FOR THE Penhill Greenfield Development Project · 2018. 1. 20. · AURECON Page i Penhill...

Western Cape Government Department

of

Human Settlements

GEOHYDROLOGICAL ASSESSMENT

FOR THE

Penhill Greenfield Development Project

AS PART OF THE

SCOPING PHASE OF THE EIA

DECEMBER 2017

DOCUMENT NUMBER

113371 GHD V1.2

Compiled by

AURECON Page i

Penhill Greenfield Development Project Geohydrology December 2017

Project Title: Geohydrological assessment for the Penhill Greenfield

Development Project

Location: Western Cape

Co-ordinates (WGS84): S 33.982940

E 18.720780

Prepared for: Western Cape Government

Department of Human Settlements

Contact person: Mr Thando Mguli

Tel: +2721-483 9482

Compiled by: Aurecon

Lynnwood Bridge Office Park

4 Daventry Street

Lynwood Manor

0081

Contact Person: Louis Stroebel

Tel No: 012 427 3151

Project team: L Stroebel

Geohydrologist

Signed on behalf of

Aurecon:

L Stroebel

Date: December 2017

AURECON Page ii


TABLE OF CONTENTS

1 INTRODUCTION ....................................................................................................................................... 1

1.1 DETAIL OF ASSESSOR .............................................................................................................................. 1 1.2 BACKGROUND .......................................................................................................................................... 1 1.3 SCOPE AND PURPOSE OF THE REPORT ..................................................................................................... 2

2 METHODOLOGY ...................................................................................................................................... 3

2.1 DESK STUDY AND CONSULTATIONS WITH AUTHORITIES .............................................................................. 3 2.2 SITE VISIT AND HYDROCENSUS ................................................................................................................. 3 2.3 AQUIFER CLASSIFICATION ........................................................................................................................ 3 2.4 IMPACT ASSESSMENT ............................................................................................................................... 3

3 AVAILABLE INFORMATION .................................................................................................................... 4

4 BASELINE ASSESSMENT ....................................................................................................................... 5

4.1 SITE LOCATION & EXTENT ........................................................................................................................ 5

4.2 GEOLOGY ................................................................................................................................................ 5 4.3 RAINFALL AND RECHARGE ........................................................................................................................ 6 4.4 GEOHYDROLOGY ..................................................................................................................................... 6 4.4.1 Intergranular aquifer types within the Sandveld Group ....................................................................... 7

4.4.2 Fractured aquifer within the Malmesbury Group ................................................................................. 7 4.4.3 National Groundwater Archive and Hydrocensus ............................................................................... 8

4.4.4 Groundwater quality .......................................................................................................................... 11

5 AQUIFER CLASSIFICATION ................................................................................................................. 12

6 IMPACT ASSESSMENT ......................................................................................................................... 15

6.1 DESCRIPTION OF POTENTIAL IMPACTS .................................................................................................... 15 6.2 ALTERNATIVE ASSESSMENTS .................................................................................................................. 16 6.2.1 Access Road ..................................................................................................................................... 17 6.2.2 Bulk Water Supply ............................................................................................................................. 18

6.2.3 Bulk Sewer ........................................................................................................................................ 19 6.2.4 Waste Water Treatment Package Plant ............................................................................................ 20

6.2.5 Realignment of the Eskom line ......................................................................................................... 21

7 CONCLUSIONS AND RECOMMENDATIONS ...................................................................................... 22

LIST OF TABLES

Table 1. Geological Formations within the study area .................................................................... 6

Table 2. Rainfall and Recharge in Quaternary Catchment G22E .................................................... 6

Table 3. Borehole data from the NGA within the study area ........................................................... 8

Table 4. Details of the well identified during the hydrocensus ........................................................ 9

Table 5. Chemical parameters compared to SANS 241-1:2015 (edition 2) drinking water standards

..................................................................................................................................................... 11

Table 6. Ratings for the Aquifer System Management and Second Variable Classifications ........ 12

Table 7. Ratings for the Groundwater Quality Management (GQM) Classification System .......... 13

Table 8. GQM index for the study area ........................................................................................ 13

AURECON Page iii


LIST OF FIGURES

Figure 1. Hand Dug Well identified during the Hydrocensus .......................................................... 9

Figure 2. Shallow water level measured in an open grave at the Welmoed Cemetery ................. 10

LIST OF APPENDICES

Appendix A: Maps

Appendix B: Laboratory Reports

Appendix C: Declaration of Independence

AURECON Page 1


1 INTRODUCTION

1.1 Detail of Assessor

Aurecon is a leading, vibrant, global group created by the fusion of three world-class companies,

Africon, Connell Wagner and Ninham Shand. Our new group has a combined 210-year history; a

staff complement of 6 700; and an office network extending across 28 countries worldwide.

Aurecon operates in all major sectors, including:

Transportation

Property

Mining and industrial

Water

Energy

Community development

This assessment was conducted by Louis Stroebel who is an Associate in the Water Unit of

Aurecon’s Tshwane Delivery Centre. His résumé is attached in Appendix A.

