surface water report - rhdhv.co.za

Construction of a Waterborne Sewer in Sun City located in Mayflower Village in Chief Albert Luthuli

Municipality –Surface Water Specialist Study

Mpumalanga Department of Rural Development and Land Reform

March 2015

DOCUMENT DESCRIPTION Client:

Mpumalanga Department of Rural Development and Land Reform Project Name:

Construction of a Waterborne Sewer in Sun City located in Mayflower Village in Chief Albert Luthuli Municipality – Surface Water Specialist Study

Royal HaskoningDHV Reference Number:

T01.JNB.000556

Compiled by:

Paul da Cruz

Date:

March 2015

Location:

Woodmead

Approval: Prashika Reddy (PrSciNat – Environmental Science – 400133/10)

_____________________________

Signature

© Royal HaskoningDHV

All rights reserved.

No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, without the written permission from Royal HaskoningDHV

TABLE OF CONTENTS

TABLE OF CONTENTS 0

GLOSSARY OF TERMS 0

ACRONYMS 2

SPECIALIST DECLARATION 2

1 INTRODUCTION 1

1.1 AIMS OF THE STUDY 1

1.2 ASSUMPTIONS AND LIMITATIONS 1

1.3 DEFINITION OF SURFACE WATER FEATURES, WETLANDS, HYDRIC SOILS AND RIPARIAN ZONES 2

1.3.1 SURFACE WATER FEATURES 2 1.3.2 WETLANDS AND AQUATIC ECOSYSTEMS 2 1.3.3 RIPARIAN HABITAT AND RIPARIAN ZONES 3

1.4 LEGISLATIVE CONTEXT 5

1.4.1 THE NATIONAL WATER ACT 5

1.4.1.1 The National Water Act and Riparian Areas – general principles

1.4.1.2 Government Notice 1199 - implications regarding Section 21c) and i) Water Uses

2 PROJECT DESCRIPTION 8

2.1.1 SITE LOCATION AND DESCRIPTION 8 2.1.2 TECHNICAL DETAILS 8

3 METHODOLOGY FOR ASSESSMENT 11

3.1 IDENTIFICATION OF SURFACE WATER FEATURES ALONG THE PROPOSED ALTERNATIVE ALIGNMENTS 11

3.2 FIELD ASSESSMENT AND WETLAND DELINEATION 11

3.3 IDENTIFICATION OF SURFACE WATER IMPACTS AND MITIGATION MEASURES 13

3.4 SURFACE WATER MAPPING 13

4 FINDINGS OF ASSESSMENT 14

4.1 STUDY AREA BIOREGIONAL CONSERVATION PLANNING CONTEXT 14

4.1.1.1 Analysis

4.2 STUDY AREA BIOPHYSICAL CHARACTERISTICS AND HOW THESE RELATE TO / AFFECT SURFACE WATER FEATURES 17

4.2.1 CLIMATE 17 4.2.2 GEOLOGY, MACRO-GEOMORPHOLOGY AND TOPOGRAPHY 17 4.2.3 MACRO DRAINAGE CHARACTERISTICS 18 4.2.4 VEGETATION TYPES 18 4.2.5 SOILS AND LANDTYPES 18

4.3 STUDY AREA SURFACE WATER CHARACTERISTICS AND OCCURRENCE 19

4.3.1 WETLAND (SURFACE WATER) OCCURRENCE AND CROSSINGS 19 4.3.2 SURFACE WATER TYPOLOGY (INCL. WETLAND HYDROGEOMORPHIC FORMS) 21

4.3.2.1 Seeps

4.3.2.2 Rivers and Channelled Valley Bottom Wetlands

4.3.2.3 Un-channelled Valley Bottom Wetland

4.3.3 WETLAND SOIL CHARACTERISTICS 27 4.3.4 VEGETATIVE CHARACTERISTICS OF SURFACE WATER FEATURES 28

5 NATURE OF THE POTENTIAL IMPACTS ON SURFACE WATER FEATURES ASSOCIATED WITH THE

PROPOSED DEVELOPMENT 32

5.1 IMPACTS ON SURFACE WATER FEATURES ASSOCIATED WITH LAYING OF BURIED PIPELINES 32

5.1.1 CONTEXT OF THE STUDY AREA 34

5.2 INDIRECT AND OTHER CONSTRUCTION-RELATED IMPACTS 35

5.3 OPERATIONAL PHASE IMPACTS 37

5.4 MITIGATION MEASURES AND RECOMMENDATIONS 38

5.4.1 GENERIC WETLAND CROSSING MITIGATION MEASURES 38 5.4.2 RIVER (AND CHANNELLED VALLEY BOTTOM WETLAND) CROSSINGS 40 5.4.3 WATER CROSSING-RELATED PERMITTING 43 5.4.4 STORMWATER CONTROL DURING CONSTRUCTION 43 5.4.5 ROAD / TRACKS AND SURFACE WATER CROSSING STRUCTURES 43 5.4.6 CHECKING AND PREVENTION OF SEWAGE LEAKS FROM THE SEWER 44 5.4.7 ALIEN INVASIVE PLANT MANAGEMENT WITHIN SERVITUDES DURING OPERATION 44

5.5 COMPARATIVE ASSESSMENT OF ALTERNATIVES 44

6 CONCLUSIONS 45

7 REFERENCES 45

List of Figures

FIGURE 1 – STUDY AREA AND PROPOSED ALIGNMENT ALTERNATIVES 10 FIGURE 2 - MPUMALANGA BIODIVERSITY SECTOR PLAN – FRESHWATER ANALYSIS 16 FIGURE 3 – QUATERNARY CATCHMENTS IN THE STUDY AREA 20 FIGURE 4 – CHANNELLED VALLEY BOTTOM WETLAND AT THE MF_ALT1_1 CROSSING POINT 21 FIGURE 5 – SEEP WETLAND (CROSSING MF_ALT2_9) ON SLOPING GROUND TO THE NORTH OF THE VALLEY FLOOR DRAINED

BY THE TRIBUTARY OF THE MPULUZI NEAR THE STADIUM 23 FIGURE 6 - SEEP WETLAND UPSTREAM OF THE PROPOSED ALIGNMENT IN THE NORTH-EASTERN PART OF THE

DEVELOPMENT SITE 25 FIGURE 7 – THE TRIBUTARY STREAM OF THE MPULUZI RIVER AT CROSSING POINT MF_ALT1_3 26 FIGURE 8 – SERIES OF SOIL HORIZONS ENCOUNTERED FROM A KROONSTAD SOIL FORM WITHIN THE SEEP WETLAND

MF_ALT1_2; SOILS FROM THE ORTHIC A HORIZON (LEFT), SOILS FROM THE UNDERLYING E HORIZON (MIDDLE) AND

SOILS FROM THE LOWER-MOST G HORIZON (RIGHT). 28 FIGURE 9 – TYPICAL VEGETATION (MOIST GRASSLAND) IN A SEEP WETLAND AT CROSSING MF_ALT1_2 30 FIGURE 10 – HYDROPHYTES IN THE SEEP WETLAND JUST DOWNSLOPE OF THE ALIGNMENT AT CROSSING MF_ALT2_8 31 FIGURE 11 – SILT LADEN WATER WITHIN THE TRENCH ALREADY EXCAVATED ALONG THE PROPOSED ALIGNMENT 35 FIGURE 12 – DAMAGE TO THE SEEP WETLAND MF_ALT1-2_5 CAUSED BY RECENT MOVEMENT OF HEAVY MACHINERY

RELATED TO PIPELINE CONSTRUCTION 37

List of Tables

TABLE 1 – TIERED WETLAND / AQUATIC ECOSYSTEM DESCRIPTORS FOR THE WETLANDS ON THE DEVELOPMENT SITE ........ 22

Glossary of Terms

Alluvial Material / deposits

Sedimentary deposits resulting from the action of rivers, including those deposited within river channels, floodplains, etc.

Anaerobic The absence of molecular oxygen.

Anthropogenic Originating in human activity.

Apedal A term indicating the a degree of aggregation of soil particles within a soil horizon, where the material is well aggregated, but without well-formed peds (individual soil aggregates); in the context of the South African Soil Classification System, apedal soils also include structureless soils (e.g. sands) and somewhat more structured soils than the above description.

Azonal A type or class of vegetation with physical and vegetative characteristics that are a response to localised edaphic (soil related) factors such as volumes and duration of activation of water and salts, rather than to macroclimatic and geological patterns on a landscape level, that would normally be the determining factors for vegetation community development. In such cases the stresses and problems that plants would encounter in a wetland or saltmarsh environment, for example, are sufficiently unique and in some cases so extreme that only highly adapted species that are sufficiently enabled to deal with those stresses and problems are encountered in these environments, thus forming their own typical vegetation composition.

Baseflow The component of river flow that is sustained from groundwater sources rather than from surface water runoff.

Colluvial Relating to gravitational forces that result in the transport and deposition of soil and / or rock fragments down hillslopes to the base of the slope.

Dystrophic In the context of soil, a dystrophic soil refers to soil that has suffered marked leaching, such that the sum of the exchangeable (as opposed to soluble) Ca, Mg, K and Na, expressed in cmolc/kg /kg clay, is less than 5. The figure is calculated from the S-value and the clay content. Such soil is said to have a low base status.

Ephemeral A watercourse that flows at the surface only periodically.

Eutrophication The process of nutrient enrichment (usually by nitrates and phosphates) in aquatic

ecosystems, such that the productivity of the system ceases to be limited in terms of the

availability of nutrients; often results in algal blooms and is often a result of

anthropogenic factors.

Facultative Occurring optionally in response to circumstances rather than by nature; applied to

wetland plants in this context – a facultative species is a species usually found in

wetlands, but occasionally found in non-wetland areas.

Fluvial The physical interaction of flowing water and the natural channels of rivers and streams.

Forb A herbaceous flowering plant other than a grass.

Gleying The process by which a material (soil) has been or is becoming subject to intense

reduction as a result of prolonged saturation by water. Gleyed soils are characterised by

grey (due to an absence of iron compounds), blue and green colours (due to an

absence of ferrous compounds).

Herb A small non woody plant in which the aerial parts die back at the end of every growing

season.

Herbaceous A plant having little or no woody tissue and persisting usually for a single growing

season.

Hydric / Hydromorphic Soils

Soils formed under conditions of saturation, flooding or ponding for sufficient periods of

time for the development of anaerobic conditions and thus favouring the growth of

hydrophytic vegetation.

Hydrology The scientific study of the distribution and properties of water on the earth’s surface.

Hydromorphy A process of gleying and mottling resulting from intermittent or permanent presence of

free water in soil. Results in hydromorphic soils.

Hydroperiod The term hydroperiod describes the different variations in water input and output that

form a wetland, characterising its ecology – i.e. the water balance of the wetland.

Hydrophilic A hydrophyte.

Hydrophyte A plant that grows in water or in conditions that are at least periodically deficient in

oxygen as a result of saturation by water – these are typically wetland plants.

Knickpoint (= rejuvenation head) – A break of slope in the long profile of a stream which results

from a fall of base level and the resultant downcutting, creating a new valley long profile

below the former level. The knickpoint is found at the transition point between the two

profiles, and migrates upstream. At a more localised level, a knickpoint can occur at the

head of a gulley or erosion channel within a river or wetland.

Lithocutanic B horizon

A subsoil horizon underlying a topsoil or other subsoil (E) horizon, and that overlies and

merges into weathering bedrock; is comprised of heterogeneous material consisting of

a mixture of soil material, and saprolite (bedrock fragments), displaying cutanic

properties.

