespective of ecological importance, so as to minimize the impacts associated with piles of anoxic sediments. In low importance systems, a three- week maximum stockpile duration is deemed appropriate.  Sediment traps should either have a solid base layer that indicates the level to which excavation should be undertaken, or in less formal designated retention / deposition areas, a set of four permanent, marked stakes could be installed to indicate the correct excavation level.

(c) Manual / mechanical sediment removal from canals, channels and waterbodies

(i) Negative impacts

i. The practice of excavating a watercourse along much of its full length represents a potentially severe impact, if undertaken on watercourses of medium or high importance, and with regularity (e.g. annually). This could potentially constitute a near- permanent loss of habitat and biota, through physical disturbance, smothering of substrata, loss of instream plant diversity and structural elements. This impact is reduced to low levels on canals and other artificial drains, since ecosystem function in these is already severely compromised. ii. Damage to riparian vegetation and bank stability may occur from numerous heavy machinery access points down the bank, stockpiles, truck turning circles and banks that may be left bare. In extreme cases, where machinery traverses the length of the bank, the entire riparian zone may become devoid of vegetation and compacted, leading to erosion and invasion by alien weeds.

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iii. Deepening of channels through over-extraction is a significant threat, as long stretches are bulldozed or excavated, without reference levels. Deepening is associated with an increased tendency for bank failure because the roots of the remaining vegetation are less and less likely to extend below the failure plane of a radial slide as accretion elevates the bank height. Deepening of channels or watercourses adjacent to wetlands can also result in a lowering of the water table which may affect wetland functioning. iv. Extensive damage to wetlands is likely during the construction of access routes to the channel clearing area, through a wetland (e.g. valley-bottom) or floodplain by:  Placement of fill over wetland / floodplain areas to construct access roads – either as a permanent feature or exacerbated further by excavation of wetland during removal of temporary fill;  Alteration of flow patterns between a channelled section and its adjacent valley-bottom) wetland or floodplain, in the case where access for machinery runs parallel to a channel.

(ii) Mitigation

Mitigation of these impacts is not required on watercourses designated as low importance. However, in systems of a medium or high importance ranking, no mitigation is possible and the approach of large-scale and indiscriminate sediment removal is regarded as having a potentially high negative significance. Instead, designated sediment retention areas should be identified or sediment traps could be retrofitted at suitable locations (see section 4.2.3 (b and c) below).

4.2.4 Channel Enclosure (a) Conversion of an open channel to an enclosed pipe / culvert system This measure is specific to the enclosing of stormwater channels / swales in high-density urban areas that are subject to extreme levels of pollution due to disposal of liquid and solid waste (often human sewage) into these open systems. This management action would only be contemplated in some engineered, wholly artificial stormwater channels draining high-density urban areas where pollution loads are high, as part of a pollution risk management strategy. Impacts are described only for the above scenario.

(i) Positive ecological impacts

i. The action would have positive consequences for the downstream receiving ecosystem, compared with open channels that are used as waste disposal conduits. Risks to public health in the immediate vicinity can also be minimised through this intervention.

(ii) Negative impacts

i. In theory the conversion of an open, earth channel to a concrete pipe represents a loss of aquatic habitat. However, the circumstances envisaged for this measure are such that all ecological function would already have been lost in these systems and further they represent a water quality threat to downstream reaches.

(iii) Mitigation

Mitigation is not required. However, the CCT Environmental Team is required to confirm the ecological state, and review water quality data collected in support of any system contemplated for closure.

4.2.5 Litter and Debris Management Litter and other debris are introduced into waterbodies by rain and wind or as a result of dumping. The accumulation of particulate litter in sediment traps is of such an order of magnitude that in some areas it poses a risk to hydraulic conveyance and is consequently a flooding threat. Elsewhere, dumping of rubble and the remains of long-demolished structures

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like pedestrian culverts or weirs constrict channels already burdened with unnaturally high flood volumes. A central component of the stormwater management undertaken by CCT is the removal of this material. A great deal of litter is trapped on natural snags in rough channels, making manual clearing the only realistic option. The progressive construction of new litter traps on badly affected systems is thus also part of this routine channel maintenance strategy.

(a) Litter and debris removal

(i) Positive ecological impacts

i. Removal of litter represents a positive ecological impact on the affected watercourses through the removal of pollutants (some litter is relatively inert, e.g. plastic bottles, but much of what enters the stormwater system comprises domestic organic waste such as nappies, food remains etc.). ii. At high densities litter smothers the substratum and retards flow and aeration, inhibiting oxygen levels in the surface sediments.

(ii) Negative impacts

i. Negative impacts may be associated with redistribution of litter downstream if it is not timeously removed. ii. Permanent damage to bankside vegetation / banks at the site where litter is hauled out of the waterbody and stockpiled is likely in systems where removal is frequent.

(iii) Mitigation

Options for the organisation of effective litter removal teams are presented in Section 9 of the EMPr (City of Cape Town, 2013), including community-level clearing, based on the experiences of CCT personnel. Installation of floating booms to ensure litter collection can take place at convenient isolated locations rather than along extended reaches of the watercourse.

(b) Removal of structures to reduce water obstruction This refers to removal of existing built structures (e.g. disused weirs) or features (e.g. rubble weirs, trash wires) that are deemed to prevent the flow of water and create an erosion or ecological risk.

(i) Positive ecological impacts

i. Removal of an erosion threat or a structure that is causing erosion in downstream reaches will improve ecological integrity.

(ii) Negative impacts

i. Localised, short-term negative impacts in the form of elevated suspended sediments are possible during removal of the obstruction. ii. If the bank supporting the structure is not reshaped / planted, this could result in an erosion nick-point.

(iii) Mitigation

Best practice for the reinstatement and planting of channel or wetland margins after clearing should be followed as per the EMPr (City of Cape Town, 2013), depending on the type and importance of waterbody.

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(c) Construction, maintenance or expansion of litter management infrastructure This refers to the construction of litter removal infrastructure such as litter traps, floating booms or screens for the purpose of removing litter from the watercourse.

(i) Positive ecological impacts

i. The ability to collect litter in designated areas will minimize both the impact of litter in channels and wetlands, as well as the disturbance from workers walking the channels to collect widely-spread litter.

(ii) Negative impacts

i. Localised, short-term construction-related impacts, such as water quality impacts associated with cement works or washing of construction tools / vehicles; disturbance of sediments and downstream sedimentation

(iii) Mitigation

Basic construction management best practices outlined in Section 10 the EMPr (City of Cape Town, 2013) will provide effective mitigation of negative impacts. Operational controls should include defining dedicated access points to the litter trap to ensure the footprint and impact is localised.

4.2.6 Construction Maintenance and Expansion of Minor Stormwater Infrastructure The network of stormwater management facilities within CCT includes a number of built structures such as headwalls, inlet and outlet structures, culverts, canals, gabions and weirs which facilitate the conveyance of water and minimise erosion. Regular evaluation of the integrity and repair work where required, is necessary to maintain the functionality of the stormwater system. In some cases changes in catchment hydrology or sediment loads requires the installation of a new works, such as additional or larger culverts, or drainage conduits from new developments.

(i) Positive ecological impacts

i. Given the integration of stormwater management and natural systems, maintaining the functionality and where necessary increasing the conveyance within the network will prevent failure, which could result in significant impacts associated with erosion and deposition in natural waterbodies downstream.

(ii) Negative impacts

i. Localised, short-term construction-related impacts, such as water quality impacts associated with cement works or washing of construction tools / vehicles; disturbance of sediments and downstream sedimentation are possible during both construction of new and repair of existing structures.

(iii) Mitigation

Basic construction management best practices outlines in Section 10 of the EMPr (City of Cape Town, 2013) will provide effective mitigation of negative impacts.

4.2.7 Maintenance of Attenuation Infrastructure These stormwater management measures include weirs, flood protection embankments; Sustainable Urban Drainage Systems (e.g. constructed wetlands detention / retention facilities, bioretention systems). This application, however, specifically excludes construction of new or expansion of existing structures that will increase the capacity of such structures, which would require a separate study and authorisation application.

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The measures envisaged for the maintenance of this stormwater management infrastructure includes most of the maintenance / management measures already discussed and described, including:  Sediment removal / reshaping of detention ponds and Sustainable Urban Drainage Systems (SUDS);  Vegetation management / removal;  Minor concrete works to repair infrastructure such as inlet / outlet structures on dams, valves, overflow structures, gabions etc.;  Purging of silt from scour valves;  Removal of bird / insect (e.g. termite) nests that may compromise integrity of banks and retaining walls;  Embankment repair may also involve mechanical earth works.

The assessment of the impacts associated with these measures is covered in the assessments in Sections 4.2.1 to 4.2.7. Basic construction management best practices outlines in Section 11 of the EMPr (City of Cape Town, 2013) will provide effective mitigation of negative impacts.

4.2.8 Recreational Access Most of these measures are unlikely to trigger the NEMA impact assessment requirements, because of their limited scale, involving the establishment where required of pedestrian footbridges, boardwalks, paths and crossings.

(i) Positive ecological impacts

i. Infrastructure such as pathways directs pedestrian and light traffic to formalised crossings, thus controlling damage to bed and banks.

(ii) Negative impacts

i. The footprint of the recreational feature represents an, albeit highly localised, loss of habitat for riparian and instream biota. ii. Short-term construction impacts include possible pollution from use of equipment and materials such as concrete.

(iii) Mitigation

Design of recreational features that traverse these waterbodies provides an opportunity for public engagement with the functions of river and wetland ecosystems. Where possible, attributes of the ecosystem that are of value and enhance appreciation of the natural world (e.g. a vista from a boardwalk across bird breeding habitat in a treatment reedbed; seasonal ponding supporting frog spawning) should be incorporated into the layout of access routes in recreational spaces, rather than a “neat and sterile" approach. Options for reduction of construction impacts are presented in Section 12 of the EMPr (City of Cape Town, 2013).

4.2.9 Management of Estuary and River Mouths Stormwater management has to include the point at which flows enter the sea, namely at discharge from stormwater pipes, river mouths and estuarine mouths, in order to deal with contingency situations involving flood risk. If a sandbar forms across the mouth, during periods of high catchment runoff this may result in high water levels backing up behind the sandbar. With additional runoff, “natural” breaching of

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the sandbar by floods is likely to cause unpredictable patterns including long-shore meanders, dune undercutting and the possible lateral flooding of property and infrastructure such as roads, railway lines, water / sanitation reticulation, or buildings. Under such emergency situations, i.e. with the threat of unpredictable flooding and subsequent damage to infrastructure, artificial breaching of the mouth is considered a necessary action to safeguard property as well as important features like buffer dunes. In a slightly different scenario, manipulation of the mouth may also be necessary: e.g. where meanders cause the mouth to run parallel along the beach for extended distances and where infrastructure is subsequently threatened, it may be necessary to redirect the mouth across the shortest route back to the sea and at a location in line with the direction of the main outflow. Finally, sand or rock accumulation may need to be periodically removed from stormwater outlets that traverse the beach. Accumulated material must be removed from these outlets to facilitate the passage of stormwater to the sea, rather than creating pooled areas in the back dunes, upper beach or upstream road infrastructure, particularly given the at-times compromised quality of stormwater. Breaching activities include:  Track-machine access onto the beach, and excavation of a channel to the sea;  Some (limited) dune reconstruction with excavated sand, where erosion has been severe;  Spreading of excavated material in a thin layer over the beach surface.

When breaching an estuary mouth, the following should be observed:  Any approved applicable Estuary Management Plans must be adhered to.  Breaching policy or Mouth Management Plans must be complied with should they exist for the particular estuary in question. These may have been structured to not only reduce the risk of flooding, but also to maximise ecological and recreational value of the estuary.  CCT should regularly engage the Estuary Management Forum (EMF) should one be in existence.

(i) Positive ecological impacts

i. Prevention of loss of landscape features such as buffer or back-dune systems. ii. Protection of residential / municipal infrastructure iii. Improved water quality in estuaries / river mouths.

(ii) Negative impacts

i. Negative impacts may be associated with heavy machinery traversing sensitive dune areas, but are relatively short-lived. ii. Breaching of estuary mouths may prematurely expose juvenile fish to the marine environment, thus preventing them from successfully completing their natural life cycle. Artificial breaching may also make a system less productive and less able to deliver goods and services.

(iii) Mitigation

Mitigation of negative impacts would involve the following:  Estuary mouth breaching must only be undertaken if approved by the CCT Environmental Team.  Mapping access routes to minimise disturbance. In particular any areas of vegetation or dune-slack wetlands should be avoided.  Attention should be given to bird nesting areas and breeding periods in the year, and avoidance of the former if artificial breaching unavoidably coincides with breeding times.

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 Breaching should generally be delayed for as long as possible until the estuary water levels are at a maximum, but without significantly increasing the flood risk.  Where feasible DEA&DP, and any relevant EMF, must be given at least 7 days notice prior to breaching the mouth.  No fishing activities should be allowed at the estuary mouth during breaching or for one week post breaching.  A breached mouth must be inspected by an appropriate CCT employee the day following breaching.  Accurate records must be kept of the mouth opening and closing.

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4.3 Constraints on the Choice of Method for Stormwater Management, in order to Minimise Impacts

Based on the potential negative impacts identified in Section 4.2, the appropriateness of different stormwater management approaches or methods was evaluated for each of the seven groups of watercourses based on similar hydrogeomorphic types (refer to Table 5), and for each of the three of Watercourse Ecological Importance Rankings (refer to Table 6). The result is, for each of the nine stormwater measures explained in 4.2, a table outlining the methods that may or may not be employed in undertaking each management task. These are provided in Appendix D. Key aspects of these restrictions are:  The restriction to manual clearing methods for the removal of vegetation in Medium and High Importance waterbodies. Mechanical methods (floating rafts / weed cutters) to be allowed in deep waters.  Restriction of reedbed and riparian indigenous vegetation removal in Medium and High Importance waterbodies to be allowed only when functional attributes (hydraulic aspects or water quality amelioration) necessitate it; not for “neatness” aesthetic reasons. No other options are possible. Only using manual methods (except in certain situations guided by site-specific Maintenance Plans).  Mechanical removal of sediments in High and Medium Importance systems only from sediment traps and sediment retention areas; installation of sediment traps upstream of High Importance wetlands to protect these systems; alternatively hand work only in these systems.  Restriction on the installation of bank or bed reinforcing in Medium and High Importance rivers to situations where no channel profile enhancement is at all possible and where built infrastructure (not gardens or open space) is directly threatened.  Stipulation of the most ecologically beneficial material to be used in reinforced structures, in Medium / High Importance systems, rather than the most convenient.

Worth highlighting as a key mitigation measure is the compulsory requirement for environmental specialist evaluation and approval. This could be provided by the “CCT Environmental Team” (typically comprising ERM District Staff and/or an Aquatic Ecologist within Stormwater Sustainability branch or an outside specialist), within the guidelines outlined in the mitigation measures, for the following stormwater management measures:  Removal of indigenous vegetation, including riparian, palustrine and submerged aquatic (e.g. Potamogeton) vegetation, except for the clearing of dam embankments and the regular cutting of reedbeds (Typha and Phragmites);  Cutting / clearing of reedbeds in unchannelled portions of valley bottom and floodplain wetlands of High Importance;  Channel profile enhancement, which would only target waterbodies of Medium to High Importance, i.e. where ecological gains are maximised for the expenditure involved in this activity.  Evaluation of the need for, extent of, and alternatives to, erosion control measures such as new gabions, groins etc., particularly where these are extensive (a gabion bank extending > 200 m is effectively canalisation);  The location and retrofitting of sediment traps on Medium and High Importance systems;  Confirmation of the desirability of channel enclosure in the event of high water quality risks.

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 The CCT Environmental Team must communicate with the personnel responsible for sediment removal, clearing of reedbeds and aquatic weeds management teams (e.g. floating alien plants) especially in cases where access to the point of clearing (the actual channel or depression) has to traverse over floodplain or valley bottom wetland vegetation. The communication should ensure that access roads to these waterbodies are properly planned and follow best practice – either as permanent access with appropriate culverts for drainage or as temporary access, constructed according to best practice.

These provisions are important in that they underpin the formal assessment of impacts, as provided in tabular form in Table E1, which is an assessment of residual impacts, assuming that the mitigation as described in Section 4.2 and the EMPr, and the restrictions as envisaged in Tables D1-D4 are implemented.

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4.4 Summary Assessment of the Impacts

Appendix E presents the significance assessment of the potential impacts associated with the seven broad types of stormwater maintenance / management measures identified in this report. This assessment presumes:  That there will be a restriction on the application of certain maintenance measures in certain receiving environments. For example, only manual removal of vegetation should be undertaken in wetlands of high ecological importance (see Appendix D, table D1).  The presented impacts are residual impacts i.e. post mitigation. The following summarises the determined impacts:  Extent: Approximately 85% of all impacts are considered to be site-specific or local impacts (<3km from the site). Approximately10% of impacts are considered regional impacts, and 5% are local – regional. No impacts of “national extent” are anticipated. All “local-regional” and “regional” impacts are positive impacts except for two: the hydrological impacts resulting from incorrectly located access roads (regional impact) and the impact on riparian and wetland margins during alien removal activities cue by access roads or paths.  Magnitude: The negative impacts of highest magnitude are the 8 (eight) Medium magnitude impacts associated with the use of chemical sprays used for the chemical control of alien vegetation and reedbeds such as Typha and possible disturbance to river valley bottoms should access be required. These anticipated impacts are however local. A total of approximately 85% of impacts are of either Local or Local-Medium magnitude.  Duration: The majority of negative impacts, such as those associated with construction or repair of infrastructure are either short term or temporary, while the long-term impacts are generally positive. Permanent negative impacts include those associated with the loss of ecological functioning within the footprints of new erosion control structures, as well as where access requirements may necessitate vegetation removal. These are however very localized impacts. Negative impacts associated with sediment removal (dredging) are generally longer term, because in some cases the frequency (often annual) can be shorter than the period required for recovery.  Status: The majority of the ecological impacts identified in Appendix E are negative impacts. However it should be noted that the very rationale behind the proposed maintenance measures is to improve stormwater water management and ecological functioning of the stormwater systems. Hence there are many positive impacts associated with these maintenance measures, but for the sake of brevity, only the key positive impacts have been listed.  Significance: The significance of the majority (approximately 90%) of the negative impacts are either very low, low or low-medium, and is to be expected considering that this is based on the assumption that the proposed measures will be undertaken as per the best practice guidelines in the EMPr i.e. will include mitigation. The negative impacts considered of “medium” significance are those associated with the use of chemical sprays, and the hydrological impact of incorrectly locating access roads and paths in floodplains. No impacts are considered to be of Medium-High or High significance.

