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Main consultant Charl de Villiers Environmental Consulting
Overberg Municipality Road Repair Project:
Basic Assessment Report on the implications of repair designs for
freshwater ecosystems
Designs by Hatch Goba Engineering
March 2014
Report by Liz Day (PhD; Pr Nat Sci)
The Freshwater Consulting Group lizday@mweb.co.za
Basic Assessment Report on the implications of proposed road repairs in the Overberg Municipal area: Freshwater Ecosystems: Assessment of Hatch Goba Engineering designs
Freshwater Consulting Group 1
TABLE OF CONTENTS
_Toc384384596
1 Introduction ........................................................................................................................................................ 2
1.1 Background .......................................................................................................................................... 2
1.2 Terms of Reference .............................................................................................................................. 2
1.3 Study area ........................................................................................................................................... 2
1.4 Information and activities informing this report ...................................................................................... 3
1.5 Limitations of this report....................................................................................................................... 3
1.6 Definitions and terminology .................................................................................................................. 4
2 Description of proposed activities ....................................................................................................................... 5
3 Description of affected freshwater ecosystems .................................................................................................. 9
3.1 Approach ............................................................................................................................................. 9
3.1.1 NEFEPA data.................................................................................................................................................. 9 3.1.2 Present State Assessments ........................................................................................................................... 9 3.1.3 EIS Assessments ............................................................................................................................................ 9 3.1.4 Ecoregion status .......................................................................................................................................... 10
3.2 Summary descriptions of affected rivers .............................................................................................. 11
3.2.1 Water management areas .......................................................................................................................... 11 3.2.2 Ecoregions ................................................................................................................................................... 11
4 Assessment of the Implications of the proposed works for freshwater ecosystems with recommendations for
mitigation ..........................................................................................................................................................22
4.1 Impacts associated with proposed construction at OH1 (Meul River) ..................................................... 22
4.1.1 Mitigation requirements to address impacts resulting from the existing structures: ................................ 22 4.1.2 Impacts associated with layout and design ................................................................................................ 23 4.1.3 Construction phase impacts ....................................................................................................................... 24 4.1.4 Overall assessment and recommendations for OH1 (ecological perspective) ........................................... 24
4.2 Impacts associated with proposed construction at OH2 ........................................................................ 25
4.2.1 Impacts associated with layout and design ................................................................................................ 25 4.2.2 Construction phase impacts ....................................................................................................................... 25 4.2.3 Overall assessment and recommendations for OH2 (ecological perspective) ........................................... 25
4.3 Impacts associated with proposed construction at OH3 (Jagersbosch River) ........................................... 25
4.3.1 Mitigation requirements to address impacts resulting from the existing structures: ................................ 25 4.3.2 Impacts associated with layout and design ................................................................................................ 25 4.3.3 Construction phase impacts ....................................................................................................................... 25 4.3.4 Overall assessment and recommendation for OH3 (ecological perspective) ............................................. 26
4.4 Impacts associated with proposed construction at OH4 (Droogas River) ................................................. 26
4.4.1 Impacts associated with Layout and design ............................................................................................... 26 4.4.2 Construction phase impacts ....................................................................................................................... 26 4.4.3 Overall assessment and recommendation for OH4 (ecological perspective) ............................................. 27
4.5 Overall implications of proposed construction activities for watercourse PES.......................................... 28
5 Construction phase management recommendaTIONS .......................................................................................29
6 National Water Act compliance considerations .................................................................................................31
7 Conclusions ........................................................................................................................................................32
8 References .........................................................................................................................................................33
Appendices ................................................................................................................................................................34
Basic Assessment Report on the implications of proposed road repairs in the Overberg Municipal area: Freshwater Ecosystems: Assessment of Hatch Goba Engineering designs
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1 INTRODUCTION
1.1 Background
Following extensive flood damage in parts of the Overberg District in recent years, including late 2013, the
Department of Transport and Public Works (DTPW) in the Western Cape proposes to undertake road
and/or bridge repairs and/or upgrades at a number of watercourse crossings. A number of the proposed
activities include triggers for a Basic Assessment in terms of the provisions of the National Environment
Management Act (NEMA) (Act 107 of 1998), and as such require authorization from the Department of
Environmental Affairs and Development Planning (DEADP). Charl de Villiers was appointed by the
Department of Transport in the Western Cape as the Environmental Assessment Practitioner (EAP) to
oversee the Basic Assessment application process. Since the proposed activities affected potentially
watercourses and/or wetlands, Freshwater Consulting cc (t/a The Freshwater Consulting Group / FCG) was
in turn appointed to provide specialist input into the Basic Assessment process, including input into
measures to mitigate against existing and likely impacts to freshwater ecosystems.
While the DTPW is currently engaged in applications for several repairs / upgrades to its roads and bridges
in the Overberg area, this report addresses only those currently being designed by Hatch Goba Engineers.
A total of four structures have been addressed in this report.
1.2 Terms of Reference
FCG’s terms of reference for this project allowed for:
• A desktop study of four proposed sites, including assessment of NFEPA and other relevant spatial
conservation planning data for the affected watercourses, and an assessment of historical GOOGLE
imagery of each site;
• A desktop assessment of the proposed repair / construction activities;
• A site visit for visual assessments of the existing watercourses and structures;
• Liaison with the project engineer regarding the proposed activities, with particular regard to the
planning of mitigation approaches;
• Compilation of a Basic Assessment Report, outlining the following:
o Descriptions of the watercourse at the affected sites;
o Descriptions of the conservation status of each affected watercourse in the vicinity of the
sites, including reference to NFEPA and other information, and comment on its accuracy;
o Level 1 Assessment of the Present Ecological State (PES) of the watercourse in the affected
reach;
o Assessment of the Ecological Importance and Sensitivity (EIS) of the watercourse in the
affected reach;
o Comment on the likely impact of the proposed construction with and without mitigation on
PES and EIS;
o Recommended mitigation measures for each site;
• Compilation of ecological Best Practice recommendations to include in the construction phase
management plans for each site.
1.3 Study area
Figure 1.1 shows the locations of the four sites (OH1 - OH4) included in the present assessment. They are
all located in the Riviersonderend catchment, and all lie at watercourse crossings on minor gravel roads,
with OH1 and OH2 being on District Road (DR) 1298, OH3 on DR1303 and OH4 on DR1310.
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Figure 1.1
Locations of proposed road repair / upgrade sites addressed in this project, showing site codes (OH1 etc.) and name
(if any) of the affected watercourse Figure courtesy Mr C. de Villiers (Project EAP)
1.4 Information and activities informing this report
The inputs provided in this report have been informed by:
• A meeting with the project engineer (Mr Dawie Malan, Hatch Goba) to discuss the proposed project
approach and various mitigation measures;
• A site visit to all of the sites included in this assessment, accompanied by Mr Charl de Villiers (project
EAP) – existing PES data for the affected rivers was ground-truthed during the site visits and EIS ratings
were carried out at each site, using the methodology outlined in Appendix A;
• Consultation of existing spatial data pertaining to the study area (NEFEPA datasets and present and
historical GOOGLE satellite imagery);
• Discussions with Mr Hans King (engineer; Department of Agriculture in the Western Cape) regarding
proposed groyne field designs in the Meul River.
1.5 Limitations of this report
No new biophysical or water quality data were collected as part of this report, which relied primarily on a
visual assessment of issues of ecological concern and existing Conservation Planning data (e.g. NEFEPA
datasets). In particular, no floral or faunal analysis or ground-truthing was carried out. Given the extent to
which the affected sites have been disturbed, these are not considered significant limitations.