Mesotrophic In the context of soils, a mesotrophic soil has suffered moderate leaching, such that the sum of the exchangeable Ca, Mg, K and Na, is 5-15 cmolc/kg clay. This figure is calculated from the S-value and the clay content. Such soil is said to have a medium base status

Obligate A species that almost always occurs in wetlands.

Plinthic Soils with plinthic characteristics contain an iron-rich, humus-poor mixture of clay with

quartz and other highly weathered minerals, with the common occurrence of reddish

redox concentrations in a layer that has a polygonal (irregular), platy (lenticular), or

reticulate (blocky) pattern, formed by the segregation, transport, and concentration of

iron. To qualify as being plinthic irreversible hardening, or a process of the development

of hardening must be present (due to the process of repeated wetting and drying).

Reach A portion / stretch of a river.

Redoximorphic Features within soil that are a result of the reduction, translocation and oxidation

(precipitation) of Fe (iron) and Mn (manganese) oxides that occur when soils are

saturated for sufficiently long periods of time to become anaerobic.

Riparian Zone The physical structure and associated vegetation of the areas associated with a

watercourse which are commonly characterised by alluvial soils, and which are

inundated or flooded to an extent and with a frequency sufficient to support vegetation

of species with a composition and physical structure distinct from those of adjacent land

areas.

Signs of Wetness Signs of wetness are signs of hydromorphism in soil, consisting of grey low chroma

colours with or without sesquioxide mottles.

Acronyms

BA – Basic Assessment (Study)

CBA – Critical Biodiversity Area

DWS – Department of Water and Sanitation (formerly Dept. of Water Affairs (DWA) or Dept. of Water Affairs and Forestry (DWAF))

EMPr – Environmental Management Programme

ESA – Ecological Support Area

HGM – Hydrogeomorphic

MBSP – Mpumalanga Biodiversity Sector Plan

MDRDLR - Mpumalanga Department of Rural Development and Land Reform

RHDHV – Royal HaskoningDHV

Specialist Declaration

I, Paul da Cruz, declare that I –

• act as a specialist consultant in the field of surface water assessment

• do not have and will not have any financial interest in the undertaking of the activity, other than remuneration for work performed in terms of the Environmental Impact Assessment Regulations, 2014;

• have and will not have any vested interest in the proposed activity proceeding;

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

• undertake to disclose, to the competent authority, any material information that have or may have the potential to influence the decision of the competent authority or the objectivity of any report, plan or document required in terms of the Environmental Impact Assessment Regulations, 2014; and

• will provide the competent authority with access to all information at my disposal regarding the application, whether such information is favourable to the applicant or not.

PAUL DA CRUZ

MAYFLOWER WATERBORNE SEWER PROJECT – SURFACE WATER ASSESSMENT

T01.JNB.000556 Page 1 Royal Haskoning DHV

1 INTRODUCTION

The Department of Rural Development and Land Reform (DRDLR) has appointed Royal HaskoningDHV

(RHDHV) to undertake a Basic Assessment (BA) Study for the proposed development of a waterborne sewer in

Sun City located in Mayflower Village in the Chief Albert Luthuli Municipality in Mpumalanga. The proposed

infrastructure crosses a number of surface water features and thus a surface water assessment is required to be

undertaken.

Surface water features (including wetlands and rivers) are a very important component of the natural

environment, as they are typically characterised by high levels of biodiversity and are critical for the sustaining of

human livelihoods through the provision of water for drinking and other human uses. As such surface water

resources and wetlands are specifically protected under the National Water Act, 1998 (Act No. 36 of 1998) and

generally under the National Environmental Management Act, 1998 (Act No. 107 of 1998) (as amended). It is in

this context that the potential impact of the proposed development on surface water features has been assessed

and a surface water assessment has been conducted as part of the BA process.

1.1 Aims of the Study

The aims of the study are to:

� Identify all surface water features along, and in immediate proximity to the alignment of the proposed

infrastructure;

� Delineate (in the field) and map all wetland and riparian zone boundaries for all alignments;

� Assess the impact of the proposed infrastructure on affected surface water resources,

� Comparatively assess alignment alternatives and recommend a preferred alternative from a surface water

perspective; and

� Recommend suitable mitigation measures, if relevant, to ameliorate or remove predicted impacts.

1.2 Assumptions and Limitations

As discussed in section 1.3 below, a definition of wetlands that is slightly different to that provided by the National

Water Act has been provided in this report. The definition used is based primarily on the presence of hydric soils,

rather than on the hydroperiod of the surface water body. It should be noted that certain surface water features

that may otherwise be termed as ‘wetlands’ have not been defined as such in this report. This does not mean

however that these surface water features are any less sensitive, or that they are not protected under the Act as

discussed below.

Only surface water features within the footprint of the proposed infrastructure and immediate surrounds were

assessed in the field as part of this study; the study does not include an assessment of the wider catchments

within which the surface water resources on the sites are located, although potential downstream impacts have

been taken into account.



During the field assessment it was noted that construction and excavation of a sub-surface pipeline had been

started along a number of parts of the proposed alignment as provided to RHDHV by the proponent. It is not

certain whether this construction is related to the proposed waterborne sewer, but was located on the alignment

provided by the proponent. For the purposes of this report it has been assumed that this construction is part of the

baseline environmental state of the wetlands assessed along the proposed alignment.

The Proponent has instructed Royal HaskoningDHV that they would undertake the Water Use Licensing Process

for the proposed development, and this process and the associated studies do not form part of RHDHV’s scope of

work. Accordingly no assessments of wetland health, wetland functionality and wetland ecological importance and

sensitivity have been undertaken as part of this assessment. These would have to be completed as part of a

separate study in support of a water use licence application.

1.3 Definition of Surface Water Features, Wetlands, Hydric Soils and Riparian Zones

1.3.1 Surface Water Features

In order to set out a framework in which to assess surface water features, it is useful to set out what this report

defines as surface water resources. In this context the National Water Act is used as a guideline. The Act includes

a number of features under the definition of water resources, i.e. watercourses, surface waters, estuaries and

aquifers. The latter two do not apply in the context of this study as estuaries are marine features and this report

does not consider groundwater, thus surface waters and water courses are applicable in this context. The Act

defines a watercourse as (inter alia):

� a river or spring;

� a natural channel in which water flows regularly or intermittently; and

� a wetland, lake or dam into which, or from which, water flows.

The definition of a water course as used in the Act is taken to describe surface water features in this report. It is

important to note that the Act makes it clear that reference to a watercourse includes, where relevant, its bed and

banks. This is important in this report, as the riparian habitat associated with riverine surface water features in the

study area have been included as an important part of surface water features and are thus given consideration in

this report.

It is equally important to note that the Act does not discriminate on the basis of being perennial, and any natural

channel, however ephemeral, is included within the ambit of water resources. This definition is applied in this

report.

1.3.2 Wetlands and Aquatic Ecosystems

The National Water Act defines a wetland 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 alludes to a number of physical characteristics of wetlands, including wetland hydrology, vegetation

and soil. The reference to saturated soil is very important, as this is the most important factor by which wetlands

are defined.

Another widely used definition of wetlands is the one used under the Ramsar Convention; wetlands are defined

as:

“areas of marsh, fen, peatland or water, whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salt, including areas of marine water the depth of which at low tide does not exceed six metres”

However the presence / absence of hydric soils is the primary determining factor used to define a surface

water feature as a wetland.

This determining factor has been utilised in this assessment. Wetland soils can be termed hydric or hydromorphic

soils. Hydric soils are defined by the U.S. Department of Agriculture Natural Resources Conservation Service

(NRCS) as being "soils that formed under conditions of saturation, flooding or ponding long enough during the

growing season to develop anaerobic conditions in the upper part". These anaerobic conditions would typically

support the growth of hydromorphic vegetation (vegetation adapted to grow in soils that are saturated and starved

of oxygen) and are typified by the presence of redoximorphic features. The presence of hydric (wetland) soils on

the site of a proposed development is significant, as the alteration or destruction of these areas, or development

within a certain radius of these areas would require authorisation in terms of the National Water Act (36 of 1998)

and in terms of the Environmental Impact Assessment Regulations promulgated under the National

Environmental Management Act, 1998 (Act No. 107 of 1998).

It should also be noted that wetlands are aquatic ecosystems. The recently developed Classification System for

Wetlands and other Aquatic Ecosystems in South Africa (Ollis et al, 2013) defines an aquatic ecosystem as:

“an ecosystem that is permanently or periodically inundated by flowing or standing water, or which has soils that are permanently or periodically saturated within 0.5 m of the soil surface”.

Wetlands are thus a type of aquatic ecosystem. Other surface water features such as streams or watercourses

may not qualify as wetlands, but would qualify as aquatic ecosystems.

1.3.3 Riparian Habitat and Riparian Zones

The National Water Act defines riparian habitat as:

“the physical structure and associated vegetation of the areas associated with a watercourse which are commonly characterised by alluvial soils, and which are inundated or flooded to an extent and with



a frequency sufficient to support vegetation of species with a composition and physical structure distinct from those of adjacent land areas”

As detailed in the then Department of Water Affairs and Forestry (DWAF, now DWS (Department of Water and

Sanitation)) 2005 guidelines for the delineation of wetlands and riparian areas, riparian areas typically perform

important ecological and hydrological functions, some of which are the same as those performed by wetlands. It is

thus important that both wetlands and riparian areas be taken into consideration when making mandatory

management decisions affecting water resources and biodiversity (DWAF, 2005).

Riparian areas include plant communities adjacent to and affected by surface and underground water features

such as rivers, streams, lakes, or drainage lines. It is important to note that these areas may be a few metres wide

along smaller systems or more than a kilometre in floodplains. Both perennial and non-perennial streams support

riparian vegetation (DWAF, 2005).

Because riparian areas represent the interface between aquatic and upland ecosystems, the vegetation in the

riparian area may have characteristics of both aquatic and upland habitats. Many of the plants in the riparian area

require plenty of water and are adapted to shallow water table conditions. Due to water availability and rich

alluvial soils, riparian areas are usually very productive. Tree growth rate is high. This is certainly the case in

riparian zones in the study area as they typically contain trees and shrubs of a height, density and species

diversity that is not present in the surrounding woodland.

Riparian areas are important as they perform the following functions (DWAF, 2005):

� storing water and thus assisting to reduce floods;

� stabilising stream banks;

� improving water quality by trapping sediment and nutrients;

� maintaining natural water temperature for aquatic species;

� providing shelter and food for birds and other animals;

� providing corridors for movement and migration of different species;

� acting as a buffer between aquatic ecosystems and adjacent land uses;

� can be used as recreational sites; and

� providing material for building, muti, crafts and curios.

These ecosystems may be considered ‘critical transition zones’ as they process substantial fluxes of materials

from closely connected, adjacent ecosystems (Ewel et al, 2001)

As discussed below riparian habitat is important from a legislative perspective – in terms of the National Water

Act.



1.4 Legislative Context

The following section briefly examines the legislation that is relevant to the scope of the surface water

assessment. The stipulations / contents of the legislation and policy that is relevant to the study are explored.

1.4.1 The National Water Act

It is important to note that water resources, including wetlands are protected under the National Water Act (Act

No. 36 of 1998) (NWA). ‘Protection’ of a water resource, as defined in the Act entails:

� Maintenance of the quality of the quality of the water resource to the extent that the water use may be used in

a sustainable way;

� Prevention of degradation of the water resource; and

� The rehabilitation of the water resource.