In summary, the very reason for undertaking these maintenance measures is to realize positive hydrological, socio-economic and ecological impacts. None of the residual impacts associated with the proposed maintenance measures are considered to be of high significance and with the strict implementation of the limitations listed in this report and the EMPr, all impacts could be mitigated to acceptable levels.

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5 CONCLUSION

This Technical Assessment Report considers the environmental impacts associated with the undertaking of nine different types of stormwater maintenance and management actions. The following approach was used in considering these impacts:  Define the management actions;  Define the receiving environment. This included defining types and watercourse importance of the different river and wetlands occurring in Cape Town. This was done using GIS with reference to detailed preceding studies.  Assess the significance of the impacts resulting from undertaking the different interventions in different rivers and wetlands. A matrix system for evaluating impacts was used. Only residual impacts (i.e. post mitigation) were presented.  Consider mitigation. For this assessment it was assumed that all recommended mitigation measures would be implemented. These are defined in the Environmental Management Programme (EMPr).

The significance of the majority of the negative impacts was assessed as being very low or low. Two impacts, namely the use of herbicides and ecological impacts associated with creating new access routes are associated with certain risks and hence may be of medium significance depending on where they are undertaken. No negative impacts of medium-high or high significance were identified. The need and desirability of undertaking the interventions management measures is undisputed. All these measures are employed by the City to ensure that the stormwater systems falling within its jurisdiction are functional, safe and support environmental processes as much as possible. Hence the very reason for undertaking these maintenance measures is to realize positive hydrological, socio-economic and ecological impacts. A number of positive, highly significant impacts were identified. The manner in which these management and maintenance measures are executed is critical for ensuring impacts are minimised, and hence this report should be read together with the EMPr which details the mitigation measures and best practise stormwater management methodologies to be used. In conclusion, the very reason for undertaking these maintenance measures is to realize positive hydrological, socio-economic and ecological impacts. None of the residual impacts associated with the proposed maintenance measures are considered to be of high significance and with the strict implementation of the limitations listed in this report and the EMPr, all impacts could be mitigated to acceptable levels.

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South African Frog Re-assessment Group (SA-FRoG), IUCN SSC Amphibian Specialist Group 2010. Xenopus gilli. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. . Downloaded on 21 May 2014.

South African Frog Re-assessment Group (SA-FRoG), IUCN SSC Amphibian Specialist Group 2010. Capensibufo rosei. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. . Downloaded on 21 May 2014. SANBI (2009). Further Development of a Proposed National Wetland Classification System for South Africa. Primary Project Report. Prepared by the Freshwater Consulting Group (FCG) for the South African National Biodiversity Institute (SANBI). South African Frog Re-assessment Group (SA-FRoG) & IUCN SSC Amphibian Specialist Group, 2010. Arthroleptella lightfooti. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2.. South African Frog Re-assessment Group (SA-FRoG) & IUCN SSC Amphibian Specialist Group, 2010.Heleophryne rosei. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2..

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Small, K., 2009. Labour Force Trends in Cape Town September 2005 to September 2007. Southern Waters Ecological Research & Consulting cc, 2000. Practitioner‟s Manual for Urban River Maintenance. Prepared for the Cape Metropolitan Council. Southern Waters Ecological Research and Consulting cc, 2002. River and vlei assessment and monitoring in the CMA: Revisiting and refining the river importance and sensitivity maps. Report for City of Cape Town, Catchment Management Division. Compiled by Harding W, Brown C, Ewart-Smith J and February R. Statistics South Africa (STATS SA), 2009. Community Survey 2007: Basic Results Western Cape. Statistics South Africa (STATS SA), 2012. Census 2011 Statistical release – P0301.4. (http://mobi.statssa.gov.za/census/Population.html). The Freshwater Consulting Group, 2009. Prioritisation of City Wetlands. Compiled by Snaddon, K. and Day, L. Submitted to City of Cape Town. Western Cape, 2006. Socio economic profile, City of Cape Town 2006.

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APPENDIX A

LISTED ACTIVITIES TRIGGERED BY PROPOSED MAINTENANCE / MANAGEMENT MEASURES

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Table A1: This table presents detailed descriptions of the legal triggers, as presented in listing notices GN 544 and GN 546 of 2010 EIA Regulations, which are relevant to the stormwater management activities in question. This is to be used as reference information when reading the Authorisation Matrix in Appendix B.

No. of Activity Detail Trigger

GN 544, Activity 11 The construction of: canals; channels; bridges; dams; weirs; bulk storm water outlet structures; marinas; jetties exceeding 50 square meters in size; slipways exceeding 50 square meters in size; buildings exceeding 50 square meters in size; or infrastructure or structures covering 50 square meters or more where such construction occurs within a watercourse or within 32 metres of a watercourse, measured from the edge of a watercourse, excluding where such construction will occur behind the development setback line. GN 544, Activity 16 Construction or earth moving activities in the sea, an estuary, or within the littoral active zone or a distance of 100 metres inland of the high-water mark of the sea or an estuary, whichever is the greater, in respect of – fixed or floating jetties and slipways; tidal pools; embankments; rock revetments or stabilising structures including stabilising walls; buildings of 50 square meters or more; or infrastructure covering 50 square meters or more – but excluding (a) if such construction or earth moving activities will occur behind a development setback line; or (b) where such construction or earth moving activities will occur within existing ports or harbours and the construction or earth moving activities will not increase the development footprint or throughput capacity of the port or harbour; (c) where such construction or earth moving activities is undertaken for purposes of maintenance of the facilities mentioned in (i)-(vi) above; or (d) where such construction or earth moving activities is related to the construction of a port or harbour, in which case activity 24 of Notice 545 of 2010 applies. GN 544, Activity 18 The infilling or depositing of any material of more than 5 cubic metres into, or the dredging, excavation, removal or moving of soil, sand, shells, shell grit, pebbles or rock of more than 5 cubic metres from: a watercourse, the sea, seashore, the littoral active zone, an estuary or a distance of 100 meters inland of the high water mark of the sea or an estuary, whichever distance is the greater – but excluding where such infilling, depositing, dredging, excavation, removal or moving (a) is for maintenance purposes undertaken in accordance with a management plan agreed to by the relevant authority, or (b) occurs behind the development setback line. GN 544, Activity 39 The expansion of canals; channels; bridges; weirs; bulk storm water outlet structures; marinas; within a watercourse or within 32 metres of a watercourse, measured from the edge of a watercourse, where such expansion will result in an increased development footprint but excluding where such expansion will occur behind the development setback line GN 544, Activity 40 The expansion of jetties by more than 50 square meters; slipways by more than 50 square meters; or buildings by more than 50 square meters infrastructure by more than 50 square meters within a watercourse or within 32 meters of a watercourse, measured from the edge of a watercourse, but excluding where such expansion will occur behind the development setback line.

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[Corrected by “Correction Notice 2” of 10 December 2010, GN No. R. 1159] GN 544, Activity 45 The expansion of facilities in the sea, an estuary, or within the littoral active zone or a distance of 100 metres inland of the high-water mark of the sea or an estuary, whichever is the greater, for fixed or floating jetties and slipways; tidal pools; embankments; rock revetments or stabilising structures including stabilising walls; buildings by more than 50 square meters; infrastructure by more than 50 square meters; facilities associated with the arrival and departure of vessels and the handling of cargo; piers; inter- and sub-tidal structures for entrapment of sand; breakwater structures; coastal marinas; coastal harbours or ports; structures for draining parts of the sea or estuary; tunnels; or underwater channels – where such expansion will result in an increase in the development footprint of such facilities but excluding where such expansion occurs: (a) behind a development setback line; or (b) within existing ports or harbours where there will be no increase in the development footprint or throughput capacity of the port or harbour. GN 546, Activities 12 The clearance of an area of 300 square metres or more of vegetation where 75% or more of the vegetative cover constitutes indigenous vegetation: Within any critically endangered or endangered ecosystem listed in terms of section 52 of the NEMBA or prior to the publication of such a list, within an area that has been identified as critically endangered in the national Spatial Biodiversity Assessment 2004; a) Within critical biodiversity areas identified in bioregional plans; b) Within littoral active zone or 100 metres inland from high water mark of the sea or an estuary, whichever distance is the greater, excluding where such removal will occur behind the development setback line on erven in urban areas.

GN 546, Activities 13 The clearance of an area of 1 hectare or more of vegetation where 75% or more of the vegetative cover constitutes indigenous vegetation, except where such removal of vegetation is required for (1) the undertaking of a process or activity included in the list of waste management activities published in terms of section 19 of the National Environmental Waste Act (Act No. 59 of 2008), in which case the activity is regarded to be excluded from this list. (2) the undertaking of a linear activity falling below the thresholds mentioned in Listing Notice 1 in terms of GN No. 544 of 2010. Critical biodiversity areas and ecological support areas as identified in systematic biodiversity plans adopted by the competent authority. National Protected Area Expansion Strategy Focus areas. In Eastern Cape, Free State, KwaZulu-Natal, Limpopo, Mpumalanga, Northern cape and Western Cape: In an estuary Outside urban areas, the following: (aa) A protected area identified in terms of NEMPAA, excluding conservancies; (bb) National Protected Area Expansion Focus areas; (cc) Sensitive areas as identified in an environmental management framework as contemplated in chapter 5 of the Act and as adopted by the competent authority. (dd) Sites or areas identified in terms of an International Convention. (ee) Core areas in biosphere reserves; (ff) Areas within 10 kilometres from national parks or world heritage sites or 5 kilometres from any other protected area identified in terms of NEMPAA of from the core area of a biosphere reserve; (gg) Areas seawards of the development setback line or within 1 kilometre from the high-water mark of the sea if no such development setback line is determined. In urban areas, the following: (aa) Areas zoned for use as public open space; (bb) Area designated for conservation use in Spatial Development Frameworks adopted by the competent authority or zoned for conservation purpose; (cc) Area seawards of the development setback line: (dd) Area of the watercourse side of the development setback line or within 100 metres from the edge of a watercourse where no such setback line has been determined. GN 546, Activities 14 The clearance of an area of 5 hectares or more of vegetation where 75% or more of the vegetative cover constitutes indigenous vegetation, except where such removal of vegetation is required for: 1. Purposes of agriculture or afforestation inside areas identified in spatial instruments adopted by the competent authority for agriculture or afforestation processes; 2. The undertaking of a process of activity included in the list of waste management activities published in terms of section 19 of the National Environmental Management: Waste Act, 2008 (Act No. 59 of 2008) in which case the activity is regarded to be excluded from this list; 3. The undertaking of a linear activity falling below the thresholds in Notice 544 of 2010.

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GN 546, Activity 16 The construction of: jetties exceeding 10 square metres in size; slipways exceeding 10 square metres in size; buildings with a footprint exceeding 10 square metres in size; or infrastructure covering 10 square metres or more where such construction occurs within a watercourse or within 32 metres of a watercourse, measured from the edge of a watercourse, excluding where such construction will occur behind the development setback line

(d) In Western Cape:

i. In an estuary; ii. Outside urban areas, in: (aa) A protected area identified in terms of NEMPAA, excluding conservancies; (bb) National Protected Area Expansion Strategy Focus areas; (cc) World Heritage Sites; (dd) Sensitive areas as identified in an environmental management framework as contemplated in chapter 5 of the Act and as adopted by the competent authority; (ee) Sites or areas identified in terms of an International Convention; (ff) Critical biodiversity areas or ecosystem service areas as identified in systematic biodiversity plans adopted by the competent authority or in bioregional plans; (gg) Core areas in biosphere reserves; (hh) Areas within 10 kilometres from national parks or world heritage sites or 5 kilometres from any other protected area identified in terms of NEMPAA or from the core area of a biosphere reserve; (ii) Areas seawards of the development setback line or within 1 kilometre from the high-water mark of the sea if no such development setback line is determined.

Iii inside urban areas: (aa) Areas zoned for use as public open space; (bb) Areas designated for conservation use in Spatial Development Frameworks adopted by the competent authority or zoned for a conservation purpose; (cc) Areas seawards of the development setback line or within 100 metres of the high water mark where no setback line. [Corrected by “Correction Notice 2” of 10 December 2010, GN No. R. 1159] GN 546, Activity 24 The expansion of (a) jetties where the jetty will be expanded by 10 square metres in size or more; (b) slipways where the slipway will be expanded by 10 square metres or more; (c) buildings where the buildings will be expanded by 10 square metres or more in size; or (d) infrastructure where the infrastructure will be expanded by 10 square metres or morewhere such construction occurs within a watercourse or within 32 metres of a watercourse, measured from the edge of a watercourse, excluding where such construction will occur behind the development setback line.

(d) In Western Cape In an estuary;

Outside urban areas, in: (aa) A protected area identified in terms of NEMPAA, excluding conservancies; (bb) National Protected Area Expansion Strategy Focus areas; (cc) Sensitive areas as identified in an environmental management framework as contemplated in chapter 5 of the Act and as adopted by the competent authority; (dd) Sites or areas identified in terms of an International Convention; (ee) Critical biodiversity areas as identified in systematic biodiversity plans adopted by the competent authority or in bioregional plans; (ff) Core areas in biosphere reserves; (gg) Areas within 10 kilometres from national parks or world heritage sites or 5 kilometres from any other protected area identified in terms of NEMPAA or from the core area of a biosphere reserve; (hh) Areas seawards of the development setback line or within 1 kilometre from the high-water mark of the sea if no such development setback line is determined.

i. Inside urban areas: (aa) Areas zoned for use as public open space; (bb) Areas designated for conservation use in Spatial Development Frameworks adopted by the competent authority or zoned for a conservation purpose. [Corrected by “Correction Notice 2” of 10 December 2010, GN No. R. 1159]

Table A2: A summary of triggers presented in Table A1.

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Activity Activity trigger Condition Requirement number 544, 11 Construction of canals, channels; weirs, stormwater Within 32 m of watercourse BAR & EMPr outlets or infrastructure (≥ 50 m2)

544, 16 Construction or earth moving activities for Within sea, estuary, littoral zone, or 100m inland of BAR & EMPr embankments, stabilising structures, or infrastructure HWM. Exclusions apply. (≥ 50 m2)

544, 18 Infilling(> 5 m3) with any material, or In watercourse, sea, seashore, littoral zone, BAR & EMPr Dredging, removal or moving(> 5 m3) any soil, sand, estuary, 100m inland of HWM. Exclusions apply. or MMP rock etc.

544, 39 Expansion of canals, channels, bridges, weirs, bulk Within a watercourse, or 32 m from watercourse. BAR & EMPr stormwater outlet structures, if development footprint is Exclusions apply. increased.

544, 40 Expansion of jetties, slipways, buildings (> 50 m2) Within a watercourse, or 32 m from watercourse. BAR & EMPr Exclusions apply.

544, 45 Expansion of facilities, including infrastructure (> Within sea, estuary, littoral zone, or 100m inland of BAR & EMPr 50 m2), embankments, stabilising structures. HWM. Exclusions apply.

546, 12 Clearing ≥ 300m2 where vegetation is ≥ 75% Various location conditions including endangered BAR & EMPr indigenous ecosystems, CBAs, littoral zone or 100 m from HWM.

546, 13 Clearing ≥ 1 ha where vegetation is ≥ 75% Various location conditions including CBAs, BAR & EMPr indigenous. ecological support areas, National Protected Area Exclusions apply. Expansion Strategy Focus areas, in an estuary, outside urban areas (various conditions), in urban areas (various conditions).

546, 14 Clearing ≥ 5 ha where vegetation is ≥ 75% All areas outside urban areas BAR & EMPr indigenous. Exclusions apply.

546, 16 Construction of infrastructure (≥10 m2) within a Within any watercourse, estuary, inside and BAR & EMPr watercourse, or 32 m from watercourse outside urban areas (various conditions).

546, 24 Expansion of infrastructure (≥10 m2) within a Within any watercourse, estuary, inside and BAR & EMPr watercourse, or 32 m from watercourse outside urban areas (various conditions).

Note regarding Development Setback lines:

The development setback line is referred to in listing notices 1 and 3 (GN 544 and GN 546) of the 2010 EIA regulations. The purpose of a development setback line is to protect sensitive environments, areas of heritage importance or a development e.g. coastal development setback lines restrict development in areas within the reaches of storm surges. Since the stormwater management actions are by definition not a new development and is undertaken as part of a maintenance and management strategy the concept of development setback lines are not applicable to the management actions defined in this report and broader application for authorisation.

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APPENDIX B

AUTHORISATION MATRIX

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Note:  The construction and expansion of any structure not listed below is excluded from this generic authorisation and will require a separate application for environmental authorisation. The Catchment, Stormwater and River Management Branch (Roads and Stormwater Department) or Environment and Heritage Management Branch (Environmental Resource Management Department) must be consulted if there is uncertainty regarding whether a particular intervention is encompassed within the table below or falls outside the scope of the generic authorisation.