Site OH2 was not included in the site visits, as it was added to the project list only latterly. Input into the
assessment of the structure at this site was based on photographs provided to Charl De Villiers (project
EAP) by Mr D. Malan.
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1.6 Definitions and terminology
The definitions for watercourses and wetlands that have been used by FCG in this project are those
specified by the National Water Act (Act 36 of 1998), which defines a “watercourse” as:
(a) a river or spring;
(b) a natural channel in which water flows regularly or intermittently;
(c) a wetland, lake or dam into which, or from which, water flows; and
(d) any collection of water which the Minister may, by notice in the Gazette, declare to be watercourse, and
a reference to a watercourse includes, where relevant, its bed and banks.
Wetlands themselves are defined in the Act 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.”
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2 DESCRIPTION OF PROPOSED ACTIVITIES
Table 2.1 provides a summary of the activities proposed at each of the four affected sites. Figures 2.1 – 2.4
comprise annotated GOOGLE imagery for each site, showing the positions of each new / upgraded
structure as well as any proposed road re-alignments and/or temporary bypass roads.
Figure 2.1
GOOGLE Satellite image showing location of proposed crossing upgrades / repairs at OH1.
Figure courtesy Charl de Villiers (project EAP). Direction of flow arrowed.
Figure 2.2
GOOGLE Satellite image showing location of proposed crossing upgrades / repairs at OH2.
Figure courtesy Charl de Villiers (project EAP). Direction of flow arrowed.
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Figure 2.2
Figure 2.3
GOOGLE Satellite image showing location of proposed crossing upgrades / repairs at OH3.
Figure courtesy Charl de Villiers (project EAP). Direction of flow arrowed.
Figure 2.4
GOOGLE Satellite image showing location of proposed crossing upgrades / repairs at OH4.
Figure courtesy Charl de Villiers (project EAP). Direction of flow arrowed.
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Table 2.1
Description of activities proposed for each of the four affected watercourse crossings
Table courtesy Charl De Villiers (project EAP).
Project Route km Structure Co-ordinates 1:50 000
sheet Current condition of structures Proposed repairs
By-
pass
Environmental
factors
contributing to
damage
OH1 DR1298 17.87 0550 34° 3'34.98"S
19°28'38.64"E
34191AB Damaged bridge over Meul River. Large
crack at SE junction of wing wall and
abutment. Portion of NE wing wall has
collapsed. Guide blocks loose due to
impact damage – apparently from
farming implements – due to inadequate
width of deck slab. Severe wash aways of
eastern approach (late 1990s, 2007 and
2012). Inadequate hydraulic capacity.
Replace existing structure with a
new in-situ concrete causeway
with sufficient hydraulic capacity,
consisting of four 5 m-long spans
with wing walls and apron slabs
upstream and downstream.
Yes
Channel
upstream
devoid of
wetland/riparian
vegetation;
intensively
bulldozed;
berms.
OH2 DR1298 18.7 34° 3'26.52"S
19°29'9.06"E
3419AB Two x 900 mm diameter pipes venting
pipe culvert crossing over unnamed
watercourse 800m E of Meul River.
Erosion of embankment at inlet, caused
by run-off from the road. Masonry
headwall in a poor state of repairs.
New in-situ concrete inlet and
outlet structures.
No
Road run-off
contributes to
localised
erosion.
OH3 DR1298 20.88 0552 34° 3'10.92"S
19°30'30.96"E
3419BA Single reinforced concrete culvert at
Jagersbosch River with significant skew
angle. Structure in good condition.
Alignment of river (apparently to create
extra farm land) causes severe erosion of
embankment approach to inlet. Signs of
minor soft water attack and minor
shrinkage cracks evident.
Provide wing walls at inlet side of
culvert to channel water into the
inlet and to protect the
approaches against erosion.
No
Watercourse
upstream
approaches
culvert at acute
angle from fields
to NE. Deeply
incised. Elevated
nick-point
several meters
upstream:
Potential head-
cut erosion? Left
bank collapsing
at bridge
support.
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OH4 DR1310 2.54 10704 34° 8'15.24"S
19°43'25.08"E
-34.137567°
19.723633°
3419BA Single cell box culvert in Droogas River
with a simply supported deck on concrete
walls and spread footings. Wing walls
have been provided. Deck has severe
local spalling on both sides. NE wing wall
has failed, resulting in damage to
abutment. Similar but less severe failure
to SW wing wall. No evidence of over-
topping suggesting adequate hydraulic
capacity. Cause of wing fall failure seems
to be inadequate footing, exacerbated by
absence of weep holes.
Replace NE wing wall of culvert
and repair junction of wing wall
to abutment.
Yes
Cultivated
catchment to
south seems to
release
substantial
volumes of
uncontrolled
run-off owing to
absence of
indigenous
vegetation
cover. No
vegetated buffer
between
watercourse and
fields.
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3 DESCRIPTION OF AFFECTED FRESHWATER ECOSYSTEMS
3.1 Approach
The summary descriptions outlined in this section for each site rely on the following data / assessment
tools, described briefly below:
3.1.1 NEFEPA data
FEPAs (Freshwater Ecosystem Priority Areas) are strategic priorities for conserving freshwater ecosystems
and supporting the sustainable use of water resources (Driver et al 2011). They were developed as part of
the National Freshwater Ecosystem Priority Areas (NFEPA) programme. FEPAs have been determined for
different river and wetland types throughout South Africa, on the basis of a number of criteria that included
ensuring that there is an adequate extent of conservation of different river and wetland ecosystem types,
that they represent adequate habitats to support threatened fish species and their migration corridors;
that free-flowing rivers (i.e. rivers without major dams) are prioritised as FEPAs, that water supply areas in
high-water yielding sub-quaternary catchments are maintained and that ecological connectivity between
systems is maintained as far as possible.
• FEPAs are often tributaries or rivers that support “hard working” rivers downstream (that is, rivers that
are heavily utilised or impacted by agricultural, industrial or other human activities). They need to stay
(or get into) good condition to manage and conserve freshwater ecosystems and to protect
downstream water resources for human use. Driver et al (2011) stress however that FEPAs do not
necessarily need to be protected from all human use. Rather, they should be supported by good
planning, decision-making and management to ensure that human use does not impact on their
condition or on the important resources they may protect downstream.
• The extent of degradation of wetlands and rivers in South Africa means that even systems considered
in the best relative condition for a particular ecosystem type may be highly degraded. Nevertheless,
the recommended condition for all river and wetland FEPAs is an Ecological Category A or B, indicative
of a system that is in an unmodified/natural to largely natural condition respectively (Driver et al 2011).
3.1.2 Present State Assessments
Present State assessments are included in the NEFEPA datasets for both rivers and wetlands. In the case of
the larger rivers, shown on the 1:500 000 these data were derived either from Kleynhans (2000), who used
the DWAF (1999) Present Ecological State (PES) methodology to determine PES for quaternary catchment
mainstem rivers or for smaller tributaries and rivers, were modelled, using the 2000 National Land Cover
(Nel et al. 2011) to allow a surrogate estimate for river condition, based on the extent of natural,
transformed or eroded land within 100m and 500m of the river course. These data were then revised on
the basis, where available, of more detailed data and/or expert opinion. Given that river and wetland
“condition” data may thus be coarse, as well as the fact that the spatial data on which they are based are
over a decade old, detailed notes collected at each assessment site were used to refine the PES category,
where appropriate. Motivation for such changes is provided in Section 3.3.