In the context of the current study and the identification of potential threats to the surface water features posed by

the proposed development of the waterborne sewage system, the definition of pollution and pollution prevention

contained within the Act is relevant. ‘Pollution’, as described by the Act is the direct or indirect alteration of the

physical, chemical or biological properties of a water resource, so as to make it (inter alia)-

� less fit for any beneficial purpose for which it may reasonably be expected to be used; or

� harmful or potentially harmful to the welfare or human beings, to any aquatic or non-aquatic organisms, or to

the resource quality.

The inclusion of physical properties of a water resource within the definition of pollution entails that any physical

alterations to a water body, for example the excavation of a wetland or changes to the morphology of a water

body can be considered to be pollution. Activities which cause alteration of the biological properties of a

watercourse, i.e. the fauna and flora contained within that watercourse are also considered pollution.

In terms of section 19 of the Act owners / managers / people occupying land on which any activity or process

undertaken which causes, or is likely to cause pollution of a water resource must take all reasonable measures to

prevent any such pollution from occurring, continuing or recurring. These measures may include measures to

(inter alia):

� cease, modify, or control any act or process causing the pollution;

� comply with any prescribed waste standard or management practice;

� contain or prevent the movement of pollutants;

� remedy the effects of the pollution; and

� remedy the effects of any disturbance to the bed and banks of a watercourse.

These general stipulations of the Act have ramifications for the proposed development as impacts on surface

water associated with the proposed development would be relevant in terms of the above sections.



Section 21 of the Act stipulates a number of water uses in terms of the Act. The most relevant in the context of the

present project are:

� 21(c) - impeding or diverting the flow of water in a watercourse; and

� 21(i) - altering the bed, banks, course or characteristics of a watercourse.

The Section 21(c) water use would apply to pipeline crossings of surface water features that create an

impounding effect on the watercourse.

The Section 21(i) water use is most likely to eventuate as a result of this development as this activity

encompasses changes to the riparian zone and to the bed (channel) of surface water features (refer to section

1.4.1.2 below).



1.4.1.1 The National Water Act and Riparian Areas – general principles

Riparian habitat is afforded protection under the National Water Act in a number of ways. Firstly reference in the

National Water Act to a watercourse includes its banks, on which riparian habitat is encountered. Riparian areas

are thus afforded the same degree of protection as the river beds and channels alongside which they occur.

Riparian habitat is also important in the context of resource quality objectives that are a critical part of the Act. In

terms of Section 13(1) of the Act resource quality objectives must be determined for every significant water

resource, and are central part of data type specifications relating to national monitoring systems and national

information systems as determined in Section 137(2) and Section 139(2) of the Act respectively. Under Section

27 of the Act resource quality objectives must be taken into account in the issuing of any licence or general

authorisation, and form a critical part of the duties of catchment management agencies. The purpose of resource

quality objectives in the Act is to establish clear goals relating to the quality of the water resources. Resource

quality is important in the context of riparian habitat as resource quality as defined in the Act means the quality of

all aspects of a water resource and includes the character and condition of the riparian habitat. In terms of

Section 26(4) of the Act, the need for the conservation and protection of riparian habitat must be taken into

account in the determination and promulgation of regulations under the Act.

1.4.1.2 Government Notice 1199 - implications regarding Section 21c) and i) Water Uses Government Notice (GN) 1199 was published in Government Gazette 32805 of 2009 and replaced GN 398 of

March 2004 as it pertains to water uses under Sections 21 c)&i) of the NWA. This notice has important

implications in terms of the definition and associated conditions for the altering of the bed, banks, course or

characteristics of a watercourse (a water use under Section 21i) of the Act), and thus needs to be considered in

the context of any development that would potentially cause lead to the Section 21i) occurring.

It is important to note that as specified by the Notice, the definition of “altering the bed, banks, course or

characteristics of a watercourse" means any change affecting the resource quality within the riparian habitat

or 1:100 year flood line, whichever is the greater distance…;

A number of conditions of the notice are important in the context of the current study:

� The water use must not cause a potential, measurable or cumulative detrimental impact on the characteristics

of a watercourse.

� Structures and hardened surfaces associated with the water use must not (inter alia) be erosive.

� The water use must not result in a potential, measurable or cumulative detrimental –

a) change in the stability of a watercourse; b) change in the physical structure of a watercourse; c) scouring, erosion or sedimentation of a watercourse; or d) decline in the diversity of communities and composition of the natural, endemic vegetation

� The water use must not result in a potential, measurable or cumulative detrimental change in the water quality

characteristics of the watercourse.

The water use must not result in a potential, measurable or cumulative detrimental change on the –

a) breeding, feeding and movement patterns of aquatic biota, including migratory species; b) level of composition and diversity of biotopes and communities of animals and microorganisms or; condition of the aquatic biota. Upon completion of the water use –



a) a systematic rehabilitation programme must be undertaken to restore the watercourse to its condition prior to the commencement of the water use;

b) all disturbed areas must be re-vegetated with indigenous vegetation suitable to the area; and c) an active campaign for controlling new exotic and alien vegetation must be implemented within a

disturbed area.

It is important to note that the GN does not apply to the use of water in terms of section 21 (c) and (i) within a 500

metre radius from the boundary of any wetland. As explored further in section 4 below, wetlands have been

identified in the area, and thus a full Water Use Licence process rather than a general authorisation process will

apply to the proposed development.

2 PROJECT DESCRIPTION

2.1.1 Site Location and Description

The Study Area is located in the south-eastern part of the Mpumalanga Province, close to its boundary and South

Africa’s boundary with the independent state of Swaziland. The development site is located roughly between the

towns of Lothair (to the west) and Mbabane in Swaziland (to the east). The development site is located in the rural

settlement of Empuluzi, which is divided up into a number of sections of which Sun City Unit C and E and

Empuluzi-C and D are traversed by the proposed pipelines. A number of other similar rural settlements are

scattered around the study area. The study area is indicated in the map in Figure 1 below.

2.1.2 Technical Details

The proposed project will entail the following main components:

� Construction of internal waterborne sanitation services and pipelines for Sun City A and B.

� Bulk sanitation infrastructure, which includes the collection of sewage in a large diameter pipeline for

transportation to the waste water purification plant.

� Re-sizing of the existing bulk infrastructure to accommodate additional flows from Sun City A and B.

� An assessment and minor upgrade of the existing Waste Water Treatment Plant (WWTP) to accommodate

the additional sewage flow from the planned development. This will entail the construction of additional

maturation ponds.

� Construction of a concrete sump (mini pump-station) and a bulk rising main pipeline from Sun City A to

convey effluent from Sun City A and B to the existing bulk service pipeline across the tributary of the Mpuluzi

River.

Scope of Work for Upgraded Waterborne Sanitation for Sun City A and B

� Clearing and grubbing of the proposed pipeline routes;

� Excavations for the proposed sewer lines of all size classes;

� Pipe bedding utilizing imported materials from commercial sources;

� Construction of 1meter diameter pre-cast concrete manholes;

� Erf connections for all households in accordance with SANS 1200 and in accordance with special 2 and 4

legged erf connections; and

� Testing of the pipelines and manholes.



Scope of Work for the Construction of a Concrete Sump and Bulk Rising Main Pipeline

� Excavation of proposed bases for the raised pipe-bridge which will support all pipeline classes. The size of

the sump will be confirmed upon the completion of the final design;

� The importing of suitable material from commercial sources for founding levels;

� The construction of a concrete sump which is 15m (L) x 9m (W) x 4,5m (D) and includes casting of 30 Mpa

concrete for bases, 250mm thick walls (both internal and external) and a surface bed slab;

� Installation of one duty and one standby submersible pumps within the concrete sump;

� Construction of an overflow (Emergency Storage Facility);

� Construction of a new rising main pipeline, which will include the following components;

o Excavations for sewer pipelines of all classes;

o Pipe bedding utilising imported material from commercial sources; and

o Laying, jointing and bedding of proposed sewer pipelines utilising a 110 mm uPVC HD Class 34m of

pipeline in accordance with DWS standards.

Scope of Work for the Construction of new Ponds at Mayflower Waste Water Treatment Works Based on

Effluent Being Generated by Sun City Development

� Clearing and grubbing for the proposed ponds;

� Bulk excavation/earthworks of proposed ponds in all classes. Size of the ponds to be confirmed upon

completion of the final design; and

� The importing of suitable material from commercial sources to line off the pond (if required).



Figure 1 – Study Area and proposed alignment alternatives



3 METHODOLOGY FOR ASSESSMENT

3.1 Identification of Surface Water Features along the proposed alternative alignments

A desktop-based identification of all surface water features crossed by, and in the immediate vicinity of the

proposed alternative alignments was undertaken using satellite basemap imagery as available in ArcGIS and on

Google Earth. Points of possible surface water occurrence were marked for groundtruthing during the field

assessment.

3.2 Field Assessment and Wetland Delineation

A focussed field assessment was undertaken during the EIAR-phase surface water assessment. This focussed

on areas of potential significant impact, in particular the larger rivers crossed, as well as areas in which the need

for clarification on the presence or boundaries of surface water features had been identified. The field assessment

focussed on wetland (hydric soil) occurrence, as well as the characterisation of the riparian zones of the larger

rivers along the alternative alignments (see section 3.3. below).

Typically the presence of wetlands is determined through wetland delineation. The accepted procedure for

wetland delineation in South Africa is based upon the DWA(F) guidelines ‘A practical field procedure for the

identification and delineation of wetlands and riparian areas’ (DWAF, 2005), which stipulates that consideration be

given to four specific wetland indicators to determine the boundary of the wetland.

The four wetland indicators are:

terrain unit - helps to identify those parts of the landscape where wetlands are more likely to occur

soil form - identifies the soil forms, as defined by the Soil Classification Working Group (1991), which are

associated with prolonged and frequent saturation

soil wetness - identifies the morphological "signatures" developed in the soil profile as a result of prolonged and

frequent saturation

vegetation - identifies hydrophilic vegetation associated with frequently saturated soils

The guidelines do mention hydrology, although it is not listed as being one of the four indicators above. However

the guidelines state that the delineation procedure is substantially facilitated by an understanding of the broad

hydrological processes that drive the frequency of saturation (DWAF, 2005).

Under most circumstances the most important indicator of the presence of hydric soils is the soil wetness

indicator, i.e. examination of redoximorphic features within the soil. The reason for this is that vegetation (the

primary factor as defined under the National Water Act) can easily respond to changes in hydrology (e.g. the

draining of a wetland), while the soil morphological signatures remain even if the wetland hydrology is altered.



In terms of the soil form indicator, the guidelines list a number of soil forms that are associated with the

permanent zone of the wetland or the seasonal / temporary zones.

For an area to be considered a wetland, redoximorphic features must be present within the upper 500 mm of the

soil profile (Collins, 2005). Redoximorphic features are the result of the reduction, translocation and oxidation

(precipitation) of Fe (iron) and Mn (manganese) oxides that occur when soils are saturated for sufficiently long

periods of time to become anaerobic. Only once soils within 500mm of the surface display these redoximorphic

features can the soils be considered to be hydric (wetland) soils. Redoximorphic features typically occur in three

types (Collins, 2005):

A reduced matrix – i.e. an in situ low chroma (soil colour), resulting from the absence of Fe3+ ions which are

characterised by “grey” colours of the soil matrix.

Redox depletions - the “grey” (low chroma) bodies within the soil where Fe-Mn oxides have been stripped out, or

where both Fe-Mn oxides and clay have been stripped. Iron depletions and clay depletions can occur.

