takoradi cooling report

8/12/2019 Takoradi Cooling Report

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TAKORADI INTERNATIONAL COMPANY

Project Asona

Once Through Cooling System to Serve T1 and T2

Environmental Impact Statement

October 2010


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Document Contro l Sheet

Client: TICOProject: Asona Once Through Cooling System Job No: B152870Title: Environmental Impact Statement Ref

Originator Checked by Reviewed by Approved byNAME NAME NAME NAME Version 1

DRAFT FORCLIENTCOMMENT

Rob Broml ey Karen Anderson Steve Mills Steve Clamp

DATE SIGNATURE SIGNATURE SIGNATURE SIGNATURE

15th Sept 2010

Document Status: Draft for Client review

Originator Checked by Reviewed by Approved byNAME NAME NAME NAME Version 2Rob Broml ey Steve Clamp Steve Clamp Steve Clamp


October 2010

Document Status: Showing amendments post discuss ions wit h the Client

Originator Checked by Reviewed by Approved byNAME NAME NAME NAME Version 3Rob Broml ey Phil Simmons Steve Clamp Steve Clamp


October 2010

Document Status: Showing amendments post discuss ions wit h the Client

REVISION STATUS

REV. Date Revision Details Prepared Checked Authorised

Copyright Jacobs Engineering U.K. Limited. All rights reserved.


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No part of this report may be copied or reproduced by any means without prior written permission from Jacobs EngineeringU.K. Limited. If you have received this report in error, please destroy all copies in your possession or control and notifyJacobs Engineering U.K. Limited.

This report has been prepared for the exclusive use of the commissioning party and unless otherwise agreed in writing byJacobs Engineering U.K. Limited, no other party may use, make use of or rely on the contents of this report. No liability isaccepted by Jacobs Engineering U.K. Limited for any use of this report, other than for the purposes for which it wasoriginally prepared and provided.

Opinions and information provided in the report are on the basis of Jacobs Engineering U.K. Limited using due skill, careand diligence in the preparation of the same and no explicit warranty is provided as to their accuracy.

It should be noted and it is expressly stated that no independent verification of any of the documents or information suppliedto Jacobs Engineering U.K. Limited has been made.


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CONTENTS

Non-Technical Summary 1

1 Introduction 6 1.1 Overview 6

1.2 Background 6

1.3 Objectives of the EIA 6

1.4 Legislative Framework and Agreements 7

1.5 Environmental Policy of TICO 9

1.6 International Environmental Requirements for Funding 10

1.7 Consultation 11

2 The Scheme 12

2.1 Description of Scheme 12

2.2 Alternatives 19

3 Baseline Environmental Conditions 21

3.1 The Natural Environment 21

3.2

Marine Ecology 22

3.3 Terrestrial Ecology 29

3.4 Landscape and Visual 30

3.5 Airborne Noise 30

3.6 Social 31

4 Impact Assessment 31

4.1 Construction Phase Impacts 31

4.2 Operational Phase Impacts of Abstraction and Discharge 36

4.3 Impacts on the Performance of Units T1 and T2 48

4.4 Cumulative Impacts 49

5 Mitigation and Residual Impacts 50

5.1 Construction Mitigation 50

5.2 Operational Mitigation 52


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6 Monitoring Plans 53

6.1 Water Quality 53

6.2 Fisheries 54

7 Impact Assessment Summary 55

8 References 59

Appendix A - Let ter from GEPA

Appendix B - Derivat ion of CO 2 Levels


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Non-Technical Summary

Introduction

Takoradi Thermal Power Plant (TTPP) is located on the southwest coast of Ghanaapproximately 15 km north west of the towns of Sekondi and Takoradi. The nearestsettlement, located 1-2 km east is Aboadze. TTPP was originally conceived as two330 MWe combined-cycle combustion turbine units. This Environmental ImpactStatement (EIS) relates to a proposed change in the type of cooling system for the twoUnits.

There are three principal types of cooling water (CW) systems which are used onthermal power plants, as follows:

air cooling, in which the plant is cooled directly by the air around it;

cooling towers, in which the plant is cooled by water, which is thentransferred to cooling towers where its temperature is reduced. Thewater is re-circulated from the towers back to the plant. Some of the CWis lost as vapour from the towers and is replaced; and,

once-through cooling, in which the plant is cooled by water which isdrawn from a large water body and then returned warm to the waterbody where the heat is dissipated.

The first unit at Takoradi (T1) has been in full, 330 MWe, combined-cycle operationsince April 1999 with two combustion turbines. The T1 steam turbine uses a coolingtower fed with seawater to cool the steam turbine condenser cooling.