Louis has 17 years’ experience in hydrogeological investigations with extensive field experience in

diverse urban, industrial, rural and remote locations. He acted as project leader for various rural

water supply programmes with the focus on the exploration and determination of sustainable

groundwater resources. In addition to his experience in groundwater exploration, he has been

involved in various contaminated land investigations (mainly hydrocarbon related) and international

experience was gained in the clean-up of land and marine-based organic contaminants during an

eight-month secondment in Europe. He is often involved in specialist groundwater investigations

for Environmental Impact Assessments and Water Use Licence Applications for the industrial,

mining and power generating Industry which ranges from the development of new underground

and opencast mines to the addition of mining infrastructure (tailings dams, pollution control dams,

waste rock dumps, smelters, etc.).

A signed “Declaration of Independence” is attached in Appendix C.

1.2 Background

The Western Cape Government Department of Human Settlements (DHS) and the City of Cape

Town (CoCT) are jointly planning a catalytic human settlements programme termed the Southern

Corridor Integrated Human Settlements Programme. The programme will upgrade 27 informal

settlements in the proximity of the N2 and benefit over 50,000 households. According to the DHS,

the programme is a cluster of discrete projects to upgrade informal settlements and to establish

greenfield human settlements. The Penhill Greenfields Development Project forms part of this of

this Programme and is the subject of this Application. The proposed Penhill Project is a residential

development which includes +/- 8,000 housing opportunities and other related mixed uses. The

Project also makes provision for commercial and industrial components as well as for agricultural

land.

AURECON Page 2


1.3 Scope and Purpose of the Report

With regards to the groundwater Scoping study, the following was required:

Undertake a desktop review of all relevant available information on the proposed

development and any relevant available information pertaining to the receiving

environment.

Attend a Plan of Study Workshop with other specialists from different fields of interest, and

undertake a site visit;

Verify and supplement desktop information with focused field work to provide a reliable

baseline assessment.

Liaise and consult with the relevant authorities, as required;

Identify any issues or sensitive elements of the receiving environment that may potentially

be impacted on by the proposal and any of its alternatives, or that may impact the proposal

and any of its alternatives, and would require further investigation during the EIA phase;

Determine preliminary mitigation options for impacts;

Identify any additional legislation and policies to be complied with, in relation to the

Specialist’s field of interest.

Undertake a preliminary analysis of alternatives, as well as the identification of possible

new alternatives (if any) to be considered to avoid potential impact to sensitive elements;

Determine a suitable methodology and Plan of Study for EIA.

Prepare a Specialist Scoping Phase Report to inform and contribute towards the Scoping

Phase of the environmental application in terms of NEMA.

This report is not intended to be an exhaustive description of the assessment, but rather serves as

a specialist geohydrological study to evaluate the overall geohydrological character of the site to

inform the impact assessment and proposed mitigation measures where applicable.

AURECON Page 3


2 METHODOLOGY

It must be stated that no intrusive groundwater investigations (other than groundwater level

recording and sampling in existing boreholes) were done and reporting is thus based on and

limited to observations made during the site visit, hydrocensus and the collation of available

information. The work completed for the purposes of compiling a geohydrological report comprised

the following:

2.1 Desk study and Consultations with authorities

Undertake a desk study of existing information available from relevant literature, the National

Groundwater Archive (NGA)1, the Department of Water and Sanitation (DWS) and published

geological and geohydrological reports.

In addition to the desk study, requests were made to the City of Cape Town2 to supply Aurecon

with geohydrological reports pertaining to the adjacent Blackheath Water Treatment Works and

Welmoed Cemetery. According to the City of Cape Town, no groundwater studies were done at

either of these two establishments.

2.2 Site Visit and Hydrocensus

A site visit was conducted to familiarise ourselves with the project area. A hydrocensus was

carried out within the project area as well as the adjacent area within a 1km radius to identify

legitimate groundwater users, the groundwater potential and quality. Where possible, groundwater

levels were also measured to assist in the understanding of groundwater flow within the project

area.

2.3 Aquifer Classification

The aquifer(s) underlying the project area was classified in accordance with “A South African

Aquifer System Management Classification by Parsons, December 1995.”3

2.4 Impact Assessment

The methodology to determine the significance of the potential impacts of the proposed

development was developed in 1995 and has been continually refined to date through the

application of it to over 400 Environmental Impact Assessment (EIA) processes by Aurecon. The

methodology is broadly consistent to that described in the Department of Environmental Affairs’

(DEA’s) Guideline Document on the EIA Regulations (1998).

1 http://www3.dwa.gov.za/NGANet/Security/WebLoginForm.aspx

2 Email sent from Ms Kirsten Jones (Aurecon) to Mr to Kevin Balfour (City of Cape Town) on the 6th of

March 2017

3 Department of Water Affairs and Forestry & Water Research Commission (1995). A South African Aquifer

System Management Classification. WRC Report No. KV77/95.

AURECON Page 4


3 AVAILABLE INFORMATION

The following information was available and relevant to the study:

1:250 000 Geology Map (3317 Cape Town)

1:500 000 Hydrogeological Map Series of the Republic of South Africa (3317 Cape Town).

An Explanation of the 1:500 000 General Hydrogeological Map, - Cape Town, Meyer PS

(2001).