Redox concentrations - Accumulation of iron and manganese oxides (also called mottles). These can occur as:

� Concretions - harder, regular shaped bodies

� Mottles - soft bodies of varying size, mostly within the matrix, with variable shape appearing as blotches or

spots of high chroma colours

� Pore linings - zones of accumulation that may be either coatings on a pore surface, or impregnations of the

matrix adjacent to the pore. They are recognized as high chroma colours that follow the route of plant roots,

and are also referred to as oxidised rhizospheres.

Under most circumstances the presence or absence of redoximorphic features within the upper 500mm of the soil

profile alone is sufficient to identify the soil as being hydric (a wetland soil) or non-hydric (non-wetland soil)

(Collins, 2005; DWAF, 2005).

Vegetation in an untransformed state is a very useful way to support the delineation of a wetland, due to plant

community transition from the middle of the wetland to the adjacent terrestrial area. The guidelines specify that

when using vegetation indicators, that focus be placed on the plant communities, rather than individual indicator

species. The dominant species in the area being assessed (hydrophytes or not) must be assessed to determine

the presence of a wetland. The DWA guidelines make reference to vegetation types typically found within the

classical zones of a wetland (permanent, seasonal, temporary), but also makes reference to the classification

methodology developed by Kotze and Marneweck (1999) as part of the Resource Directed Measures for

Protection of Water Resources for Wetland Ecosystems which is based on the identification of obligate and

facultative wetland species, and the relative coverage of these species in terms of whether the area being

assessed is likely to display hydric conditions, possible display hydric conditions, or not at all.

Lastly, the hydrological framework for wetlands is covered in an appendix of the guidelines. This is based on the

longitudinal classification of river channels into three different zones based on their hydrological activation:

A Section – baseflow never occurs, and the water table never occurs at the surface (typically headward channels)

B Section – channels within the zone of a fluctuating water table, only being characterised by baseflow when the

saturated zone is in contact with the channel bed

C Section – channels that are always in contact with the zone of saturation, and thus always experiencing

baseflow (i.e. being perennial in nature)



Typically wetland habitat will never occur in the A section due to the insufficient period of saturation, while Section

B and C channels will contain wetland habitat due to a sufficient period of saturation. In terms of the classical

zonation of a wetland, the permanent wetland zone will typically only be found in the C Section, while the B

section is only characterised by the presence of seasonal and temporary zones.

Use was made of a GPS to identify important points (e.g. wetland boundaries). These GPS points were converted

into a GIS shapefile to allow these points to be mapped and to facilitate the delineation of the surface water

feature boundaries.

The field-based assessment was also used to confirm the hydrogeomorphic forms of all wetlands potentially

affected by the proposed alignment.

3.3 Identification of Surface Water Impacts and Mitigation Measures

All potential impacts that could be caused by the proposed development that would affect surface water features

along the alternative alignments have been identified and have been detailed. Mitigation measures to either of the

alternative alignments to ensure that the identified impact does not materialise, or to ameliorate / limit the impact

to acceptable levels have been stipulated.

3.4 Surface Water Mapping

All surface water features along the proposed alignments were mapped. A shapefile of surface water features

(wetlands) has been created.



4 FINDINGS OF ASSESSMENT

4.1 Study Area Bioregional Conservation Planning Context

It is important to examine the bioregional conservation planning context in order to determine whether any surface

water features in the study area have been designated as being sensitive in a regional context. The designation of

sensitivity to any surface water features potentially affected by a proposed development is important as these

impacts would take on greater importance, being significant at a regional or even national level, rather than in just

a localised context.

The bioregional conservation planning process in the Mpumalanga Province has recently been updated with the

release of the Mpumalanga Biodiversity Sector Plan (MBSP) 2013 that replaces the Mpumalanga Biodiversity

Conservation Plan completed in 2007 that hitherto provided information on biodiversity sensitivity in the province.

Although no handbook for the MBSP currently exists, the data is available for assessment and has been analysed

in this study. The MSBP assessment comprises of a terrestrial assessment as well as a surface water

assessment, with the surface water assessment identifying sensitive surface water features. The MSBP has

identified Critical Biodiversity Areas (CBAs) as well as Ecological Support Areas (ESAs) and the following sub-

categories under each category.

ESAs:

� ESA – Fish Support Points

� ESA – Water Source Areas

� ESA – Important Sub-catchments

� ESA – Wetland Clusters

� ESA – Wetlands

CBAs:

� CBA – aquatic species

� CBA Rivers

� CBA Wetlands

It should be noted that the Freshwater component of the MBSP has been based on the freshwater analysis

undertaken as part of the National Freshwater Ecosystem Priority Areas (NFEPA) Database compilation (Mervyn

Lotter, pers. comm.1). As such it is important to note that the NFEPA database has thus not needed to be

consulted as part of this assessment of the bioregional surface water conservation features.

4.1.1.1 Analysis

Figure 5 indicates the occurrence of surface water related CBAs and ESAs in the study area. There are no ESAs

that have been designated along, or in the immediate vicinity of the proposed development. Importantly the

Mpuluzi River that flows south-eastwards (just to the east of the proposed sewer alignment) has been designated

as a CBA River. No CBA wetlands have been designated close to the proposed alignment. The designation of the

1 Mervyn Lotter - Biodiversity Planner at Mpumalanga Tourism & Parks Agency



Mpuluzi River as a CBA River is important, as the wetlands and the tributary of the Mpuluzi that is crossed by the

sewer alignment feed directly into this CBA River. Thus impacts on the wetlands and streams in the study area

could indirectly impact the CBA river through downstream impact processes.

ESA fish support points for Varicorhinus nelspruitensis, a near threatened fish species are located to the east of

the development site. Although widespread the species occurs in small rivers and streams and the area of

occupancy is probably less than 2,000 km² and many of the numerous subpopulations are small and impacted

upon by sedimentation, agriculture, alien fish invasions and illegal gill netting. It is therefore considered possible

that the species might qualify as Vulnerable under criterion B should many of these small subpopulations prove

non-viable in the longer term (Engelbrecht et al, 2007). It is possible that this species could occur within the

Mpuluzi River and its tributary (as crossed by the proposed alignment).

In the context of the analysis of the catchments of surface water features in the study area, the study area

comprises of areas that are heavily modified (due to urban development and forestry), but the remainder of the

area have been designated as important subcatchments (refer to Figure 5). The importance of untransformed

areas of natural grassland, parts of which are seepage wetlands must be emphasised.

Lastly the entire study area and its surrounds has been designated as an ESA Water source area, and has been

designated as part of a National Strategic Water Source Area. These are areas that supply a disproportionate

amount of mean annual runoff to a geographical region of interest, i.e. >50% of MAR.

The management of rivers and catchment areas is thus important in this context, and the mitigation of potential

surface water-related impacts associated with this development must be considered in this context.



Figure 2 - Mpumalanga Biodiversity Sector Plan – Freshwater Analysis



4.2 Study Area Biophysical Characteristics and how these relate to / affect surface water features

4.2.1 Climate

The study area lies within the Great Escarpment that separates the high interior plateau of the sub-continent (the

Highveld) from the lower-lying areas of Mpumalanga Province and Swaziland to the east that are typically referred

to as the Lowveld within a southern African context. Precipitation within the escarpment on the eastern seaboard

of South Africa is greater than the lower-lying areas to the east due to the occurrence of orographic rainfall

(uplifting of moisture-laden air masses). The mean annual rainfall figures for the Empuluzi area is just over

900mm/annum (South Africa Rainfall Atlas2).

Rainfall is highly seasonal with rainfall predominantly occurring in the summer months, with the months of

November to March accounting for the highest monthly rainfall figures (South Africa Rainfall Atlas). This high

seasonality of precipitation has implications for the hydrology of the area, entailing that river flows are typically

much higher in the summer months. The area typically experiences mild summer temperatures, whilst winters are

generally cold with a high incidence of frost days (Mucina and Rutherford, 2006).

4.2.2 Geology, Macro-geomorphology and Topography

The study area is typically underlain by rocks that represent the earliest parts of South Africa’s geological history.

The wider study area is underlain by Archaean granitoid intrusions which fall into the Mpuluzi granite batholith

which forms part of the Nelspruit suite. The granite outcrops commonly, forming prominent outcrops in parts of the

landscape.

A system to classify the macro-drainage characteristics of South Africa has been developed, in terms of this

classification the study area is found within the Great Escarpment Geomorphic Province, although the

development site is located close to its boundary with the South-eastern Coastal Hinterland Province; the

province is characterised by high relief and mountainous topography. The province is characterised by rivers with

steep longitudinal profiles of with numerous waterfalls as hard barriers are crossed (Partridge et al, 2010). Rivers

in this province are typically deeply incised and valley cross-sectional profiles narrow. As described above the

Great Escarpment is a significant source of runoff for the majority of South Africa’s and Swaziland’s east flowing

rivers (Partridge et al, 2010).

The topography on the development site is not as incised as the site’s location within the Great Escarpment

Geomorphic Province would suggest. The Mpuluzi River drains a relatively wide, shallow valley, thus the

topography in the area is gently undulating with no excessive slopes encountered. Localised outcropping of

granite bedrock occurs in certain places. This slightly undulating topography is conducive to the presence of

hillslope seepage wetlands where groundwater seepage occurs on footslopes and midslopes.

2 http://134.76.173.220/rainfall/index.html



4.2.3 Macro Drainage Characteristics

The study area is located within the W55C quarternary catchment. This catchment is drained by the lower-most of

three wider reaches of the Mpuluzi River within South Africa as it drains eastwards from the wider catchment

divide between the Komati catchment (to the north) and the uSuthu River catchment (into which the Mpuluzi River

falls). The Mpuluzi River is thus a tributary of the uSuthu River which eventually joins the Phongolo River to form

the Maputo River which drains into the Indian Ocean in southern Moçambique. This quarternary catchment is

located within the northern part of the Usuthu to Mhlatuze Water Management Area.

4.2.4 Vegetation Types

Only one vegetation type occurs in the study area – the KaNgwane Montane Grassland vegetation type. This

vegetation type from the grassland biome is characterised by undulating hills and plains on the eastern edge of

the escarpment, being transition between the Highveld and Escarpment. The vegetation structure is comprised of

a short closed grassland layer with many forbs and scattered shrubs that are limited to rocky outcrops (Mucina

and Rutherford, 2006).

In spite of no distinct wetland vegetation types occurring in the study area (as mapped by the Mucina and

Rutherford national vegetation classification assessment), wetlands and certain rivers in the study area are likely

to display vegetative characteristics of the Eastern Temperate Freshwater Wetlands vegetation type that is

embedded within the wider grassland biome vegetation types. The Eastern Temperate Freshwater Wetlands

vegetation type is described as being characterised by flat landscapes or shallow depressions that are filled with

temporary water bodies supporting zoned systems of vegetation that form temporary flooded grasslands and

ephemeral herblands (Mucina and Rutherford, 2006).

4.2.5 Soils and Landtypes

The wider study area falls within the Ac37 landtype. Ac Landtypes are characterised by Red-Yellow apedal

(dominantly ((> 40%) red and yellow)), freely drained soils, being dystrophic and/or mesotrophic in character.

These landtypes are typically associated with high rainfall areas, where soils are subjected to moderate (=

mesotrophic) to intense (= dystrophic) leaching of nutrients from the soil profile. Soils are thus mostly low in base

elements (K, Ca, Mg, Na). A broad range of textures may occur3.

Within the Ac37 Landtype the Clovelly (Yellow-brown Apedal Unspecified) and Hutton (Red Apedal Unspecified)

Soil Forms are the most dominant soil forms. Along with area of rock, a number of less commonly-occurring soils

forms occur including the Glenrosa soil form. A number of wetland soil forms typically occur in this setting,

including the Cartref, Longlands Avalon and Katspruit Soil Forms.