3.1.3 EIS Assessments
This report utilised the Ecological Importance and Sensitivity (EIS) methodology developed by DWAF (1999)
to derive EIS ratings for the watercourses at each assessed site (OB1-OB6). DWAF (1999) defines the
ecological importance of a river as an expression of its importance to the maintenance of ecological
diversity and functioning on local and wider scales, while ecological sensitivity (or fragility) refers to the
system’s ability to resist disturbance and its capability to recover from disturbance once it has occurred
(resilience). Both abiotic and biotic components of the system are taken into consideration in the
assessment of ecological importance and sensitivity. Importantly, it should be noted that EIS ratings are
strongly biased towards the potential importance and sensitivity of particular system as it would expected
to be under unimpaired conditions. This means that the present ecological status or condition (PES) is
generally not considered in determining the ecological importance and sensitivity per se (DWAF 1999). The
following components are considered in an EIS assessment, namely:
Basic Assessment Report on the implications of proposed road repairs in the Overberg Municipal area: Freshwater Ecosystems: Assessment of Hatch Goba Engineering designs
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• The presence of rare and endangered species, unique species (i.e. endemic or isolated populations) and
communities, intolerant species and species diversity should be taken into account for both the
instream and riparian components of the river.
• Habitat diversity
• biodiversity in its general form
• The importance of the particular river or stretch of river in providing connectivity between different
sections of the river
• The presence of conservation or relatively natural areas along the river section
• The sensitivity (or fragility) of the system and its resilience (i.e. the ability to recover following
disturbance) of the system to environmental changes.
• The above biotic and abiotic determinants are scored, and the median score is calculated to derive the
ecological importance and sensitivity category. These categories are defined in Table 3.1.
Note that in the present case, the biotic component of the assessment was not however completed, due to
a lack of data for these systems. It is however unlikely that inclusion of the biotic component would have
altered the final EIS score for the watercourses at each site, given that it is the higher of the EIS categories
that is utilised, and the biotic components for all sites is unlikely to be accorded a higher rating than
“moderate” for any of the affected systems. This assumption is based on river condition and the NEFEPA
datasets.
Table 3.1 Ecological importance and sensitivity categories (Table after DWAF 1999).
Ecological
Importance And
Sensitivity
Categories
General Description
Very high
Quaternaries/delineations that are considered to be unique on a national or
even international level based on unique biodiversity (habitat diversity,
species diversity, unique species, rare and endangered species). These rivers
(in terms of biota and habitat) are usually very sensitive to flow
modifications and have no or only a small capacity for use.
High
Quaternaries/delineations that are considered to be unique on a national
scale due to biodiversity (habitat diversity, species diversity, unique species,
rare and endangered species). These rivers (in terms of biota and habitat)
may be sensitive to flow modifications but in some cases, may have a
substantial capacity for use.
Moderate
Quaternaries/delineations that are considered to be unique on a provincial
or local scale due to biodiversity (habitat diversity, species diversity, unique
species, rare and endangered species). These rivers (in terms of biota and
habitat) are usually not very sensitive to flow modifications and often have a
substantial capacity for use.
Low/marginal
Quaternaries/delineations that are not unique at any scale. These rivers (in
terms of biota and habitat) are generally not very sensitive to flow
modifications and usually have a substantial capacity for use.
3.1.4 Ecoregion status
The national ecoregional classification (Kleynhans et al. 2005) was used as a broad mechanism to categorise
watercourses at each site. This classification system divides the country’s rivers into 31 distinct ecoregions,
or groups of rivers which share similar physiography, climate, geology, soils and potential natural
vegetation.
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3.2 Summary descriptions of affected rivers
Figures 3.1 and 3.2 and Table 3.2 provides summary information regarding the ecological condition,
importance and sensitivity and catchment characteristics as included in the NEFEPA datasets for the water
courses in the vicinity of the structures proposed for upgrading / repair. Ecological condition (i.e. PES) data
reflect both NEFEPA data, and the results of ground truthing, carried out at the site during the field
assessments.
Summary descriptions of the main ecological issues affecting habitat integrity in each of the watercourses
at the crossing points is presented in table form in Table 3.3, which includes photographic illustrations of
each site. The following subsections provide brief information regarding broad spatial and ecological
features, and comments on PES and EIS.
3.2.1 Water management areas
All of the affected sites lie within the Department of Water Affairs’ Breede Water Management Area (WMA
19). Each WMA has been divided into several smaller sub-Water Management Areas, based on the
catchments of large tributaries within the WMA. In this regard, the NEFEPA data (Nel et al 2011) show that
all four of the assessed sites lie in sub Water Management Area 33 (Riviersonderend). Table 3.2 and
Figures 3.1 and 3.2 illustrate which of these sub WMAs have been categorized as FEPA sub-quaternary
catchments, on the basis of particular criteria included in the NEFEPA conservation planning process (Nel et
al 2011).
3.2.2 Ecoregions
Consideration of the Kleynhans et al (2005) Level 1 Ecoregion spatial data, as included in the NEFEPA River
datasets, shows that all four sites lie in Ecoregion 22. This ecoregion (the Southern Coastal Belt Ecoregion)
is described in Kleynhans et al (2005) as encompassing the rivers in the southern portion of the Breede
River Basin (Brown and Fowler 2000), and is characterised by the following, after Brown and Fowler (2000):
• Terrain comprising low plains, closed hills with moderate relief, open hills with high relief, and low
mountains with high relief;
• Altitude that varies from 0 to 600 mamsl;
• Rock types include quartzitic sandstone, shale, sand and biotite granite overlain by sand-clay, sand-clay-
loam, loam-sand, clay-loam and sand-loam soils;
• Natural terrestrial vegetation that is dominated by a variety of thicket, fynbos and renosterveld, with
patches of forest in the Riversonderend range. In the present study area, NEFEPA vegetation data,
based on the South African Vegetation Map (Mucina and Rutherford 2006) identifies natural wetland
vegetation on the site as Southwest Shale Fynbos;
• Moderate rainfall (400 to > 1200 mm a-1) and mean annual temperatures between 18 and 22 °C.
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Table 3.2 Descriptions of watercourse condition in the vicinity of each of the proposed structural upgrades, including both ground-truthed PES and EIS
ratings and NEFEPA data.
Site
code River
Brief description
based on site visit
(see also Table 3.2)
Water course condition (PES)
EIS
(see data
in
Appendix
A)
National Freshwater Ecosystem Priority Area (NFEPA) status
NFEPA
Wetlan
d
PES
Ground-truthed PES (as
assessed during site
visit)
River FEPA
or
associated
Sub-
quaternary
catchment?
Wetland
FEPA ?
FEPA
attributes
Wetland
type
(NWCS (Ollis
et al 2013)
Levels 3 and
4)
Wetland
Vegetation
Group
OH1 Meul Rv
River severely
degraded and prone
to high levels of
ongoing channel
destabilisation – no
associated wetland
habitat
Class C
Class E: erosion,
sedimentation, loss of
almost all indigenous
instream vegetation and
habitat and all riparian
vegetation; severe alien
invasion
Low /
Marginal
No No
CRANE (i.e.
wetlands in
sub-
quaternary
catchments
with
sightings of
threatened
crane
species (Nel
at al 2013);
also
associated
with more
than three
other
wetlands
East Coast
Shale
Renostervel
d Floodplain
wetland: no
wetland
identified in
this study East coast
shale
renosterveld
OH2
Un-named
tributary of
the Rivier-
sonderend,
just east of
Meul Rv
Narrow channel, with
high levels of
agricultural
encroachment,
abstraction (dams)
and channelization
Class C
Class D – low confidence
assessment based on
photographs and
GOOGLE imagery only:
channelization, woody
alien invasion along
channel; abstraction;
poor habitat quality; low
levels of buffering; poor
connectivity to mountain
areas upslope
Low /
Marginal
Phase 2
FEPA No
OH3 Jagersbosc
h Rv
River degraded – but
morphology
upstream still
representative of
natural valley bottom
wetland type
Class C
Class D: high levels of
disturbance adjacent to
the stream upstream of
structure; large-scale
loss of indigenous
riparian and instream
vegetation; natural
upstream morphology
still recognisable;
Moderate
Phase 2
FEPA No
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Site
code River
Brief description
based on site visit
(see also Table 3.2)
Water course condition (PES)
EIS
(see data
in
Appendix
A)
National Freshwater Ecosystem Priority Area (NFEPA) status
NFEPA
Wetlan
d
PES
Ground-truthed PES (as
assessed during site
visit)
River FEPA
or
associated
Sub-
quaternary
catchment?