National Groundwater Archive, Department of Water & Sanitation

AURECON Page 5


4 BASELINE ASSESSMENT

4.1 Site Location & Extent

The proposed Penhill Greenfield Development Project is located on the eastern boundary of the

City of Cape Town (Appendix A, Map 1). The proposed site is within the urban edge, east of the

urban nodes of Blackheath and Eersterivier, with the Stellenbosch agricultural areas to the east of

the site. The proposed site is bordered by and accessible from Van Riebeeck Road to the west.

The site is owned by the DHS and is currently undeveloped and used for informal farming

activities. The site comprises of 192 hectares (ha) and is located on 10 farm portions. The existing

zoning of the site is Agricultural I, characterised by small scale farming including dwellings and

fields.

There are gravel roads that transverse the site, which are used to access the plots and the existing

infrastructure. Eucalyptus trees line some of the internal roads on the site, and are located in

avenues adjacent to the site. Multiple servitudes can be observed on site, the most significant

being the 400kV transmission line. There are also servitudes for 11kV, 66kV and 132kV overhead

lines and two water supply pipelines.

To increase the available space for development and maximise the configuration of the layout, the

development proposal includes for the alignment of a section of the 66kV overhead powerline on

the site. The western portion of the 66 kV line will be relocated from its current alignment, so that it

runs parallel and adjacent to the 132 kV and the 400 kV lines further north on the site. This will

involve the decommissioning of approximately 1.3 km of overhead line, and construction of a new

section of 1.5 km of the line to adjoin the path of the other two lines. This new section is partly on

site (1.2 km) and offsite (300 m). The width of the new servitude required off and on the site is 11m

either side of the centreline (22m in total) according to Eskom standards. Also as part of the

development a Main intake substation would be required on the site, as well as approximately

three distribution substations, supplied from the main intake substation, as well as several mini

substations. It is the intention that the Department of Human Settlements is the applicant for these

works and following construction they would become the property of Eskom, and would continue

being maintained throughout their operational life by Eskom.

A series of five stormwater detention ponds are very prominent features adjacent to but outside the

site, between the site and Van Riebeeck Road. To the north of the site is the Blackheath Water

Treatment Works with associated sludge drying beds, with the Welmoed Cemetery to the south,

and a railway line to the west on the opposite side of Van Riebeeck Road.

4.2 Geology

The area is characterised by Quaternary-age sediments overlying basement rocks of the Sandveld

and Malmesbury Groups. The Geological Survey of South Africa (now the Council for

Geoscience) has mapped the area at 1:250 000 scale (map sheet 3318 Cape Town). The

geological setting is presented in Map 2 (Appendix A). The main geology of the area is listed in

Table 1.

AURECON Page 6


Table 1. Geological Formations within the study area

Group Formation Lithology

Sandveld Springfontein Fine to medium grained quartzitic sand

Malmesbury Tygerberg Grey to green phyllitic shale, siltstone and medium to fine grained

impure sandstone (greywacke)

4.3 Rainfall and Recharge

The study area falls within quaternary catchment G22E. The mean annual precipitation and

annual recharge figures for this quaternary catchment is presented in Table 1. The values used

were derived from the WR90 data set as contained in the “Groundwater Resources Directed

Measures”4 software.

Table 2. Rainfall and Recharge in Quaternary Catchment G22E

G22E

Mean Annual Rainfall (mm) 572

Annual Recharge (mm) 49.76

Percentage Recharge 8.7%

The Western Cape has a semi-arid Mediterranean climate, which is strongly influenced by the cold

Benguela ocean current and coastal winds. The Cape Town climate is characterised by dry warm

summer months (October to April) and wetter cool winter months (from May to September) with

most rainfall occurring between May and August.

4.4 Geohydrology

A description of the geohydrology is given in the following paragraphs making use of existing

information accompanied by a field visit (1 and 2 March 2017). It must be stated that no intrusive

groundwater investigations (other than groundwater level recording and sampling) were done and

site specific reporting is thus based and limited to observations made during the field visit,

hydrocensus and available information which included a search of DWS’s National Groundwater

Archive (NGA). This database holds information on depth to groundwater, groundwater quality,

borehole yield and construction, amongst other aspects.

Based on the published 1:250 000 geohydrological map (3317 Cape Town) and “An Explanation of

the 1:500 000 General Hydrogeological Map (Meyer, 2001)” the site is underlain by both fractured

and intergranular aquifer types. The surface lithology includes undifferentiated metamorphic rocks

4 “Groundwater Resources Directed Measures” Software (Version 4.0.0.0). Department of Water Affairs &

Water Research Commission.

AURECON Page 7


(mixed lithologies), as well as undifferentiated coastal deposits (unconsolidated to semi-

consolidated sediments including sand, calcrete, calcarenite, aeolianite, marine gravel, clay,

silcrete and limestone).

4.4.1 Intergranular aquifer types within the Sandveld Group

The Sandveld Group consist of four formations, namely the Springfontein Formation, Velddrift

Formation, Langebaan Formation and Witzand Formation. The Springfontein formation consist

mainly of well sorted, fine to medium grained quartz sand, virtually free of mud.