3 http://www.agis.agric.za/agisweb/soils.html



4.3 Study Area Surface Water Characteristics and Occurrence

4.3.1 Wetland (Surface Water) Occurrence and Crossings

A number of surface water crossings have been identified along both sewer alignment alternatives. These have

been named according to the alternative (e.g. Alt1_1). Figure 5 below indicates the location of these crossings

along each alignment.

Dominantly (> 40%) red and yellow, freely drained, apedal (= structureless) soils. Normally associated with high

rainfall areas, where soils are subjected to moderate (= mesotrophic) to intense (= dystrophic) leaching of

nutrients from the soil profile. Soils are thus mostly low in base elements (K, Ca, Mg, Na). A broad range of

textures may occur.



Figure 3 – Quaternary catchments in the Study Area



4.3.2 Surface Water Typology (incl. Wetland Hydrogeomorphic Forms)

Wetlands and surface water features can be found all across a landscape. The landscape can be divided up into

a number of units (refer to the figure below), each of which can contain wetlands. Wetlands occurring on these

different terrain units typically differ in terms of their formative processes and hydrological inputs, and thus differ in

terms of their functionality.

In the context of the study area, it is important to note that surface water features do not only occur in valley

bottoms where depositional processes typically lead to valley bottom wetland formation. Wetlands are also

encountered on sloping ground above the valley bottom on the surrounding footslopes and higher midslopes.

These wetlands are rather characterised by colluvial processes and the input of sub-surface water inputs.

The classification of wetland form has been based upon the most updated wetland classification system for South

Africa – the Classification System for Wetlands and other Aquatic Ecosystems in South Africa (Ollis et al, 2013).

The system uses a six-tiered approach for classifying inland aquatic systems, including wetlands. Levels 4 and 5

(hydrogeomorphic (HGM) unit and hydrological regime respectively) are the focal points of the classification

system – i.e. these describe the functional unit (Ollis et al, 2013). The table below indicates the tiered

classification for the surface water features on the development site.

Figure 4 – Channelled Valley Bottom Wetland at the MF_Alt1_1 crossing point



Table 1 – Tiered Wetland / Aquatic ecosystem descriptors for the wetlands on the development site

Seep Wetlands Un-channelled Valley Bottom Wetlands

Rivers / Channelled Valley Bottom Wetlands

Level 1 – System Inland

Level 2 – Regional Setting (NFEPA WetVeg Group)

Mesic Highveld Grassland – Group 5

Level 3 – Landscape Unit

Slope Valley Floor Valley Floor

Level 4 – HGM Unit Seep Un-channelled valley bottom wetland

River / channelled valley bottom wetland

Level 4B – Seep outflow characteristic / River longitudinal zonation

Without channelled outflow Lower Foothills stream

Level 5 – Hydrological Regime / Period of inundation

Intermittently inundated Unknown (Perennial)

Level 5B – Period of Saturation

Seasonally Saturated

Level 6 – Other descriptors

Natural vs. Artificial - Natural

Salinity - Fresh (non-saline)

Substratum Type – Sandy Soil Substratum Type – Sandy to loam soils

Substratum Type - Gravel (some bedrock)

Geology – Mpuluzi Granite (Nelspruit Suite)

Vegetation Cover – Vegetated –

Herbaceous (Grasses and herbs and forms dominant with geophytes present)


Herbaceous (Grasses, rushes and reeds) dominant


Herbaceous (Grasses, rushes and reeds) dominant with some shrubs

Page | 23

4.3.2.1 Seeps

As indicated in Table 4 above, two predominant types of surface water features were located in the study area. A

number of Seep wetlands were encountered, being located within the terrain setting of sloping ground. Under

the Ollis et al (2013) classification system, a seep is defined as:

“A wetland area located on gently to steeply sloping land and dominated by colluvial (i.e. gravity-driven),

unidirectional movement of water and material down-slope”

In seep wetlands water inputs are primarily via subsurface flows from the upslope catchment of the wetland.

Water movement through the seep is mainly in the form of interflow, with diffuse overland flow (known as

sheetwash) often being significant during and after rainfall events (Ollis et al, 2013). The slopes in the study area,

although gentle is sufficient for the presence of colluvial processes that are associated with seep wetlands.

Movement of water down the slope, rather than the deposition of water within the wetland, is the predominant

hydrological driver.

Figure 5 – Seep wetland (Crossing MF_Alt2_9) on sloping ground to the north of the valley floor drained by the tributary of the Mpuluzi near the stadium

Page | 24

Seeps are often associated with lithologies that cause groundwater to discharge to the surface, or are located in

topographic positions that either cause groundwater to discharge to the land surface or rain-derived water to

‘seep’ down-slope as subsurface interflow (Ollis et al, 2013). In the case of the seep wetlands in the study area

wetland, soils within the area are largely sandy in nature, thus being permeable and well-drained. The largest

portion of the water movement in the landscape that is derived from precipitation enters the soil strata and moves

with the slope as very shallow sub-surface flow (interflow). However in addition discharge of groundwater to the

surface appears to be related to the presence of granite bedrock that may force groundwater to discharge to the

surface.

The sub-categorisation of seeps in the study area relates to the nature of the outflow, with seeps either having

channelled or without channelled outflow. The latter case applies, as in the case of most seep wetlands there is

no distinct natural channel into which water flow through the wetland outputs into the downstream drainage

system, although one seep wetland enter the Mpuluzi River valley floor and becomes an un-channelled valley

bottom. In the case of the seep wetlands in the north-eastern part of the alignment, there is no channel that forms

on the footslopes above the valley floor drained by the Mpuluzi River, rather surface water and sub-surface water

feeds diffusely into the riparian corridor of the river that appears to be characterised by silty alluvial sediment.

The level 5 descriptor is of a wetland that is intermittently inundated but seasonally saturated. Due to the terrain

setting of sloping ground sub-surface flow is likely to predominate, with standing water at the surface only

occurring intermittently over the whole wetland during the wettest times of the year. However the wetland

substrate is expected to be waterlogged for sufficient periods of time in the wet season (summer) to allow the

development of anaerobic conditions typical of wetlands and to support a vegetation community consisting of

grass and sedge species that typically favour seasonally moist conditions.

Seep wetlands were primarily encountered in the eastern and southern parts of the study area. An extensive

series of seep wetlands was encountered in the north-eastern part of the development site on the western

footslopes and start of the midslopes of the Mpuluzi River valley. An extensive seep wetland was encountered just

to the east of the sports stadium (MF_Alt1_2) on the sloping ground to the west of the one of the narrow

channelled valley bottom wetlands. Although not crossed by the proposed waterborne sewer, a similar extensive

seep is located on the footslopes between the tributary of the Mpuluzi River and the sports stadium.

A number of direct points of groundwater seepage were noted in these seep wetlands, particularly in those along

the eastern-most part of the alignment. Groundwater outflow from these springs was noted. In one instance (at

crossing MF_Alt2_8) a spring was located immediately adjacent to, and downslope of a granite outcropping

suggesting that groundwater seepage is directly related to granite bedrock outcropping.

Page | 25

Figure 6 - Seep wetland upstream of the proposed alignment in the north-eastern part of the development site

4.3.2.2 Rivers and Channelled Valley Bottom Wetlands Rivers and Channelled valley bottom wetlands have been grouped together as certain water courses in the study

area share characteristics of both.

Under the Ollis et al 2013 classification system, a river is defined as:

“A linear landform with clearly discernible bed and banks, which permanently or periodically carries a

concentrated flow of water. A river is taken to include both the active channel and the riparian zone as a unit “

Rivers are characterised by concentrated surface flow from upstream channels and tributaries but other inputs

can include diffuse surface or subsurface flow (e.g. from an upstream seepage wetland), interflow (e.g. from

valley side-slopes), and/or groundwater inflow (Ollis et al, 2013).

The riverine tributary of the Mpuluzi River that drains eastwards to the north of the stadium displays a distinct

channel with concentrated flow. This river is crossed by both Alternatives 1 and 2 at MF_Alt1_3 and MF_Alt2_11

respectively. This watercourse is classified predominantly as a river, however it also displays some characteristics

of a channelled valley bottom wetland, in particular the presence of hydromorphic soils on the channel banks.

There is not sufficient wetland habitat within the channel and riparian zone to characterise it as a channelled

valley bottom wetland, although this is likely to be a result of accelerated erosion along stretches of the river.

Page | 26

Under the characterisation of longitudinal river zonation, the Mpuluzi River that drains just to the east of the

development site is classified as a lower foothills stream. A stream in this setting is described as:

“a lower gradient, mixed-bed alluvial channel with sand and gravel dominating the bed, with possible local

bedrock-controls. Reach types typically include pool-riffle or pool-rapid, with sand bars being common in pools.

Pools are of significantly greater extent than rapids or riffles.” (Ollis et al, 2013)

The tributary of the Mpuluzi as crossed by the proposed sewer falls into this classification and is characterised by

a gravel and silt-dominated bed with some areas of granite bedrock outcropping, set in a somewhat wide valley

floor.

Figure 7 – The tributary stream of the Mpuluzi River at crossing point MF_Alt1_3

Page | 27

A number of other valley bottom systems that drain into the tributary of the Mpuluzi from the south display similar

characteristics and have been defined as channelled valley bottom wetlands but are believed to naturally have

been un-channelled before the development of gulley erosion within them (crossings MF_Alt2_112-15). As

defined by Ollis et al (2013), channelled valley-bottom wetlands must be considered as wetland ecosystems that

are distinct from, but sometimes associated with, the adjacent river channel itself, which must be classified as a

‘river’. Dominant water inputs to these wetlands are from the river channel flowing through the wetland, either as

surface flow resulting from flooding or as sub- surface flow, and/or from adjacent valley-side slopes (as overland

flow or interflow).

4.3.2.3 Un-channelled Valley Bottom Wetland

One wetland in the study area was noted to be an un-channelled valley bottom wetland (crossing MF_Alt1_4). A

channelled seep wetland runs through an area of rock outcrops, entering the valley floor of the Mpuluzi River and

becoming an un-channelled valley bottom wetland. The wetland is crossed by he proposed pipeline close to the

point at which it changes from a channelled to an un-channelled wetland.

Under the Ollis et al 2013 classification system, an un-channelled valley bottom wetland is defined as being:

characterised by their location on valley floors, an absence of distinct channel banks, and the prevalence of

diffuse flows.

These wetlands are generally formed when an upstream channel loses confinement and spreads out over a wider

area, causing the channelised flow to spread out, becoming. As in the case of the example in the study area, this

is typically due to a change in gradient brought about by a change in base level at the downstream edge of the

wetland and the resulting accumulation of sediment.

4.3.3 Wetland Soil Characteristics

It is important to report on soil characteristics encountered as part of this wetland assessment includes the

identification of (delineation) hydromorphic soils.

Soils were sampled in a number of sloping locations where vegetation communities dominated by hydrophytes

were noted. Hydromorphic soils were located in all of these settings, corresponding with the presence of a

wetland vegetative composition. A number of wetland soil forms were noted in these locations, with the presence

and combination of certain subsoil horizons associated with hydromorphic soils being identified. The following

wetland soil forms were identified in the seepage wetlands in the eastern part of the alignment (on the eastern

periphery of Mayflower village) and in the vicinity of the sports stadium in the order in which they were most

commonly encountered:

� Kroonstad (A→E→G)

� Cartref (A→E→Lithocutanic B)

� Katspruit (A→G)

� Fernwood (A→E→Unspecified)

Page | 28

The presence of E horizons in many of the soil sample points is indicative of the lateral movement of sub-surface

water (interflow) within the substratum that has resulted in the removal of colloidal matter (iron oxides, silicate clay

and organic material). G horizons that are present within the Kroonstad and Katspruit soil forms were widely

encountered in the seep wetlands sampled in the development area, and are indicative of the presence of a

permanently inundated zone within the lower portion of the soil profile, but which is located at relatively shallow

depth (between 40cm-1m of the soil surface). This water table rises seasonally to saturate the upper parts of the

soil profiles in these locations, resulting in the presence of iron (and less frequently manganese) mottling in the A

horizon that was noted at many of the sample locations.