 “Construction” and “expansion” are interpreted as per the definitions in the listing notice 1 (GN R544) of the EIA Regulations (2010).  Only those activities triggering the need for a BAR & EMP (blue) are considered further in terms of impacts. Table B1: Triggers in terms of NEMA that may apply to each of the stormwater maintenance measures, and that precipitate EIA requirements. Activities triggering the need for a BAR &EMPr are highlighted in blue.

No. Maintenance / Description of sub-types of Activity Trigger description Authorisation management measures trigger required measure number 1 Vegetation 1.1. Aquatic (submerged and Activities Cleared area is <300 m2 or vegetation removed is <75% indigenous None management in / floating) vegetation 12, 13, 14 management adjacent to of GN 546 1.2. Reedbed and indigenous Cleared area is ≥300 m2 and 75% or more of the vegetation removed constitutes indigenous vegetation BAR & EMPr waterbodies emergent vegetation depending on the  (incl. all management location of the wetlands, rivers, 1.3. Riparian / marginal intervention. See Sustainable vegetation management Urban Drainage Techniques employed include: listed activities. Systems  Manual removal (SUDS), artificial  Mechanical removal wetlands, dams)  Biocontrol No trigger No trigger None  indigenous  Chemical control species include  Manipulation of water levels cosmopolitan  Burning Typha and Phragmites 2 Erosion control 2.1 River channel profile Activity 16 Construction or earth moving activities in the sea, an estuary, or within the littoral active zone or a distance of BAR & EMPr enhancement (i.e. limit or halt of GN 544 100 metres inland of the high-water mark of the sea or an estuary, whichever is greater, in respect of (vi) erosion by reduction of stream infrastructure covering 50 square metres or more where such construction or earth moving activities are NOT bed and embankment gradients) undertaken for the purposes of maintenance of the facilities NOTE: Construction or earth moving within 100 m of the high-water mark, but covering less than 50 None square metres does not require authorisation

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No. Maintenance / Description of sub-types of Activity Trigger description Authorisation management measures trigger required measure number Activity 18 Infilling / depositing of any material of more than 5 cubic metres, or BAR & EMPr of GN 544 Dredging, excavation, removal or moving of sand, soil, rock of more than 5 cubic meters, into or from: (i) a water course (ii) the sea (iii) seashore (iv) littoral zone, estuary or distance of 100 metres inland of the high water mark of the sea of an estuary whichever distance is the greater where the work is NOT for maintenance purposes NOTE: Adding or removing less than 5 cubic metres of material does not require authorisation. Note None also that the actions listed under Activity 18 that are undertaken for maintenance purposes, and that are executed in line with the approved EMPr (which addresses maintenance activities), would not require authorisation. Activity 39 The expansion of (ii) channels within a watercourse or within 32 metres of a watercourse, measured from the BAR & EMPr of GN 544 edge of the watercourse, where such expansion will result in an increased development footprint but excluding where such expansion will occur behind the development setback line Activity 45 The expansion of facilities in the sea, an estuary, or within the littoral active zone or a distance of 100 metres BAR & EMPr of GN 544 inland of the high-water mark of the sea or an estuary whichever is greater for, (iii) embankments, (iv) stabilising structures or (vi) infrastructure by more than 50 square metres where such expansion will result in an increase in the development footprint of such facilities, but excluding where such construction occurs behind the development setback line Activity 16 The construction of infrastructure of 10 square metres or more within a watercourse or within 32 metres of a BAR & EMPr of GN 546 watercourse measured from the edge of a watercourse within sensitive geographical areas identified within the notice. NOTE: The construction of infrastructure within 32 metres of a watercourse AND within sensitive None geographical areas BUT covering less than 10square metres does not require authorisation. Activity 24 The expansion of infrastructure of 10 square metres or more within a watercourse or within 32 metres of a BAR & EMPr of GN 546 watercourse measured from the edge of a watercourse within sensitive geographical areas identified within the notice. 2.2 Construction, maintenance Activity 11 The construction of (v) weirs or (xi) infrastructure or structures covering 50 square metres or more where such BAR & EMPr and expansion of erosion control of GN 544 construction occurs within a watercourse or within 32 metres of a watercourse, measured from the edge of a structures. watercourse, excluding where such construction occurs behind the development setback line NOTE: The construction of structures within 32 metres of a watercourse BUT covering less than 50 None Examples are: square metres does not require authorisation.  Rockpile weirs, riprap linings, Activity 16 Construction or earth moving activities in the sea, an estuary, or within the littoral active zone or a distance of BAR & EMPr

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No. Maintenance / Description of sub-types of Activity Trigger description Authorisation management measures trigger required measure number sandbag weirs, Gabions, of GN 544 100 metres inland of the high-water mark of the sea or an estuary, whichever is greater, in respect of (vi) which could extend to a infrastructure covering 50 square metres or more where work is NOT undertaken for the purpose of canalised section maintenance of facilities  Geocells Construction or earth moving activities in the sea, an estuary, or within the littoral active zone or a distance of MMP  Articulated concrete blocks,  Geofabrics 100 metres inland of the high-water mark of the sea or an estuary, whichever is greater, in respect of (vi) infrastructure covering 50 square metres or more where such construction or earth moving activities are undertaken for the purposes of maintenance of the facilities. NOTE: Construction or earth moving within 100 m of the high-water mark, but covering less than 50 None square metres does not require authorisation Activity 18 Infilling / depositing of any material of more than 5 cubic metres into, or BAR & EMPr of GN 544 Dredging, excavation, removal or moving of sand, soil, rock of more than 5 cubic metres from: (i) a water course (ii) the sea (iii) seashore (iv) littoral zone, estuary or distance of 100 metres inland of the high water mark of the sea of an estuary whichever distance is the greater where the work is NOT for maintenance purposes Infilling / depositing of any material of more than 5 cubic metres into, or MMP Dredging, excavation, removal or moving of sand, soil, rock of more than 5 cubic metres from: (i) a water course (ii) the sea (iii) seashore (iv) littoral zone, estuary or distance of 100 metres inland of the high water mark of the sea of an estuary whichever distance is the greater where the work is for maintenance purposes NOTE: Adding or removing less than 5 cubic metres of material does not require authorisation. Note None also that the actions listed under Activity 18 that are undertaken for maintenance purposes, and that are executed in line with the approved EMPr (which addresses maintenance activities), would not require authorisation. Activity 39 The expansion of (ii) channels within a watercourse or within 32 metres of a watercourse, measured from the BAR & EMPr of GN 544 edge of the watercourse, where such expansion will result in an increased development footprint but excluding where such expansion will occur behind the development setback line Activity 45 The expansion of facilities or infrastructure in the sea, an estuary or within the littoral active zone or a distance BAR & EMPr of GN 544 of 100 metres inland of the high-water mark of the sea or an estuary by more than 50 square metres,

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No. Maintenance / Description of sub-types of Activity Trigger description Authorisation management measures trigger required measure number whichever is the greater. Note: The expansion of facilities within100 metres of the high-water mark of the sea or an estuary by None LESS than 50 square metres does not require authorisation. Activity 16 The construction of infrastructure covering 10 square metres of more within a watercourse or within 32 metres BAR & EMPr of GN 546 of a watercourse measured from the edge of a watercourse within sensitive geographical areas identified within the notice. NOTE: The construction of infrastructure within 32 metres of a watercourse AND within sensitive None geographical areas BUT covering less than 10square metres does not require authorisation. Activity 24 The expansion of infrastructure of 10 square metres of more within a watercourse or within 32 metres of a BAR & EMPr of GN 546 watercourse measured from the edge of a watercourse within sensitive geographical areas identified within the notice. NOTE: The expansion of infrastructure within 32 metres of a watercourse AND within sensitive None geographical areas BUT covering less than 10square metres does not require authorisation. 3 Sediment 3.1 Construction maintenance Activity 11 The construction of (v) weirs or (xi) infrastructure or structures covering 50 square metres or more where such BAR & EMPr management in and expansion of sediment traps of GN 544 construction occurs within a watercourse or within 32 metres of a watercourse, measured from the edge of a canals, rivers and / retention areas watercourse, excluding where such construction occurs behind the development setback line waterbodies (inter NOTE: The construction of structures within 32 metres of a watercourse BUT covering less than 50 None alia vleis, 3.2 Manual /mechanical square metres does not require authorisation. wetlands, sediment removal from sediment Activity 16 Construction or earth moving activities in the sea, an estuary, or within the littoral active zone or a distance of BAR & EMPr estuaries, traps / retention areas of GN 544 100 metres inland of the high-water mark of the sea or an estuary, whichever is greater, in respect of (vi) Sustainable Urban infrastructure covering 50 square metres or more where work is NOT undertaken for the purpose of Drainage Systems maintenance of facilities (SUDS) e.g. 3.3 Manual/ mechanical constructed sediment removal from canals, Construction or earth moving activities in the sea, an estuary, or within the littoral active zone or a distance of MMP wetlands, dams channels and waterbodies 100 metres inland of the high-water mark of the sea or an estuary, whichever is greater, in respect of (vi) etc.) infrastructure covering 50 square metres or more where such construction or earth moving activities are undertaken for the purposes of maintenance of the facilities.

NOTE: Construction or earth moving within 100 m of the high-water mark, but covering less than 50 None

square metres does not require authorisation

Activity 18 Infilling / depositing of any material of more than 5 cubic metres into, or BAR & EMPr of GN 544 Dredging, excavation, removal or moving of sand, soil, rock of more than 5 cubic metres from: (i) a water course (ii) the sea (iii) seashore

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No. Maintenance / Description of sub-types of Activity Trigger description Authorisation management measures trigger required measure number (iv) littoral zone, estuary or distance of 100 metres inland of the high water mark of the sea of an estuary whichever distance is the greater where the work is NOT for maintenance purposes Infilling / depositing of any material of more than 5 cubic metres into, or MMP Dredging, excavation, removal or moving of sand, soil, rock of more than 5 cubic metres from: (i) a water course (ii) the sea (iii) seashore (iv) littoral zone, estuary or distance of 100 metres inland of the high water mark of the sea of an estuary whichever distance is the greater where the work is for maintenance purposes NOTE: Adding or removing less than 5 cubic metres of material does not require authorisation. Note None also that the actions listed under Activity 18 that are undertaken for maintenance purposes, and that are executed in line with the approved EMPr (which addresses maintenance activities), would not require authorisation. Activity 16 The construction of infrastructure covering 10 square metres of more within a watercourse or within 32 metres BAR & EMPr of GN 546 of a watercourse measured from the edge of a watercourse within sensitive geographical areas identified within the notice. NOTE: The construction of infrastructure within 32 metres of a watercourse AND within sensitive None geographical areas BUT covering less than 10square metres does not require authorisation. Activity 24 The expansion of infrastructure of 10 square metres of more within a watercourse or within 32 metres of a BAR & EMPr of GN 546 watercourse measured from the edge of a watercourse within sensitive geographical areas identified within the notice. NOTE: The expansion of infrastructure within 32 metres of a watercourse AND within sensitive None geographical areas BUT covering less than 10square metres does not require authorisation. 4 Channel 4.1 Conversion of open channel Activity 16 Construction or earth moving activities in the sea, an estuary, or within the littoral active zone or a distance of BAR & EMPr enclosure (in low cost housing / informal of GN 544 100 metres inland of the high-water mark of the sea or an estuary, whichever is the greater, in respect of (iii) areas that are subject to extreme embankments, (iv) rock revetments or stabilising structures including stabilising walls, (vi) infrastructure levels of pollution due to disposal covering 50 square metres or more where such construction or earth moving activities are NOT undertaken for of liquid and solid waste into the purposes of maintenance of the facilities. these open systems) to a closed NOTE: Construction or earth moving within 100 m of the high-water mark, but covering less than 50 None pipe/ culvert system square metres does not require authorisation Activity 18 Infilling / depositing of any material of more than 5 cubic metres, or BAR & EMPr

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No. Maintenance / Description of sub-types of Activity Trigger description Authorisation management measures trigger required measure number of GN 544 Dredging, excavation, removal or moving of sand, soil, rock of more than 5 cubic meters, into or from: (i) a water course (ii) the sea (iii) seashore (iv) littoral zone, estuary or distance of 100 metres inland of the high water mark of the sea of an estuary whichever distance is the greater where the work is NOT for maintenance purposes. NOTE: Adding or removing less than 5 cubic metres of material does not require authorisation. Note None also that the actions listed under Activity 18 that are undertaken for maintenance purposes, and that are executed in line with the approved EMPr (which addresses maintenance activities), would not require authorisation. Activity 45 The expansion of facilities, or infrastructure in the sea, an estuary or within the littoral active zone or a distance BAR & EMPr of GN 544 of 100 metres inland of the high-water mark of the sea or an estuary, whichever is the greater by more than 50 square metres. Note: The expansion of facilities within100 metres of the high-water mark of the sea or an estuary by None LESS than 50 square metres does not require authorisation. Activity 16 The construction of infrastructure covering 10 square metres of more within a watercourse or within 32 metres BAR & EMPr of GN 546 of a watercourse measured from the edge of a watercourse within sensitive geographical areas identified within the notice. NOTE: The construction of infrastructure within 32 metres of a watercourse AND within sensitive None geographical areas BUT covering less than 10square metres does not require authorisation. Activity 24 The expansion of infrastructure of 10 square metres of more within a watercourse or within 32 metres of a BAR & EMPr of GN 546 watercourse measured from the edge of a watercourse within sensitive geographical areas identified within the notice. NOTE: The expansion of infrastructure within 32 metres of a watercourse AND within sensitive None geographical areas BUT covering less than 10square metres does not require authorisation. 5 Litter and debris 5.1 Litter and debris Activity 18 Infilling / depositing of any material of more than 5 cubic metres into, or dredging, excavation, removal or BAR & EMPr management (to management using either of GN 544 moving of sand, soil, rock of more than 5 cubic meters, from: remove pollution, mechanical or manual methods (i) a water course improve (ii) the sea aesthetics, ensure (iii) seashore hydraulic (iv) littoral zone, estuary or distance of 100 metres inland of the high water mark of the sea of an estuary functioning of whichever distance is the greater where the work is NOT for maintenance purposes.

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No. Maintenance / Description of sub-types of Activity Trigger description Authorisation management measures trigger required measure number system is not Infilling / depositing of any material of more than 5 cubic metres into, or dredging, excavation, removal or MMP compromised) moving of sand, soil, rock of more than 5 cubic meters, from: (i) a water course (ii) the sea (iii) seashore (iv) littoral zone, estuary or distance of 100 metres inland of the high water mark of the sea of an estuary whichever distance is the greater where the work is for maintenance purposes. NOTE: Adding or removing less than 5 cubic metres of material does not require authorisation. Note None also that the actions listed under Activity 18 that are undertaken for maintenance purposes, and that are executed in line with the approved EMPr (which addresses maintenance activities), would not require authorisation. 5.2 Removal of structures to Activity 18 Dredging, excavation, removal or moving of sand, soil, rock of more than 5 cubic metres from: BAR & EMPr reduce water obstruction of GN 544 (i) a water course (ii) the sea (iii) seashore (iv) littoral zone, estuary or distance of 100 metres inland of the high water mark of the sea of an estuary whichever distance is the greater where the work is NOT for maintenance purposes Dredging, excavation, removal or moving of sand, soil, rock of more than 5 cubic metres from: MMP (i) a water course (ii) the sea (iii) seashore (iv) littoral zone, estuary or distance of 100 metres inland of the high water mark of the sea of an estuary whichever distance is the greater where the work is for maintenance purposes NOTE: Adding or removing less than 5 cubic metres of material does not require authorisation. Note None also that the actions listed under Activity 18 that are undertaken for maintenance purposes, and that are executed in line with the approved EMPr (which addresses maintenance activities), would not require authorisation. 5.3 Construction, maintenance, Activity 11 The construction of (xi) infrastructure or structures covering 50 square metres or more where such construction BAR & EMPr and expansion of litter of GN 544 occurs within a watercourse or within 32 metres of a watercourse, measured from the edge of a watercourse, management infrastructure. excluding where such construction occurs behind the development setback line. NOTE: The construction of structures within 32 metres of a watercourse BUT covering less than 50 None

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No. Maintenance / Description of sub-types of Activity Trigger description Authorisation management measures trigger required measure number square metres does not require authorisation. Activity 16 Construction or earth moving activities in the sea, an estuary, or within the littoral active zone or a distance of BAR & EMPr of GN 544 100 metres inland of the high-water mark of the sea or an estuary, whichever is greater, in respect of (vi) infrastructure covering 50 square metres or more where work is NOT undertaken for the purpose of maintenance of facilities Construction or earth moving activities in the sea, an estuary, or within the littoral active zone or a distance of MMP 100 metres inland of the high-water mark of the sea or an estuary, whichever is greater, in respect of (vi) infrastructure covering 50 square metres or more where such construction or earth moving activities are undertaken for the purposes of maintenance of the facilities NOTE: Construction or earth moving within 100 m of the high-water mark, but covering less than 50 None square metres does not require authorisation Activity 18 Infilling / depositing of any material of more than 5 cubic metres into, or dredging, excavation, removal or BAR & EMPr of GN 544 moving of sand, soil, rock of more than 5 cubic meters, from: (i) a water course (ii) the sea (iii) seashore (iv) littoral zone, estuary or distance of 100 metres inland of the high water mark of the sea of an estuary whichever distance is the greater where the work is NOT for maintenance purposes. Infilling / depositing of any material of more than 5 cubic metres into, or dredging, excavation, removal or MMP moving of sand, soil, rock of more than 5 cubic meters, from: (i) a water course (ii) the sea (iii) seashore (iv) littoral zone, estuary or distance of 100 metres inland of the high water mark of the sea of an estuary whichever distance is the greater where the work is for maintenance purposes. NOTE: Adding or removing less than 5 cubic metres of material does not require authorisation. Note None also that the actions listed under Activity 18 that are undertaken for maintenance purposes, and that are executed in line with the approved EMPr (which addresses maintenance activities), would not require authorisation. Activity 45 The expansion of facilities or infrastructure in the sea, an estuary or within the littoral active zone or a distance BAR & EMPr of GN 544 of 100 metres inland of the high-water mark of the sea or an estuary, whichever is the greater, by more than 50 square metres where such expansion will result in an increase in the development footprint of such facilities.