The Sandveld Group deposits constitute what is known as the Cape Flats Aquifer (CFA). The

aquifer is regionally unconfined and internally is essentially free of lateral hydraulic or geological

boundaries which may influence regional behaviour. Sands of the Springfontein Formations

constitute the main target for groundwater abstraction from the CFA. These sands range in grain

size from very fine to very coarse and are generally well-sorted and well-rounded. These

formations do, however, possess a degree of heterogeneity and anisotropy due to vertical and

lateral grain size gradation and the occurrence of sandstone, clay or calcrete lenses. The bedrock,

which consists of weathered Malmesbury Group meta-sediments, is generally regarded as an

impervious basement.

4.4.1.1 Borehole Yields

According to the regional 1:500 000 scale groundwater map of Cape Town (3317), median

borehole yields within this geological unit varies between 0.1 ℓ/s to 0.5 ℓ/s.

4.4.1.2 Groundwater Quality

Electrical Conductivities (ECs) of groundwater vary between 30 and 250 mS/m. Determinants

seldom exceed maximum recommended limits and groundwater generally displays a sodium-

chloride-calcium-alkaline nature. There is a concern, especially in densely populated areas,

regarding the vulnerability of these aquifers to pollution.

4.4.2 Fractured aquifer within the Malmesbury Group

The Malmesbury Group is generally regarded as an impervious basement. However in places the

Malmesbury Group contains brecciated and transmissive fault zones resulting in a fractured

aquifer with high yielding boreholes. The aquifer is recharged directly principally from rainfall.

Groundwater exploration in the Malmesbury Group is often problematic due to poor exposure, the

largely argillaceous and thus incompetent nature of many of the lithological units and the overall

structural complexities.

4.4.2.1 Borehole Yield

According to the regional 1:500 000 scale groundwater map of Cape Town (3317), median

borehole yields within this geological unit varies between 0.5 ℓ/s to 2.0 ℓ/s.

4.4.2.2 Groundwater Quality

Groundwater quality varies considerably, probably due to the variable lithologies and recharge

conditions, and ECs range between 10 and 1 000 mS/m. The best quality groundwater can be

obtained in areas where groundwater movement takes place, such as dislocation zones and areas

where alluvium covers arenaceous rocks. Determinants seldom exceeds recommended limits in

arenaceous units where groundwater turnover takes place. Sodium, magnesium, chloride and

sulphate often exceed maximum recommended limits and even maximum allowable limits in

AURECON Page 8


argillaceous units. Groundwater in the Malmesbury Group is generally of a sodium-chloride-

alkaline nature.

4.4.3 National Groundwater Archive and Hydrocensus

A search of the NGA within a radius of 3km from the project boundary delivered a total of 13

boreholes. Under circumstances where the coordinate accuracy of most of the boreholes

enumerated in the NGA is not better than 10 000 m, their positions are at least constrained to the

boundaries of the topocadastral farms on which they are located. The associated hydrogeological

data and information therefore provides only a broad overview of groundwater conditions rather

than site-specific.

Table 3. Borehole data from the NGA within the study area

ID Map ID Latitude Longitude Water level

(mbgl)5 Yield (L/s)

EC (mS/m)

3318DC00072 NGA1 -33.9544 18.72982 9.14 2.31 ~

3318DC00073 NGA2 -33.95856 18.73259 24.08 0.82 ~

3318DC00074 NGA3 -33.96273 18.74092 10 2.4 ~

3318DC00075 NGA4 -33.96273 18.74093 ~ ~ ~

3318DC00076 NGA5 -33.96274 18.74092 30.5 0.05 ~

3318DC00077 NGA6 -33.96273 18.74094 ~ ~ ~

3318DC00078 NGA7 -33.96275 18.74092 11.58 1.87 ~

3318DC00079 NGA8 -33.96273 18.74095 ~ ~ ~

3318DC00080 NGA9 -33.96276 18.74092 ~ ~ ~

3318DC00081 NGA10 -33.96273 18.74096 18.29 0.57 ~

3318DC00082 NGA11 -33.96277 18.74092 ~ ~ ~

3318DC00091 NGA12 -33.95884 18.72593 28.64 0.3 142

3318DC00093 NGA13 -33.97884 18.71509 0.3 ~ 52

An attempt was made to locate the boreholes listed in the NGA and verify data, but none of the

boreholes could be found at the provided coordinates. Provided yields of the boreholes are in

accordance with published data, but water levels are questionable. The relatively deep water

levels could be attributed to water levels measured shortly after drilling without allowing adequate

time for water levels to return to static levels.

A hydrocensus was performed within and adjacent to the project area up to a 1km radius. Only

one hand dug well (Figure 1) was found and a water level measured, as well a sample retrieved for

chemical analysis. A summary of the most important data pertaining to this well is summarised in

Table 4. The locations of the well, together with NGA boreholes are presented in Map 3 (Appendix

A)

5 Meters below ground level

AURECON Page 9


Table 4. Details of the well identified during the hydrocensus

BH nr.

Coordinates (decimal degrees)

(WGS84)

Owner / Contact details Depth (m) Static

water level (*mbgl)

Equipment User

application

Estimated Yield

(l/hour)

PEBH1 S33.98294 E18.72078 Unknown Unknown 1.6 0.97

Submersible

Pump

Crop

Irrigation

500

*meters below ground level

From the hydrocensus it became evident that groundwater is not a major source of potable water

within the project area. Groundwater is mainly used for irrigation/stock watering as the water is too

brackish for human consumption (personal communication with locals).