Where a transition from wetlands to non-wetland areas was noted, this was marked by the disappearance of

redoximorphic features from the soil, and a change in the dominant soil forms encountered. Soils just outside of

the wetland boundaries typically displayed either a Glenrosa soil form (A→Lithocutanic B) or a Griffin soil form

(A→Yellow-brown apedal B→Red apedal B). These soil forms are not wetland soil forms and display no

distinctive hydromorphic characteristics.

Figure 8 – Series of soil horizons encountered from a Kroonstad Soil Form within the seep wetland MF_Alt1_2; soils from the Orthic A Horizon (left), soils from the underlying E horizon (middle) and soils from the lower-most G horizon (right).

Soft plinthic and hard plinthic B horizons were noted in some wetlands in the study area. Soft plinthic horizons are

typically associated with a seasonally rising and falling water table and are often encountered in wetlands. Hard

plinthic horizons (also noted as ferricrete) were noted along certain of the channelled valley bottom wetlands

feeding into the tributary of the Mpuluzi River near the sport stadium, having been exposed by gulley erosion in

these (naturally un-channelled) wetlands.

The presence or soil wetness indicators and wetland soil forms was utilised as the primary means by which to

identify wetlands on the development site, with vegetation performing a strong supporting function as discussed

below.

4.3.4 Vegetative Characteristics of Surface Water Features

As discussed in section 4.2.4 above the study area falls within the Grassland Biome and the KaNgwane Montane

Grassland Vegetation Type, thus all wetlands, in particular the seep wetlands on the development site were

Page | 29

characterised by herbaceous rather than woody vegetation, comprising of grasses, sedges, herbs and forbs, with

rushes and reeds occurring in certain places.

The site survey was conducted in mid-February during the growing season and thus vegetation was typically

flowering with many species displaying inflorescences. The state of vegetation allowed vegetation community

differences between wetlands and surrounding non-wetland areas to be scrutinised. A distinct divergence in

species composition between wetland areas and non-wetland habitats was noted, with the presence and

dominance of grass and sedge species in wetland areas that are not encountered elsewhere on the site.

Seep wetlands took the form of a damp (moist) grassland, characterised by a short sward dominated by certain

grass and sedge species. Certain grass species were noted to be dominant within these seep areas. Andropogon

eucomis was the most commonly encountered species within the seep wetlands on the site occurring in the

slightly drier parts of the wetland. Other species that occur in both wetlands and in surrounding grassland such as

Loudetia simplex, Eragrostis gummiflua, Sporobolus africanus and Hyparrhenia filipendula were also noted to be

common in these direr parts of the seep wetlands. In the wetter parts of the wetland where standing water was

typically encountered and in areas of active groundwater seepage, a number of other species were noted to be

dominant including Leersia hexandra, Miscanthus junceus, Paspalum notatum and sedge species such as

Schoenoplectus corymbosus, Kyllinga ***, Fuirena pubsecens, The flowering plant Dissotis princeps that typically

occurs in marshy environments was also noted from one of the seep wetlands.

Page | 30

Figure 9 – Typical vegetation (moist grassland) in a seep wetland at crossing MF_Alt1_2

The short un-channelled valley bottom located that drains onto the valley floor of the Mpuluzi River is

characterised by a mix of grasses and reeds with the most dominant species being Miscanthus junceus and

Phragmites australis, with Leersia hexandra noted to be very common.

In the channelled valley bottom wetlands and watercourses (tributary of the Mpuluzi) hydrophytes were typically

noted to be restricted to within the macro-channel, which is narrow in the case of the channelled valley bottoms

wetlands draining northwards into the tributary of the Mpuluzi. Grass and certain sedge species including Leersia

hexandra, Paspalum dilatatum and Paspalum notatum only occurred along the active channel, or in areas where

seepage from the soil profile as exposed by eroding banks was present. Where lateral seepage zones were not

present on the margins of the macro channel bank, terrestrial species or marginal hydrophytes such as Eragrostis

plana and Sporobolus africanus occurred. Along the tributary stream of the Mpuluzi hydrophytes (species such as

Leersia hexandra, Andropogon eucomis and some clumps of Miscanthus junceus) were noted to be limited to the

margins of the active channel with the upper channel banks being dominated by Eragrostis plana.

Some naturally-occurring woody riparian vegetation was encountered along certain stretches of the tributary

stream of the Mpuluzi but was nowhere common. Woody shrubs of two species – Buddleja salvifolia and

Page | 31

Diospyros lycioides – were noted to be present, but were outnumbered by alien invasive shrub species such as

Solanum mauritianum and Acacia mearnsii.

Figure 10 – Hydrophytes in the seep wetland just downslope of the alignment at crossing MF_Alt2_8

Page | 32

5 NATURE OF THE POTENTIAL IMPACTS ON SURFACE WATER FEATURES ASSOCIATED WITH THE PROPOSED DEVELOPMENT

5.1 Impacts on Surface Water Features associated with laying of buried pipelines

Owing to the nature of construction of a pipeline as proposed, which would involve the excavation of a trench in

order for the pipeline to be placed underground, the most important potential impact of the proposed pipeline on

wetlands along the proposed routes relates to the disturbance and potential erosion of wetland soils. For the

riverine environments in the study area the key potential impacts relate to habitat disturbance and changes in

water quality. The laying of the pipeline through the trenching method would entail the disturbance and removal of

wetland and riparian vegetation, and the excavation of soils within the wetland and along the riverbanks. Water is

an erosive force, and the exposed soils could be eroded, especially in the permanently wet parts of the wetlands

where above ground or underground flow / seepage of water through the wetland would naturally occur. If the flow

of water and seepage out of the wetland soils is not controlled, this could initiate a ‘knickpoint’ which may lead to

development of gulley (donga) erosion into the upstream part of the wetland. Any eroded material would be

deposited in the downstream portion, potentially causing sedimentation in that part of the wetland which may

smother the existing vegetation, leading to further impacts on this part of the wetland.

The pipeline trench may become a route for preferential drainage within a wetland, especially if fine-grained

imported padding material (through which water would easily drain) is used to surround the pipeline or line the

trench, or if the trench was aligned in the direction of the water flow through the wetland, and not perpendicular to

it. This material could form horizontal or vertical drains inside the trench that would act to drain wetland units, as a

preferred waterway through the trench would be provided. This may also result in a deterioration of water quality

as minerals are leached out of the soil, whilst increasing the soil erosion potential. The creation of altered

drainage could lead to erosion through the concentration of flow, and the loss of diffuse flow which would cause

desiccation of certain parts of the wetland.

When trenching is undertaken through a wetland, especially through the permanently saturated parts of the

wetland, the trench is likely to be flooded. This was evident along parts of the proposed alignment in which

trenching had already commenced within seepage wetlands in the north-eastern parts of the alignment – the high

water table had been intersected. The seepage water that enters the trench is likely to contain silt, due to

construction activities. If this silt-laden water were to flow into downstream parts of the wetland, or be extracted

from the trench and deposited elsewhere (as part of a dewatering operation) in the wetland it could cause a

detrimental effect on the wetland or downstream watercourses. The discharge of the water from the trench within

the wetland could be construed to be pollution under the National Water Act if this water contains silt. The

discharge of silt-laden water into downstream watercourse / wetland could be construed to be an alteration to the

physical and biological characteristics of that water resource as excess siltation within a wetland or river can

cause an alteration to the wetland hydrology and can have a negative impact on both river and wetland fauna and

flora, such as reduced primary productivity, smothering of benthic aquatic organisms, and clogging of gills for both

Page | 33

fishes and aquatic invertebrates. Furthermore, excessive siltation reduces habitat heterogeneity, thus affecting in

turn the ecological and hydrological functions related to the wetland vegetation and aquatic habitats. This process

would adversely affect the resource quality and would also have an impact on a number of aquatic organisms that

inhabit, and are dependent on the wetland vegetation.

Trenching within a river or smaller fluvial surface water feature will inevitably result in physical disturbance and

modification to the river bed and channel. This in turn will alter all instream and riparian habitat characteristics

including flow characteristics in the area of construction and reduce habitat heterogeneity, as far down as the

microhabitat level. The suitability and availability of the aquatic habitat is highly significant for inhabitation by

aquatic organisms, and ultimately contributes to the overall ecological integrity and health of a river system. The

long term effects of bed and channel modification could be severe if the river is not re-configured to as close to

the pre-construction state as possible. If this is undertaken, the direct effects of the pipeline should be limited to

the duration of construction. However, indirect effects such as downstream changes in erosion and deposition

patterns, as a result of bed/channel (bulldozing, trenching, levelling) and flow modifications (diversions and

abstractions) in the construction area, may be develop. These changes must be monitored for and appropriately

mitigated upon construction completion.

The re-instatement of vegetation within the wetland and within riparian zones of channels after pipeline

construction is a critical factor in the prevention of impacts on both wetlands and rivers. The excavation of a

trench for a pipeline within a wetland or across a river will necessitate the removal of vegetation within the

footprint of the trench and in adjacent areas where machinery will move / be placed. If vegetation is not re-instated

after trenching, or is not properly re-instated (e.g. if vegetation from the permanently wet zones was placed in the

temporary wet zone of the wetland near the wetland boundary causing it to die), soils would remain exposed.

Wetland and riparian vegetation play a very important role in binding soils and if vegetation was not properly

restored, the potential for wetland soils being vulnerable to desiccation and erosion would markedly increase, thus

leading to the possible onset of erosion in the wetland and the riparian zone.

Lastly, the returning of soils and other strata in wetland in random fashion (not in the order in which they were

taken out), especially the non-reinstatement / non-creation of impervious strata within the wetland could have a

significant impact on the hydrology of the wetland. If topsoil were not reinstated at the surface of the wetland,

vegetation restoration may not be successful.

The abstraction of large volumes of water for construction purposes from a riverine system would lead to localised

and possible downstream (reduced input to streams and rivers) implications. The impact of water abstraction

would be more pronounced for small and/or ephemeral streams, which may suffer reduced flows, and

consequently impaired habitat availability and suitability for aquatic fauna, and thus overall deterioration in

ecosystem health. Water abstraction should thus only be undertaken in larger rivers (as stipulated in the outcome

of a Water Use License Application), which are known to carry sufficient water to sustain ecologically functioning

of aquatic ecosystems without jeopardising downstream user groups, including the downstream natural

environment.

Page | 34

In general, the biota in the wetland and river courses will be disturbed, but this is likely to be a disturbance that is

limited to the length of time of construction through the wetland / river. Biota are likely to return to the wetland /

river, provided that the habitat integrity remains in a similar state to the pre-construction state.