The T2 unit is currently a 220 MW plant, consisting of two combustion turbinesexhausting directly to atmosphere. The existing T2 Unit is to be expanded to its finalcapacity of 330 MWe, by the addition of a steam turbine to convert it to combined-cycleoperation. It is proposed that the expanded T2 plant will be cooled by a new once-through CW system from the sea. The once-through cooling system is also proposed toreplace the existing seawater fed cooling tower system of steam turbine generator unitat T1. Once-through cooling systems are common at power plants globally, includingfor plants with far greater heat rejection and in locations where seawater mixingconditions are less favourable. Seawater cooling systems are now best practice inEurope.

In accordance with Ghanaian environmental legislation an environmental impactassessment is required to be carried out for this proposed change to once-through

cooling for T1 and T2. It should be noted that the above mentioned expansion of thepower plant of Unit T2 to its final capacity is proposed to be implemented in parallel tothe change in CW system. The environmental impact of Unit T2 to its final capacity hasbeen previously assessed, but this was a number of years ago and an environmentalupdate of the proposed T2 expansion will be prepared, and presented as a separatedocument (Jacobs, 2010).

A number of international agreements and treaties, in addition to World Bankrequirements and Ghanaian legislation have been considered in this assessment of theproposed new CW system.


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Proposed Scheme

The key components of the proposed CW system are: sub-sea intake structure and conduits;

onshore pump house, intake, outfall conduits (including the intake anddischarge chambers); and,

sub-sea outfall conduits and diffuser structures.

The sub-sea route corridors for the intake and outfall conduits are proposed to belocated close to the existing seawater intake and outfall pipes which serve theseawater cooling tower supply to T1. The location is between the existing sub-seaWest African Gas Pipeline (WAGP) in the west and an existing sub-sea oil pipeline forthe use of TTPP, which extends out to a mooring buoy, in the east.

The intake and outfall conduits are likely to be constructed by sinking precast concrete

units or high density polyethylene (HDPE) pipes into a shallow trench dredged on theseabed. Where the conduits come ashore they will be buried in a trench leading to theCW pump house. It is likely that coffer damming will be required for pipeline installationat the beach location. The scheme includes two intake and two outfall conduits, andprovides semi-independent cooling systems for Units T1 and T2.

To limit the environmental impacts of the CW system a low velocity side entry (LVSE)intake structure will be installed whereby water is abstracted 90 degrees to the current.The intake will be located in a water depth of around 13 m, approximately 2 kmoffshore. The LVSE intake structure is likely to be constructed on-land, floated out andsunk into position. The intake velocity at the entry screen will be restricted to < 0.3 ms -1 thus allowing any adult and juvenile fish to swim against the current and removethemselves from the influence of the intake current. A number of coarse screens

(100 mm spacing) located at the intake entrance will prevent the entry of large debris,and any mammals and reptiles.

Discharge will be via a number of diffusers to facilitate mixing of the water. These willbe installed on each outfall conduit and will take account of the need to achieve goodinitial dilution, the prevention of possible wave slam forces, and the prevention ofdamage from any fishing and shipping activities. It is expected that the dischargeconduits will run approximately 1.2 km offshore and discharge in a minimum waterdepth of around 8.5 m. The temperature of the discharged water at the edge of themixing zone will be < 3 oC.

The CW system will include an electro-chlorination system which is required to limitbiofouling. The electro chlorination system will automatically chlorinate at the pre-setintervals.

A pump house will be located adjacent to the southern boundary of the TTPP (Plate 2-1) and will house a number of seawater pumps supplying T1 and T2. Drum screens willscreen debris entering the condenser. Debris is impinged, lifted out of the water andsprayed into collection baskets.


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Potential Environmental Impacts of Once-Through Cooling

The main issues concerning construction and operation of the proposed system areaddressed below considering both positive and negative impacts.. This assessmentaddresses the impacts of changing from the current, seawater tower system of cooling,to a once-through system for both Units in combined-cycle operation.

Construct ion Phase Impacts Summary

It is expected that a large number of marine mammals and reptiles frequent the watersof Takoradi for transiting or foraging especially in the vicinity of the Sherbro and RoaniBanks which have a diverse range of flora and fauna. It is anticipated that any marinemammals or reptiles that may happen to be present in the vicinity of works would moveaway during operations if disturbed. It would be expected that mammals and reptileswould return following completion of the works. However, a potential significant impactmay exist on species within close proximity of the works and therefore mitigationmeasures are proposed.

Only fish located in the vicinity of piling activities during construction are predicted to be

at risk of injury. Fish, by their nature are highly mobile and therefore able to move outof areas where acoustic disturbance is occurring, limiting the likelihood of physicalinjury. Therefore, only minor impacts are predicted on fish species in the immediatevicinity of piling activities and no significant impacts further afield.

Delivery of general construction material, including materials required for concrete, willput considerable pressure on the existing road network around TTPP. Despite the factthat the access roads around the TTPP site are in good condition, there will be someunavoidable disruption to traffic flow and increased risk of vehicle accidents and injuryto pedestrians.