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No. Maintenance / Description of sub-types of Activity Trigger description Authorisation management measures trigger required measure number Note: The expansion of facilities within100 metres of the high-water mark of the sea or an estuary by None LESS than 50 square metres does not require authorisation. Activity 16 The construction of infrastructure covering 10 square metres of more within a watercourse or within 32 metres BAR & EMPr of GN 546 of a watercourse measured from the edge of a watercourse within sensitive geographical areas identified within the notice. NOTE: The construction of infrastructure within 32 metres of a watercourse AND within sensitive None geographical areas BUT covering less than 10square metres does not require authorisation. Activity 24 The expansion of infrastructure of 10 square metres of more within a watercourse or within 32 metres of a BAR & EMPr of GN 546 watercourse measured from the edge of a watercourse within sensitive geographical areas identified within the notice. NOTE: The expansion of infrastructure within 32 metres of a watercourse AND within sensitive None geographical areas BUT covering less than 10square metres does not require authorisation. 6 Construction, 6.1 Stormwater outlets, dam Activity 11 The construction of (vi) bulk stormwater outlets or (xi) infrastructure or structures covering 50 sq metres or BAR & EMPr maintenance and scour valves, headwalls and of GN 544 more where such construction occurs within a watercourse or within 32 metres of a watercourse, measured expansion of minor culverts from the edge of a watercourse, excluding where such construction will occur behind the development. setback stormwater line. infrastructure NOTE: The construction of structures within 32 metres of a watercourse BUT covering less than 50 None square metres does not require authorisation. Activity 16 Construction or earth moving activities in the sea, an estuary, or within the littoral active zone or a distance of BAR & EMPr of GN 544 100 metres inland of the high-water mark of the sea or an estuary, whichever is the greater, in respect of (iii) embankments, (iv) rock revetments or stabilising structures including stabilising walls, (vi) infrastructure covering 50 square metres or more where such activities are NOT undertaken for maintenance purposes. Construction or earth moving activities in the sea, an estuary, or within the littoral active zone or a distance of MMP 100 metres inland of the high-water mark of the sea or an estuary, whichever is the greater, in respect of (iii) embankments, (iv) rock revetments or stabilising structures including stabilising walls, (vi) infrastructure covering 50 square metres or more where such activities are undertaken for the purposes of maintenance of the facilities. NOTE: Construction or earth moving within 100 m of the high-water mark, but covering less than 50 None square metres does not require authorisation Activity 18 Infilling / depositing of any material of more than 5 cubic metres into, or dredging, excavation, removal or BAR & EMPr of GN 544 moving of sand, soil, rock of more than 5 cubic meters, from: (i) a water course (ii) the sea

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No. Maintenance / Description of sub-types of Activity Trigger description Authorisation management measures trigger required measure number (iii) seashore (iv) littoral zone, estuary or distance of 100 metres inland of the high water mark of the sea of an estuary whichever distance is the greater where the work is NOT for maintenance purposes. Infilling / depositing of any material of more than 5 cubic metres into, or dredging, excavation, removal or MMP moving of sand, soil, rock of more than 5 cubic meters, from: (i) a water course (ii) the sea (iii) seashore (iv) littoral zone, estuary or distance of 100 metres inland of the high water mark of the sea of an estuary whichever distance is the greater where the work is for maintenance purposes. NOTE: Adding or removing less than 5 cubic metres of material does not require authorisation. Note None also that the actions listed under Activity 18 that are undertaken for maintenance purposes, and that are executed in line with the approved EMPr (which addresses maintenance activities), would not require authorisation. Activity 39 The expansion of (i) canals, (ii) channels, (iv) weirs, (v) bulk stormwater outlet structures within a watercourse BAR & EMPr of GN 544 or within 32 metres of a watercourse, measured from the edge of a watercourse, where such expansion will result in an increased development footprint but excluding where such expansion will occur behind the development setback line. Activity 16 The construction of infrastructure covering 10 square metres of more within a watercourse or within 32 metres BAR & EMPr of GN 546 of a watercourse measured from the edge of a watercourse within sensitive geographical areas identified within the notice. NOTE: The construction of infrastructure within 32 metres of a watercourse AND within sensitive None geographical areas BUT covering less than 10 square metres does not require authorisation. Activity 24 The expansion of infrastructure of 10 square metres of more within a watercourse or within 32 metres of a BAR & EMPr of GN 546 watercourse measured from the edge of a watercourse within sensitive geographical areas identified within the notice. NOTE: The expansion of infrastructure within 32 metres of a watercourse AND within sensitive None geographical areas BUT covering less than 10square metres does not require authorisation. 7 Maintenance of 7.1 Weirs Activity 16 Construction or earth moving activities in the sea, an estuary, or within the littoral active zone or a distance of BAR & EMPr attenuation 7.2 Retention / detention ponds, of GN 544 100 metres inland of the high-water mark of the sea or an estuary, whichever is the greater, in respect of (iii) infrastructure. dams registered in terms of the embankments, (iv) rock revetments or stabilising structures including stabilising walls or (vi) infrastructure covering 50 square metres or more where such construction or earth moving activities are NOT undertaken for

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No. Maintenance / Description of sub-types of Activity Trigger description Authorisation management measures trigger required measure number National Water Act as dams with purposes of maintenance of the facilities. Excludes a Safety Risk construction of 7.3 Flood protection Construction or earth moving activities in the sea, an estuary, or within the littoral active zone or a distance of MMP new or expansion embankments / berms 100 metres inland of the high-water mark of the sea or an estuary, whichever is the greater, in respect of (iii) of existing 7.4 SUDS facilities embankments, (iv) rock revetments or stabilising structures including stabilising walls or (vi) infrastructure structures that will 7.5 Other dams / ponds covering 50 square metres or more where such construction or earth moving activities are undertaken for increase the purposes of maintenance of the facilities. capacity of such NOTE: Construction or earth moving within 100 m of the high-water mark, but covering less than 50 None structures. square metres does not require authorisation Activity 18 Infilling / depositing of any material of more than 5 cubic metres into, or dredging, excavation, removal or BAR & EMPr Dam Safety of GN 544 moving of sand, soil, rock of more than 5 cubic meters, from: Regulations are (i) a water course applicable to (ii) the sea specific registered (iii) seashore dams. (iv) littoral zone, estuary or distance of 100 metres inland of the high water mark of the sea of an estuary whichever distance is the greater where the work is NOT for maintenance purposes. Infilling / depositing of any material of more than 5 cubic metres into, or dredging, excavation, removal or MMP moving of sand, soil, rock of more than 5 cubic meters, from: (i) a water course (ii) the sea (iii) seashore (iv) littoral zone, estuary or distance of 100 metres inland of the high water mark of the sea of an estuary whichever distance is the greater where the work is for maintenance purposes. NOTE: Adding or removing less than 5 cubic metres of material does not require authorisation. Note None also that the actions listed under Activity 18 that are undertaken for maintenance purposes, and that are executed in line with the approved EMPr (which addresses maintenance activities), would not require authorisation. Activity 12 Cleared area is ≥300 m2 and 75% or more of the vegetation removed constitutes indigenous vegetation, BAR & EMPr of GN 546 located within a geographically sensitive area. Cleared area is <300 m2 or vegetation removed is <75% indigenous, located within a geographically sensitive None area.

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No. Maintenance / Description of sub-types of Activity Trigger description Authorisation management measures trigger required measure number 8 Recreational 8.1 Construction, maintenance No trigger No change in footprint of structure None access and expansion of footbridges, Activity 11 The construction of (iii) bridges or (xi) infrastructure or structures covering 50 square metres or more where BAR & EMPr boardwalks or bird hides. of GN 544 such construction occurs within a watercourse or within 32 metres of a watercourse, measured from the edge of a watercourse, excluding where such construction will occur behind the development setback line. NOTE: The construction of structures within 32 metres of a watercourse BUT covering less than 50 None square metres does not require authorisation. Activity 16 Construction or earth moving activities in the sea, an estuary, or within the littoral active zone or a distance of BAR & EMPr of GN 544 100 metres inland of the high-water mark of the sea or an estuary, whichever is greater, in respect of (vi) infrastructure covering 50 square metres or more where such construction or earth moving activities are NOT undertaken for the purposes of maintenance of the facilities. Construction or earth moving activities in the sea, an estuary, or within the littoral active zone or a distance of MMP 100 metres inland of the high-water mark of the sea or an estuary, whichever is greater, in respect of (vi) infrastructure covering 50 square metres or more where such construction or earth moving activities are undertaken for the purposes of maintenance of the facilities NOTE: Construction or earth moving within 100 m of the high-water mark, but covering less than 50 None square metres does not require authorisation Activity 18 Infilling / depositing of any material of more than 5 cubic metres into, or dredging, excavation, removal or BAR & EMPr of GN 544 moving of sand, soil, rock of more than 5 cubic meters, from: (i) a water course (ii) the sea (iii) seashore (iv) littoral zone, estuary or distance of 100 metres inland of the high water mark of the sea of an estuary whichever distance is the greater where the work is NOT for maintenance purposes. Infilling / depositing of any material of more than 5 cubic metres into, or dredging, excavation, removal or MMP moving of sand, soil, rock of more than 5 cubic meters, from: (i) a water course (ii) the sea (iii) seashore (iv) littoral zone, estuary or distance of 100 metres inland of the high water mark of the sea of an estuary whichever distance is the greater where the work is for maintenance purposes. NOTE: Adding or removing less than 5 cubic metres of material does not require authorisation. Note None also that the actions listed under Activity 18 that are undertaken for maintenance purposes, and that

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No. Maintenance / Description of sub-types of Activity Trigger description Authorisation management measures trigger required measure number are executed in line with the approved EMPr (which addresses maintenance activities), would not require authorisation. Activity 39 The expansion of bridges within a watercourse or within 32 metres of a watercourse, measured from the edge BAR & EMPr of GN 544 of a watercourse, where such expansion will result in an increased development footprint but excluding where such expansion will occur behind the development setback line. Activity 40 The expansion of infrastructure by more than 50 square metres within a watercourse or within 32 metres of a BAR & EMPr of GN 544 watercourse, measured from the edge of a watercourse, but excluding where such expansion will occur behind the development setback line. NOTE: The expansion of infrastructure within 32 metres of a watercourse, BUT by less than 50 square None metres does not require authorisation. Activity 45 The expansion of infrastructure in the sea, an estuary or within the littoral active zone or a distance of 100 BAR & EMPr of GN 544 metres inland of the high-water mark of the sea or an estuary, whichever is greater by more than 50 square metres. Note: The expansion of facilities within100 metres of the high-water mark of the sea or an estuary by None LESS than 50 square metres does not require authorisation. Activity 16 The construction of infrastructure covering 10 square metres of more within a watercourse or within 32 metres BAR & EMPr of GN 546 of a watercourse measured from the edge of a watercourse within sensitive geographical areas identified within the notice. NOTE: The construction of infrastructure within 32 metres of a watercourse AND within sensitive None geographical areas BUT covering less than 10square metres does not require authorisation. Activity 24 The expansion of infrastructure of 10 square metres of more within a watercourse or within 32 metres of a BAR & EMPr of GN 546 watercourse measured from the edge of a watercourse within sensitive geographical areas identified within the notice. NOTE: The expansion of infrastructure within 32 metres of a watercourse AND within sensitive None geographical areas BUT covering less than 10square metres does not require authorisation. 9 Management of 9.1 Breaching: removal of sand Activity 18 Infilling / depositing of any material of more than 5 cubic metres into, or dredging, excavation, removal or BAR & EMPr river / estuary bars deposited in mouth of GN 544 moving of sand, soil, rock of more than 5 cubic meters, from: mouths 9.2 Straightening: redirecting (i) a water course meandering mouth across the (ii) the sea shortest route directly towards (iii) seashore the sea (iv) littoral zone, estuary or distance of 100 metres inland of the high water mark of the sea of an estuary whichever distance is the greater where the work is NOT for maintenance purposes.

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No. Maintenance / Description of sub-types of Activity Trigger description Authorisation management measures trigger required measure number Infilling / depositing of any material of more than 5 cubic metres into, or dredging, excavation, removal or MMP moving of sand, soil, rock of more than 5 cubic meters, from: (i) a water course (ii) the sea (iii) seashore (iv) littoral zone, estuary or distance of 100 metres inland of the high water mark of the sea of an estuary whichever distance is the greater where the work is for maintenance purposes. NOTE: Adding or removing less than 5 cubic metres of material does not require authorisation. Note None also that the actions listed under Activity 18 that are undertaken for maintenance purposes, and that are executed in line with the approved EMPr (which addresses maintenance activities), would not require authorisation.

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APPENDIX C

DETAILED DESCRIPTION OF MAINTENANCE / MANAGEMENT MEASURES

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Table C1: Description of rationale, methods and frequency of the proposed stormwater maintenance / management measures.

No Management Trigger Basic description of management Labour method Method details Motivation and frequency measure summary measure 1 Vegetation management

1.1 Aquatic None (alien Alien invasive submerged and / or floating When: Often annually, or as needed. (submerged vegetation) alien species such as hyacinth, parrot’s and feather and kariba weed are cleared from floating)vegeta GN 546 areas where they are problematic. Although tion (12,13,14) clearing of alien species does not trigger the management where listed activities, best practise methods will removal of nevertheless be followed. 1.1.1 Manual indigenous Usually full-time CCT Workers wade into watercourse and Where: Mainly in shallow areas or relatively removal vegetation Removal of indigenous (submerged) employees or cut or pull vegetation by hand and small systems (e.g. vleis, estuaries, dams, is vegetation is contemplated, but only within a casual/contract labourers. load onto a raft / remove to the bank. Sustainable Urban Drainage Systems, canals concerned detailed maintenance plan that addresses Teams can be up to 40 Material is stockpiled on bank to dry and choked watercourses). (e.g the particulars of the watercourse. people. Labour intensive. then loaded onto vehicle (e.g. digger- pondweed) loader) with trailer. 1.1.2 Mechanical Usually involves Clearing from banks: Where: Deep systems, or at culverts & outlets removal excavator, or floating reed Usually a longboom excavator (13m of channels and valley bottom wetlands where cutter, and tractor/trailer or 21m) on tracks with water bucket is water levels prevent manual clearing, and for material removal. used. Material usually removed from where road access is possible. site via tractor/truck and trailer. In-channel clearing: Where: Mud-dozer, or Bobcat: Wide but shallow waterbodies; access is Operates within the channel, pushing usually from one or more points close to plant material into position for where material is to be removed. removal by excavator. Floating cutter / weed harvester Used in deep water, especially for submerged vegetation (incl. indigenous vegetation) 1.1.3 Biocontrol None Involves the release of Technical specifications differ Where: Only relevant to some plant species at biocontrol agents (e.g. according to the biocontrol agent densities that will support the biocontrol agent. insects) into populations of the target species. Target species are alien invasives.

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No Management Trigger Basic description of management Labour method Method details Motivation and frequency measure summary measure 1.1.4 Chemical None Involves the spraying of Technical specifications differ Where: Waterbodies of low conservation control infestations of alien according to the species’ uptake of importance, where infestation is very dense; vegetation with chemical poison. Follow-up removal of plant follow-up removal as per manual / mechanical poison. matter from watercourse is required details. as per manual / mechanical details. 1.1.5 Manipulation No EIA Involves the release of Draw-down results in the stranding Where: Only relevant to. dams, impounded of water level trigger. water through and death of floating or submerged rivers and man-made lakes. impoundment valves or vegetation, which can either rot in situ Water Act: the lowering of an outlet or more often is removed by machine Gen. Auth weir. e.g. dozer. (TBC) 1.2 Reedbed and GN 544 Tends to involve removal of potentially large Why: Aesthetics, improve hydrological indigenous (18) areas (≥300m2) of indigenous cosmopolitan functioning, contribute to water quality emergent reeds (Typha and Phragmites). amelioration by stimulating reed growth in vegetation SUDS, improves security by reducing cover GN 546 Clearing of non-reedbed areas of >75% for vagrants. (12,13,14) indigenous vegetation is subject to specific When: often annually, or as needed. 1.2.1 Manual environmental planning. Usually full-time CCT Workers wade into watercourse and Where: Only in shallow areas i.e. relatively removal employees or casual / cut vegetation by hand / brush cutter. small systems (e.g. Sustainable Urban Clearing of unchannelled portions of contract labourers. Teams Material is stockpiled on bank to dry Drainage Systems, canals and choked reedbed with high ecological importance can be up to 40 people. then loaded onto vehicle (e.g. digger- channels) or margins of dams and larger shall be approved the CCT Environmetnal Labour intensive. loader) with trailer. Effective in wetlands. Team, and subject to a site-specific localised areas, but slow. Maintenance Plan. 1.2.2 Mechanical Usually involves Clearing from banks: Where: Deep systems, or at culverts & outlets removal excavator, or floating reed Usually a longboom excavator (13m of channels and valley bottom wetlands where cutter, and tractor/trailer or 21m) on tracks with water bucket is water levels prevent manual clearing, and for material removal. used. Material is usually removed where road access is possible. from site via tractor/truck and trailer. Limitations include the reach of a machine, and in some cases road access may need to be constructed. In-channel clearing: Where: Wide but shallow channels that e.g. Mud-dozer, or Bobcat: experience encroachment of reeds; access Operates within the channel, pushing usually from one or more points close to material into position for removal by where material is to be removed. excavator. Where: Used for removing aquatic vegetation Floating cutter / weed harvester where water is deep.