Figure 1. Hand Dug Well identified during the Hydrocensus

The adjacent Blackheath Water Treatment Works and Welmoed Cemetery were also visited in

search of possible monitoring boreholes. No boreholes were found, but a water level measured in

an open grave (1.2 mbgl) confirmed the shallow water level measured in borehole PEBH1 (Figure

2).

AURECON Page 10


Figure 2. Shallow water level measured in an open grave at the Welmoed Cemetery

AURECON Page 11


4.4.4 Groundwater quality

A water sample was collected from the identified borehole PEBH1 and submitted to Aquatico

Scientific (SANAS accredited laboratory) in Pretoria for a major cation/anion analysis. This was

done to establish the baseline water quality on-site. Laboratory reports of the chemical analysis

are presented Appendix B. The analytical results were compared with the SABS drinking water

standards (SANS 241-1:2015, edition 2) (Table 5). Water is classified unfit for human

consumption if the Standard Limits are exceeded.

Table 5. Chemical parameters compared to SANS 241-1:2015 (edition 2) drinking water

standards

Sample Nr. PEBH1

Standard

Limits

Ca 51.70 ~

Mg 14.70 ~

Na 46.00 200K 1.89 ~

Mn 0.00 0.1

Fe 0.24 0.3

F 0 1.5

NO3-N 0.24 11

NH4-N 0.03 1.5

Al 0 0.3

PO4 0.08 -

Cl 101.0 300

SO422.5 250

TDS 302 1200

T-Alk 104 ~

pH 7.90 5.0 - 9.7EC 61 170

Notes

0 = below detection limit of analytical technique

Exceeds standard limits

Yellow = Acceptable

EC measurements in mS/m, other parameters in mg/ℓ.

From Table 5 it can be concluded that the water quality in the sampled well falls within SABS

Drinking Water Standards. Furthermore, the measured EC concentration (61 mS/m) corresponds

with the published Hydrogeological Map value of between 30 and 150 mS/m for Intergranular

aquifer types within the Sandveld Group.

AURECON Page 12


5 AQUIFER CLASSIFICATION

The aquifer(s) underlying the project area were classified in accordance with “A South African

Aquifer System Management Classification, December 1995.”

Classification has been done in accordance with the following definitions for Aquifer System

Management Classes:

Sole Aquifer System: An aquifer which is used to supply 50% or more of domestic water

for a given area, and for which there is no reasonably available alternative sources should

the aquifer be impacted upon or depleted. Aquifer yields and natural water quality are

immaterial.

Major Aquifer System: Highly permeable formations, usually with a known or probable

presence of significant fracturing. They may be highly productive and able to support large

abstractions for public supply and other purposes. Water quality is generally very good

(Electrical Conductivity of less than 150 mS/m).

Minor Aquifer System: These can be fractured or potentially fractured rocks which do not

have a high primary permeability, or other formations of variable permeability. Aquifer

extent may be limited and water quality variable. Although these aquifers seldom produce

large quantities of water, they are important for local supplies and in supplying base flow for

rivers.

Non-Aquifer System: These are formations with negligible permeability that are regarded

as not containing groundwater in exploitable quantities. Water quality may also be such that

it renders the aquifer unusable. However, groundwater flow through such rocks, although

imperceptible, does take place, and needs to be considered when assessing the risk

associated with persistent pollutants.

Based on information collected during the hydrocensus it can be concluded that the aquifer system

in the study area can be classified as a “Minor Aquifer System”. Although groundwater is not a

sole source of water, boreholes are used on small scale for a number of uses.

In order to achieve the Groundwater Quality Management Index a points scoring system as

presented in Table 6, Table 7 and Table 8 was used.

Table 6. Ratings for the Aquifer System Management and Second Variable Classifications

Aquifer System Management Classification

Class Points Study area

Sole Source Aquifer System:

Major Aquifer System:

Minor Aquifer System:

Non-Aquifer System:

Special Aquifer System:

6

4

2

0

0 – 6

2

Second Variable Classification

(Weathering/Fracturing)


High:

Medium:

Low:

3

2

1

3

AURECON Page 13


Table 7. Ratings for the Groundwater Quality Management (GQM) Classification System

Aquifer System Management Classification


Sole Source Aquifer System:

Major Aquifer System:

Minor Aquifer System:

Non-Aquifer System:

Special Aquifer System:

6

4

2

0

0 - 6

2

Aquifer Vulnerability Classification


High:

Medium:

Low:

3

2

1

3

The occurring aquifer(s), in terms of the above definitions, is classified as a minor aquifer system.

The vulnerability, or the tendency or likelihood for contamination to reach a specified position in the

groundwater system after introduction at some location above the uppermost aquifer, in terms of

the above, is classified as high. A shallow water table (<1 mbgl at places) and intergranular

primary aquifer underlie the site.