If HDPE pipes were to be used, their delivery would not affect local road links. This isbecause these pipes are extruded at their manufacturing plant in Norway. They are

then floated in lengths up to 500 m, and towed to site from Norway. They would remainfloating offshore until installation.

It is understood that the intake structure would be constructed on land before beingfloated out and sunk into position. Local road traffic disruption could therefore occurwhen the structure is moved from the fabrication area to the shore.

Takoradi International Company (TICO) and Volta Rivers Authority (VRA), therespective operators of T1 and T2, have considerable experience in managingconstruction related impacts on the local population, having been involved in the TTPPdevelopment for over 10 years.

There are expected to be no significant effects on local community infrastructure as a

result of the CW system construction. The construction of the CW system is expectedto have a moderate beneficial impact with regard to employment opportunities due tothe worker requirements for the site preparation and construction stages.

Operational Phase Impacts Summary

The operation of T1 and T2 with a once-through seawater CW system fully meets therequirements of current World Bank guidelines and Equator Principles, and results in


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considerable benefits compared to the use of seawater cooling tower systems at T1and T2. This includes:

Increase in outputs of the existing T1 and proposed T2 steam turbines.Better cooling leads to better steam turbine performance thus providingadditional energy to Ghana.

Further increased energy output of existing T1 and T2 combustionturbines and also reduced fuel use, both because of reduced corrosionand fouling of combustion turbine compressors, thus providing furtheradditional energy to Ghana. This results from the elimination ofseawater cooling towers, which are causing extreme corrosive saline airconditions.

Reduction in CO 2 emissions as a result of displacement of other thermalgeneration by the extra energy resulting from direct cooling for T1 andT2 whilst maintaining the same or less fuel usage.

Reduced maintenance costs of all civil and mechanical steel

components at TTPP, resulting from the elimination of seawater coolingtowers, which are causing corrosive saline air conditions. The drift forthe sea water cooling towers is causing saline air conditions resulting insevere damage.

Noise reduction due to the removal from service of the cooling towerfans, and that the proposed new pumphouse will play a beneficial role inscreening TTPP noise at the southern acquisition boundary.

Socioeconomic benefits. As a result of construction a number of short-term employment opportunities for local skilled labour will arise.

The once-through CW system will abstract and discharge up to a maximum of 16 m 3s -1

of seawater from structures located approximately 2 km from the shoreline. Thelocation has been selected for environmental reasons and the design of the structuresis based on compliance with recognised international standards. The impact of the sub-sea intake and outfall structures during operation has been assessed as follows:

Abstraction of water. Abstraction will result in the entrapment of marineorganisms, mainly flora, mobile invertebrates and juvenile fish. Designmitigation measures will include a low velocity side entry intake systemwhereby low velocities will mean the majority of mobile fauna canescape the intake. Coarse meshed screens at the intake entrance willalso stop any marine mammals or reptiles entering the intake. Finemeshed screens located in the pumphouse will screen out any debris, ormarine organisms, greater than about 10 mm. The impacts after thesemitigation measures have been put in place have been assessed asminor.

Discharge of water. The discharge will be a maximum of 9.5 oC warmerthan the surface temperature at the discharge point. In normal operationthe discharge will be 7.5 oC above the ambient sea surface temperature.

Apart from heating the water and intermittent chlorination the quality ofthe discharge water will be unchanged from the source water. Thedischarge diffuser system installed as a mitigation measure to aid mixing


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will result in a T of 0.5 C at 100 m and impacts from the dischargehave been assessed as minor.

It is anticipated that marine flora and fauna will take advantage of thesub-sea structures. Significant populations will develop on the underseasurfaces as evidenced from previous inspections of the existing sub-seaconduits. This is assessed as a minor benefit

.

Main Findings

The primary impacts of the proposed use of once-through cooling, for units T1 and T2,compared to using cooling tower systems for both units, are assessed to be substantialbenefits during the operational phase, and which are quantified in this report as follows:

A saving of some 110 000 tonnes/year of C0 2 emissions, due toincreased energy production replacing other thermal generation (refer to

Appendix B)

The additional energy output available to the population of Ghana,equivalent to an additional installed capacity of about 20 MWe. Actualper capita electrical energy use of customers is not available, howeveran average use of 500 W/person can be considered as a reasonablesupply. On this basis the additional available capacity would beequivalent to that needed to supply a population of 40 000 people.

No significant adverse environmental impacts from the proposed scheme are predictedwith the identified mitigation measures in place.

Since TTPP was originally conceived, there has been a global shift in recognising, asan environmental priority, the need to improve the efficiency of power generation and toreduce CO 2 emissions. Considering this and the adverse climate conditions in Ghana

for effective tower cooling system operation, it would be difficult to justify continued useof cooling towers at TTPP for units of the size of T1 and T2.