5.1.1 Context of the study area

As discussed above, there are a number of seep wetlands as well as channelled valley bottom wetlands and a

riverine system in the study area. Construction and trenching along the alignment provided by the proponent was

noted to have already commenced along the eastern parts of the alignment, including within all of the seep

wetlands along this part of the alignment. The effects of construction were not only limited to the trenching and

stockpiling of excavated material, but a number of areas of the seep wetlands were noted to have been damaged

by the uncontrolled movement of heavy machinery over large parts of the wetlands. In spite of a prominent human

footprint in these seep wetlands on the footslopes and midslopes of the Mpuluzi River valley (households and

household compounds have been established in certain of the wetlands) the presence of a seasonally high water

table and wetland vegetation that retained a largely natural character meant that these wetlands are sensitive to

disturbance by heavy machinery movement. The trenching, and subsequent cessation of construction with the

continued exposure of the open trench without pipe laying has left the affected wetlands vulnerable to siltation of

the stockpiled material during heavy rainfall events.

The major river / stream crossing is of the tributary of the Mpuluzi River. The crossing point is located immediately

adjacent to a drift across the river which is used as a vehicular access to cross the stream, linking parts of the

wider Empuluzi settlement. The reach is thus already impacted by human activities, as well as being subject to

heavy grazing pressure by livestock. This has resulted in the erosion of the banks of the stream at the crossing

point. The crossing point is also characterised by a relatively more gently-sloping cross-sectional gradient as

compared to upstream portions of the stream which have much higher, more incised macro-channel banks which

will make construction easier and which will lessen the potential for erosion and the need for the construction of

large structures (gabions) to re-create channel banks. Due to the high human footprint the vegetation within the

riparian zone of the stream is similarly impacted with the presence of grass species typical of a disturbed,

overgrazed area, and no woody vegetation present.

A low volume (dry weather) baseflow within the stream was noted, which is beneficial in the context of potential

amelioration of construction impacts as this flow will be able to impounded and flumed or bypassed through the

works. The bed of the stream was noted to consist of transported sandy sediment.

The most significant risk of construction of the pipeline across this stream relates to the mobilisation of silt and

other sediment, and possibly other pollutants into the downstream watercourse if pipe excavation rather than

horizontal directional drilling occurs. This risk is particularly pronounced if spate flows occur within the stream

during construction. It is thus very important that the mitigation measures as specified in section 5.4 below be

implemented, and that if possible that construction occur during the winter dry season.

Page | 35

Figure 11 – Silt laden water within the trench already excavated along the proposed alignment

The smaller channelled valley bottom wetlands draining into the tributary stream are characterised by narrow and

more incised gradients with the presence of hard plinthic layers in places. The risk of siltation and bank collapse

during construction is similar to that of the tributary stream of the Mpuluzi above and is magnified by the sloping

setting. Similar mitigation measures, in particular relating to reconstruction of banks are important at these sites.

5.2 Indirect and Other Construction-related Impacts

The process of constructing the waterborne sewer could also indirectly impact surface water resources. A number

of activities, especially those relating to the access of construction vehicles along, and in the vicinity of the

alignment can result in damage to and impacts on surface water resources.

Construction vehicles and machinery that access and move along the alignment during construction would

typically cross wetlands and other watercourses. In the case of seep wetlands (damp grassland) it is highly

unlikely that a specific running track or similar measure would be constructed as a standard construction

measure. Thus the movement of heavy machinery involved in the excavation and trenching of a pipeline would

cause significant damage to wetland soils through compaction and through the creation of rills or linear

depressions where vehicles have moved. Such impacts were noted to have occurred in certain of the wetlands

assessed along the north-eastern part of the alignment where the random movement of heavy vehicles and

machinery had created large areas of soil and vegetation disturbance across a large area. The magnitude and

Page | 36

intensity of this impact on the affected part of the wetland was significant, and could potentially lead to a

permanent impact on the wetland if not correctly mediated.

In addition the following impacts on surface water resources can result from construction activities associated with

the proposed development:

� A lack of / poor stormwater controls being put in place on the construction site. This may result in the creation

of runoff containing pollutants such as cement and oils being transported by stormwater runoff into nearby

drainage systems.

� The dumping of construction material, including fill or excavated material into, or close to surface water

features that may then be washed into these features.

� Spills of hazardous materials, especially oils and other hydrocarbons that may be washed into, or infiltrate

nearby surface water features.

� The conducting of certain construction-related activities (such as cement batching) too close to surface water

features or without the implementation of certain controls that may lead to the direct or indirect pollution of the

surface water feature.

� The lack of provision of ablutions that may lead to the conducting of ‘informal ablutions’ within or close to a

surface water feature that may lead to its pollution by faecal contaminants.

� The interaction of untrained construction workers with wetlands and water resources, which could result in the

washing if equipment in rivers, for example.

Page | 37

Figure 12 – Damage to the Seep wetland MF_Alt1-2_5 caused by recent movement of heavy machinery related to pipeline construction

Most of these and other potential construction-related impacts can be minimised or adequately mitigated by

controlling construction activities on the basis of an appropriately designed Environmental Management

Programme (EMPr), with emphasis on construction-phase mitigation.

5.3 Operational Phase Impacts

In addition to construction-phase disturbance impacts, sewer lines can exert a significant impact on surface water

features and the associated aquatic environment if raw sewage leaks from the sewer pipeline or associated

infrastructure such as manholes.

Untreated sewage as will be transported by the proposed waterborne sewer is highly dangerous to both human

health and to the environment. Raw sewage contains bacteria (such as e-coli), microbial pathogens and viruses

that are highly hazardous to human health if people come into contact with, or ingest water polluted with sewage.

Page | 38

In an ecological context, sewage is highly detrimental to aquatic ecosystems. Human waste contains nitrates,

phosphates, and organic matter are utilised by algae and bacteria to proliferate in aquatic ecosystems such as

rivers and other waterbodies. An oversupply of such nutrients caused by ingress of sewage into a water body

causes these organisms to overpopulate to the point where they use up most of the dissolved oxygen that is

naturally found in water, making it difficult for other organisms in this aquatic environment to find oxygen required

to sustain life. This situation can thus result in the death of aquatic organisms such as fish, thus causing

degradation in the resource quality of the aquatic resource.

In addition sewage inflows to rivers and other aquatic ecosystems can increase the turbidity and amount of

suspended sediments within the water, which would reduce light available for plant growth, smother in-stream

habitats, and damage fish gills and respiratory structures of other species. Sewage can also alter the temperature

of water in the aquatic environment. Domestic sewage may also contain other household chemicals such as a

degree of chlorine that can also act as a pollutant in aquatic ecosystems.

Should a sewage leak from the waterborne sewer enter the environment through above ground spillage that could

drain into a nearby surface water feature, or seep into shallow groundwater, this would constitute the pollution of

the water resource. Poor management and maintenance of sewage infrastructure in South Africa is a major

contributor to water pollution and efforts must be made to ensure that the sewer does not cause pollution of

adjacent resources.

5.4 Mitigation Measures and Recommendations

Note: No detailed wetland and river crossing methodologies have been provided for assessment, thus

only generic crossing methodologies have been able to be provided.

5.4.1 Generic Wetland Crossing Mitigation Measures

The following generic mitigation measures must be applied to all wetlands crossed.

Preparation for works:

� All sensitive areas close to, but not within the physical footprint of the works must be physically designated /

signed as being sensitive. This can be done with danger tape, or ideally sensitive areas should be fenced off

prior to the start of construction to avoid accidental entry of people or machines;

� The area in which topsoil and subsoil is to be stockpiled must be identified. It is important that topsoil and

subsoil be stockpiled separately. Stockpiles of excavated material must be placed either outside the wetland

or adjacent to the trench so as to minimise the area of disturbance in the wetland;

� In steeply-sloping settings, measures must be taken to ensure that soil and other debris does not slump into

the downstream wetland from the works area;

� If machinery needs to access areas of saturated wetland soils, it is recommended that a running track be

constructed into the wetland to avoid damage to soils and vegetation. The running track can comprise of

bogmats or crushed stone.

Page | 39

Handling water flow through the works area:

� Due to the possible presence of flowing water in wetlands, the flow within the wetland must be prevented from

moving through the works area and thus potentially mobilising silt and other potential pollutants into the

downstream / downslope parts of the wetland. Flow must thus be bypassed around the works – it is typically

recommended that a temporary impounding structure (such as a low clay wall along with sand bags) must be

constructed across the wetland to impound water behind the works. This ponded water must be either

pumped into the downstream wetland, or must be flumed through the works. No trenching or other

construction must occur within an area of active flow, and trenching must be conducted in as dry an

environment as possible;

� Any seepage water in the works area (including in the trench) must be pumped out of the works area to be

discharged into the downstream wetland. If water in the trench contains silt is suspension, dewatered water

from the works area must be passed through a silt trap (silt lagoon) in order to ensure that silt in suspension is

removed as far as possible;

� Silt must be carefully removed from the silt trap / lagoon prior to it being removed, and must not be dumped in

the wetland or its immediate catchment;

� In the case of channelled wetlands, it is recommended that a silt trap be placed across the channel

downstream of the works to capture any silt released from the works. Silt captured behind the silt trap must be

carefully removed manually prior to the silt trap being removed, and the silt must not be re-deposited in the

wetland.

Trenching, pipe-laying and reinstatement

� It is very important that topsoil from the trench through the wetland area be removed and stored separately

from subsoil;

� The natural substrate (subsoil) is to be reinstated to the trench as far as possible (taking into account

technical pipeline safety and cover requirements);

� The original topsoil must be reinstated to the wetland within the trench area, as this topsoil will contain a

natural seed bank;

� The wetland must be reinstated as far as possible to its natural structure, and substrate must not be

reinstated in such a way as to obstruct water movement within the wetland. If gabion mattresses are used

above the pipeline, topsoil must be reinstated at the surface of the wetland;

� No pipeline stabilisation measures must cause the obstruction of sub-surface flow through the wetland. As

such rock gabions are supported for this purpose;

� If free-draining fines material is placed around the pipe to protect it – i.e. sand, in a context of natural clayey

substrate that is much less pervious, it is recommended that clay plugs be used within this layer of fines to

ensure that the fines around the pipe does not become a path for ‘preferential drainage’ through the wetland,

thus altering the sub-surface hydrology;

� Material such as excess rock that is not required as part of the works or for reinstatement must not be

dumped in the wetland, and must be properly disposed of or reused at another location;

� All areas in which embankments / banks are reinstated outside of the channel / wetland bed with topsoil must

be re-vegetated with a suitable indigenous soil mix, using Hydroseeding. All such areas of topsoil

reinstatement must be covered with geotextile or similar hessian sacking-type material which must be staked

into the ground;

Page | 40

� All areas in which a running track has been created must have the running track material fully removed once

reinstatement is finished;

� Areas where soils have been compacted through the movement of machinery must be lightly ripped / scarified

and the original ground level restored; and

� All temporary impounding structures must be removed prior to construction works being concluded.

Other:

� The works area must be fenced off from livestock for a period (at least 6 months) after the end of construction

to ensure that vegetation in the works area is able to re-grow without being affected by cattle trampling; and

� The wetland works area must be monitored for signs of erosion after construction has been concluded.

5.4.2 River (and channelled valley bottom wetland) Crossings

The tributary stream of the Mpuluzi that is crossed by Alternative 1 at Crossing MF_Alt1_3 is likely to contain

some form of flow into the dry season due to the presence of wetlands in its catchment, thus it is possible that

flow within this watercourse will need to be managed as part of the construction process. This is expanded on

below.

The four channelled valley bottom wetlands that drain into the tributary stream of the Mpuluzi and which are

crossed by the sewer line alternatives are narrow wetland features which due to accelerated erosion display more

affinities with fluvial river systems that typical valley bottom wetlands. The following mitigation measures should

also be applied to these four crossings.

Preparation for in-river construction works:

� It is strongly recommended that works take place in winter (the dry season) when flow velocities will be at

their lowest, and thus more easily manageable.