The level of groundwater protection based on the Groundwater Quality Management Classification:

GQM Index = Aquifer System Management x Aquifer Vulnerability

= 2 X 3 = 6

Table 8. GQM index for the study area

GQM Index Level of Protection Study Area

<1

1 - 3

3 - 6

6 - 10

>10

Limited

Low Level

Medium Level

High Level

Strictly Non-Degradation

6

Aquifer Susceptibility

Aquifer susceptibility, a qualitative measure of the relative ease with which a groundwater body

can be potentially contaminated by anthropogenic activities and which includes both aquifer

vulnerability and the relative importance of the aquifer in terms of its classification, in terms of the

above, is classified as medium.

Aquifer Protection Classification

The ratings for the Aquifer System Management Classification and Aquifer Vulnerability

Classification yield a Groundwater Quality Management Index of 6 for the study area, indicating

that medium level groundwater protection may be required.

AURECON Page 14


Due to the medium GQM index calculated for this area, a medium level of protection is needed to

adhere to DWS’s water quality objectives. Reasonable and sound groundwater protection

measures are recommended to ensure that no cumulative pollution affects the aquifer, even in the

long term.

In terms of DWS’s overarching water quality management objectives which is (1) protection of

human health and (2) the protection of the environment, the significance of this aquifer

classification is that if any potential risk exist, measures must be triggered to limit the risk to the

environment, which in this case is the (1) protection of the Primary Underlying Aquifer and (2) the

limited number of groundwater users within the project and adjacent area.

AURECON Page 15


6 IMPACT ASSESSMENT

6.1 Description of Potential Impacts

Before assessing the potential impacts on the geohydrological environment, the following

assumptions need to be kept in mind as stated in the provided “Project Description”.

Water supply: Water reticulation infrastructure will comprise meters, house connections, water

mains, valves and fire hydrants fed from municipal water supply. No groundwater will be used.

Sewage: The development will connect to new formal sewer infrastructure at the south-western

corner of the site.

Waste water treatment – package plant: The City of Cape Town have stated that the Zandvliet

Wastewater Treatment Works (WWTW) can only accommodate the Penhill development once the

first phase of the treatment works upgrade is completed in December 2022. Therefore, a

temporary wastewater treatment package plant is planned to be established on the Penhill site to

provide for the disposal of wastewater from the Penhill development before December 2022.

Domestic Waste: Waste will be collected and disposed off-site in a landfill site.

The most significant impacts on the groundwater considered as part of the impact assessment is

listed below:

Construction Phase

Waste generated during construction activities;

Generation of domestic waste water discharge; and

Accidental spills of materials stored and handled.

Operation Phase

Generation of domestic waste and waste water; and

Development will have impermeable surfaces (paving roads, etc.) and this will reduce direct

recharge to groundwater beneath these surfaces.

Decommissioning Phase

The Project is an affordable housing development that would almost entirely transform the current

site. Given the fact that demand for housing in the City of Cape Town is expected to continue to

grow into the future, and the Project is designed for incremental growth, there is a very limited

possibility that this Project would be decommissioned. It is most likely that with correct and ongoing

maintenance of the infrastructure, and necessary replacements as and when certain infrastructure

reaches its design life, it would be replaced with something of equal or improved standard.

Therefore the Project is expected to likely exist into perpetuity and no decommissioning phase was

assessed.

AURECON Page 16


6.2 Alternative Assessments

The Conceptual Development Framework (CDF) process has identified two layout alternatives,

Alternative A (preferred) and Alternative B. The primary distinguishing factor between them is the

layout of the agricultural land. From a groundwater point of view, no other impacts for the

alternatives were identified other than those identified for the proposed layout. The significance of

the identified impacts also remains unchanged.

LAYOUT ALTERNATIVEA1:E20Short description

Description of alternative specific

attributes (environmental / social)

List of negative impacts

List of positive impacts

List of potential mitigations

Nature Negative Negative

Duration Short term Short term

Extent Small Small

Magnitude Medium Medium

Probability Medium Medium

Confidence Medium Medium

Reversibility Reversible Reversible

Resource irreplaceability High High

Mitigatability Medium Medium

Significance Low Low

Ranked preference (from 1-2)

Motivation for preferred alternative

Contamination of groundwater due to:

• Waste generated during construction activities;

• Generation of domestic waste and waste water;

• Accidental spills of materials stored and handled;

• Loss of recharge areas due to impermeable surfaces (paving roads, etc.) during operation.

1) Good housekeeping practises

2) Adequate Ablution Facilities

3) Storage and handling of materials as per industry specifications

4) Adeaqutely trained persons in Emergency Spill Response Procedures

5) Formal Stormwater Network, Sewage Network & Domestic Waste Disposal Services

Impact on the groundwater for both alternatives is similar to that of the considered layout. From a

groundwater point of view, the 2 options will have a similar impact on the geohydrological environment.

Assessment

Conclusion1 1

Alternative A (preferred) Alternative BAn ‘L shaped’ agricultural area which will provide a

more suitable interface with the agricultural areas

upslope to the east of the site.

Based on a consolidated agricultural area as one

block on the east of the site, to allow for a 500m

buffer with the Welmoed Cemetery.

No different than preferred option.

AURECON Page 17


6.2.1 Access Road

ACCESS ROADShort description






AssessmentNature Negative

Duration Short term

Extent Small

Magnitude Medium

Probability Medium

Confidence Medium

Reversibil ity Reversible

Resource irreplaceability High

Mitigatability Medium

Significance Low

Ranked preference


Contamination of groundwater during construction

activities due to:

• Waste generated;


• Accidental spil ls of materials stored and handled.