Wetland
FEPA ?
FEPA
attributes
Wetland
type
(NWCS (Ollis
et al 2013)
Levels 3 and
4)
Wetland
Vegetation
Group
OH4 Droogas Rv
River degraded – but
still retains relatively
natural instream
(valley bottom
wetland) habitat;
little erosion or
sedimentation
evident
Class C
Class C /D – nutrient-
enriched, with minimal
buffers; cattle grazed
and trampled but still
morphologically
relatively intact
Moderate
Phase 2
FEPA No
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Table 3.3 Site level descriptions and photographic illustrations of ecological issues affecting the current state of the watercourses at each crossing
A. Site OH1 – Meul River
NWCS river classification: Lower foothill river
NWCS wetland classification: channeled valley bottom wetland
Description of the river at the site Main drivers of ecological degradation Main concerns regarding ecological effects of present
road / bridge structure
The river channel is highly disturbed, with little or no
instream vegetation, and the instream habitat comprising
shallow pools and riffles occurs on a loose matrix of
gravel, sand and rocks with high levels of instability in
high flow.
The right hand river bank downstream of the bridge
retains largely indigenous marginal vegetation.
Elsewhere, the banks have been bulldozed, bermed or
eroded and comprise loose, bare gravels and sand.
A working hypothesis to explain the evident channel
destabilisation assumes that it results from combined
effects of historical intrusion of agricultural activities
into the floodplain, and extensive alien invasion of the
river channel, resulting in constriction of the channel in
flood flows (see 2009 aerial views below) and breaking
out of channel in the upper cactchment, to erode
vulnerable agricultural areas, as far as line of windbreak
beefwood trees, which further constricted flows,
sending them back into the channel, with high
sediment and rock load, and devastating downstream
effects. Subsequent floods (see 2012 close-up)
assumed to have scoured the now destabilized
channel, devoid of both alien and natural wetland
vegetation. Retention of beefwoods downstream of
OH-1facilitates catastrophic creation of new side-
channels (Photo OH1-D) by constricting overtopping
onto floodplain, resulting in severe in-channel
disturbance and large-scale outbreaks in large flood
events.
• Bridge now too narrow for new flow and flood
regime, with high load of sediment and rocks
• Overtopping of bridge at OH-1 leading to further
erosion downstream, including diversion of high
flows into eastern floodplain areas
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Photo OH1-A
Meul River downstream from the bridge at OH1, showing line of
beefwoods along right hand banks and severe channel
destabilisation
Photo OH1-B
Meul River upstream of bridge showing severe loss of natural
instream habitat (assumed to comprise channelled valley
bottom wetland)
Photo OH1-C
View from upstream onto damaged bridge at OH1, showing
narrow structure blocked by high sediment / cobble loads
Photo OH1-D
View immediately east of Photo H1-A, showing erosion path
onto agriculural floodplain beyond beefwoood line, resulting in
severe erosion
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Sequence of aerial photogrpahs of the Meul River
Meul River in 2004 (arrowed) showing vegetated channel; high levels of alien invasion with
remnant wetland patches:
2006 view of Meul River showing dense invasion of channel
2009: large-scale erosion of the whole length of the Meul River. Area included in following
sequence of “close-ups” circled
2004 close-up showing agricultural encroachment into the floodplain in upper river reaches, with
lines of (assumed) windbreak alien trees (beefwood?) (arrowed)
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2009 close-up showing breakthrough of flood flows along invaded side channel (arrowed), and
erosion of agricultural fields along the windbreak line
2012close-up showing ongoing destabilisation of the main channel, and less erosion of the
abutting floodplain, once alien vegetation had been eroded (or otherwise removed) from the
main channel
B Site OH2 – Unnamed tributary of the Riviersonderend
NWCS river classification: Lower foothill river
NWCS wetland classification: channeled valley bottom wetland
Description Main drivers of ecological degradation Main concerns regarding ecological effects of present
road / bridge structure
Despite its classification as within a Phase 2 FEPA sub-catchment
(see Table 3.2), the channel at OH2 is considered of ecological
importance today only in terms of stable conveyance of flows
through its catchment; in NEFEPA terms, it is a “hard-working”
system, with high levels of upstream abstraction and no wetland
areas visible from GOOGLE aerial photography. Rehabilitation to
a better PES class is not considered realistic, although it would
be possible. At the existing culvert, the channel is shaded by
alien trees, which further reduce indigenous vegetation and
habitat quality.
• Channelisation
• Large-scale abstraction of a small catchment
• Lack of ecological connectivity with upstream areas
and downstream Riviersonderend as a result of
agriculture; minimal buffer areas
• Culverts contribute to channelization of stream – but
small stream considered of low ecological importance
given extent of degradation; channel appears
currently stable at road crossing
• Localized effects of erosion off road into channel
Note: All photographs below supplied by Hatch Goba engineers. Site unvisited by FCG
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Photo OH2-A
Narrow, channelised stream at OH2, showing shading of the
channel by alien vegetation.
Photo OH2-B
View of culvert from the road – left hand side culvert is
upstream
Photo OH2-C
Channelised culvert
2012 GOOGLE image showing unnamed system at OH2 in higly agriculural aea, with low
ecological connectivity
C Site OH3 – Jagersboschrivier
NWCS river classification: Lower foothill river
NWCS wetland classification: channeled valley bottom wetland
Description Main drivers of ecological degradation Main concerns regarding ecological effects of present
road / bridge structure
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Relatively small river system, confined by alien trees on
right hand bank and agricultural fields on left hand banks
but not deeply incised until it approaches culvert. A small
headcut has formed just upstream of the culvert, and is
likely to result in ongoing channel incision in upstream
reaches and progressive river degradation.
Instream habitat quality at the culvert is low, comprising
cobble / gravel riffles, shallow pools and sand bars, the
latter occurring on the right hand part of the channel
where sedimentation occurs. Shading by alien trees and
steep, eroding banks limit the extent of indigenous
marginal vegetation.
• Alien invasion
• Headcut erosion
• Lack of ecological buffering
• Localized constriction at the road
• Loss of indigenous wetland and riverine vegetation.
Despite the above, the river is considered rehabilitable to
a better PES, through alien clearing and establishment of
indigenous vegetation in the upstream reaches, provided
that the headcut is addressed.
The angle of the culvert results in ongoing erosion of the
river bank (Photo OH3-C), and the associated turbulence
when large flows hit this bank and are diverted into the
culvert are assumed to have led to the formation of the
headcut visible in Photo OH3-B.
Photo OH3-A
Upstream view of culvert and stream at OH3
Photo OH3-B
Headcut (arrowed) at OH3, with fill platform on left of photo
Photo OH3-C
Eroding left hand bank to be stabilised byproposed works
D Site OH4 – Droogas Rivier
NWCS river classification: Lower foothill river
NWCS wetland classification: channeled valley bottom wetland
Description Main drivers of ecological degradation Main concerns regarding ecological effects of present
road / bridge structure
River primarily affected by poor water quality (nutrient
enrichment); retains relatively natural (assumed)
morphological features of a channeled valley bottom
wetland, despite extensive agricultural development.