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1 Introduction

1.1 Overview

Jacobs Engineering UK Ltd was commissioned by Takoradi International Company(TICO) to prepare an Environmental Impact Statement (EIS) for a direct seawatercooling system for Takoradi Thermal Power Plant (TTPP). The cooling water (CW)system proposed is of a once-through type and will be used by Unit T1 and theproposed expanded Unit T2.

The requirement to undertake an EIS was driven by TICO Environmental Policy,Ghanaian legislation and the need to be able to satisfy Equator Principle requirementsin terms of environmental assessment for projects being considered for financialassistance from international lending agencies.

1.2 Background

TTPP is located on the southwest coast of Ghana approximately 15 km north west ofthe towns of Sekondi and Takoradi. The nearest settlement, located 1-2 km east is

Aboadze.

TTPP was originally conceived as two 330 MWe (megawatts of electricity) combined-cycle combustion turbine units. Each combined-cycle unit comprises two 110 MWecombustion turbine generator units associated with boilers to recover heat from thecombustion turbine exhausts. The steam is then used to drive a steam turbine whichincreases the generation by around 120 MWe. The net output to the grid of the CCGTunit can vary from approximately 320 MWe (air-cooled condenser) to up to 340 MWe(once-through cooling, low ambient temperature).

The first unit at Takoradi (T1) has been in full combined-cycle operation since April1999 with two combustion turbines. The T1 steam turbine uses a cooling tower fed withseawater to cool the steam turbine condenser CW.

The T2 unit currently consists of two combustion turbines exhausting directly toatmosphere (referred to as open-cycle or simple-cycle). It is proposed to utilise the heatcurrently being discharged to the atmosphere to power a new T2 steam turbinegenerator thus increasing the output of T2 by up to 120 MWe and increasing the cycleefficiency from 31% to around 45% to 48.5%, depending on the steam turbine coolingoption chosen.

This document deals solely with the CW system for T1 and T2 which will serve the

expanded T2, and replace the existing seawater cooling tower system of T1 and the aircooled system at T2. The application for a new consent to convert T2 to a combined-cycle plant by the addition of two heat recovery boilers and a steam turbine will bemade in a separate submission that will take the form of an EIS Update..

1.3 Objectives of the EIA

The objectives of the EIA are to:


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Compile all relevant information relating to the proposed scheme whichincludes providing a description of the baseline data of the surroundingarea to TTPP.

Identify important receptors. Identify potential impacts of the scheme arising from construction and

operation. Determine the level of impacts and identify mitigation measures to

ameliorate any significant adverse impacts.

This EIS has been structured in accordance with Guidelines from the World Bank(2007) (Operational Directive 4.01, 2007) and with reference to International FinanceCorporation (IFC) environmental guidance (IFC, 2008) and the Equator Principles.

Section 1 provides an introduction to the project, consultationundertaken and relevant legislation.

Section 2 provides information about the proposed scheme and itsbenefits. The alternative solutions are also discussed.

Section 3 provides a comprehensive description of the environment tothe southwest of Ghana and in the vicinity of the TTPP.

Section 4 discusses the positive and negative impacts from theproposed scheme during construction and operation. Section 5 details the mitigation measures discussed in Section 4 and

residual impacts. Section 6 proposes a post commissioning monitoring programme.

1.4 Legislative Framework and Agreements

The proposed scheme is required to comply with international, national and regionallegislation. A number of national Acts have been passed in Ghana in addition to thesigning of a number of national and international treaties and conventions which seekto conserve key ecosystems. These include:

Gulf of Guinea Large Marine Ecosystem Project (1999). Memorandum of Understanding Concerning Conservation Measures for

Marine Turtles of the Atlantic Coast of Africa (1999). Convention on Biological Diversity (1994). Convention of Fisheries Cooperation among African States Bordering

the Atlantic Ocean (1991). Convention on Wetlands of International Importance (Ramsar) (1988). Convention on the Conservation of Migratory Species of Wild Animals

(1988). Convention for Cooperation in the Protection and Development of the

Marine and Coastal Environment of West and Central African Region

(Abidjan Convention) (1981, ratified in 1989).The above agreements have been considered in the impact assessment and are citedin the World Banks key international agreements on the environment.

The Ghanaian Environmental Protection Agency (EPA) has as its mandate the EPA Act 1994 (Act 490) to ensure compliance in planning and execution of all developmentactivities. This led to the implementation of the Ghana EIA Procedures in 1995 which,among other objectives, seek to provide an avenue for the involvement of the public,private proponents and agencies in the assessment and review of proposed


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undertakings (Sampong, 2010). This is to ensure that the concerns and needs of theaffected population are considered and addressed. Schedule 2 of the L.I. 1652specifically lists the construction of offshore and onshore pipelines as one of theundertakings for which the EIA process is mandatory (WAGP, 2004).