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No Management Trigger Basic description of management Labour method Method details Motivation and frequency measure summary measure Within-floodplain or valley-bottom Where: Only relevant to unchannelled portions mechanical clearing: of reedbed with high conservation importance e.g. All-terrain or amphibious as part of a biodiversity management plan. harvesters; track excavator Operates within the floodplain or wetland where soil conditions permit access. 1.2.3 Chemical None Involves the spraying or Technical specifications differ Where: Very limited application in reedbeds; control wiping with chemical according to the species’ uptake of on small scale. poison. poison. Follow-up removal of plant matter from watercourse is required as per manual / mechanical details. 1.2.4 Burning None Involves the controlled Appropriate weather conditions Where: Only appropriate where there are no burning of designated especially wind. Specialised fire threats to infrastructure / public and where stands of reeds. management teams with equipment sufficiently dry / dead material is present to (e.g. blowers) and fire-fighting burn. Useful in dense, dry stands of reeds. precautions in place. 1.2.5 Manipulation No EIA Involves the release of Effective in that no follow-up clearing Where: Only relevant to dams, impounded of water levels trigger. water through is required; the management strategy rivers and man-made lakes; draw-down must impoundment valves or controls growth and expansion of persist for a lengthy period to cause Water Act: the lowering of an outlet reeds droughting of littoral reedbed vegetation. Gen. Auth weir. (TBC) 1.3 Riparian / GN 546 Limited to removal of large areas (≥300m2) Why: Retain dam wall structural integrity. marginal (12,13,14) of vegetation in dry detention ponds and Ensure conveyance or storage capacity. vegetation GN 546 dam walls, which is usually a combination of Facilitate recreational use of grassed dry (12,13,14) alien and indigenous. detention ponds

Clearing of indigenous riparian vegetation is When: as needed; annually for detention generally only envisaged where there is a ponds/dams. 1.3.1 Manual threat of flooding and no alternative to CCT employees or casual Workers use slashers, pangas or Where: Dam walls or similar steep areas removal channel capacity, confirmed by specialist labourers clear vegetation scythes to cut vegetation or tree- where vehicle access is problematic. input. Where the integrity of infrastructure by hand. Labour intensive. poppers to pull young trees. Material such as pipelines, gabions, footbridges, loaded onto vehicle (e.g. tractor with dam walls etc is threatened removal of trailer). vegetation (regardless of whether it is Trees that pose a risk to dam wall indigenous or alien) will be necessary. safety / integrity are felled if required.

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No Management Trigger Basic description of management Labour method Method details Motivation and frequency measure summary measure 1.3.2 Mechanical CCT employees or casual Cut material loaded onto vehicle (e.g. Where: Dam walls or similar steep areas removal In cases where vegetation management / contract labourers clear tractor with trailer). where vehicle access is possible. Large around dams / dam walls, which are grass or low shrubs using areas which require tractor mowers. registered as Dams with a Safety Risk in brush cutters, or tractor terms of the NWA legislation (section 120), mowers. is necessary, the requiremens of routine inspection / maintenance plans are to be adhered to,

Although clearing of alien vegetation does not trigger the listed activities, best practise methods will nevertheless be followed.

1.3.3 Biocontrol None Involves the release of Technical specifications differ Where: Only relevant to some plant species at biocontrol agents (e.g. according to the biocontrol agent densities that will support the biocontrol agent. insects) into populations of the target species. Target species are alien invasives. 1.3.4 Chemical None Involves the painting of cut Technical specifications differ Where: All waterbodies where infestation is control stumps or spraying of according to the species’ uptake of very dense; follow-up removal as per manual / young re-growth of alien poison. Follow-up removal of plant mechanical details. vegetation with chemical matter from watercourse is required poison. as per manual / mechanical details. 1.3.5 Burning None Involves the controlled Appropriate weather conditions Where: Only appropriate where there are no burning of designated especially wind. Specialised fire threats to infrastructure / public and where marginal vegetation management teams with equipment sufficiently dry / dead material is present to (e.g. blowers) and fire-fighting burn. Useful in dense, dry stands of reeds. precautions in place.

2 Erosion Control

2.1 River channel GN 544 River channel profile enhancement would Manual and mechanical  Minor earthwork to widen channels Where: Narrow, high energy watercourses or profile (16, 18, 39, trigger authorisation requirements for earth and reduce the gradient profile of in-filled channels and their adjacent wetlands enhancement 45) moving activities and excavation, and banks. where increased depths and velocities cause removal or moving of materials from  Stabilising eroded earth erosion, and where improved biodiversity GN 546 watercourses. embankments and channel beds value can be realised.

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No Management Trigger Basic description of management Labour method Method details Motivation and frequency measure summary measure (16, 24) with geotextiles, gabions etc.  Rehabilitation of new banks Why: To reduce erosion potential (by including vegetation planting. managing flow depth and velocities) and improve biodiversity. River channel profile enhancement is also undertaken during small scale stream rehabilitation projects.

When: Infrequent. As needed. 2.2 Construction, GN 544 The installation, expansion and Manual and mechanical  Clearing work areas of vegetation. Where: Banks and beds of watercourses. maintenance (11, 16, 18, maintenance of various erosion control  Preparation of earth bed. and expansion 39, 45) measures would trigger authorisation  Temporary diversion of water away Why: Reduce or prevent erosion, to protect / of erosion requirements if the infrastructure covers from working bank. reinforce infrastructure such as sewer lines, control GN 546 ≥50 m2, or≥10m2within sensitive  Manual placement/packing of manholes, water pipe crossings, footbridges, infrastructure (16, 24) geographical areas, or infilling/ excavation structure e.g. gabions. stormwater outlets etc. 3 of ≥5 m .  Minor rehabilitation/re-vegetation works. When: Infrequent. As needed. These include: Rockpile weirs, riprap linings, sandbag weirs, gabions, geocells, articulated concrete blocks, geofabrics. 3 Sediment Management

3.1.Construction, GN 544 The construction and expansion of sediment Manual and mechanical  Clearing work areas of vegetation. Where: Beds of watercourses and maintenance (11, 16, 18, traps would trigger an authorisation  Preparation of earth bed. waterbodies. and expansion 40) requirement if the infrastructure covers  Manual placement/packing of of sediment ≥50m2. structure e.g. gabions. Why: Prevent excessive sedimentation of traps / GN 546  Concrete works during watercourses which poses a flood risk to retention (16, 24) Removal or infilling of material of ≥5m3 will construction. property, infrastructure and public safety and areas also be required during construction and  Minor rehabilitation/revegetation which may reduce ecological functioning.

operation (maintenance) of the structure. works.  Repair of structure when necessary When: Infrequent. As needed. 3.2 Manual/ GN 544 Only silt removal ≥5m3 for non-maintenance Why: Improved hydrological functioning of the mechanical (18) activities, in certain environments, triggers system, leading to improved environmental sediment the need for authorisation. When conditions and reducing flood risk, which removal from undertaken for maintenance activities and poses a threat to property, infrastructure and sediment traps covered by an approved EMPr which public safety. Removal of contaminated / retention addresses maintenance activities, no other sediments contributes to water quality areas and authorisation is needed. improvement. other stormwater Hence this item includes sediment removal When: Infrequent. As needed (usually Annual

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No Management Trigger Basic description of management Labour method Method details Motivation and frequency measure summary measure infrastructure during minor construction activities such as or less frequently). e.g. culverts construction of litter traps etc. and coastal stormwater outlets

Manual: Use of spades and buckets, labour Where: Extremely localised areas in high- can walk to the location of the importance watercourses; in stormwater clearing activity. Small team of management infrastructure e.g. culverts and workers may undertake limited coastal outlets where machine access is not removal by hand. possible Mechanical: Clearing from banks: Where: Sediment traps or designated Usually a longboom excavator (13m sediment deposition / retentions areas or 21m) on tracks with water bucket is which may be up to 500 m2, within channels or used, depending on the size of the vleis, where they often are associated with sediment trap / retention area. inlet / outlet structures. Material usually removed from site via tractor/truck and trailer after the material has dried out somewhat.

In-channel clearing: Mud-dozer may operate within the designated sediment retention area in the channel, pushing material into position for removal by excavator. Floating excavator is sometimes used. 3.3 Manual/ Mechanical Clearing from banks: Where: Beds of watercourses and water mechanical Usually a longboom excavator (13m bodies. sediment or 21m) on tracks with water bucket is removal from used. On rare occasions a drag line canals and may be used. Material usually river channels removed from site via tractor/truck and trailer after the material has dried out somewhat (usually within 2 weeks).

In-channel clearing:

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No Management Trigger Basic description of management Labour method Method details Motivation and frequency measure summary measure Mud-dozer within the channel, pushing material into position for removal by excavator. Floating dredger is sometimes used. 4 Channel enclosure

4.1 Conversion of GN 544 Conversion of open engineered stormwater Manual and mechanical  Clearing of stormwater channel. Where: Engineered open stormwater an open (16,45) channels (in low cost housing / informal  Temporary diversion of stormwater. channels in low cost housing and informal engineered areas that are subject to extreme levels of  Preparing trench bedding. settlement areas with no natural drainage, and channel into a GN 546 pollution due to disposal of liquid and solid  Laying pipe and backfill. where there is an associated health and closed pipe/ (16, 24) waste into these open systems) to a closed  Closing temporary diversion. safety risk due to the stormwater becoming culvert or underground pipe/ culvert system contaminated by liquid and solid waste that is system. inappropriately disposed of into these open stormwater systems.

Why: Enclosure of stormwater channels under these very specific circumstances will reduce the health risk for adjacent communities, and will furthermore prevent pollution of downstream receiving watercourses.

When: Very infrequent. As needed. 5 Litter and debris management

5.1 Litter and GN 544 Removal of debris from a watercourse may Mechanical: Removal from banks: Where: Beds of watercourses and water debris removal (18) include removal of soil, sand, shells, shell Most removal of large An excavator e.g. longboom bodies, stormwater management using either grit, pebbles or rock. debris would be done excavator (13m or 21m) may be infrastructure e.g. litter traps, culverts, outlets mechanical or mechanically, and usually used. Material usually removed from manual (Litter removal itself does not trigger the involves an excavator, and site via tractor/truck and trailer. Why: Removal of litter is required for water methods. regulations) tractor/trailer for material quality improvement, hydrological functioning removal. and aesthetic reasons.

When: As needed. 5.2 Removal of GN 544 Limited to the removal of structures where Manual and mechanical  Demolishing structures by hand or Where: Narrow watercourses where structures to (18) ≥5m3 of material is removed where work is using an excavator. structures are impeding flow reduce water not for maintenance purposes.  Removal of structures or pieces obstruction The management action is unlikely to be thereof from the banks. Why: To improve flow, Removal of structures triggered during the removal of structures,  Removal from the area by truck. will improve the hydrological functioning of the unless ≥5 m3 of natural material is removed system

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No Management Trigger Basic description of management Labour method Method details Motivation and frequency measure summary measure during the process of removal of the structure/s. When: Infrequent. As needed. 5.3 Construction, GN 544 The construction of any infrastructure of Manual and mechanical  Clearing work areas of vegetation. Where: Beds of watercourses and maintenance (11, 16, 18, ≥50 m2 within a watercourse, or ≥10 m2  Preparation of earth bed. waterbodies. and expansion 45) within specific geographical areas, or  Removal of sediment. of litter infilling/dredging of >5 m3will trigger an  Concrete works during Why: Capture water-borne litter and therefore management GN 546 authorization requirement. construction. facilitate its collection from a single accessible infrastructure (16, 24)  Minor rehabilitation/ revegetation location. such as litter works. traps, cross When: Infrequent. As needed. nets & booms 6 Construction and maintenance of minor stormwater infrastructure

Construction, GN 544 In some cases changes in catchment Manual and mechanical Construction activities would typically Where: Watercourses, existing stormwater maintenance and (11,16, 18, hydrology or sediment loads requires the include: infrastructure, outlets on beaches. expansion of minor 39, 40) installation of a new works, such as Manual labour will be used  Concrete works. stormwater additional or larger pipe culverts. for minor brickworks and  Vegetation removal during Why: Regular maintenance of stormwater infrastructure. GN 546 site preparation. construction, and vegetation infrastructure will ensure proper functioning (16, 24) Straightforward and on-going repair-work management during maintenance. and prevent structure failure. Culverts allow required to ensure that the network of Bulldozer and excavators  Securing vehicle access to the site water to flow underneath a road or other stormwater conduits, inlets outlets, and used as well as truck and and delivering materials. feature which otherwise restricts water protection measures continue to function trailer for removing  Labour intensive construction and movement. Headwalls act as stabilizing according to system requirements. material. maintenance. structures and prevent erosion. When: Construction: Infrequent, as required. Maintenance: Regular inspections will determine the frequency of maintenance. 7 Maintenance of stormwater attenuation infrastructure

7.1 Weirs GN 544 Occasional and regular “housekeeping” of Manual and mechanical Maintenance activities, including Where: Watercourses 7.2 Retention/ (16,18) attenuation infrastructure, from dams to those required in terms of detention flood embankments, to grassed swales and Bulldozer and excavators maintenance / operational manuals Why: Maintenance of weirs, dams, and flood GN 546, SUDS facilities to ensure that they continue used as well as truck and (where such manuals exist), for protection embankments is necessary to ponds an dams (12) to function according to system trailer for removing example: ensure integrity of the infrastructure and thus regisrered in requirements. material.  Sediment removal / reshaping of the ability to continue providing attenuation, terms of the detention .ponds & SUDS flood protection and/or water quality National Water Maintenance on specific registered dams  Vegetation management / removal. improvement functions. In systems registered Act as dams includes: outlet valves and pipes,  Minor concrete works to repair in terms of the National Water Act’s Dam embankments, spillway, erosion control infrastructure such as inlet / outlet Safety Regulations, maintenance is a

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No Management Trigger Basic description of management Labour method Method details Motivation and frequency measure summary measure with a safety areas, stormwater outlets, measuring structures, valves, overflow legislated requirement. risk. notches, nest removal from embankments. structures, gabions etc. 7.3 Flood Maintenance area extends for at least 10m  Purging of silt from scour valves When: Infrequent. As required. protection downstream of toe of dam embankments  Removal of bird / insect nests that may compromise integrity of banks embankments/ and retaining walls. berms  Embankment repair may also 7.5 Other dams/ involve mechanical earth works. ponds. (Excludes new or expansion of existing structures that will increase their capacity). 8 Recreational access

8.1 Construction, GN 544 Minor works to integrate public open space Manual and mechanical Construction activities on footbridges, Where: Watercourses. maintenance (11, 16, 18, use with the stormwater network within the boardwalks, paths and crossings and expansion 39, 40, 45) CCT. would entail: Why: Allow recreational access to, and of footbridges,  Securing vehicle access to the site crossing of watercourses. boardwalks or GN 546 and delivering materials. bird hides. (16, 24)  Labour intensive construction. When: Construction of new infrastructure is  Concrete / timber work. infrequent. Maintenance of existing  Clearing of vegetation in the infrastructure will be determined by regular footprint of the structure. inspections. 9 Management of estuaries / river mouths

Management of GN 544 Mechanical Activities may include: Where: River / estuary mouths river / estuary (18)  A mud dozer to move sand / silt mouth from the mouth. Why: To prevent flooding and damage to infrastructure or dune cordons. 9.1 Breaching:  Stockpiling of sand adjacent to

removal of mouth. When: Infrequent. Undertaken as and when sand bars needed under the following specific deposited in circumstances: if a sandbar has formed mouth across the mouth resulting in high water levels 9.2 Straightening: and backup behind the sandbar, or if weather redirecting forecast predicts heavy rainfall. If extreme

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No Management Trigger Basic description of management Labour method Method details Motivation and frequency measure summary measure meandering mouth meander threatens infrastructure such mouth across as roads, railway lines, water / sanitation the shortest reticulation, or buildings. route directly towards the sea

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APPENDIX D

RESTRICTIONS ON METHODS EMPLOYED FOR STORMWATER MAINTENANCE / MANAGEMENT DEPENDING ON THE TYPE AND IMPORTANCE CATEGORY OF WATERBODY

NOTE: The restrictions presented below have only been tabled for three of the nine proposed measures. Only these three measures were addressed in this manner because they represent the measures with the largest areal extent, where the footprint of the works is potentially large and not necessarily focused on a particular piece of infrastructure. For these three, there is value is limiting them depending on the importance of the receiving watercourse.

For the other measures, there is little or no value in specifying a range of limitations since they would, by their very nature, not be applied as widely, and in any event, a set of generic principles for construction and maintenance, that would be applicable to all waterbody types, have been defined in the EMPr. These generic principles are to be adhered to during operations.

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Table D1. Restriction on methods for floating and submerged aquatic vegetation removal for different types and importance categories of waterbody. Waterbody types are from Table 4 and Importance Ranking from Table 5.