• poor water quality (nutrient enrichment);
• grazing and trampling by cattle
• agricultural encroachment
• invasion of margins by kikuyu grass
Existing structure appears adequate for river / wetland
type and characteristics, with stable valley bottom
wetland upstream providing erosion control in flooding,
and floods overtopping road relatively harmlessly (from
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an ecological perspective) without resulting in large-scale
erosion. Concentration of flows through culvert may
have resulted in some channel deepening downstream,
shown by reduced width of reedbed fringe across river.
Photo OH4-A
Damaged culvert at OH4, looking upstream at bridge from right
hand bank
Photo OH4-B
Downstream view of Droogas channel from road culvert at OH4
Photo OH4-C
Upstream view of Droogas channel from road culvert at OH4.
Note algae in channel (showing probable nutrient enrichment)
and dense reedbed in shallow upstream reaches
Basic Assessment Report on the implications of proposed road repairs in the Overberg Municipal area: Freshwater Ecosystems: Assessment of Hatch Goba Engineering designs
Freshwater Consulting Group 21Figure 3.2 Site OH4 in the Riviersonderend River catchment, shown in relation to FEPA data, with green polygons illustrating FEPA wetlands, thick blue lines showing FEPA
rivers (i.e. rivers included in the National 1:50 000 rivers database) and purple polygons depicting River FEPA sub-quaternary catchments, labelled in terms of
FEPA River status (if any). Note that OH4 lies within a Phase 2 FEPA catchment.
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4 ASSESSMENT OF THE IMPLICATIONS OF THE PROPOSED WORKS FOR FRESHWATER ECOSYSTEMS WITH RECOMMENDATIONS FOR MITIGATION
This section identifies concerns regarding the potential impacts of proposed road repair and upgrading
activities, from a freshwater perspective. The assessed activities are as described in Section 2. These are
assessed in light of the ecological information provided in Section 3, particularly in Table 3.3, which sought
to identify key ecological concerns in the present state of the affected systems, and to highlight particular
areas of sensitivity.
Mitigation measures are also outlined in this section. These have been developed as far as possible in
consultation with the design engineers (Hatch Goba), and seek to achieve as far as possible either impact
avoidance or minimization. Note that where mitigation measures require implementation of generic “Best
Practice” measures during construction phases, these are as outlined in Section 5. In some cases however,
mitigation measures have been recommended to address the high levels of impact to aquatic ecosystems
that have accrued as a result of the existing structures, bearing in mind that these impacts are often
compounded by poor landuse practices – in particular, the failure by local landowners to control or
properly remove, invasive alien vegetation along water courses
4.1 Impacts associated with proposed construction at OH1 (Meul River)
4.1.1 Mitigation requirements to address impacts resulting from the existing structures:
The existing structure contributed to the extent of flood damage in downstream areas, and in particular to
the erosion of the floodplain on the left hand side of the channel (Table 3.3; Photo OH1-C). The existing
structure was too narrow and its culvert sizes too small to allow for the high levels of sediment and rock
generated by the destabilised, eroding river system upstream. This said, the destabilisation of the
upstream reaches of the river is believed to have resulted primarily from an unfortunate combination of
floodplain encroachment and stabilisation with rows of (alien) trees, invasion of the river channel by alien
vegetation and subsequent large-scale flood events (initially around 2009) (see Table 3.3). Full blame for
the destabilisation of the downstream reaches of the river cannot be apportioned to the existing culvert,
although it seems reasonable to allot some responsibility to this road structure.
In order to redress this effect, at least in part, and bearing in mind that such activities would render the
new proposed structure more sustainable in the future, it is recommended that the following activities be
included in the road construction programme:
i. The DTPW should liaise with the Department of Agriculture (DA) regarding the proposed
installation of a groyne field in the Meul River, and ensure that bank erosion and channel migration
in the reaches at least 50m upstream and downstream of the crossing are controlled by groynes,
designed in keeping with the objectives of the broader DA flood and erosion control programme.
Such structures ideally need to be in place before the start of the present proposed activities – in
the event that delays in their authorization through DA are considered likely, it is recommended
that the DTPW either work with DA to prioritise approval and construction of the structures that
would affect the present road, or design and obtain authorization for such structures separately. It
is noted in this regard that the proposed design at OH1 already assumes implementation of the
groyne field, and allows for a lower invert level in the crossing than that required at present, given
that the river would be downcut by concentration of flood flows;
ii. The existing berms upstream of the culvert should be pulled back and graded at an angle no
steeper than 1:4 for at least a distance of 30m upstream of the proposed new structure – note that
these activities would need to take cognisance of the location and design of the groynes, outlined
above;
iii. The regraded banks should be planted with locally indigenous hardy vegetation that has the
principle function of ensuring bank stability; the hardy Carpobrotus sp. (suurvygie) could be
considered in this regard, although its contribution to desirable ecological functions such as the
provision of quality river marginal vegetation habitat is very low;
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iv. Allowance should be made for irrigation and other maintenance activities in planted areas over at
least one full year cycle;
v. Excess material from the graded river banks, as well as deposited material from the channel should
be spread in the eroded floodplain, with the aim of controlling the ongoing passage of river flows
into this area, outside of major flood flows;
vi. The line of alien trees along the left hand river bank downstream of the bridge should be removed,
using species-appropriate alien clearing methods – Working for Water guidelines should be used in
this regard. The full line of alien vegetation shown in Figure 4.1 (mainly Beefwood (Casuarina
cunninghamiana)) should be removed – it is recommended that the DTPW liaise with the local
landowner in this regard;
vii. Cleared areas should be stabilised by a combination (as appropriate) of bank shaping and planting
with locally indigenous plant species;
viii. Local landowners should be required to participate in long-term alien maintenance clearing
activities.
4.1.2 Impacts associated with layout and design
A Positive aspects
• The proposed new structure would be wider than the current one, and extend across a channel width
of some 20m, including (on the basis of a GOOGLE channel width measurement) the full current width
of the enlarged channel. This, coupled with the greater culvert size (each one would have a 5m wide
opening) would decrease flood-related erosion and sedimentation risks in the vicinity of the road, as
large sediment /debris should be able to pass through the structure unhindered.
• If the proposed road and culvert rehabilitation activities were coupled with the mitigation measures
outlined in Section 4.1.1, particularly with regard to the planned installation of groynes along this
section of the river, then it is likely that a better quality of riverine habitat, albeit not one resembling
the natural Reference Condition for this wetland type, would be established at least in the vicinity of
the road. In the absence of such measures, it is unlikely that the river will ever achieve a level of
stability that is not succeeded by its disturbance regime, which prevents the establishment of any
quality riverine or wetland habitat in these reaches.
B Negative Impacts
• Ongoing erosion of the destabilised river channel and its margins, as a result of lack of adequate plant
cover;
• In the event that existing concrete and other waste associated with the present channel is not
removed, its persistence in the channel would constitute an ongoing potential trigger for erosion as a
result of diversion of flows off the hard structure, as well as being visually displeasing.
Mitigation requirements:
i. Allowance must be made for the establishment of a continuous swathe of appropriate, locally
indigenous vegetation along at least the wetted bottom of the bank of the river, but ideally up the
bank as well, for a distance of 30m up- and downstream of the proposed structure, to prevent
erosion. It is strongly recommended that dense stands of Palmiet reeds (Prionium serratum)
should be utilised for this purpose. Other plant species used should be selected in consultation
with a botanist and/or river ecologist, to ensure they meet the required criteria of being hardy,
locally indigenous and suited to the conditions in which they are planted;
ii. All concrete and other debris associated with the present road crossing should be removed from
the river bed and banks as soon as the requirement for a construction-phase bypass road is over,
and disposed of outside of the 1:50 year flood line for the river;
iii. Planted areas should be subjected to a short-term maintenance programme that includes where
necessary, weeding, plant replacement and irrigation, over at least one full annual cycle.
