GCS - APPENDIX 20 · 2019. 7. 15. · Construction Work Method Statement: Watercourse Crossings 7 |...

APPENDIX 20

METHOD STATEMENT

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Construction Work Method Statement

Project: Mngeni Shaft

Activity: Type 1, 2, 3, 4, 5 Watercourse Crossings (Mvalo River, Umfolozi River, Umngeni River and

various non-perennial streams)

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Table of Contents

TABLE OF CONTENTS .............................................................................................................................................. II

LIST OF APPENDICES .............................................................................................................................................. II

LIST OF MAPS ......................................................................................................................................................... II

1 DESCRIPTION OF ACTIVITY .............................................................................................................................. 1

2 PROGRAMME ................................................................................................................................................. 6

3 METHODOLOGY .............................................................................................................................................. 6

3.1 TYPICAL CONSTRUCTION SEQUENCE .......................................................................................................................... 6

3.2 PLANT AND RESOURCES REQUIRED ........................................................................................................................... 6

3.3 ENVIRONMENTAL IMPACT MANAGEMENT ................................................................................................................. 7

3.4 MONITORING AND REVIEW STRATEGY .................................................................................................................... 11

4 RESPONSIBILITIES AND PRESCRIBED OCCUPATIONS ..................................................................................... 13

5 DECLARATIONS ............................................................................................................................................. 15

5.1 DESIGN ENGINEER .............................................................................................................................................. 15

5.2 SITE MANAGER .................................................................................................................................................. 15

5.3 ENVIRONMENTAL CONTROL OFFICER ..................................................................................................................... 15

APPENDICES......................................................................................................................................................... 16

List of Appendices

APPENDIX A: ENGINEERING DRAWINGS

List of Maps

Map 1: Power Line Crossings............................................................................................................................................ 2

Map 2: Clean and Dirty Water Pipeline Crossings (ZAC Plant to Mngeni Shaft) ... Error! Bookmark not defined.

Map 3: Dirty Water Pipelien Crossings ( Mngeni to Ngwabe PCD) ......................... Error! Bookmark not defined.

Construction Work Method Statement: Watercourse Crossings

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1 Description of Activity

The project consists of three pipelines Watercourse crossings through the existing culverts, a new culvert as

well as one below the stream bed. The first pipeline will be carrying clean water from the existing ZAC Plant

to the newly proposed Mngeni Adit, the second carrying dirty water from the Mngeni Adit to the ZAC

Process Plant and the third one carrying dirty water from Mngeni Adit to an existing Pollution Control Dam

(PCD) at the Ngwabe Shaft.

The process will involve the excavation of the soil to an approximate depth of 1,500 meters (m), laying of

the pipe and the subsequent infilling of the trench. The

The project also includes the installation of electricity power lines that will traverse from the substation at

ZAC offices, across the Mvalo River, across various non-perennial streams and across Umfolozi River to

Umngeni Adit. This will involve digging approximately to a depth of a 1.2m for the wooden poles to be

installed on the ground and carry electricity wiring above ground. The poles will be in pairs along the

longest sections of Umvalo River as well as Umfolozi river crossings.

A new access road will also be constructed across a non-perennial stream that is a tributary of the Black

Umfolozi River.

The pipelines cross a total of 7 watercourses with extent and localities indicated in Map 2. Start and end

coordinates are summarized in Table 1.

The crossings are categorized as follows (refer Maps 1 to 3):

Type 1: Applicable where the pipeline crosses the watercourse attached to an existing culvert/bridge with

minimal disturbance to the watercourse or wetland

Type 2: Applicable where the pipeline crosses the watercourse attached to a new culvert with minimal

disturbance to the watercourse or wetland

Type 3: Pipeline crosses the watercourse below the ground/river bed, with minor environmental impacts

during construction only.

Type 4: Powerline crossings where the power line crosses the watercourse or wetland above ground with

no significant impact on the environment except during construction particularly for the poles that will have

to be unavoidable installed within the wetland or watercourse. All effort will be made to ensure all the

powerline poles are positioned outside the sensitive areas like watercourse or wetlands, but where this

cannot be avoided, measures will be taken to ensure the poles have minimal impact on the watercourse.