The legislative functions conferred on EPA by the Act, included the authority to requestfrom categories of undertakings, enterprises, construction or development anenvironmental impact assessment and/or environmental management plan to regulatethe type, quantity, conditions or concentrations of substances that may be released intothe environment.

In order to give effect to provisions of the Act on environmental management theEnvironmental Assessment Regulations 1999 (LI 1652) was enacted in February 1999,consistent with Section 28 of the Act 490.

The LI sets out the requirements for environmental permitting, environmental impactassessment (EIA), the production of preliminary environmental reports (PERs) andsubsequent environmental impact statements (EISs), environmental certificates andenvironmental management plans (EMPs).

The Environmental Management Plan (EMP) procedure is not only a regulatory tool tobe enforced pursuant to Section 24 of LI 1652, but also a compliance promotion tool toensure effective preventive, minimization and mitigation of potential impact of industriesthat existed prior to the coming into force of LI 1652. Construction and operation ofThermal Power Plants is one of the undertakings for which an EMP is required.

Ghana, like many other countries, has endorsed the sustainable concept of economicdevelopment that includes environmental consideration. In 1991, the Governmentadopted the National Environmental Action Plan (NEAP-91), and the NationalEnvironmental Policy, which provided the broad policy framework for theimplementation of the Action Plan. Ghanas Environmental Policy aims at ensuring asound management of resources and the environment in such a manner so as to avoid

over-exploitation and damage to the environment.Two laws relating to fisheries in Ghana concern improving fisheries regulation andmanagement. These are the Fisheries Law (1991) implemented under the FisheriesResource Management and Protection Act and the Fisheries Commission Act (Act 47,1993). The relevance of these laws is relating to the accidental entrapment of marineorganisms during the operational phase of the scheme and potential impacts fromnoise and vibration during the construction phase.

The Beaches Obstructions Ordinance of 1897 prevents the removal of obstructions(including wrecks, rocks and beach material) without special permission. The relevanceof this law is that the scheme will cross the shoreline and potentially the Sherbro Bank.

As a result appropriate permits may need to be obtained.

Maritime Zones (Delimitation) Law (1986) urban panning and development. Thescheme will require permission under this Law.

The EPA has developed sector specific effluent quality guidelines for discharges intonatural water bodies which include values for the thermal power plant sector (GIBBEnvironmental, 1999). The parameters are shown in Table 1-1 and represent maximumpermissible values.


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Table 1-1: Effluent quality guidelines for discharges into natural water bodies (GIBBEnvironm ental 1999)

Parameter Thermal Power Plant SectorpH Between 6 - 9

Biological OxygenDemand (BOD) (mg/l) 50

Total suspended solids(TSS) (mg/l) 50

Temperature increase < 3 C above ambientChemical Oxygen

Demand (COD) (mg/l) 250Turbidity (NTU) 75

Table 1-2 : World Bank/IFC effluent quality guidelines for discharges into natural waterbodies

Parameter mg/l, except pH and temppH 6 9TSS 50Total residual Chlorine(TRO)

0.2

Temp increase by thermaldischarge from coolingsystem

Site specific requirement to beestablished by the EnvironmentalImpact Statement.

Elevated temperature areas dueto discharge of once-throughcooling water (e.g., 1 oC above,2 0C above, 3 oC above ambientwater temp) should be minimisedby adjusting intake and outfalldesign through the projectspecific EIS depending on thesensitive aquatic ecosystemsaround the discharge point.

The cooling system which is the subject of this EIS does not involve any additionsexcept temperature and chlorine for which the relevant guidelines are highlightedabove.

1.5 Environmental Policy of TICO

Takoradi International Company (TICO) is 90% owned by TAQA Energy and istherefore bound by TAQA environmental management systems as well as localmanagement systems.

The management of TAQA, and the Plant Operator TICO, are committed toobservance of policies and responsible operating practices to promote the protection


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and enhancement of the natural and social environments in which the companyoperate. TICO environmental policy is to operate at all times in a manner consistentwith sound environmental practices in order to minimise, to the maximum extentpractical, the impact that the companys operations have on the environment in whichthe company operates.

1.6 International Environmental Requirements fo r Funding

1.6.1 Equator Principles

The Equator Principles were developed by the private sector banks and were launchedin June 2003 for the purpose of determining, assessing, and managing the social andenvironmental risk in project financing. The Principles were modelled on theenvironmental standards of the World Bank and the social policies of the InternationalFinance Corporation.