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4.1.3 Construction phase impacts
Construction phase impacts are likely to be of high intensity but locally confined, and readily managed
through implementation of standard impact mitigation measures. Impacts are likely to include:
• Diversion of river flows and further destabilisation of river banks as a result of construction of a
temporary bypass road;
• Increased downstream sediment and turbidity from bank and bed disturbance (the river is however
already prone to these effects as a result of high erosion);
• Contamination of the river as a result of receipt of construction-associated materials;
• Trampling and disturbance to the (already disturbed) river bed and banks in the vicinity of the existing
and new structures.
The above impacts would all be exacerbated if construction took place during the wet season when the
water table was high, or during a period when a storm event occurred.
Mitigation requirements
A Construction Phase Environmental Management Programme (CEMP) must be implemented during
construction, such that specifically addresses the need for reduction of construction-associated impacts on
watercourses, including the measures outlined in Section 5.
Special attention should be paid to management of the diversion of flows and the placement and removal
of the bypass road during construction. While the extent of riverine disturbance in these reaches suggests
that a bypass could be located on either side of the existing structure, rehabilitation and management of a
bypass road would be more readily achieved if the bypass was located on the upstream side of the
structure, as the right hand river margins downstream of the bridge still include wetland and riverine
habitat, while the upstream channel is narrower and the channel margins are already steep, bermed and
degraded. Mitigation measures affecting the bypass road should include the following:
i. Construction activities involving the use of a bypass road should at least take place outside of the
rainy season, to reduce the risk of flooding and wash-away of the bypass, although it is recognized
that summer storms do occur in this area, and result in considerable flood damage;
ii. The bypass road should allow for the passage of flows beneath the road, whether in pipes or other
devices,
iii. The bypass road should be completely removed following construction, and its footprint
rehabilitated, allowing for:
a. regrading of the river bank to a river ecologist’s specifications
b. replanting of the disturbed river bank – using the specifications for planting and short-term
maintenance outlined in Section 4.1.2B
c. removal of all foreign material from the river bed and banks (pipes etc.).
4.1.4 Overall assessment and recommendations for OH1 (ecological perspective)
Implementation of the proposed structure at OH1 would, in the absence of any mitigation measures aimed
at stabilizing the high rates of erosion and sedimentation taking place upstream in the Meul River be likely
to perpetuate an unstable system.
Implementation of the proposed mitigation measures, along with the planned improved road structure,
would be considered a positive impact, of low to medium significance, nevertheless associated with high
levels of risk that degradation has proceeded too far for real rehabilitation to be feasible.
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4.2 Impacts associated with proposed construction at OH2
4.2.1 Impacts associated with Layout and design
A Positive impacts
The proposed repairs to the existing culvert headwalls would be expected to have low levels of positive
impact on the affected watercourse, at a very local scale, by reducing the volumes of eroded sediment
entering the channel off the road.
4.2.2 Construction phase impacts
Such impacts would include short-term disturbance of the channel in the vicinity of the headwalls, the
potential passage of dewatered material into the watercourse and contamination of the watercourse by
construction associated materials such as cement. Such impacts would be considered negative, but
localised, taking place at low magnitude and over a short period of time only.
The above impacts would however be exacerbated if construction took place during the wet season when
the water table was high, or during a period when a storm event occurred.
Mitigation requirements
The requirements of a comprehensive CEMP must be met during construction (see Section 5). In addition,
it is recommended that the woody alien trees shown in Table 3.3 (Photograph OH2-A) should be removed
for a distance of 20m upstream of the culvert, and the length of channel; thus exposed should, where
necessary, be stabilized with the planting of appropriate locally indigenous plant species.
4.2.3 Overall assessment and recommendation for OH2 (ecological perspective)
The ecological implications of the proposed activities at OH2 are considered negligible, assuming
implementation of mitigation measures.
4.3 Impacts associated with proposed construction at OH3 (Jagersbosch River)
4.3.1 Mitigation requirements to address impacts resulting from the existing structures:
The present structure at OH3 has contributed to the creation of a small headcut in the channel just
upstream of the structure. If not addressed, this headcut will result in ongoing cycles of channel incision in
the upstream reaches of the river, reducing any likelihood of future rehabilitation of these reaches.
It is thus strongly recommended that a condition of approval of the proposed structural repairs at this site
be that the headcut is addressed through the installation of a low gabion weir, designed to control the
effective channel gradient upstream of the headcut, and prevent the upstream migration of this feature.
The weir should be designed by an engineer with appropriate experience in this regard, and set far enough
back into the channel banks, such that it will not be bypassed or undermined by high flows.
4.3.2 Impacts associated with Layout and design
The proposed wing wall designs would be associated with positive ecological impacts, as they would reduce
ongoing erosion and sedimentation of the channel in its downstream reaches.
4.3.3 Construction phase impacts
As in the case of proposed construction activities at OH2, such impacts would include short-term
disturbance of the channel in the vicinity of the upstream headwall and the energy dissipation weir, the
potential passage of dewatered material into the watercourse and contamination of the watercourse by
construction associated materials such as cement. Such impacts would be considered negative, but
localised, taking place at low magnitude and over a short period of time only.
The above impacts would however be exacerbated if construction took place during the wet season when
the water table was high, or during a period when a storm event occurred.
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Mitigation requirements
Once again, it is recommended that the requirements of a comprehensive CEMP must be met during
construction (see Section 5).
4.3.4 Overall assessment and recommendation for OH3 (ecological perspective)
Implementation of the proposed construction measures at OH3 would be likely to result in impacts of low
to negligible negative significance if the minor mitigation measures recommended were included.
Addressing the headcut upstream of the existing structure is considered an important measure to address
otherwise ongoing impacts that have been triggered by the existing structure.
4.4 Impacts associated with proposed construction at OH4 (Droogas River)
4.4.1 Impacts associated with Layout and design
The design of the proposed repairs and replacement of the existing culvert wing walls are considered
unlikely, per se, to result in any impacts to freshwater ecosystems in the vicinity of OH4, and the existing
structure does not appear to have resulted in significant long-term changes to the river system.
4.4.2 Construction phase impacts
These would include disturbance of the channel and river bank during removal and replacement of
damaged structures, damage to wetland vegetation (particularly if construction activities such as the
construction of a bypass road took place upstream of the bridge), potential accumulation of rubble waste in
the river or its margins if all waste associated with the project was not removed; contamination of the
watercourse by construction associated materials such as cement. Given the apparently high nutrient load
of the river, and an assumed high concentrations of total ammonia1, an increase in river pH as a result of
the passage of cement into the water, could trigger ammonia toxicity in the river. This is because ammonia
exists in two forms in water bodies, namely as potentially toxic un-ionised NH3, and as non-toxic ionized
NH4+. The proportion of the former increases with increasing alkalinity, particular where pH > 8 (DWAF
1996). Although such events would, in a construction process, be short-lived, their implications would
potentially be much longer-lived, if they resulted in mortalities to aquatic fauna.
The implications of a bypass road would potentially be of greatest concern along this channel that is
considered morphologically relatively unimpacted. In particular, disturbance of the channel upstream of
the culvert would be considered of medium-to-high negative significance, as it would result in high levels of
disturbance to a section of channel in (relatively) good condition, potentially triggering upstream erosion or
other impacts.