Importance ranking for Acceptable methods with appropriate restrictions Watercourse stormwater maintenance and Type management measures 1) Rivers: HIGH (Category 1 or 2) Vegetation removal not typically required in such systems (aquatic vegetation seldom becomes problematic), however if required, then the same constraints as for Medium Upland Importance systems (below), should be applied. Gorge Foothill MEDIUM (Category 3) Manual, with machine only to collect / load dumped / dry material, single track pedestrian access to channel; areas for temporary storage to be outside of riparian strip; machine access track not to be closer than 5 m from top of bank; pre-identified (& limited) stockpiles. LOW (Category 4 or 5) Manual or mechanical as desired; range of machinery; bank channelisation acceptable, but limit to one side (see EMPr for general guidelines, but implement only as far as practical) 2) Rivers: HIGH (Category 1 or 2) Manual only and / or with raft-collection; labour to carry to temp storage / loading area for truck which must be >10 m from floodplain/ riparian edge in designated areas; maximum Lowland storage 2 two weeks Lowland with floodplain MEDIUM (Category 3) Manual with raft-collection or long-boom machine on bank only to collect hand-pulled material, access track for machine limited to one path per 1 km river length and not to be closer than 1 m from top of bank; no steepening of bank / channelization allowed (track machine travelling to and fro along bank to access water surface); if access across floodplain required, this to follow stringent guidelines in the EMPr. LOW (Category 4 or 5) Manual or mechanical as desired; range of machinery incl. mud dozer, drag-lines; bank / berm formation acceptable (see the EMPr for general guidelines, but implement only as far as practical) 3) Wetlands: HIGH (Critical Biodiversity Area) Manual only; stockpiling by hand outside of wetland buffer; removal by machine from Wetland stockpile only. transitional rivers; MEDIUM (Critical Ecological Manual only to prevent channelization with long-boom machine on edge only to collect Valley-bottom Support Area / Category 3) hand-pulled material, access track not to be closer than 1 m from top of bank; if access wetlands; across floodplain required, this to follow stringent guidelines in the EMPr. Floodplain LOW (Other Ecological Support Manual or mechanical; berms for machine travel within wetland acceptable if valley bottom wetlands Areas / Category 4 or 5) of low Importance, but not to prevent flow – see guidelines in the EMPr. 4) Wetlands: HIGH (Critical Biodiversity Area) Manual only; stockpiling by hand outside of wetland buffer; removal by machine from seeps stockpile only; pedestrian access lines through seep to be brush-cut. MEDIUM (Critical Ecological Manual only to prevent channelization with long-boom machine >1 m from edge only to Support Area) collect hand-cut material, access track not to be closer than 1 m from edge of seep); and only one access point to the edge per 100m; pedestrian access lines through seep to be brush-cut. LOW (Other Ecological Support Manual or mechanical; berms for machine travel within wetland acceptable but not to Areas) prevent flow – see guidelines in the EMPr. 5) Wetlands: HIGH (Critical Biodiversity Area) Manual only or with raft / weed harvester (where Potamogeton is target); stockpiling by hand outside of wetland buffer; removal by machine from stockpile only Flat & depressions MEDIUM (Critical Ecological Manual only to prevent disturbance / deepening with long-boom machine on edge only to Support Area) collect hand-pulled material, alternatively floating weed harvester; access track not to be closer than 5 m from edge unless very large system; if access across littoral / marginal vegetation required, this to follow stringent guidelines in the EMPr. LOW (Other Ecological Support Manual or mechanical; berms for machine travel within wetland acceptable but not to Areas) prevent flow – see guidelines in the EMPr. 6) Wetlands: HIGH (Critical Biodiversity Area) Not applicable (High and Medium Importance categories do not exist for DAMS

Dams MEDIUM (Critical Ecological Support Area) LOW (Other Ecological Support Manual or mechanical as desired Areas) 7) Estuaries HIGH Manual with raft-collection. Mechanical removal to be limited to floating weed harvester. Labour to carry to temp storage / loading area for truck which must be >10 m from floodplain edge in designated areas; maximum storage time 2 weeks;

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Table D2. Restriction on methods for reedbed and emergent in-channel vegetation control for stormwater management, for different types and importance categories of waterbody.9

Importance ranking for Acceptable methods with appropriate restrictions Watercourse stormwater maintenance and Type management interventions (Ecological Priority (City)) 1) Rivers: HIGH (Category 1 or 2) Not applicable (reedbed formation does not occur in these river types)

Upland MEDIUM (Category 3) Gorge Foothill LOW (Category 4 or 5) 2) Rivers: HIGH (Category 1 or 2) Only for functional (e.g. maintaining hydraulic flow) not aesthetic reasons (e.g. mowing or reed trimming). Manual only; temp storage >10 m from floodplain/ riparian edge in Lowland designated areas; 2-yr cycle of removal; if access across floodplain required, this to follow Lowland with stringent guidelines in the EMPr. floodplain MEDIUM (Category 3) Only for functional (e.g. maintaining hydraulic flow) not aesthetic reasons (e.g. mowing or reed trimming). Manual with long-boom machine on bank only to collect hand-cut reeds, access track for machine limited to one path per 1 km river length (incl. through floodplain, which would have to be constructed on berm); in-house check on hydrological changes; 2-yr cycle of removal; if access across floodplain required, this to follow stringent guidelines in the EMPr. LOW (Category 4 or 5) Manual or mechanical as desired; range of machinery BUT depth of excavation of (reedbed) root material to be set on site (e.g. permanent stake or level of downstream weir etc. not to cause ponding / deepening of channel (see EMPr for general guidelines, but implement only as far as possible) 3) Wetlands: HIGH (Critical Biodiversity Area) Only for functional (e.g. maintaining hydraulic flow) not aesthetic reasons (e.g. mowing or Wetland reed trimming) and all woody alien. Manual only; stockpiling by hand outside of wetland transitional margin; removal by machine from stockpile only. rivers; Valley-bottom MEDIUM (Critical Ecological Only for functional (e.g. maintaining hydraulic flow) not aesthetic reasons (e.g. mowing or wetlands; Support Area / Category 3) reed trimming). Manual only; access track not to be closer than 1 m from top of bank; if Floodplain access across valley bottom required, this to follow stringent guidelines in the EMPr wetlands LOW (Other Ecological Support Manual or mechanical; depth of excavation of (reedbed) root material to be set on site; Areas / Category 4 or 5) berms for machine travel within wetland acceptable but not to prevent flow – see the EMPr for guidelines 4) Wetlands: HIGH (Critical Biodiversity Area) Only for functional (e.g. maintaining hydraulic flow) not aesthetic reasons (e.g. mowing or seeps reed trimming). Manual only; stockpiling by hand outside of wetland buffer; removal by machine from stockpile only; pedestrian access lines through seep to be brush-cut. MEDIUM (Critical Ecological Only for functional (e.g. maintaining hydraulic flow) not aesthetic reasons (e.g. mowing or Support Area) reed trimming). Manual only to prevent channelization with long-boom machine >1 m from edge only to collect hand-cut material, access track not to be closer than 5 m from edge of seep); and only one access point to the edge per 100m; pedestrian access lines through seep to be brush-cut and removed from seep. LOW (Other Ecological Support Manual or mechanical; berms for machine travel within wetland acceptable but not to Areas) prevent flow; depth of excavation of (reedbed) root material to be set on site. 5) Wetlands: HIGH (Critical Biodiversity Area) Only for functional (e.g. maintaining hydraulic flow) not aesthetic reasons (e.g. mowing or reed trimming). Manual only; stockpiling by hand outside of wetland buffer; removal by Flat machine from stockpile only &depressions MEDIUM (Critical Ecological Only for functional (e.g. maintaining hydraulic flow) not aesthetic reasons (e.g. mowing or Support Area) reed trimming). Manual only; stockpiling by hand >5 m from edge; removal by machine from stockpile; access track not to be closer than 5 m from edge. LOW (Other Ecological Support Manual or mechanical; berms for machine travel within wetland acceptable but not to Areas) prevent flow; depth of excavation of (reedbed) root material to be set on site / determined according to aims e.g. preventing re-growth (detention ponds). 6) Wetlands: HIGH (Critical Biodiversity Area) Importance category does not exist for dams (all “Low”).

9Note: removal of indigenous vegetation in High and Medium Importance systems is precluded unless approved by CCT Environmental Team.

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Dams MEDIUM (Critical Support Area) Importance category does not exist for dams (all “Low”). LOW (Other Ecological Support) Manual or mechanical as desired . 7) Estuaries HIGH Only for functional (e.g. maintaining hydraulic flow) not aesthetic reasons (e.g. mowing or reed trimming). Manual only; temp storage >10 m from edge in designated areas; 2-yr cycle of removal; if access across floodplain required, this to follow stringent guidelines in the EMPr.

Table D3. Restriction on methods for erosion control structures for different types and importance categories of waterbody

Importance ranking for Acceptable methods with appropriate restrictions Watercourse stormwater maintenance and Type management interventions (Ecological Priority (City)) 1) Rivers: HIGH (Category 1 or 2) Limited to where no channel profile enhancement at all possible and where built infrastructure is directly threatened; minimise height / steps in gabions to allow riparian Upland MEDIUM (Category 3) planting; ensure internal / external engineering and ecologist input; softest options in Gorge terms of materials (see ranked structures in EMPr, Box 4) Foothill LOW (Category 4 or 5) As required; use softest options possible; allow marginal / instream vegetation to be establish where possible e.g. low steps for gabions; removal of alternate blocks in reno mattress for root establishment – see the EMPr. 2) Rivers: HIGH (Category 1 or 2) It is unlikely naturally functioning systems will receive significant quantities of stormwater and require erosion control. Nonetheless, if required, then the same Lowland constraints as for Medium Importance systems (below), should be applied. Lowland with floodplain MEDIUM (Category 3) Low steps for gabions / reno or preferably sub-surface with earth overlay 0.5 m, where AND maintenance of channel flow essential, but allowing overtopping onto floodplain. LOW (Category 4 or 5) As required; use softest options possible.

3) Wetlands: HIGH (Critical Biodiversity Area) Gabion weirs< 1 m above the natural ground surface are permitted; use softest options Wetland in terms of materials (see ranked structures e.g. geocells); aim to improve channel / transitional wetland interface; replanting plan essential. rivers; Valley-bottom MEDIUM (Critical Ecological Gabion weirs < 1 m; use softest options in terms of materials; bank gabions in wetlands; Support Area / Category 3) channelled valley bottoms to be limited to where erosion is serious; maximum length Floodplain 100 m; single gabion rise only i.e. protrude above ground level by < 1 m; set low to wetlands allow flow in to valley-bottom; reno footprint only part of gabion weir; replanting plan essential. LOW (Other Ecological Support As required; use softest options possible. Areas / Category 4 or 5) 4) Wetlands: HIGH (Critical Biodiversity Area) Aim to improve channel / wetland interface through reinstating eroded channel base seeps level; gabion weirs < 0.5 m above the natural ground surface are permitted; for erosion MEDIUM (Critical Ecological use softest options in terms of materials (see ranked structures e.g. trash racks, Support Area) geocells); replanting plan essential. LOW (Other Ecological Support As required; use softest options possible. Areas) 5) Wetlands: HIGH (Critical Biodiversity Area) Erosion control not typically needed in such systems. For managing localised erosion at stormwater outlets and culverts, See best practice activities presented for measure Flat & MEDIUM (Critical Ecological 6.1 (Construction, maintenance and expansion of minor stormwater infrastructure). depressions Support Area) LOW (Other Ecological Support Areas) 6) Wetlands: HIGH (Critical Biodiversity Area) Importance category does not exist for dams (all “Low”).

Dams MEDIUM (Critical Ecological Importance category does not exist for dams (all “Low”). Support Area) LOW (Other Ecological Support As required Areas) 7) Estuaries HIGH Unlikely that this will be required. If required, ensure low steps for gabions, reno or preferably sub-surface with earth overlay 0.5 m, allowing overtopping onto floodplain.

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Table D4. Restriction on methods for sediment removal for different types and importance categories of waterbody.

Importance ranking for Acceptable methods with appropriate restrictions Watercourse stormwater maintenance and Type management interventions (Ecological Priority (City)) 1) Rivers: HIGH (Category 1 or 2) Manage sediment at source as per catchment management best practice. Sediment removal unlikely for such systems but if required may take place from sediment traps / Upland designated sediment removal areas or stormwater infrastructure (hand or machine); Gorge Location of these with in-house ecologist input (+ engineer). Ensure no channel Foothill modification allowed from sediment removal process. MEDIUM (Category 3) Manage sediment at source as per catchment management best practice. Sediment removal unlikely for such systems but if required may take place from sediment traps / designated sediment removal areas or stormwater infrastructure (hand or machine); Location of these with in-house ecologist input (+ engineer). Ensure no channel modification allowed from sediment removal process. LOW (Category 4 or 5) Sediment removal unlikely for such systems but where required manual or mechanical methods as desired; depth of excavation of to be set on site (e.g. permanent stake or level of downstream weir) not to cause ponding / deepening of channel; channelization for access ok but restrict to one bank 2) Rivers: HIGH (Category 1 or 2) From sediment traps / designated removal areas or stormwater infrastructure (hand or machine); location and construction of these with in-house senior ecologist input (+ Lowland & engineer). Lowland with Sediment traps to be located preferably upstream of important floodplain or valley floodplain MEDIUM (Category 3) bottom reaches to protect them - rather than traversing through floodplain / valley bottom; If unavoidable, and access across floodplain / valley bottom required, this to AND follow stringent guidelines in the EMPr. No excavation in unchannelled wetlands without a site-specific Maintenance Plan– 3) Wetlands: preferably allow depositional process / trap unnatural sediment upstream in “designated Wetland sediment retention area”. Sediment removal in such wetlands may include the transitional supported reeds (subject to site specific Maintenance Plan) rivers; Valley-bottom LOW (Category 4 or 5) Manual or mechanical as desired; range of machinery including mud dozer; depth of wetlands; excavation of to be set on site (e.g. permanent stake or level of downstream weir) not to Floodplain cause ponding / deepening of channel; berms / channelization for access permitted, but wetlands care to maintain hydrological pattern / lateral flooding should be exercised. 4) Wetlands: HIGH (Critical Biodiversity Area) Sediment removal unlikely to be necessary in wetland seeps, but if required around seeps stormwater infrastructure (inlets etc.), no channel modification allowed for sediment removal i.e. manage sediment at source as per catchment management best practice MEDIUM (Critical Ecological Sediment removal unlikely to be necessary in wetland seeps, but if required around Support Area) stormwater infrastructure (inlets etc.), no channel modification allowed for sediment removal i.e. manage sediment at source as per catchment management best practice. LOW (Other Ecological Support Sediment removal unlikely to be necessary in wetland seeps. No specific restrictions if Areas) required around stormwater infrastructure (inlets etc.) 5) Wetlands: HIGH (Critical Biodiversity Area) Manual only at designated sediment retention areas and at inlet / outlet structure.

Flat MEDIUM (Critical Ecological Manual or mechanical, but from designated sediment retention areas and at inlet / &depressions Support Area) outlet structure; depth of excavation of to be set on site (e.g. permanent stake) to prevent deepening; stockpile >5 m from edge, outside riparian fringe; access track not to be closer than 5 m from edge unless very large system; if access across marginal / littoral vegetation required, this to follow stringent guidelines in the EMPr. Sediment removal in such wetlands may include the supported reeds (subject to site specific Maintenance Plan) LOW (Other Ecological Support Manual or mechanical as desired; range of machinery incl. mud dozer; depth of Areas) excavation of to be set on site (e.g. permanent stake or level of downstream weir) not to cause ponding / deepening. 6) Wetlands: HIGH (Critical Biodiversity Area) Importance category does not exist for dams (all “Low”).

Dams MEDIUM (Critical Ecological Importance category does not exist for dams (all “Low”). Support Area) LOW (Other Ecological Support Manual or mechanical as desired; range of machinery incl. mud dozer; depth of Areas) excavation of to be set on site (e.g. permanent stake or level of downstream weir) not to

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cause ponding / deepening. 7) Estuaries HIGH Sediment removal in estuaries will tend be limited to designated areas at outlet mouth management and at river inlets at the upstream extent of the estuary unless part of an approved rehabilitation plan. Further details are provided in Section 13 of the EMPr.

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APPENDIX E

ASSESSMENT OF THE IMPACTS OF STORMWATER MAINTENANCE / MANAGEMENT MEASURES ON WATERBODIES WITHIN CCT

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Key terms for use with impact table (Table E3)

Table E1. Categories of different rivers and wetlands based on hydrogeomorphology

Type grouping for Stormwater System type River / Wetland Hydrogeomorphic Type Classification Maintenance Assessment

 Gorge (GO)  Mountain streams and transitional rivers (MS)  Upland floodplain rivers (UFP) Group 1 – Gorges, mountain and foothill  Foothill cobble bed (FCB) rivers  Foothill gravel bed (FGB)

Rivers  Lowland rivers (LR)  Lowland floodplain river (LLFP) Group 2 – Lowland and lowland floodplain rivers  Wetland transitional rivers (WT)

Inland systems Group 3 - Valley bottom and floodplain  Valley-bottom wetlands (VBW) and wetlands; wetland transitional rivers including floodplain wetlands

 Seeps (S) Group 4 - Seeps

 Flats & Depressions (FD) Wetland Group 5 - Flats and depressions  Depressions Dams (D)  Note: these include natural and semi- natural features, but exclude features associated with Waste Water Treatment Group 6 - Dams Works (WWTW).

 River mouth (RM)  Permanently Open (PO) Estuaries Estuaries Group 7 - Estuaries  Temporary Open/Closed (TOC)  Including marinas.