� Spill prevention measures must be put in place both up and down stream of the area where works are to be

installed prior to any activities taking place. Other spill response equipment must also be onsite during

activities.

� If works are conducted in low flow (and for the 4 channelled valley bottom wetlands crossed): Prior to the

onset of works, flow in the river must be impounded behind the works in order that the works can be

completed in a ‘dry’ environment. It is recommended that a temporary impoundment consisting of clay and

sand bags be constructed across the channel. Water must be pumped / flumed past the works and

discharged downstream. The works area should be pumped dry once the impoundments have been

completed, and any aquatic fauna stranded in the works area must be safely relocated to the downstream

river channel.

� If works have to be undertaken during high flow periods with higher volumes of baseflows in the Mpuluzi

Tributary: it is recommended that river flow be allowed to bypass the works on one side of the channel with

temporary structures placed (e.g. sand bags etc.) to keep the works dry. Once work is completed on the one

side, the river flow should be diverted through the newly constructed pipe section and restored substrate and

work can be completed on the opposite side.

Page | 41

� In both cases above, temporary structures must be constructed to withstand any rock-hammering / blasting

activities that may need to be undertaken to trench into the substrate.

� Machinery access routes: due to the sensitivity of the riparian zones surrounding the rivers / streams, an

access right of way for heavy machinery working in the river bed must be created and demarcated. A form of

running track may need to be created to allow the safe movement of machinery into the river bed. The

running track can consist of crushed rock placed on top of the wetland soils to form a running track, or

bogmats, if available.

� Due to safety requirements in the case of steep banks, the banks may need to be re-profiled to allow

machinery to safely access the river bed.

� Stormwater control measures must be put in place to ensure that no silt from the access into the river bed

transports silt into the channel or the riparian zone.

� The channel upstream and downstream of the road must remain free of vehicular access – This must be

demarcated as such.

� Topsoil on the banks of the river must be removed from the running track area and from the trench footprint.

This must be stored separately for reinstatement.

� A silt trap must be installed in the downstream part of the channel to trap any silt mobilised as part of the

works. The integrity of these traps must be checked for the duration of the works.

Page | 42

In-river construction works:

� Once preparatory works in the river have been completed (as per above for low flow or high flow conditions),

work can commence on the removal of the existing substrate and construction of the pipeline in the channel.

� It is very important to restore the channel bed substrate to as close to natural conditions as possible, thus

prior to trenching, any loose material in the works area lying on top of the bedrock must be removed and

separately stored for reinstatement.

� Once the loose substrate has been removed, the existing (bedrock) substrate that comprises the current

channel bed must be removed from the channel down to the level of bottom of the trench. All rocky material

not to be re-used for reinstatement must be removed from the river channel and not dumped into the river or

its associated riparian zone. If it is to be re-used for the new gabion structures it must be temporarily stored

outside of the riparian zone, preferably in area of existing impact.

� The pipeline as it crosses the river must be protected from scour within the channel (bed) of the river. It is

thus recommended that the pipeline be encased, e.g. in concrete or within a rock gabion structure (i.e. gabion

mattress) in the pipeline trench.

� Any rock gabions placed into the excavated trench both on the upstream and downstream sides of the trench

must be properly secured to avoid being displaced.

� The level of any protective structures (e.g. gabion mattress) placed over the pipeline must allow any loose

cobbles and rocks that previously occurred in the bed of the stream to be placed back on top of the gabion

mattress without creating an impounding feature.

� Once the protective structure has been fully constructed, the original channel substrate (e.g. cobbles or small

boulders that were removed prior to trenching in the bed) needs to be carefully reinstated either by hand, or

with an excavator. Reinstatement of this material must ensure that the channel bed is returned to as close to

a pre-construction state as possible.

� All seepage water in the works areas must be regularly pumped out to ensure that the works area is dry.

Water pumped out (dewatered) must be first passed through a silt trap (silt lagoon) before being discharged

back into the downstream watercourse. Water must be checked for signs of contamination of oil before being

dewatered; if oil is noted such water must not be re-discharged into the natural environment, but taken off site

and treated or disposed of at a suitable landfill site.

� The water in the works area must be dewatered. Any aquatic fauna trapped in the works area once it has

been pumped dry must be carefully relocated into the downstream section.

Reinstatement and completion of the works:

� The banks of the river must be restored to as natural (pre-construction) a profile as possible. Topsoil from the

banks must be reinstated to the re-profiled banks.

� In order to not create a convenient pathway for livestock to access the river by means of the excavated right

of way that is created across both banks (thus creating a risk of disturbance of soils and erosion), the original

bank profile must be recreated, with the use of gabions where required.

� Reinstated topsoil must be re-seeded (preferably by Hydroseeding)

� The re-created banks and reinstated topsoil must be covered with a geotextile / hessian sacking material that

is staked into the banks to protect the soils and allow for natural re-vegetation.

� As described above the channel substrate must be returned to the channel bed over the trench and works

area to mimic a pre-construction state as far as possible.

Page | 43

� The running track (if constructed), must be carefully removed, ensuring that no foreign material is left in the

wetland or on the channel banks. Soils underlying the running track must be lightly ripped (scarified) if found

to have been compacted.

� It is strongly recommended that all rehabilitating areas be fenced off to prevent livestock from damaging soils

and young plants.

� All temporary impounding structures must be fully removed from the river bed once the works are complete,

and no foreign material must be left in the river channel.

5.4.3 Water Crossing-related permitting

� It should be noted that the proponent is undertaking a water use licensing process separately from the

Environmental Authorisation process being undertaken by RHDHV.

� Refer to Section 1.4.1 for permitting requirements relating to the National Water Act and associated

regulations

� If any temporary or permanent surface water crossing structures are required (including the upgrading of

existing crossings) to be constructed / developed, the required authorisations in terms of Section 21 of the

National Water Act must be obtained.

� All wetland and other surface water crossings would constitute Section 21 c) and i) water uses as prescribed

by the National Water Act. Accordingly a full water use licence would need to be acquired for all of the

crossings.

5.4.4 Stormwater control during Construction

� Although it is recognised that implementing full stormwater control measures on a construction site (i.e. a

dynamic situation) is difficult, measures must be taken to ensure that stormwater is controlled as far as

possible and that all silt and other foreign materials are prevented from entering any surface water feature

located adjacent to or crossed by the construction servitude during the construction phase.

� Stormwater control is particularly important in riparian zones with steep slopes, and in sloping seep wetlands

which are highly susceptible to erosion.

� Stormwater containing silt must be prevented from entering any wetland or river, through the use of retarding

features such as berms or silt fences

� No drains / ditches of any form must be constructed into wetlands as a temporary measure to divert

stormwater from the construction servitude.

5.4.5 Road / Tracks and surface water crossing structures

� No temporary roads or construction accesses must be constructed through any wetland or other surface

water feature not crossed by the proposed sewer line unless there is no other feasible option for access to the

alignment.

� It is also strongly recommended that no permanent access roads / tracks along the servitude be constructed

through any surface water feature. Rather existing track / road crossings of these surface water features

Page | 44

should be used (even if they are a distance upstream or downstream of the crossing) and upgraded where

necessary.

� No track / access road must be developed through any seep wetland, even if the wetland is located away

from the alignment.

In the event of the need for a the development of a vehicular access river crossing:

� Should culverts be used as the structure for crossing a river or watercourse, culvert structures must be placed

so that the base of the culvert is located at the current level of the current bed of the watercourse. No water

must be impounded behind the culvert structure at a level lower than the base of the culvert during low flows.

In addition the culvert must not create a step (drop in levels) between its base and the downstream

watercourse that would hinder the movement of aquatic biota up the system.

� Where channelled wetlands / watercourses crossed by the road / access track are associated with adjacent

areas of wetland or riparian habitat which would be subject to periodic inundation by spate flows in the

channel (caused by overtopping of the banks of the channel), the crossing structure must be extended to

include this area of wetland / riparian habitat to the boundary of the wetland / riparian habitat.

� All tracks / access roads that are developed must have formal stormwater measures included in the design so

that no erosion develops on these tracks that could lead to the siltation of downslope surface water features.

� All such crossing structures must be authorised under the National Water Act and associated regulations.

5.4.6 Checking and Prevention of Sewage Leaks from the sewer

� Once the sewer becomes operational it is critical that regular checks regarding the integrity of the sewer

system must be undertaken to check for the presence of any sewage leakages. This must incorporate regular

physical checks of the integrity of the system especially in the vicinity of surface water features.

� Any detected leakages must be immediately remediated and the affected portion of the sewer system

repaired to stop the sewage leakage into the environment.

5.4.7 Alien Invasive Plant Management within servitudes during operation

.

5.5 Comparative Assessment of Alternatives

Two alternative alignments have been presented for comparative assessment by the proponent. These alternative

alignments need to be assessed in order to recommend a preferred alternative from a surface water perspective.

Six (6) surface water features are crossed by Alternative 1, whereas eleven (11) surface water features are

crossed by Alternative 2. There thus nearly double the number of surface water crossings along Alternative 2 than

Alternative 1. Alternative 1 would thus be associated with an impact on a lower number of watercourses, and thus

the overall impact of the alternative would be lower than that of Alternative 2. Accordingly, Alternative 1 is

preferred from a surface water perspective.

Page | 45

6 CONCLUSIONS

The waterborne sewer will affect a number of surface water features along both alternatives. The development of

the underground pipeline will affect wetlands through the construction of the sewer which entails the physical

disturbance of wetland soils and vegetation by pipeline trenching. A number of other indirect impacts could occur,

including the development of erosion and siltation and pollution of downstream wetlands and watercourses.

A number of mitigation measures have been specified to avoid or reduce these impacts. In the context of lowering

the degree of impact of the proposed sewer on surface water features, it is important that Alternative 1 be

developed rather than Alternative 2, as a much lesser number of surface water features would be crossed by

Alternative 1 and the overall impact of the sewer would thus be of lesser intensity and overall significance.

7 REFERENCES

Collins, N.B., 2005, Wetlands: The basics and some more. Free State Department of Tourism, Environmental and Economic Affairs.

Department of Water Affairs and Forestry, 2005, A Practical field procedure for identification and delineation of wetlands and riparian areas, Final Draft

Engelbrecht, J., Bills, R. & Cambray, J. 2007. Varicorhinus nelspruitensis. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 11 March 2015.

Ewel, K.C., Cressa, C., Kneib, R.T., Lake, P.S., Levin, L.A., Palmer, M.A., Snelgrove, P. and Wall, D.H., 2001. Managing critical transition zones. Ecosystems 4, 452–460.

Mucina, L., and Rutherford, M.C., 2006. The Vegetation of South Africa, Lesotho and Swaziland, Strelitzia 19, South African National Biodiversity Institute, Pretoria.

Ollis, D.J., Snaddon, C.D., Job, N.M. and Mbona, N. 2013. Classification System for Wetlands and other Aquatic Ecosystems in South Africa. User Manual: Inland Systems. SANBI Biodiversity Series 22. South African National Biodiversity Institute, Pretoria.

Partridge, T. C., Dollar, E. S. J., Moolman, J. and Dollar, L. H.:2010. The geomorphic provinces of South Africa, Lesotho and Swaziland: A physiographic subdivision for earth and environmental scientists', Transactions of the Royal Society of South Africa, 65: 1, 1 — 47

Soil Classification Working Group, 2006, Soil Classification – A Taxonomic System for South Africa, Memoirs on the Agricultural Natural Resources of South Africa, No. 15

surface water report - rhdhv.co.za

Documents