The above impacts would all be exacerbated if construction took place during the wet season when the
water table was high, or during a period when a storm event occurred.
Mitigation requirements
i. Once again, the requirements of a comprehensive CEMP must be met during construction (see
Section 5), with particular attention paid to prevent of the passage of cementitious material into
the river.
ii. In addition, the following measures around the location and management of a bypass road are
considered essential:
a. The bypass may not be located on the upstream side of the existing road culvert and this
section of the river and its margins to a distance of 30m on either side of the river must be
managed as a no-go area for all construction personnel and their vehicles and materials;
b. Ideally, the construction process should be managed without a bypass road;
1 Note that no water quality data have informed these comments, which were based on the extent of algae in the river and the
proximity of herds of cattle
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c. If a bypass is essential, it must be located downstream of the road, and should be subject
to the following controls:
o The bypass should allow for the passage of flows beneath it, whether in pipes or other
devices,
o The bypass should be completely removed following construction, and its footprint
rehabilitated, allowing for:
� regrading of the river bank to a river ecologist’s specifications
� replanting of the disturbed river bank and the re-establishment of Phragmites
australis vegetation, using the specifications for planting and short-term
maintenance outlined in Section 4.1.2B
� removal of all foreign material from the river bed and banks (pipes etc.).
4.4.3 Overall assessment and recommendation for OH4 (ecological perspective)
Provided that the essential mitigation measures outlined in Section 4.4.2 are implemented, the negative
implications of the proposed road / culvert repairs could be limited to low levels significance only.
Construction activities, while thus quite acceptable from an ecological perspective, should however take
cognisance of the need for protection of the river in the vicinity of the road crossing, particularly given its
status as a system in a Phase 2 River FEPA – sub catchments earmarked for future rehabilitation.
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4.5 Overall implications of proposed construction activities for watercourse PES
Table 4.1 outlines the estimated implications for Present Ecological State (PES) of the proposed
interventions at each watercourse, compared to the present and assuming implementation both with and
without mitigation measures.
Table 4.1
Estimated PES of affected watercourses, assuming implementation with and without mitigation
measures (with mitigation measures including measures for addressing impacts resulting from the
present structure)
Site
code
Pre-construction PES Estimated Post construction PES in the vicinity of
the crossing
(as assessed during site
visit)
With full mitigation Without mitigation
OH1 Class E Class D/E Class E
OH2 Class D Class D Class D
OH3 Class D Class D Class D (but degrading)
OH4 Class C /D Class C /D Class D
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5 CONSTRUCTION PHASE MANAGEMENT RECOMMENDATIONS
Construction phase management of the various construction sites included in this project is aimed at
minimizing disturbance of watercourses and other wetlands, as a result of construction activities. In order
to achieve this, the following activities need to be considered in a Construction Phase Environmental
Management Programme (CEMP), namely activities that are likely to:
• cause bank disturbance;
• result in potential pollution of the water course as a result of allowing the passage (direct, or by
seepage, surface spillage or overflow) of pollutants such as sediment, cement, fuels, litter or other
waste into watercourses;
• increase the likelihood of invasion by alien plants;
• increase disturbance as a result of human access to river / wetland areas;
• negatively affect the success of planned river bank rehabilitation activities.
The following restrictions should be specifically included in the CEMP, with the proviso that, where it can be
shown that an alternative approach poses the same or lesser ecological risk, as agreed by an independent
ecologist; such an alternative may be considered instead. This measure allows for a degree of plasticity in
the implementation of the CEMP, and takes cognizance of the need, during construction, for alternative
approaches to be taken in the light of unforeseen practical difficulties in project implementation. The
following measures are recommended for inclusion in the CEMP:
• Work site and storage locations:
o no vehicles, fuels or construction materials are to be stored such that waste can leak, blow
or be washed into any watercourse; areas for the stockpiling of construction materials
should moreover be located at least 40m from the nearest watercourse;
o refueling of construction vehicles is to take place only from approved, bunded areas,
located at least 40m away from the nearest watercourse;
• Protection of the watercourse from disturbance:
o the construction disturbance area along the watercourse should be minimized, and this
minimum practical disturbance area should be demarcated before the start of construction
activities. All areas outside of this zone should be regarded as no-go areas during
construction, with the exception of personnel engaged in required alien clearing and bank
rehabilitation activities outside of construction disturbance zones;
• Where dewatering is required as part of construction activities, provision must be made for the
settlement of sediment in temporary sediment ponds or other devices, managed so as to prevent
the passage of sediment-rich water into the watercourse; such systems must also be designed such
that they do not result in the passage of concentrated flow into watercourses, likely to result in
erosion;
• Where the use of cement is required in or in the vicinity of watercourses, method statements must
be prepared by the contractor to show how prevention of contamination of watercourses is to be
achieved;
• Construction activities within watercourses must not take place during the wet season (i.e. any
activities requiring the diversion of flows must take place between October and April only), and
construction schedules should be managed within these time frames; and efforts must be made to
manage construction sites such that storm events occurring during construction do not result in
runoff from into watercourses from stockpiled or other construction material or waste;
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• Rehabilitation activities specified in mitigation measures, including rehabilitation of temporary
bypasses or defunct structures must also take place outside of the wet season, and immediately
after the completion of construction activities at a particular site;
• Rehabilitation activities:
o requirements for alien clearing procedures should be carried out in accordance with
species-specific guidelines outlined by Working for Water documentation, or as
recommended by an experienced alien clearing specialist;
o bank rehabilitation activities should make provision for input by a river ecologist into the
final shaping and planting of these areas;
o any area accidentally disturbed during construction should be rehabilitated after
construction, with input from a riverine specialist where such areas lie within a
watercourse or other wetland;
• Waste management:
o adequate provision should be made for the containment of waste associated with the
construction site, including provision for toilets and litter management and removal;
o no tools or other construction materials may be washed in watercourses, and water used
for washing must be managed such that it does not contaminate any watercourse;
o all waste generated by construction activities (including rubble, litter etc.) is to be removed
from the site and disposed of at an appropriate approved site.
In the event that authorization by DEADP was granted for the proposed activities, Method Statements
would need to be developed by the Contractor that clearly showed how the above objectives and measures
are addressed in the proposed scope of Works.
Adherence to the CEMP would need to be a condition of authorisation for the project, and its
implementation should be overseen by a competent independent Environmental Control Officer or similar,
with allowance for input where necessary from a river ecologist.
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6 NATIONAL WATER ACT COMPLIANCE CONSIDERATIONS
The preceding sections of this report have addressed the requirements of NEMA with regard to the
assessment of the various proposed road repair or rehabilitation activities. However, in addition to
requiring authorization in terms of NEMA, the proposed activities also need to comply with the
requirements of the National Water Act (NWA). In this regard, the NWA makes provision for a General
Authorisation (GA) relating to sections 21(c) and (i) of the NWA, but stipulates conditions that would guide
a decision as to the applicability of the General Authorisation.
Table 6.1, adapted from a template developed by Charl de Villliers for this project, addresses each of these
conditions / criteria with regard to the six proposed structural upgrades / rehabilitation projects assessed in
this report. This table should be used as the basis on which to approach DWA with regard to the extent to
which the proposed activities are likely to be generally authorised in terms of GN 1199 (2009), as opposed
to those requiring authorisation through a Water Use License Application (WULA) or other process.
Table 6.1
Assessment of proposed activities at each site against DWA criteria for General Authorisation of the
activities in terms of GN 1199 (2009).
Table template developed by Charl de Villliers for this project. Items ticked indicate that the
criterion has been met. Table completed, assuming FULL implementation of proposed
mitigation activities, and implementation without mitigation measures (bracketed).