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Table E2. Impact ratings for the interventions

Category Rating levels Explanation Extent Site: Extending to <500 m reach of river or <10% of the area of a wetland Local (Loc.) Extending up to < 3 km from site or up to 50% of wetland Regional (Reg.) Extending over a full river reach / wetland which is considered to have implications for biodiversity within the CCT Municipality National (Nat.) Affecting a whole category of waterbodies, which is deemed to have implications for national biodiversity Magnitude Low (L) Natural and/or social functions and/or processes are negligibly altered. Medium (M) Natural and/or social functions and/or processes are notably altered. High (H) Natural and/or social functions and/or processes are severely altered. Duration Temporary Once-off occurrence, implemented over a discrete period (e.g. weeks). (Temp) Short term (ST) Measure is repeated at some interval (e.g. annually), but the impact is considerably shorter-lived than the period required for recovery, such that the ecosystem remains in its pre- disturbance state >80% of the time Medium term the impact of the management measure is shorter-lived than the period required for recovery, (MT) such that the ecosystem remains in its pre-disturbance state for > 40 - 80% of the time and in some partially-recovered state for some of the time Long term (LT) the impact of the management measure persists >60% of the time between impacts, such that the ecosystem exists in its pre-disturbance state for <40% of the time and in some only partially- recovered state for the majority of the time Permanent the impact of the management measure is such that the ecosystem cannot recover between the (Perm) implementation of maintenance measures, and persists in some modified form (depending on the magnitude of the impact) Probability/ Improbable (IMP) Little or no chance of occurring (< 10% chance of occurring) frequency Possible (POSS) 10 – 39 % chance of occurring Probable (PRO) 40 - 59% chance of occurring Highly probable 60 – 95% chance of occurring (HPRO) Definite (DEF) >95% chance of occurring. Status POS Positive A benefit. NEG Negative A cost. Impact No impact A potential concern or impact, which upon evaluation is found to have no impact if the required significance mitigation is undertaken. with Very low (VL) o Temporary or Short-term impacts of low magnitude on site specific scale mitigation Low (L) o Medium-term to permanent impacts, with low magnitude on a site-specific scale. o Temporary to permanent impacts, with low magnitude on a local scale. o Temporary to short-term impacts, with medium magnitude on a local to regional scale. o Medium-term impacts of medium magnitude on a local or smaller scale M – Medium o Permanent impacts of medium or high magnitude on a site-specific scale. o Long-term impacts of medium magnitude on a local scale. o Medium-term impacts of medium magnitude on a regional scale o Medium-term impacts of high magnitude on local scale o Short-term impacts of high magnitude on regional to national scale H – High o Permanent impacts of medium or high magnitude, on a local to national scale, o Long-term impacts of medium or high magnitude, on a regional to national scale, o Medium-term impacts of medium magnitude on a national scale o Medium-term impacts of high magnitude on a regional to national scale

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Table E3. Assessment and rating of environmental impacts identified for all stormwater management measures.

Impact Stormwater Mitigation Watercourse Eco Significance No. management Type Environmental Impact (EMPr

Type priority with

Extent Status

measure Duration section) Magnitude

Frequency mitigation Probability / ACTIVITY OR WATERCOURSE SPECIFIC IMPACTS OF AQUATIC VEGETATION MANAGEMENT

Aquatic Vegetation 1 Management 1.1 Aquatic Note: manual The ongoing eradication or control of aquatic alien vegetation has a Reg. M HPRO POS H 5.1 (submerged / removal only in H positive impact on ecosystem function, through removing the Group 1 M floating) alien or M ecosystems. stresses on water and habitat quality. long invasive vegetation 1.1.1 Manual

management. removal, 1.1.2 Selective and controlled harvesting of indigenous submerged Loc. L-M PRO POS L 5.1 Mechanical aquatic vegetation (Potamogeton) may improve water quality. removal. med

Damage to riparian vegetation through stockpiling of material too Site L IMP NEG VL 5.1 close or on the bank. short

Damage to riparian vegetation from heavy machinery access points Site L IMP NEG VL 5.1 may leave banks bare, increasing erosion potential. short

Disturbance of river bed sediments and resulting increased turbidity / Site L DEF NEG VL 5.1 smothering of or loss of habitat e.g. for fish, invertebrates, frogs. temp The ongoing eradication or control of aquatic alien vegetation has a Loc. L-M HPRO POS L 5.1 positive impact on ecosystem function, through removing the L

stresses on water and habitat quality. med

Selective and controlled harvesting of indigenous submerged Site L-M PRO POS L 5.1 aquatic vegetation (Potamogeton) may improve water quality. med

Damage to riparian vegetation through stockpiling of material too Site L IMP NEG VL 5.1

close or on the bank. temp

Damage to riparian vegetation from heavy machinery access points Site L IMP NEG VL 5.1 may leave banks bare, increasing erosion potential. short Disturbance of river bed sediments and resulting increased turbidity / Site L DEF NEG VL 5.1

smothering of or loss of habitat e.g. for fish, invertebrates, frogs. temp

Appendix J. Technical Assessment Report Page 102

Impact Stormwater Mitigation Watercourse Eco Significance No. management Type Environmental Impact (EMPr

Type priority with

Extent Status

measure Duration section) Magnitude

Frequency mitigation Probability / The ongoing eradication or control of aquatic alien vegetation has a Reg. M HPRO POS H 5.1 Group 2 - positive impact on ecosystem function, through removing the H, M Group 5 stresses on water and habitat quality. long

Selective and controlled harvesting of indigenous submerged Loc. L-M PRO POS L 5.1 aquatic vegetation (Potamogeton) may improve water quality. med

Damage to riparian vegetation through stockpiling of material too Site L POSS NEG VL 5.1 close or on the bank. short

Damage to riparian vegetation from heavy machinery access points Site L POSS NEG VL 5.1 may leave banks bare, increasing erosion potential. short

Disturbance of river bed sediments and resulting increased turbidity / Site L DEF NEG VL 5.1 smothering of or loss of habitat e.g. for fish, invertebrates, frogs. temp The ongoing eradication or control of aquatic alien vegetation has a Loc. L-M HPRO POS L 5.1 positive impact on ecosystem function, through removing the L stresses on water and habitat quality. med

Selective and controlled harvesting of indigenous submerged Site L-M PRO POS L 5.1 aquatic vegetation (Potamogeton) may improve water quality. med

Damage to riparian vegetation through stockpiling of material too Site L IMP NEG VL 5.1 close or on the bank. temp

Damage to riparian vegetation from heavy machinery access points Site L IMP NEG VL 5.1 may leave banks bare, increasing erosion potential. short

Disturbance of river bed sediments and resulting increased turbidity / Site L DEF NEG VL 5.1 smothering of or loss of habitat e.g. for fish, invertebrates, frogs. temp The ongoing eradication or control of aquatic alien vegetation has a Loc. L HPRO POS L 5.1

positive impact on ecosystem function, through removing the Group 6 L

stresses on water and habitat quality. long

Disturbance of river bed sediments and resulting increased turbidity / Site L DEF NEG VL 5.1 smothering of or loss of habitat e.g. for fish, invertebrates, frogs. temp

Appendix J. Technical Assessment Report Page 103

Impact Stormwater Mitigation Watercourse Eco Significance No. management Type Environmental Impact (EMPr

Type priority with

Extent Status

measure Duration section) Magnitude

Frequency mitigation Probability /

Group 1 - Biocontrol agents where they can be introduced are highly effective Reg. M HPRO POS H 5.1 1.1.3 Biocontrol. H,M,L in reducing proliferation of alien vegetation. Group 6 long The ongoing eradication or control of aquatic alien vegetation has a Reg. M HPRO POS H 5.1 positive impact on ecosystem function, through removing the Group 1 M 1.1.4 Chemical stresses on water and habitat quality. long Control.

Chemical sprays on floating plants enter the water column and Loc. M- PRO NEG M 5.1 depending on the chemical can be harmful to non-target species of H med plants and animals.

Dead material left rotting within the waterbody after chemical Loc. M- HPRO NEG L 5.1 spraying will reduce water quality. H

temp

Odour caused by smell of rotting plant matter piled along the banks Loc. L DEF NEG L 5.1 as it dries out – this drying out period is a necessary step in the

removal of the material. temp

The ongoing eradication or control of aquatic alien vegetation has a Loc. L HPRO POS L 5.1

positive impact on ecosystem function, through removing the Group 1 L

stresses on water and habitat quality. long

Chemical sprays on floating plants enter the water column and Loc. L PRO NEG L depending on the chemical can be harmful to non-target species of

short plants and animals.

Dead material left rotting within the waterbody after chemical Loc. L HPRO NEG L 5.1 spraying will reduce water quality.

temp

Odour caused by smell of rotting plant matter piled along the banks Loc. L DEF NEG L 5.1 as it dries out – this drying out period is a necessary step in the

temp removal of the material. The ongoing eradication or control of aquatic alien vegetation has a Reg. M HPRO POS H 5.1 Group 2 - positive impact on ecosystem function, through removing the H,M Group 6 stresses on water and habitat quality. long

Chemical sprays on floating plants enter the water column and Loc. M- PRO NEG M 5.1 depending on the chemical can be harmful to non-target species of H plants and animals. med

Appendix J. Technical Assessment Report Page 104

Impact Stormwater Mitigation Watercourse Eco Significance No. management Type Environmental Impact (EMPr

Type priority with

Extent Status

measure Duration section) Magnitude

Frequency mitigation Probability /

Dead material left rotting within the waterbody after chemical Loc. M HPRO NEG L 5.1 spraying will reduce water quality. med Odour caused by smell of rotting plant matter piled along the banks Loc. L DEF NEG L 5.1 as it dries out – this drying out period is a necessary step in the

removal of the material (social impact). temp

The ongoing eradication or control of aquatic alien vegetation has a Loc. L HPRO POS L 5.1

positive impact on ecosystem function, through removing the L

stresses on water and habitat quality. long

Chemical sprays on floating plants enter the water column and Loc. L PRO NEG L 5.1 depending on the chemical can be harmful to non-target species of plants and animals. short

Dead material left rotting within the waterbody after chemical Loc. L HPRO NEG L 5.1 spraying will reduce water quality. med

Odour caused by smell of rotting plant matter piled along the banks Loc. L DEF NEG L 5.1 as it dries out – this drying out period is a necessary step in the removal of the material. temp The ongoing eradication or control of aquatic alien vegetation has a Loc. L HPRO POS L 5.1

1.1.5. Group 1 - positive impact on ecosystem function, through removing the Manipulation of L Group 6 stresses on water and habitat quality. long water levels.

Water-level manipulation (draw-down; only in dams and regulated Loc. L DEF NEG L 5.1

systems) may result in rotting of stranded vegetation and affect med water quality. 1.2 Reedbed and Note: manual Water quality improvement of stormwater passing through filtration Loc. M PRO POS M-H 5.2 indigenous removal only in H Group 2 - reedbeds and vegetated channels / swales (Typha capensis and - H,M emergent vegetation or M ecosystems Group 4 Phragmites australis) is maximised by optimal reed management. Reg. long management. 1.2.1 Mechanical removal, 1.2.2 Management of reeds like Typha capensis in wetlands improves Loc. L-M PRO POS L-M 5.2 Manual removal. floral biodiversity and wetland structure in instances where it allows -

for re-establishment of a more diverse habitat and flora. Reg. long

Prevention of channel erosion associated with clogged channels. Loc. M PRO POS L-M 5.2

med

Appendix J. Technical Assessment Report Page 105

Impact Stormwater Mitigation Watercourse Eco Significance No. management Type Environmental Impact (EMPr

Type priority with

Extent Status

measure Duration section) Magnitude

Frequency mitigation Probability /

Indiscriminate and frequent clearing of conservation-worthy Loc. M IMP NEG L-M 5.2 vegetated channels and reedbeds destroys habitat and biota. med The incorrect location / failure to remove access roads across Loc. M IMP NEG M 5.2 floodplain or valley bottom may change hydrological patterns and -

cause flooding / erosion or cut off adjacent wetlands. Reg. long

The stockpiling of reeds and emergent plant material too close to or Site L IMP NEG VL 5.2 on the banks of channels or wetland margins causes damage to

short riparian vegetation. Uncontrolled access - denuded banks destroys the riparian zones Loc. M IMP NEG L-M 5.2 alongside reedbed rivers, with a loss of the buffering that these

provide to instream water quality. med

Clearing from both banks destroys the river corridor that riparian Loc. L IMP NEG L 5.2 vegetation provides.

short

Water quality improvement of stormwater passing through filtration Loc. M PRO POS M 5.2 reedbeds and vegetated channels / swales (Typha capensis and L Phragmites australis) is maximised by optimal reed management. long

Prevention of channel erosion associated with clogged channels. Loc. L PRO POS L 5.2

long

Indiscriminate and frequent clearing of conservation-worthy Loc. L POSS NEG L 5.2 vegetated channels and reedbeds destroys habitat and biota. med The incorrect location / failure to remove access roads across Loc. L-M IMP NEG L-M 5.2 floodplain or valley bottom may change hydrological patterns and

cause flooding / erosion or cut off adjacent wetlands. long

Creation / deepening of channels through floodplains / seeps by Site L POSS NEG L 5.2 over-excavating to remove all of root zone. med

The stockpiling of reeds and emergent plant material too close to or Site L PRO NEG L 5.2 on the banks of channels or wetland margins causes damage to

riparian vegetation. med

Appendix J. Technical Assessment Report Page 106

Impact Stormwater Mitigation Watercourse Eco Significance No. management Type Environmental Impact (EMPr

Type priority with

Extent Status

measure Duration section) Magnitude

Frequency mitigation Probability / Denuded banks destroy the riparian zones alongside reedbed rivers, Site L POSS NEG L 5.2 with a loss of the buffering that these provide to instream water

quality. med

Clearing from both banks destroys the river corridor that riparian Site L POSS NEG L-M 5.2 vegetation provides. long

Spillages of hydraulic fluids and or diesel from mechanical plant can Loc. L PRO NEG L 5.2 pollute river and wetland systems, killing resident organisms. temp Management of reeds like Typha capensis in wetlands improves Loc. M HPRO POS M 5.2

floral biodiversity and wetland structure in instances where it allows

Group 5 H,M for re-establishment of a more diverse habitat and flora. long

The stockpiling of reeds and emergent plant material too close to Site M IMP NEG L 5.2 wetland margins causes damage to riparian (littoral, marginal)

vegetation. short

Damage to wetlands from placement of fill over wetland / floodplain Site L-M IMP NEG L 5.2

areas to construct access roads – either as a permanent feature or

exacerbated further by excavation of wetland during removal of temporary fill. med

Water quality improvement of stormwater passing through filtration Loc. L HPRO POS L 5.2 reedbeds and vegetated channels / swales (Typha capensis and Group 5 - L Phragmites australis) is maximised by optimal reed management.

Group 6 short

Indiscriminate and frequent clearing of conservation-worthy Loc. L POSS NEG L 5.2 vegetated channels and reedbeds destroys habitat and biota. med

Creation / deepening of depressions by over-excavating to remove Site M POSS NEG L 5.2 all of root zone leads to steeper side slopes and loss of littoral

habitat. med

Appendix J. Technical Assessment Report Page 107

Impact Stormwater Mitigation Watercourse Eco Significance No. management Type Environmental Impact (EMPr

Type priority with

Extent Status

measure Duration section) Magnitude

Frequency mitigation Probability / The stockpiling of reeds and emergent plant material too close to or Site L DEF NEG VL 5.2 on the banks of channels or wetland margins causes damage to

riparian vegetation. short

Damage to wetlands from placement of fill over wetland / floodplain Site L PRO NEG VL 5.2

areas to construct access roads – either as a permanent feature or exacerbated further by excavation of wetland during removal of temporary fill. short

Spillages of hydraulic fluids and or diesel from mechanical plant can Loc. L PRO NEG L 5.2 pollute river and wetland systems, killing resident organisms. temp Management of reeds like Typha capensis in wetlands improves Loc. M HPRO POS M 5.2

1.2.3 Chemical Group 1 - floral biodiversity and wetland structure in instances where it allows H,M,L for re-establishment of a more diverse habitat and flora. Control. Group 6 long

Chemical sprays near river / wetlands may enter the water column Loc. M- PRO NEG M 5.2

and depending on the chemical can be harmful to non-target species H

of plants and to animals. med

Group 1 - No Trigger, best practice addressed in EMP nonetheless. N/A N/A N/A N/A N/A 5.2 1.2.4 Burning. H,M,L Group 6 N/A Water-level manipulation (draw-down) to control growth of emergent Loc. L PRO NEG L 5.2 1.2.5 Manipulation Group 1 - / littoral vegetation, may have other implications for water quality, L

of water levels. Group 6 and also may have downstream implications as a result of flow short modification.

1.3) Riparian/ Note: manual Group 1 - Improvement in dry-season baseflows, increased moisture levels in Reg. M HPRO POS M-H 5.3 marginal vegetation removal only in H H,M bank soils and longer hydroperiod. Group 2 long

management. or M ecosystems

1.3.1 Mechanical Improved biodiversity value. Reg. M HPRO POS M-H 5.3 removal, 1.3.2 long Manual removal. Lateral erosion / bank instability as a result of felled woody debris Loc. L IMP NEG L 5.3 not being removed from the channel, and / or bank erosion as a

result of slope clearing without replanting or stabilization. med

Appendix J. Technical Assessment Report Page 108

Impact Stormwater Mitigation Watercourse Eco Significance No. management Type Environmental Impact (EMPr

Type priority with

Extent Status

measure Duration section) Magnitude

Frequency mitigation

Probability /

Short-medium term increase in in-stream sediment transport as Loc. L PRO NEG L 5.3 med accumulated sediments exposed to the natural flow. -

short

Disturbance as a result of access roads or paths and camps. Loc. L HPRO NEG L 5.3

short

Improvement in dry-season baseflows, increased moisture levels in Loc. L HPRO POS L 5.3 L bank soils and longer hydroperiod. long Lateral erosion / bank instability as a result of felled woody debris Loc. L POSS NEG L 5.3

not being removed from the channel, and / or bank erosion as a

result of slope clearing without replanting or stabilization. med

Disturbance as a result of access roads or paths and camps. Site L HPRO NEG VL 5.3

short

Group 3 - Improvement in moisture levels in wetlands invaded by terrestrial Loc. M HPRO POS M 5.3 H,M species because of the high water use by alien woody species. Group 6 long Improved biodiversity value. Loc. M HPRO POS M 5.3

long

Loss of habitat where felled vegetation is simply stockpiled within a Loc. L-M IMP NEG L 5.3 wetland. med Disturbance as a result of access roads or paths and camps, Loc. M IMP NEG M 5.3 especially in densely vegetated wetlands where alien species are -

interspersed among natural plants. Reg. long

Improvement in dry-season baseflows in channels because of the Loc. L HPRO POS L 5.3 high water use by alien woody species, and/or increased moisture L levels in subsurface soils and longer hydroperiod. long

Loss of habitat where felled vegetation is simply stockpiled within a Loc. L POSS NEG L 5.3

wetland. med

Appendix J. Technical Assessment Report Page 109

Impact Stormwater Mitigation Watercourse Eco Significance No. management Type Environmental Impact (EMPr

Type priority with

Extent Status

measure Duration section) Magnitude

Frequency mitigation Probability / Disturbance as a result of access roads or paths and camps, Site L HPRO NEG VL 5.3 especially in densely vegetated wetlands where alien species are

interspersed among natural plants. short

Biocontrol agents where they can be introduced are highly effective Reg. M HPRO POS M-H 5.3 Group 1 - 1.3.3 Biocontrol. H,M,L in reducing proliferation of alien vegetation. Group 6 long

1.3.4 Chemical Group 1 - Improvement in moisture levels in wetlands invaded by terrestrial Loc. M HPRO POS M 5.3 H,M,L species because of the high water use by alien woody species. control. Group 6 long Chemical sprays near river / wetlands may enter the water column Loc. M- POSS NEG M 5.3 and depending on the chemical can be harmful to non-target species H

of plants and to animals. med

Group 1 - No Trigger, best practice addressed in EMP nonetheless. N/A N/A N/A N/A N/A 5.3 1.3.5 Burning. H,M,L Group 6 N/A ACTIVITY OR WATERCOURSE SPECIFIC IMPACTS OF EROSION CONTROL Essentially rehabilitation of natural functioning to address erosion. Reg. H DEF POS H 6.1 Multiple positive impacts include biodiversity enhancement,

2.1 River channel Group 1 - improved function, and increased lateral connectivity. Not applicable g 2 Erosion Control. profile H,M Group 4 (not warranted) for Low importance systems. lon enhancement.