The principles apply to all new project financings globally with total project capital costsof US$10 million or more. They also apply to all project financings covering expansionor upgrade of an existing facility where changes in scale of scope may createsignificant environmental and/or social impacts, or significantly change the nature ordegree of an existing impact.

1.6.2 International Finance Corporation

IFC require that projects applying for funding should be:

environmentally and socially acceptable in accordance with IFCenvironmental and social policies;

in accordance with the World Bank Groups Pollution Prevention and Abatement Handbook, 1998;

meet provisions set in the World Bank Groups Occupational Health andSafety Guidelines; and

in accordance with the host countrys environmental requirements.

1.6.3 World Bank

World Bank Group Environment, Health, and Safety Guidelines (EHS guidelines) weredeveloped in 2008 and are used by the IFC as a source of technical information duringproject appraisal. Guidance from the IFCs Environmental, Health and SafetyGuidelines for Thermal Power Plants (IFC, 2008) has been used to inform bestpractice.

This EIS has been structured in accordance with Guidelines from the World Bank(2007) (Operational Directive 4.01, 2007).


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1.7 Consultation

An extensive literature review and consultation process was undertaken to generatebaseline data and information to prepare the EIS. Guidance on the EIS was obtainedfrom:

Environmental, Health and Safety Guidelines for Thermal Power Plants,2008. International Finance Corporation, World Bank Group.

World Bank Environmental Assessment Process Operational Policy 4.01(2007).

World Bank Environmental Assessment Process Operational Policy 4.01(2007), Annex A

World Bank Environmental Assessment Process Operational Policy 4.01(2007), Annex B

World Bank Environmental Assessment Process Operational Policy 4.01

(2007), Annex C

Equator Principals (2006)

Ghanaian, Environmental Protection Agency Act 1995.

Key baseline data were obtained from the following sources:

Environmental Impact Assessment, West African Gas Pipeline, 2004. West African Pipeline Company (WAGP).

Acres International Ltd, TTPP Environmental Assessment, Volumes 1 & 2,1995.

GIBB Environmental, Takoradi thermal power plant proposed expansion,Supplementary Environmental Statement, 1999

Jacobs, 2004. T2 Cooling Water Study, Stage 1 Report.

Dr A.K.. Armah, 2010. University of Ghana.

Additional baseline work was undertaken by Jacobs in 2010 to supplement previousdata reported.

Consultation in relation to ecology has been undertaken with various stakeholders. Asummary of key meetings at which the scope of the assessment work was discussed isprovided in Table 1-2.

In August 2010 Jacobs submitted preliminary information to the Ghanaian EPAregarding the proposed CW scheme through an environmental screening report(Jacobs, 2010b). In September 2010 a formal response to this report was receivedfrom the Ghanaian EPA, a copy of which is presented in Appendix 1.


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Table 1-3: Summary of consultation meetings undertaken to discuss the scheme andcollect b aseline data.

Date Attendees Discuss ion

24/06/2010 EPA, Accra Explore permitting approach

Obtain environmental data11/08/2010 EPA Western Regional

Office, Takoradi.Discussions around EPA process andtimescales.

EPA do not hold any further baselinedata other than that collected by TTPPand WAGP.

11/08/2010 Shama Canoe FishingCouncil

Baseline fisheries data were gatheredon fishing methods, species caught,fishing grounds, and seasonalfluctuations in catches.

12/08/2010 Maritime Authority, Accra EIS should be submitted to MA as partof the planning process.

The MA will need to instigate anexclusion zone around the proposedstructures and give permission to workinside the current exclusion zone of theWAGP.

12/08/2010 Dr A. K. Armah, University ofGhana, Accra

Baseline data collected for the WAGPwas disclosed as well as localknowledge of the flora and fauna.

2 The Scheme

2.1 Description of Scheme

The key components of the CW system are: Intake structure and conduits; onshoreintake chamber; pumphouse; condenser; onshore discharge chamber; and, outfallconduits and structure (Figures 2-1 & 2-3). The sub-sea route corridor for the intakeand outfall conduits will be located between the WAGP in the west and the currentintake and outfall conduits for the seawater cooling tower supply to T1. An oil pipeline,extending out to a single point mooring, is located further to the east (Figure 2-4).

It should be noted the installation of the new condenser for T2 falls under a separateEIS, for the T2 Expansion (Jacobs, 2010a).


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Figure 2-1: Schematic illustration of the CW system.

2.1.1 Intake and Outfall Conduits and Structures

The construction of the intake and outfall conduits will be the responsibility of the futureEPC contractor, however the conduits are likely to be constructed either by sinking pre-

cast concrete units or high density polyethylene (HDPE) pipes into a shallow trenchdredged on the seabed. It is not known at this stage where pre-cast concrete unitsmight be constructed: this could be off-site or on-site, however it is understood thatHDPE pipes, if used, would be manufactured in Norway and brought to the site by sea.Where the conduits come ashore they will be buried in trenches extending to the CWpumphouse. It is likely that coffer damming will be undertaken for installation of thesections across the beach.