Loss of recharge on road surface during Operation

Phase.


2) Adequate Ablution Facil ities

3) Storage and handling of materials as per industry

specifications

4) Adeaqutely trained persons in Emergency Spill

Response Procedures

5) Storm water run-off must be addressed by the

design engineers to adequately manage run-off from

these areas to stormwater detention ponds where

groundwater recharge can take place.

Conclusionn/a

n/a

Except for construction activities, the project will

have very l ittle impact on the groundwater quality.

No impact on groundwater table as groundwater

supply during construction purposes will be from a

municipal supply.Road surface will reduce direct

recharge to groundwater, transferred to stormwater

ponds.

Only alternativeNorthern link road ± 1.1km in length with a 25m

servitude, and connect with Jeripiko Road to the

north.

AURECON Page 18


6.2.2 Bulk Water Supply

BULK WATER SUPPLYShort description







Duration Short term

Extent Small

Magnitude Medium

Probability Medium

Confidence Medium

Reversibility Reversible



Significance Low

Ranked preference


Conclusionn/a

n/a

Reservoir upslope of the site including ±1km bulk

pipeline and associated access road, with a 10m

servitude.


have no impact on the groundwater quality. No

impact on groundwater table as groundwater


municipal supply.


activities due to:



• Accidental spills of materials stored and handled.




specifications


Response Procedures

Only alternative

AURECON Page 19


6.2.3 Bulk Sewer

BULK SEWERShort description







Duration Short term

Extent Small

Magnitude Medium

Probability Medium

Confidence Medium




Significance Low

Ranked preference


n/a

n/a





municipal supply. Formal sewer pipeline will have

no impact on groundwater quality as opposed to

french drains.


activities due to:



• Accidental spills of materials stored and handled.




specifications


Response Procedures

Conclusion

Only alternativeA ±6km bulk sewage pipeline will be required which

is proposed primarily within the road reserve along

Van Riebeeck Road and Baden Powell Road. Should

it need to cross properties it would require a

servitude in the order of up to 7 m wide depending

on the depth.

AURECON Page 20


6.2.4 Waste Water Treatment Package Plant

WASTE WATER TREATMENT

PACKAGE PLANTShort description






Nature Positive Negative

Duration Medium term

Extent Low

Magnitude Medium

Probability Medium

Confidence Medium

Reversibil ity Reversible

Resource irreplaceability Medium


Significance Medium

Ranked preference


Only alternative

A temporary wastewater treatment package plant is

planned on the site to provide for the disposal of

wastewater from the development before December

2022. The package plant would have a footprint in

the order of 2 ha and would need to be located at

the lowest part of the site in the south western

corner. The treatment capacity of the package plant

would be approximately 3,000 kl per day and it

would discharge the treated effluent into the

existing underground stormwater system at the

south western corner of the site. The re-use of the

treated effluent will be considered in further stages

of the project. The package plant would include a

storage tank of approximately 2,000 kl capacity.


have no impact on the groundwater quality if

operated according to design specifications. No



municipal supply. Treated effluent will be

discharged via the existing underground stormwater

system. If effluent is treated to required quality, the

plant and treated effluent will have no impact on

groundwater quality as opposed to french drains.


activities due to:



• Accidental spil ls of materials stored and handled.

Contamination of groundwater during operational

phase due to:

• Spillages of untreated sewage or treated sewage

not meeting effluent standard at package plant.

•Spillages of untreated sewage or treated sewage

not meeting effluent standard due to blocked

stormwater.


2) Adequate Ablution Facil ities


specifications


Response Procedures

5) Adequate Operation and Maintenance of the

Sewage Treatment Plant and Storm Water System

Assessment

Conclusionn/a

n/a

AURECON Page 21


6.2.5 Realignment of the Eskom line

TRANSMISSION LINE

REALIGNMENTShort description







Duration Short term

Extent Small

Magnitude Medium

Probability Medium

Confidence Medium




Significance Low

Ranked preference





specifications


Response Procedures

Conclusionn/a

n/a

Only alternative

The western portion of the 66 kV line will be

relocated from its current alignment, so that it runs

parallel and adjacent to the 132 kV and the 400 kV

lines further north on the site. This will involve the

decommissioning of approximately 1.3 km of

overhead line, and construction of a new section of

1.5 km of the line to adjoin the path of the other two

lines. This new section is partly on site (1.2 km) and

offsite (300 m). The width of the new servitude

required off and on the site is 11m either side of the

centreline (22m in total).





municipal supply.


AURECON Page 22


7 CONCLUSIONS AND RECOMMENDATIONS

Based on information acquired during the desk study, hydrocensus and consequent impact

assessment, it can be concluded that the development will have a “Negligible Negative” impact on

the groundwater environment after implementation of appropriate mitigation measures.

Noteworthy impacts are mainly associated with the Construction Phase where groundwater

contamination can occur if irresponsible waste management and fuel/hazardous material storage

occur.