Type 5: Applicable where the access road crosses a non-perennial watercourse with minimal disturbance

to the watercourse or wetland during construction.

This Work Method Statement pertains to all the above mentioned pipeline and power line crossings.


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Map 1: Powerline crossings

Map 2: Clean & Dirty Water pipeline crossings


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Map 3: Dirty Water pipeline Crossings from Mngeni to ZAC Plant

Map 4: Road Crossings


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Table 1: Schedule of Crossings

Type of Crossing Crossing Name Crossing type River Type Material Type Start Coordinates End Coordinates

Powerline Mvalo crossing Type 4 Perennial Stream

Wooden Electricity Pole 28013'19.94"S 31040'52.06"E

28013'18.66"S 31040'53.73"E

Powerline Existing Culvert1 Type 4 Non-perennial Stream


28012'59.80"S 31041'19.49"E

Powerline Stream Crossing 1 Type 4 Non-perennial Stream


28012'50.08"S 31041'28.65"E

Powerline Existing Culvert 2 Type 4 Non-perennial Stream


28012'24.17"S 31041'50.34"E

Powerline Umfolozi River Bridge Type 4 Perennial Stream


28011'10.26"S 31043'02.97"E

Powerline Proposed Culvert 3 - Access Road

Type 4 Non-perennial Stream


28011'07.15"S 31043'10.58"E

Access Road Proposed Culvert 3 Type 5 Non-perennial Stream

Concrete Culvert Pipes 28011'07.12"S 31043'9.22"E

Clean Water Pipeline Existing Culvert1 Type 1 Non-perennial Stream

HDPE Pipe in PVC Sleeve

28011'10.94"S 31043'01.76"E

Clean Water Pipeline Stream Crossing 1 Type 1 Non-perennial Stream

HDPE Pipe Encased in Concrete

28012'24.30"S 31041'48.99"E

Clean Water Pipeline Existing Culvert 2 Type 1 Non-perennial Stream

HDPE Pipe in PVC

Sleeve

28012'51.31"S 31041'27.82"E

Clean Water Pipeline Umfolozi River Bridge Type 1 Perennial Stream

HDPE Pipe in PVC

Sleeve

28012'59.41"S 31041'17.68"E

Clean Water Pipeline Proposed Culvert 3 - Access Road

Type 2 Non-perennial Stream


28010'46.58"S 31042'51.79"E

Dirty Water Pipeline 1 Existing Culvert1 Type 1 Non-perennial Stream


28011'10.94"S 31043'01.76"E

Dirty Water Pipeline 1 Stream Crossing 1 Type 3 Non-perennial Stream

HDPE Pipe Encased in Concrete

28012'24.30"S 31041'48.99"E


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Dirty Water Pipeline 1 Existing Culvert 2 Type 1 Non-perennial Stream

HDPE Pipe in PVC

Sleeve

28012'51.31"S 31041'27.82"E

Dirty Water Pipeline 1 Umfolozi River Bridge Type 1 Perennial Stream

HDPE Pipe in PVC

Sleeve

28012'59.41"S 31041'17.68"E

Dirty Water Pipeline 2 Mngeni River Type 1 Perennial Stream

HDPE Pipe in PVC

Sleeve

28010'46.58"S 31042'51.79"E


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2 Programme

The start and closure dates for construction activities will be confirmed after the issuance of a Water Use

Licence.

3 Methodology

Works will be carried out in compliance with the design drawings and the environmental management

reports and in accordance with the following Work Method Statement (WMS):

The WMS will be brought to the attention of all persons associated with the undertaking of these

activities and such measures as necessary will be taken to bind such persons to the requirements

herein.

A copy of the WMS and all the relevant documents will be available on site at all times.

3.1 Typical construction sequence

A typical construction sequence is summarized below:

Conduct a comprehensive site investigation to build up an informed picture of the task.