The scheme includes two intake and two outfall conduits, thus providing a degree ofindependence for T1 and T2. Abstraction will be via a single intake unit at a combinedmaximum rate of 16 m 3s -1; 8 m 3s -1 each. The design of the intake structure will takeaccount of:

the need to prevent debris entering the system by providing a coarseouter bar screen;

the need to limit intake velocity through the bar screen to mitigateorganisms becoming entrapped;

the need to provide an intake sill which is above the sea bed level tominimise the amount of sediment and seaweed drawn into the intake;

the impact of debris such as plastics, nets; possible collision with ship or anchors; possible wave slam forces; and,


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layout of a diffuser for a biocide system

To limit the environmental impacts of the CW system a low velocity side entry (LVSE)intake structure will be installed whereby water is abstracted so that the water flow intothe intake is at 90 degrees to the current. The intake will be located in a water depth ofaround 13 m, approximately 2 km offshore. The LVSE intake structure is likely to beconstructed on-land, floated out and sunk into position. The intake velocity at the entryscreen will be restricted to < 0.3 ms -1 thus allowing adult and juvenile fish to swimagainst the current and remove themselves from the influence of the intake current. Anumber of coarse screens (100 mm spacing) located at the intake entrance will preventthe entry of large debris, mammals and reptiles. Figure 2-2 illustrates the intakestructure.

Figure 2-2: Intake Struct ure

The structure will need to be sufficiently large to permit the low intake velocity required.It will also need to be sufficiently deep that the worst likely wave does not affect theintake. This will also permit a margin to allow small vessels to pass overhead. It isenvisaged that the clearance over the intake structure will be 6.5 m at the Lowest

Astronomical Tide (LAT) which means that the depth will be greater than the shallowsof the adjacent Sherbro bank.

The discharge from the cooling system will be via two discharge pipes, one for T1 andone for T2. Each discharge will be fitted with a number of diffuser nozzles. The outfalldesign will take account of:

the need to achieve good initial dilution; discharge water upwards, thus avoiding contact with the sea bed under

all conditions; prevent possible wave slam forces; and minimise the potential for damage to and from fishing and shipping

activities.

It is expected that the discharge conduits will run approximately 1.2 km offshore, todischarge through a diffuser in a minimum water depth of around 8.5 m. The conduitswill be laid either as precast concrete units, steel or HDPE pipes into a shallow trenchdredged on the seabed as for the intake conduits. It is not anticipated that blasting will


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be required to excavate rock to bury the pipeline. Water will be discharged at amaximum temperature of 9.5 oC above the ambient temperature at the surface at thedischarge point. Figure 2-3 illustrates the discharge structure.

Figure 2-3: Discharge Structure

The CW system will include an electro-chlorination system which will automaticallychlorinate sections of the system at pre-set intervals. The free chlorine at the dischargewill be controllable and set to concentrations that minimise the discharge of freechlorine.

2.1.2 Pumphouse

A pumphouse will be located adjacent to the southern boundary of the TTPP (Plate 2-1) and will consist of a number of seawater pumps supplying T1 and T2. Thepumphouse will contain two forebays supplying T1 and T2. Each forebay will havegratings and drum screens. Each drum screen is made of a horizontal axis drum whoseouter circumference contains a fine mesh. Each screen rotates continuously at its axiswith unscreened seawater being introduced within the drum from each flank andscreened water being withdrawn from behind its outer surface. Impinged debris andfish will be lifted clear of the seawater and wash water sprays will then flush impingedmaterial into a collection gully or basket.

FIRST DIFFUSER ONWESTERN OUTFALL

LAST DIFFUSER ONEASTERN OUTFALL

2 x 2.5m INTAKE

2.5mEASTERN

2.5mWESTERN


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Plate 2-1: Photograph show ing pro posed intake pumping st ation viewed from so uth.

The pumphouse superstructure may entail a building footprint of approximately 41 m by9.2 m and of 9 m height.

2.1.3 Reverse Osmosi s Plant

A Reverse Osmosis (RO) plant is described and assessed within the application for anew consent to convert T2 to a combined-cycle plant (Jacobs, 2010a). T1 and T2 willuse seawater RO to provide desalinated water for use in the preparation of de-ionisedwater for the steam turbine. This water will then be discharged into the CW system. Itshould be noted that a T1 RO plant is already in operation and therefore the onlyaddition is a T2 RO plant.

2.1.4 Redundant Structures

With the implementation of the proposed once-through cooling system, the existingTTPP seawater system will become redundant. The existing system will be kept inplace as a stand-by until such time as the operator (Volta River Authority) is satisfiedthe new installation is functioning satisfactorily. On acceptance, a decision will be takenas to whether the on-shore works (i.e. cooling towers and existing intake building) willbe either demolished or retained. It is understood that the existing off-shore works(intake and outfall system) will be left in-situ.