Short- term increase in in-stream sediment transport or deposition Loc. L PRO NEG L 6.1

(depending on the ecosystem, position along the river etc.), as the

system adjusts to a new equilibrium. short

Where no other options are available due to space constraints, Loc. L-H PRO POS L-H 6.2 these measures assist in preventing the spread of erosion from - localised nick-points and consequent loss of habitat and Reg.

downstream siltation. (Assumption: for any structure chosen, from

2.2 Erosion control Group 1 - soft options to engineered, the positive impacts associated with the

H,M erm structures. Group 4 prevention of erosion outweigh the negatives). p

Appendix J. Technical Assessment Report Page 110

Impact Stormwater Mitigation Watercourse Eco Significance No. management Type Environmental Impact (EMPr

Type priority with

Extent Status

measure Duration section) Magnitude

Frequency mitigation Probability /

Loss of ecological function: instream / riparian / littoral vegetation Site L-H DEF NEG L-H App B and lateral connectivity; insolation and warming. -

perm Loc. Construction-related impacts, such as water quality impacts Loc. L PRO NEG L App N associated with cement works or washing of construction tools /

vehicles; disturbance of sediments and downstream sedimentation. temp

Prevents the spread of erosion from localised nick-points and Loc. L-M PRO POS L-M App B consequent loss of habitat and downstream siltation. (Assumption:

for any structure chosen, from soft options to engineered, the Group 1 - L positive impacts associated with the prevention of erosion outweigh Group 4 the negatives). perm

Loss of ecological function: instream / riparian / littoral vegetation Site L-M DEF NEG L-M App B and lateral connectivity; insolation and warming. - Loc. perm Construction-related impacts, such as water quality impacts Loc. L PRO NEG L App B associated with cement works or washing of construction tools /

vehicles; disturbance of sediments and downstream sedimentation. temp

ACTIVITY OR WATERCOURSE SPECIFIC IMPACTS OF SEDIMENT MANAGEMENT 3.1 Construction/ Short-term negative impacts of the installation of sediment traps - Loc. L-M PRO NEG L 7.3 expansion of disturbance of bed sediment and pollution from construction Sediment sediment traps/ Group 1 - materials. 3 retention areas. H, M Management. Group 5 temp

More long-lived impacts associated with access to the site e.g. Reg. L-M IMP NEG M 7.3 damage to riparian zones / lateral wetland areas, diversion of natural flow, compaction and dredging (mitigation = to select

appropriate location - see D4). perm

Short-term negative impacts of the installation of sediment traps - Site L PRO NEG VL-L 7.3 Group 1 - L disturbance of bed sediment and pollution from construction -

Group 6 short materials. Loc.

Appendix J. Technical Assessment Report Page 111

Impact Stormwater Mitigation Watercourse Eco Significance No. management Type Environmental Impact (EMPr

Type priority with

Extent Status

measure Duration section) Magnitude

Frequency mitigation Probability / More long-lived impacts associated with access to the site e.g. Loc. L IMP NEG L 7.3 damage to riparian zones / lateral wetland areas, diversion of

natural flow, compaction and dredging (mitigation = to select perm appropriate location - see D4). Sediment traps situated in an appropriate position along a channel in Reg. M HPRO POS M-H 7.3 developed catchments minimize the negative impact of anthropogenically-increased sediment loads being deposited along 3.2 Manual/ the full river course. NOTE: designated sedimentation areas may mechanical

include the limited area around inlet and outlets of culverts, pipes, sediment removal Group 1 - 3 & H, M points where canals enter detention ponds etc. Also deposited from sediment Group 5 sediments are also often with associated reeds or other vegetation. long traps/ retention areas.

Removal of sediments that are contaminated or heavily enriched Loc. L-M HPRO POS L-M 7.3 with nutrients can contribute to eutrophication of waterbodies, - especially in shallow lakes and vleis. Under these conditions, Reg.

removal of sediment can improve water quality. med

Impacts associated with access to and around the site (as above). Reg. L-M IMP NEG M 7.3.2

perm

Disturbed / resuspended sediments and associated nutrient / Loc. M DEF NEG L 7.3.3

organic loads (and plants) can be transported to downstream reaches during excavation of sediment traps, smothering habitat and animals and reducing light penetration and oxygen availability. temp

Sediment traps situated in an appropriate position along the Loc. L HPRO POS L 7.3.1

longitudinal profile of a river has a “positive” impact insofar as it Group 1 - 3 & L minimizes the negative impact of anthropogenically-increased Group 5 - 6 sediment loads being deposited along the full river course. long

Appendix J. Technical Assessment Report Page 112

Impact Stormwater Mitigation Watercourse Eco Significance No. management Type Environmental Impact (EMPr

Type priority with

Extent Status

measure Duration section) Magnitude

Frequency mitigation Probability / Removal of sediments that are contaminated or heavily enriched Loc. L HPRO POS L 7.3.3

with nutrients can contribute to eutrophication of waterbodies,

especially in shallow lakes and vleis. Under these conditions, removal of sediment can improve water quality. long

Disturbed / resuspended sediments and associated nutrient / Site L DEF NEG VL-L 7.3.3.

organic loads (and plants) can be transported to downstream - reaches during excavation of sediment traps, smothering habitat and Loc. animals and reducing light penetration and oxygen availability. temp

Temporary loss of all habitat and biota, albeit in low importance Site L-M HPRO NEG VL-L 7.3.3 3.3 Manual/ systems - through physical disturbance, smothering of substrata, -

mechanical Group 1 - 3 & loss of instream plant diversity and structural elements. Loc. removal from L

Group 5 - 6 short canals, channels and waterbodies.

ACTIVITY OR WATERCOURSE SPECIFIC IMPACTS OF CHANNEL ENCLOSURE Only indicated for artificial (L) Group 2 - Group 4 systems at would Loc. L-M HPRO POS L-M 10.1 otherwise be used as waste disposal conduits with no reasonable 4.1 Conversion of

alternative. The action would have positive consequences for the Channel an open channel Group 2 - 4 L downstream receiving ecosystem, compared with open channels. Enclosure. to an enclosed Group 4 med pipe system.

ACTIVITY OR WATERCOURSE SPECIFIC IMPACTS OF REMOVAL OF LITTER AND DEBRIS

5.1 Litter and Group 1 - H,M,L Removal of litter represents a positive ecological impact on the Loc. L-M DEF POS L 9.1.2 5 Removal of litter debris removal Group 6 affected watercourses through the removal of pollutants. and debris. using either short

mechanical or L Permanent damage to bankside vegetation / banks at the site where Loc. L IMP NEG L 9.1.2

manual methods. litter is hauled out of the waterbody and stockpiled. short

5.2 Removal of Group 1 - H.M.L Removal of an erosion threat or a structure that is causing erosion in Loc. M DEF POS M-H 9.2.1 structures to Group 6 downstream reaches will improve ecological integrity.

reduce water perm obstruction.

Appendix J. Technical Assessment Report Page 113

Impact Stormwater Mitigation Watercourse Eco Significance No. management Type Environmental Impact (EMPr

Type priority with

Extent Status

measure Duration section) Magnitude

Frequency mitigation Probability /

Elevated suspended sediments are possible during removal of the Site L POSS NEG VL 9.2.1 obstruction. temp

5.3 Construction/ Group 1 - H.M.L Improves performance of litter removal, reduces impacts of people Loc. M DEF POS M 10.1

expansion of litter Group 6 along length of channel. long management

infrastructure. Water quality, sediment impacts associated with construction. Loc. L-M PRO NEG L 10.1

temp

ACTIVITY OR WATERCOURSE SPECIFIC IMPACTS OF CONSTRUCTION AND MAINTENANCE OF MINOR STORMWATER INFRASTRUCTURE 6 Construction and 6.1 Stormwarer Group 1 - H,M,L Properly functioning stormwater system reduces erosion and Loc. M HPRO POS L-M 10.1 maintenance of outlets, dam scour Group 6 deposition in natural waterbodies downstream.

minor stormwater valves, headwalls short infrastructure. and culverts.

Water quality, sediment impacts associated with construction. Loc. L-M PRO NEG L 10.1

temp

ACTIVITY OR WATERCOURSE SPECIFIC IMPACTS OF MAINTENANCE OF ATTENUATION INFRASTRUCTURE Maintenance of 7.1 Weirs, 7.2 Group 1 - H,M,L Properly functioning stormwater system reduces erosion and Loc. L-M HPRO POS L 10.1 attenuation Retention/ Group 6 deposition in natural waterbodies downstream. 7

infrastructure. detention ponds short and dams, 7.3 Floor protection Water quality, sediment impacts associated with maintenance work, Loc. L-M PRO NEG L 10.1 embankments/ e.g. earthworks on embankments.

berms, 7.4 SUDS facilities, 7.5 Other dams/ ponds. temp

ACTIVITY OR WATERCOURSE SPECIFIC IMPACTS OF MAINTENANCE OF RECREATIONAL ACCESS

Appendix J. Technical Assessment Report Page 114

Impact Stormwater Mitigation Watercourse Eco Significance No. management Type Environmental Impact (EMPr

Type priority with

Extent Status

measure Duration section) Magnitude

Frequency mitigation Probability / Infrastructure, such as pathways, directs pedestrian and light traffic Loc. L DEF POS L 10.1, Recreational Group 1 - to formalised crossings, controlling damage to bed and banks. 12.1.1 8 8.1 Construction H,M,L Access. and maintenance Group 6 perm of footbridges,

boardwalks or bird The footprint of the recreational feature represents an, albeit highly Site L DEF NEG L 10.1, hides. localised, loss of habitat for riparian and instream biota. 12.1.1. perm

Short-term construction impacts include possible pollution from Site L PRO NEG L 10.1, washing vehicles and equipment. - 12.1.1. Loc. temp ACTIVITY OR WATERCOURSE SPECIFIC IMPACTS OF MANAGEMENT OF RIVER/ESTUARY MOUTHS 9.1 Breaching: Prevention of loss of landscape features such as buffer or back- Loc. M PRO POS L-M 13.1 Management of 9 river/ estuary removal of sand Group 7 H,M,L dune systems. - mouths. bars deposited in Reg. short mouth.

Improved water quality in estuaries / river mouths. Loc. M POSS POS L-M 13.1

9.2 Straightening: med redirecting meandering mouth Impacts may be associated with heavy machinery traversing Loc. L PRO NEG L 13.2 sensitive dune areas, but are relatively short-lived. across the shortest route directly towards temp the sea.

Appendix J. Technical Assessment Report Page 115

APPENDIX F

PHOTOGRAPHS

Appendix J. Technical Assessment Report Page 116

No Management Photographs measure

(1.2) Reedbed and indigenous emergent 1 vegetation management.

Reed cutters removing Typha by hand (District 2 Indiscriminate clearing of vegetation from a watercourse by Section of deep Typha where machine clearing of both

Kraaifontein) hand (District 6 Athlone) sediment and Typha is required (District 7 Khayelitsha)

Erosion control (2.1) River channel 2 profile enhancement.

Same watercourse further downstream after rehabilitation A deep channel requiring reshaping of banks (District 4 Narrow, deep watercourse pre-rehabilitation involving widening and reduce slope of banks Somerset West)

Appendix J. Technical Assessment Report Page 117

Erosion control (2.2) Construction, maintenance and 2 expansion of erosion control structures.

Erosion control – gabion lining on an eroding bend. Note Cross gabions such as this prevent erosion of the river bed Erosion control structure with limited footprint

the stepped gabion allowing planting midway up the vertical (District 8 Plumstead)

Sediment management (3.3) Manual/ 3 mechanical removal from canals, channels and waterbodies.

In excess of 1m (depth) of silt had previously accumulated Silt accumulating downstream of a structure (District 2 Culvert requiring desilting (District 2 Kraaifontein) at the base of this bridge. It has since been removed. Kraaifontein) (District 2 Kraaifontein)

Appendix J. Technical Assessment Report Page 118

Sediment removal (3.3) Manual/ mechanical 3 removal from canals, channels and waterbodies.

Long-boom excavator used for removing sediment (District Small bobcat dozer / excavator suited for moving smaller Heavily silted watercourse (District 1 Blaauwberg) 1 Blaauwberg) volumes of sediment.

(4.1) Conversion of an open channel to an enclosed pipe/ culvert system. Only in extreme cases where 4 pollution entering the watercourse is a health and safety risk and no other alternative available.

Possible candidate site for enclosing drainage line (CT Possible candidate site for enclosing drainage line if Possible candidate site for enclosing artificial stormwater

Central District) dumping became worse (District 7 Khayelitsha) drainage line due to severe health risks (District 6 Athlone)

Appendix J. Technical Assessment Report Page 119

Litter and debris 5 management.

Litter traps may be installed in watercourses where litter is Removal of debris dumped along edge of waterbody (District 1 Manual cleaning of a litter trap (District 8, Plumstead) a significant concern .(District 1 Blaauwberg) Blaauwberg)

Construction, maintenance and 6 expansion of minor stormwater infrastructure.

Concrete headwall (District 4 Somerset West) Gabion headwall (District 1 Blaauwberg)

Appendix J. Technical Assessment Report Page 120

Maintenance of 7 attenuation infrastructure.

Bank requiring raising to prevent flooding (District 7 Detention pond (District 6 Athlone) Inlet to detention pond (District 6 Athlone) Khayelithsa)

Management of river / estuary mouth 9.1 Breaching: removal of sands bars deposited in 9 mouth 9.2 Straightening: redirecting meandering mouth across the shortest route directly towards the sea.

Estuary where sand movement has previously been Estuary where sand movement has previously been

undertaken (District 6 Athlone) undertaken (District 6 Athlone)

Appendix J. Technical Assessment Report Page 121 DOCUMENT CONTROL IP 180_B

CLIENT : City of Cape Town PROJECT NAME : CCT Surface Stormwater Systems PROJECT No. : J31110 TITLE OF DOCUMENT : ENVIRONMENTAL AUTHORISATION FOR MAINTENANCE AND MANAGEMENT INTERVENTIONS UNDERTAKEN BY THE CITY IN ITS SURFACE STORMWATER SYSTEMS: ASSESSMENT REPORT ELECTRONIC \\CAPETOWN-6\projects\J31110 (CCT Stormwater LOCATION : Maintenance)\G_Outgoing Docs (Reports)\Final BAR\Appendix J. Technical assessment report\Appendix J CCT Stormwater Technical Assessment Report_2014.09.26_final.docx Approved By Reviewed By Prepared By ORIGINAL NAME NAME NAME W. Fyvie W. Fyvie W. Fyvie / M. Vosloo / K. Parkinson DATE SIGNATURE SIGNATURE SIGNATURE Dec 2013

Prepared by Prepared By Prepared By FINAL NAME NAME NAME W Fyvie W Fyvie W Fyvie/ K Parkinson DATE SIGNATURE SIGNATURE SIGNATURE 25 September 2014

This report, and information or advice, which it contains, is provided by GIBB solely for internal use and reliance by its Client in performance of GIBB duties and liabilities under its contract with the Client. Any advice, opinions, or recommendations within this report should be read and relied upon only in the context of the report as a whole. The advice and opinions in this report are based upon the information made available to GIBB at the date of this report and on current SA standards, codes, technology and construction practices as at the date of this report. Following final delivery of this report to the Client, GIBB will have no further obligations or duty to advise the Client on any matters, including development affecting the information or advice provided in this report. This report has been prepared by GIBB in their professional capacity as Consulting Engineers. The contents of the report do not, in any way, purport to include any manner of legal advice or opinion. This report is prepared in accordance with the terms and conditions of the GIBB contract with the Client. Regard should be had to those terms and conditions when considering and/or placing any reliance on this report. Should the Client wish to release this report to a Third Party for that party's reliance, GIBB may, at its discretion, agree to such release provided that: (a) GIBB written agreement is obtained prior to such release, and (b) By release of the report to the Third Party, that Third Party does not acquire any rights, contractual or otherwise, whatsoever against GIBB and GIBB, accordingly, assume no duties, liabilities or obligations to that Third Party, and (c) GIBB accepts no responsibility for any loss or damage incurred by the Client or for any conflict of GIBB interests arising out of the Client's release of this report to the Third Party.

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