Conduct a topographical survey of the area to be crossed and the pipeline routes.

Provide construction drawings for all the stages of construction.

Excavate to the trenches in accordance with the approved pipeline route

Lay the pipes and backfill and compact the trenches in accordance with the engineering

drawings

Clean and rehabilitate the construction area

All Environmental and Health and Safety requirements and good practice to be adhered to.

3.2 Plant and resources required

The plant and resources required for the construction of the watercourse crossings will include, inter alia:

Dozer for clearing of the area affected by the crossing including clearing of vegetation and

stockpiling of topsoil for future top soiling and grassing of new road batters.

Excavators.

Crane of sufficient lifting capacity and reach for pipe laying of precast concrete pipes.

Tipper trucks for the delivery of bedding material and road fill material to be placed over the

pipes.

Small Compaction equipment for pipe bedding and restricted fill around the pipe culvert.

Heavy compaction equipment for compaction of the bulk fill for the road prism.

On-site concrete batching plant for the concrete apron slabs for the pipe culvert.

Concrete delivery vehicles for wet concrete.

Formwork, reinforcing steel and the necessary equipment and tools for assembly.

Equipment for the construction of the brick headwalls as detailed.

Equipment and labour for the positioning and packing of gabion and reno-mattress baskets or

stone pitching, as appropriate and as agreed with the Environmental Consultant, to control and

obviate any erosion.

Light equipment and labour to dress backfill, topsoil and re-vegetate all exposed areas.

Road building equipment for the construction of road layers over the road prism (Fill) once it has

been successfully placed and compacted to a predetermined level above the overt of the pipe

culvert.

Equipment for this final operation will include tippers, graders, rollers as well as necessary

equipment for kerb laying and ultimately prime applicators and premix pavement laying

equipment.


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3.3 Construction method for pipes laid in trenches

This method will be used where pipes are conventionally laid in trenches and backfilled to natural ground

level.

Remove topsoil and stockpile for later use.

Excavate trench for pipeline to the design level.

If the material is firm, normal excavation techniques will apply. In soft material shoring of the trench

sides may be required. In hard rock material trench excavation may require the use of pneumatic

breakers or blasting.

Install temporary dewatering pumps to keep the excavation dry (if required due to groundwater

ingress).

Construct storm water diversion berms where required.

Place concrete encasement if required. The top level will be determined by the storm water

channel level.

Place bedding, lay pipe, place and compact selected fill over the pipeline.

Construct manholes, where required. Manholes will be constructed along the pipeline route at

changes in grade and direction.

Backfill to specification.

Dress backfill, topsoil and re-vegetate all exposed areas.

Table 2: Schedule of Drawings (Refer Appendix A)

Description Plan Number Date

Umfolozi Bridge crossing ME-ZAC-010 April 2019

Mngeni River Bridge Crossing ME-ZAC-011 April 2019

Crossing over Culvert Bridge No1 ME-ZAC-011 April 2019



Environmental Management Strategy

3.3 Environmental Impact Management

Changes and impacts to hydrology at landscape level; alteration of stream flow; increased erosion and

deterioration of water quality (turbidity) are addressed in the design of the road and watercourse crossings

(refer to design drawings set out in Table 3) by the incorporation of sound environmental design principles

as set out in the Brief Report. Integrated Water Licence Application for the proposed Mngeni Shaft Project.

Nevertheless, certain activities and aspects associated with the actual construction of the road according

to these designs may still cause impacts as a result of how these activities are undertaken, where, when

and the duration thereof. These include:

Clearing of the road footprint (including extending activities beyond the maximum impact foot print)

Establishment and management of the construction camp/s

Management of construction materials (movement, storage, preparation/handling)

Management of machinery (movement, storage, maintenance)

Management of sanitation and waste (movement, storage)

Management of storm water

Management of sediment (structures and containment)

Rehabilitation


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Possible impacts associated with these activities are listed in Table 5 below along with environmental

significance ratings pre and post mitigation (i.e. indicating effectiveness of the mitigation measures set out

in Table 6).