Groundwater impacts during the operational phase are appropriately mitigated by formal

infrastructure proposed in the Concept Development Plan:

No groundwater will be used for potable water and water reticulation infrastructure will

comprise meters, house connections, water mains, valves and fire hydrants fed from

municipal water supply.

Formal storm water run-off infrastructure channelling run-off to storm water detention ponds

where a portion of run-off will be recharged to the local aquifer.

The development will connect to new formal sewer infrastructure at the south-western

corner of the site.

Waste will be collected and disposed off-site in a landfill site.

It is the assessor’s professional opinion that adequate information was available to appropriately

assess the impact of the proposed development on the geohydrological environment. Although no

further fieldwork is required, the groundwater impacts will be assessed in further detail in the EIA

Phase through application of the Aurecon standard methodology for impact assessment.

AURECON


APPENDIX A

MAPS

AURECON


APPENDIX B

LABORATORY REPORT

Test Report Page 1 of 1

Client:

Address:

Report no:

Project:

Aurecon

Lynwood Bridge Office Park, No. 4 Daventry str., Pretoria, 0081

38028

Aurecon

Date of certificate:

Date accepted:

Date completed:

Revision:

10 March 2017

06 March 2017

10 March 2017

0

Lab no:

Date sampled:

Sample type:

Locality description:

Analyses Unit Method

The results relates only to the test item tested.

Results reported against the limit of detection.

A = Accredited N = Non accredited O = Outsourced S = Sub-contracted NR = Not requested RTF = Results to follow NATD = Not able to determine

Results marked 'Not SANAS Accredited' in this report are not included in the SANAS Schedule of Accreditation for this laboratory.

Uncertainty of measurement available on request for all methods included in the SANAS Schedule of Accreditation.

www.aquatico.co.za 89 Regency Drive, R21 Corporate Park, Centurion, South Africa Tel: +27 12 450 3800 Fax: +27 12 450 3851

40886

06-Mar-

2017

Water

PEBH1

A pH @ 25°C pH ALM 20 7.90

A Electrical conductivity (EC) @ 25°C mS/m ALM 20 60.9

A Total dissolved solids (TDS) mg/l ALM 26 302

A Total alkalinity mg CaCO3/l ALM 01 104

A Chloride (Cl) mg/l ALM 02 101

A Sulphate (SO₄) mg/l ALM 03 22.5

A Nitrate (NO₃) as N mg/l ALM 06 0.244

A Ammonium (NH₄) as N mg/l ALM 05 0.025

A Orthophosphate (PO₄) as P mg/l ALM 04 0.081

A Fluoride (F) mg/l ALM 08 0.312

A Calcium (Ca) mg/l ALM 30 51.7

A Magnesium (Mg) mg/l ALM 30 14.7

A Sodium (Na) mg/l ALM 30 46.0

A Potassium (K) mg/l ALM 30 1.89

A Aluminium (Al) mg/l ALM 31 <0.002

A Iron (Fe) mg/l ALM 31 0.239

A Manganese (Mn) mg/l ALM 31 <0.001

A Total hardness mg CaCO3/l ALM 26 190

AURECON


APPENDIX C

DECLARATION OF INDEPENDENCE

APPLICATION FORM FOR ENVIRONMENTAL AUTHORISATION IN TERMS OF NEMA EIA LISTED ACTIVITIES – December 2014

DECLARATION

THE SPECIALIST

I Louis Stroebel, as the appointed specialist hereby declare/affirm the correctness of the

information provided or to be provided as part of the application, and that I:

in terms of the general requirement to be independent:

o other than fair remuneration for work performed/to be performed in terms of this

application, have no business, financial, personal or other interest in the activity or

application and that there are no circumstances that may compromise my objectivity;

or

o am not independent, but another specialist that meets the general requirements set

out in Regulation 13 have been appointed to review my work (Note: a declaration by

the review specialist must be submitted);

in terms of the remainder of the general requirements for a specialist, am fully aware of

and meet all of the requirements and that failure to comply with any the requirements may

result in disqualification;

have disclosed/will disclose, to the applicant, the Department and interested and

affected parties, all material information that have or may have the potential to influence

the decision of the Department or the objectivity of any report, plan or document

prepared or to be prepared as part of the application;

have ensured/will ensure that information containing all relevant facts in respect of the

application was/will be distributed or was/will be made available to interested and

affected parties and the public and that participation by interested and affected parties

was/will be facilitated in such a manner that all interested and affected parties were/will

be provided with a reasonable opportunity to participate and to provide comments;

have ensured/will ensure that the comments of all interested and affected parties

were/will be considered, recorded and submitted to the Department in respect of the

application;

have ensured/will ensure the inclusion of inputs and recommendations from the specialist

reports in respect of the application, where relevant;

have kept/will keep a register of all interested and affected parties that participate/d in

the public participation process; and

am aware that a false declaration is an offence in terms of regulation 48 of the 2014 NEMA

EIA Regulations.

Signature of the specialist:

Aurecon South Africa Pty (Ltd)

Name of company:

13 April 2017

Date:

Date post:	31-Oct-2020
Category:	Documents
Upload:	others
View:	1 times
Download:	0 times

FOR THE Penhill Greenfield Development Project · 2018. 1. 20. · AURECON Page i Penhill...

Documents