Criteria for ‘General Authorisation’, in terms of GN1199 of 18-
12-2009)
OH1 OH2 OH3 OH4
(1) Water use must not cause detrimental impact on
characteristics of watercourse
√ (X) √ (X) √ (X) √ (X)
(2) Water use must not have a detrimental impact on....
(a) others’ use of water or land √ (X) √ (√) √ (X) √ (X)
(b) public health or safety √ (X) √ (√) √ (√) √ (√)
(3) Structures and hardened surfaces must not...
(a) be erosive √ (√) √ (√) √ (X) √ (√)
(b) be structurally unstable √ (X) √ (√) √ (X) √ (√)
(c) induce any flooding √(X) √ (√) √ (√) √ (√)
(d) be a health and safety hazard √ (X) √ (√) √ (√) √ (√)
(4) Water use must not result in detrimental....
(a) change in stability of a watercourse √(X) √ (√) √ (X) √ (X)
(b) change in physical structure of a watercourse √(X) √ (√) √ (X) √ (X)
(c) scouring, erosion or sedimentation √(X) √ (√) √ (X) √ (X)
(d) decline in diversity of communities, composition of
natural indigenous vegetation
√ (X) √ (√) √ (X) √ (X)
(5) Water use must not result in detrimental change in
quantity, velocity, pattern, timing, water level and
assurance of flow in a watercourse
√ (X) √ (√) √ (√) √ (X)
(6) Water use must not result in detrimental change in
water quality characteristics of watercourse
√(X) √ (√) √ (X) √ (X)
(7) Water use must not result in detrimental change to...
(a) breeding, feeding and migratory patterns of aquatic
biota, including migratory species
√ (?) √ (?) √ (?) √ (?)
(b) level of composition of biotopes and communities of
animals and micro-organisms
√ (?) √ (?) √ (?) √ (?)
(c) condition of aquatic biota √(X) √ (√) √ (X) √ (X)
Proximity to a watercourse
Wateruse must not lie within 500m of a wetland – in
this case, assumed to be the Riviersonderend
wetlands (tick means this criterion met)
√ √ √ √
Basic Assessment Report on the implications of proposed road repairs in the Overberg Municipal area: Freshwater Ecosystems: Assessment of Hatch Goba Engineering designs
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7 CONCLUSIONS
This report has addressed the issues associated with the proposed rehabilitation / repair of four structures
located on Overberg Roads. With the inclusion of rehabilitation measures, none of these activities were
considered unacceptable from a freshwater ecology perspective.
Included in mitigation measures at two of the sites (OH1 and OH3) is the need to address impacts resulting
from the existing structures. Such measures are considered crucial elements relating to the successful
implementation of the proposed structures, to prevent ongoing, frequent disturbance to the river channel
as a result of flood damage that is not only ecologically devastating but is financially expensive as well (in
the case of OH1) and to prevent active headcut erosion of the channel at OH3. In the case of OH1,
however, it is noted that the major drivers of structural failure have probably involved various landuses
upstream, including the invasion of the river channel by alien vegetation. Given how extensive this
problem is in the region, it is recommended that stringent measures should be set in place regionally to
ensure that local landowners address this issue, using best practice clearing and rehabilitation measures, to
avoid ongoing damage to watercourses and road infrastructure, considering that while aliens appear to be
kept out of agricultural areas, they are allowed to spread unregarded along riparian zones, with the
resource value of these channels seemingly being disregarded, until severe damage accrues along access
points. This point has been reiterated in other reports by FCG, assessing flood-damaged roads and road-
damaged rivers in the Overberg area.
Basic Assessment Report on the implications of proposed road repairs in the Overberg Municipal area: Freshwater Ecosystems: Assessment of Hatch Goba Engineering designs
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8 REFERENCES
Brown, C. and Fowler, J. 2000. Breede River Basin Study. Preliminary Assessment of the Breede River Basin.
Southern Waters Report for MBB, Ninham Shand and Jakoet & Associates, for the Department
of Water Affairs and Forestry.
Department of Water Affairs and Forestry. 1996. South African Water Quality Guidelines. Volume 7:
Aquatic Ecosystems. Department of Water Affairs and Forestry. Pretoria.
Department of Water Affairs and Forestry. 2004. Development of a framework for the assessment of
wetland ecological integrity in South Africa. Phase 1: Situation Analysis. by MC Uys. Contributors
G Marneweck and P Maseti. Report No. 0000/00/REQ/0904 ISBN No.: 0-621-35474-0. Resource
Quality Services, Department of Water Affairs and Forestry, Pretoria, South Africa.
Department of Water Affairs and Forestry. 2005. A Practical Field Procedure for Identification and
Delineation of Wetlands and Riparian Areas. Department of Water Affairs and Forestry, Pretoria
Job, N., Snaddon, K., Day, E. (Liz), Nel, J. and Smith-Adao, L. 2008. C.A.P.E. fine-scale planning
project: Aquatic Ecosystems of the Upper Breede River Valley Planning Domain. Report to CAPE.
Driver, A, Nel, J.L., Snaddon, K., Murray, K., Roux, D., Hill, L., Swartz, E.R., Manuel, J. and Funke, N. 2011.
Implementation Manual for Freshwater Ecosystem Priority Areas. WRC Report No. 1801/1/11.
ISBN 978-1-4312-0147-1. Pretoria.
Kleynhans, CJ, Thirion, C and Moolman, J (2005). A Level I River Ecoregion classification System for South
Africa, Lesotho and Swaziland. Report No. N/0000/00/REQ0104. Resource Quality Services,
Department of Water Affairs and Forestry, Pretoria, South Africa.
Kleynhans, CJ, Thirion, C and Moolman, J. 2005. A Level I River Ecoregion classification System for South
Africa, Lesotho and Swaziland. Report No. N/0000/00/REQ0104. Resource Quality Services,
Department of Water Affairs and Forestry, Pretoria, South Africa.
Mucina L and Rutherford MC (eds) (2006). The Vegetation of South Africa, Lesotho and Swaziland. Strelitzia
19. South African National Biodiversity Institute, Pretoria.
Ollis DJ, Snaddon CD, Job NM 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.
SANBI. 2009. Further development of a proposed National Wetland Classification System for South Africa.
Primary Project Report (Final Draft). Prepared by the Freshwater Consulting Group for the South
African National Biodiversity Institute (SANBI).
Basic Assessment Report on the implications of proposed road repairs in the Overberg Municipal area: Freshwater Ecosystems: Assessment of Hatch Goba Engineering designs
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APPENDICES
Basic Assessment Report on the implications of proposed road repairs in the Overberg Municipal area: Freshwater Ecosystems: Assessment of Hatch Goba Engineering designs
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APPENDIX A: RESULTS OF EIS DETERMINATIONS
Table A1 presents the EIS scores attributed to river reaches at the different sites assessed in this study,
using the methodology of DWAF (1999) as outlined in Section 3.1.3. Note that, due to a lack of data, the
biotic component of the sites was not considered. Assessments took account of the irreparable level of
disturbance of some systems (e.g. the Meul River), as well as of the level of agricultural development in the
broader area, making riverine corridors increasingly important at a landscape level.
Table A1 Results of EIS assessments carried out at proposed road works sites
Criteria OH1 OH2 OH3 OH4
HABITAT
Diversity of aquatic habitat types 1 1 1 2
Refuge value of habitat types 1 1 1 2
Sensitivity of habitat to flow changes 2 2 2 2
Sensitivity of habitat to WQ changes 3 3 3 2
Migration route/corridor 1 1 2 2
Protected/natural areas 0 1 1 1
Median score 1 1 1.5 2
EIS Category Low/ Marginal Moderate
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