Table 3: Impacts and Significance Ratings

Impact Environmental Significance

Before Mitigation After Mitigation

Alteration of flow regimes, including but not limited to:

Concentrated flows Moderate Low

Temporary river diversions Moderate Low

Deterioration of water quality (mainly turbidity), including but not limited to:

Sedimentation High Moderate

Accidental spills (hydrocarbons, other hazardous

chemicals) Low Low

Contamination via stormwater runoff Moderate Low

Disturbance of riparian an instream habitat (i.e. changes to the physical structure of the watercourses as well as

vegetation), including but not limited to:

~ Erosion Moderate Low

~ Soil compaction Moderate Low

~ Damage to vegetation Moderate Moderate

~ Alien species establishment Moderate Low

The measures to manage the above impacts as derived from the documents set out in Table 4 are

presented in Table 6.


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Table 4: Mitigation Measures

Impact Measures (What and Where) When, Duration Responsibility Uncertainties

General (relevant to all impacts) Environmental awareness training must

be provided for all contractors and

workers, appropriate to the activity and

addressing the mitigation measures

contained in the documents listed in

Table 4 as well as in this work method

statement

Before construction

commences ECO None

A maximum impact footprint (15m width

along the routing of the road) must be

appropriately delineated and sign

posted

Before construction

commences Contractor None

Sensitive areas not within the impact

footprint must be clearly demarcated

and sign posted “No Go”

Before construction

commences

Contractor

ECO

Wetland Specialist

None

Construction activities shall begin

upstream and proceed downstream

Ongoing (duration of

construction phase) Contractor None

Construction camps shall be located

outside the extent of any watercourse

and must be recovered and removed

shortly after construction has been

completed

Ongoing

(Removal within 3

weeks of completion of

construction)

Contractor None

Machinery and equipment must be kept

in good working order



Alteration of flow regimes

Concentrated flows

Temporary river diversions

Downstream flows must be maintained

during construction of crossings



Temporary instream diversions must allow

for adequate flow and a dry works area

must be maintained – diversions must be

located within the active channel and

may not breach the historical terraces

Duration of crossing

construction

Contractor None

Deterioration of water quality (mainly

turbidity), including but not limited to:

Sedimentation

Accidental spills (hydrocarbons,

other hazardous chemicals)

Contamination via stormwater

runoff

Standard best environmental practice

housekeeping rules must be applied with

regards to refuse management,

ablutions, fire prevention etc.)


construction and

Operational phase)

ECO

Contractor

None

Storage, washing and maintenance of

equipment and machinery must be

undertaken outside the extent of any

watercourse and only in demarcated

areas where runoff and spills are

managed in an environmental sound

manner


construction phase)

Contractor None


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Sanitation and waste management

facilities must be located outside of the

extent of a watercourse and must be

managed in an environmental sound

manner


construction phase)

Contractor None

Materials must be stored outside the

extent of any watercourse, and

transported and prepared/handled in an

environmentally sound manner, in

compliance with relevant legislation -

discharges into watercourses must be

prevented as far as reasonably possible

and stockpiles must be protected from

erosion


construction phase)

Contractor None

An emergency plan (i.e. measures for

prevention, detection, management and

reporting) must be prepared for dealing

with accidental spills and leaks in

compliance with relevant legislation and

regulations


construction phase)

ECO

Environmental

Superintendent

None

Sediment traps and fencing must be

utilised to prevent excess levels of

sediments entering watercourses from

work areas and afterwards disposed of in

a lawful manner


construction phase)

Contractor None

Berms or porous structures?

Contamination of stormwater runoff must

be prevented


construction phase)

Contractor None

Stormwater must be diverted into

vegetated buffer zones and not directly

into surface water – concentrated flows

must be prevented and velocities may

not exceed 0.5m/s


construction phase)

Contractor None

Trench breakers?

Disturbance of riparian an instream

habitat (i.e. changes to the physical

structure of the watercourses as well as

vegetation), including but not limited to:

~ Erosion ~ Soil compaction ~ Damage to vegetation ~ Alien species establishment

Vegetation must not be cleared beyond

the impact footprint (it is recognised that

loss of habitat within this footprint is

inevitable)


construction phase)

Contractor None

The breeding, nesting and feeding

habitats and natural movement patterns

of aquatic biota within and along the

impact foot print of the road must be

identified and demarcated and all

reasonable measures must be taken not

to disturb these

Before construction

commences


construction phase)

Contractor

ECO

Wetland Specialist

None


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Equipment and machinery must only be

operated within the delineated impact

footprint


construction phase)

Contractor None

Mechanical vibrations must be minimised

in the vicinity of stream banks


construction phase)

Contractor None

Dust must be suppressed in the vicinity of

sensitive areas


construction phase)

Contractor None

Slope and bank stabilisation measures

must be implemented where appropriate


construction phase)

Contractor None

Rehabilitation of work areas must

commence immediately after

construction is completed of designated

work packages (i.e. crossings, refer Table

2) – refer CEMP, P10)

Refer construction

programme

Contractor None

Gravel removed during construction must

be replaced with similar consistency and

diameter after construction is completed

of designated work packages

Refer construction

programme

Contractor None

Soils that become compacted must be

loosened to an appropriate depth to

allow for seed germination once

construction activities are completed (i.e.

crossings, refer Table 2)

Refer construction

programme

Contractor None

Disturbed areas must be re-vegetated

with only indigenous vegetation

Refer construction

programme

Contractor None

Alien vegetation recruitment must be

eradicated and controlled using

standard methods approved by DWA

Ongoing (lifetime of

road)

Contractor None

3.4 Monitoring and Review Strategy

Monitoring and reporting will be undertaken as set out in the reports listed in Table 4. Specific provisions are set out in Table 5 below. Steps for non-

compliance with this method statement is set out on P29-30 of the CEMP.

Table 5: Monitoring and Review Measures

What Where When Responsibility Reporting Requirements

Benthic diatoms Crossings with flowing water During the wet and dry season Aquatic Specialist National Water Act

Invertebrates Crossings with flowing water During the wet and dry season Aquatic Specialist National Water Act

Fish Crossings with flowing water During the wet and dry season Aquatic Specialist National Water Act

Alien Vegetation All sites Quarterly in a year ECO National Water Act/NEMA

Turbidity Crossings with flowing water;

10m downstream

1st measurement, before

construction commences, 2nd

not later than 3hrs after

ECO

National Water Act


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What Where When Responsibility Reporting Requirements

activities commenced

Habitat All sites Prior to and post construction ECO NEMA Closure cost assessment

Wetland crossings Prior to and post construction Wetland specialist Refer WUL, P7 and 8

Emergency and pollution

incidents1

All sites At all times Contractor

ECO

Section 19 and 20 of the

National Water Act


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4 Responsibilities and Prescribed Occupations

Occupation Role/Responsibility

Project Engineer (PE) Ensure that the proposed design of the structures takes into

consideration the location and existing environmental conditions at

the site.

Ensure that all facets of environmental protection are properly

addressed during the design.

Project Manager (PM) Appoint appropriately qualified contractors to co-ordinate, supervise and

expedite different tasks.

[Note: Appointment of contractors will be subject to scrutiny and final approval

of the Project Engineer as will numerous other facets of the work undertaken on

site i.e. the PM will not act alone or independently of the Project Engineer in this

regard.]

Ensure adherence to any laws and standards relevant to the

construction of the facility.

Ensure all facets of the work undertaken are properly and competently

directed, guided and executed.

Ensure adherence to statutory safety, health and environment (SHE)

standards and ensuring the construction activities comply with the

EMP.

Overall responsibility and accountability for the site during the

construction phase.

Construction of the facility to contractual specifications.

Contractors and Sub-

Contractors

Manage and operate their activities with due care and diligence.

Comply with the requirements of the EMP.

Avoid and/or limit any adverse impacts they may have on the

environment by the proper design and construction of the proposed

development.

Report back to the PM on issues / non-conformances.

Control predicted impacts that may occur so as to meet acceptable

standards, both as a legal and a moral responsibility to the

environment within which they operate.

Ensure transparency in their operation and environmental

management of the site.

Ensure that all facets of the work undertaken are properly and

competently directed, guided and executed during construction.

Ensure construction of the facility is to contractual specifications.

Ensure adherence to laws and standards relevant to the construction

of the facility.

Ensure adherence to statutory SHE standards during construction and

ensuring the construction activities comply with the EMP. Any new or

amendments to existing mitigation measures to address areas of

concern notified by the EM are to be acted on as necessary by the

contractor.

Environmental

Manager (EM)

Determination of the conformance of the site with the EMP criteria and

compliance with the DAEA conditions of authorization.

Liaison person with the DAEA, ECA and IAPs, if required.

Identification of possible areas of improvement.

Assessment of the suitability or effectiveness of the EMP.

Undertake ongoing monitoring of the site through regular site visits and

record key findings. This includes photographic monitoring.

Monitor implementation of the EMP by the contractor/s.

Advise the PM on actions or issues impacting on the environment and

provide appropriate recommendations to address and rectify these


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matters.

Ensure that the contractor/s has a copy of the EMP and all agreed

Method Statements.

Ensure that the conditions stipulated in the DAEA conditions of

authorization and any other laws and standards relevant to the project

are being complied with.

Update and revise the EMP as necessary in liaison with IAPs and other

affected parties and authorities as required.

The EM shall advise the PM to suspend part or all of the works if the

contractor and/or any sub-Contractor, suppliers, etc. fail to comply

with both the EMP and establishment procedures supplied (which are

to be agreed upon between the contractor and PM prior to

construction).

Environmental

Compliance Auditor

(ECA)

A suitably qualified and experienced independent environmental

consultant/auditor to undertake audits of construction activities to

ensure compliance with this EMP, the environmental authorization and

any other relevant legislation.

Submission of audit reports to the DEAT and DAEA.

Advise the EM, PM and/or ZAC on actions or issues impacting on the

environment and provide appropriate recommendations to address

and rectify these matters.

Assess suitability of the EMP’s effectiveness and identify possible areas

of improvement.

Health and Safety

Officer (HSO)

Provide support to the EM in monitoring the execution of the EMP by

maintaining a presence on the site.

Undertake routine site inspections and provide information to EM.

Monitoring activities as specified by the EM.

Maintain incident register and report back at monthly meetings.


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5 Declarations

5.1 Design Engineer

The work described in this Work Method Statement, if carried out according to the methodology described,

is satisfactorily mitigated to prevent avoidable environmental harm.

Signed Print Name

Date

5.2 Site Manager

I understand the contents of the Work Method Statement and the scope of works required from me.

Signed Print Name

Date

5.3 Environmental Control Officer

The works described in this Work Method Statement are approved.

Signed Print Name

Date


Appendices

APPENDIX A: CONSTRUCTION DRAWINGS

APPENDIX B: WATER USE LICENCE

APPENDIX C: BRIEF REPORT. INTEGRATED WATER LICENCE APPLICATION FOR THE MNGENI ADIT PROJECT

APPENDIX D: ENVIRONMENTAL MANAGEMENT PLAN FOR THE MNGENI ADIT PROJECT

APPENDIX E: SPECIALIST STUDY. IMPACTS OF STREAM CROSSINGS ON AQUATIC ECOSYSTEMS AND

AQUATIC MONITORING PLAN

APPENDIX F: PROJECT [ADD]. DRAFT CONSTRUCTION ENVIRONMENTAL MANAGEMENT PLAN

Appendix 20.pdf (p.1)Work Method Statement GB.pdf (p.2-19)

GCS - APPENDIX 20 · 2019. 7. 15. · Construction Work Method Statement: Watercourse Crossings 7 |...

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