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Figure 2-3: Proposed layout of the CW conduits and pump house in relation to the existing footprint of TTPP


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Figure 2-4: Existing i nfrastructure in the vicinity of TTPP


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2.1.5 Delivery of Material

The majority of construction material will be delivered to the site by truck. In general, allmajor equipment will be delivered by ship to the Port of Takoradi, offloaded andtransferred to site by road. A batching plant is expected to be set up on site duringconstruction which will reduce the number of lorries using the road network duringconstruction.

2.2 Alternatives

The current T2 open-cycle arrangement with the combustion turbines exhaustingdirectly to the atmosphere has an efficiency of 31%. The proposal is to recover the heatin the exhaust from the combustion turbines and generate steam in heat recoverysteam generators. This steam will then be used to generate more electricity in a steamturbine plant. In order to condense the steam back to water so that it can be pumpedback into the boilers a cooling arrangement is required.

Three basic cooling options exist for power plants:

1) An air-cooled condenser system, which uses electrically driven fans todrive air through a heat exchanger, which is the equivalent of very largecar radiator. The heat from condensation of the steam from the turbineexhaust is passed to the air. A large amount of electricity is used to drivethe fans, and the system has a very high condensation temperature.

2) A cooling tower system, which is the current situation at T1. The coolingtower cools water by breaking it up into small droplets which are cooled bya current of air created by large fans. The water is then returned to thecondenser to cool more steam. A proportion of the water is lost in theprocess and has to be replenished. At T1 seawater is used in this system.The fans use less power than those in the air-cooled system and the

temperature of the returned water is lower than in the case of the aircooled condenser, but around 10 C higher than the direct-cooled option. A great deal of the cooling effect is due to the evaporation of some of thecooling water. Sea water cooling towers are less efficient than fresh waterequivalents and low level cooling towers are less efficient than full sizenatural draught towers. The Takoradi T1 cooling tower represents asignificant efficiency loss.

3) Direct cooling by circulating seawater, the proposed new scheme for bothT1 and the future expanded T2. Cool seawater is continually supplied tothe condenser to cool the steam from the steam turbine and is dischargedwarm back at sea.

A detailed cooling options appraisal was previously undertaken by Jacobs (2004). Thepotential application of three alternative cooling options for TTPP were compared, withthe aim of determining whether it would be desirable for the cooling water approach atTTPP to be revised in future developments. This options appraisal consideredefficiency, economics, environmental, and engineering aspects and concluded that adirect once-through cooling water system would provide considerable benefits and wasthe preferred option.


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In summary an air-cooled system, although probably the cheapest to construct, wouldbe the least thermodynamically efficient option. This is made worse by the highambient temperatures which can occur at Takoradi.

The use of seawater cooling towers (as currently for T1) have a number of issuesincluding:-

Better efficiency than an air cooled condenser but still low Efficiency reduced in high temperature and high humidity. The system requires both large water pumps and large fans on the cooling

tower. Seawater towers are less efficient than their fresh water equivalents The cooling towers cause improved, but still salt spray which is causing

serious damage to the combustion turbines which significantly reduces theirefficiency and increases plant maintenance.

The once-through seawater cooling option provides the greatest efficiency, increasingoutput by around 10 MWe for each combined-cycle unit compared to the seawatercooling tower for the same fuel burned and the same CO 2, NO x and SO 2 emitted. Thisresults from an increased efficiency of steam turbine and the reduction in power

consumption from not using cooling tower fans. The upgraded T2 plant should achieve48% efficiency, compared to 31% presently in open-cycle operation.

To maximise efficiency, once-through cooling systems are common at power plantsglobally, including for plants with far greater heat rejection and in locations, such asriver estuaries, where water mixing conditions are less favourable than they are atTakoradi.


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3 Baseline Environmental Conditions

The following section summarises the environmental baseline conditions within thevicinity of TTPP for which the assessment of impacts will be based. The study areaonly includes the nearshore coastal environment (within 3 km of the shore) and theterrestrial environment that could potentially be impacted by the proposed scheme. Theproposed cooling water (CW) structures run for a distance of approximately 2 km fromthe high water mark out to sea, they cross the beach and run inland to the power plant.The installation will therefore cross the subtidal, intertidal and terrestrial environment.

3.1 The Natural Environment

At Takoradi the continental shelf is at its widest, up to 90 km from the coast. Thesubstrate is estimated to be predominantly sandy-mud, with patches of harder sand.Onshore and nearshore rocky outcrops exist composed of folded rocks,metamorphosed sediments and volcanic rocks associated with granite.

The upper shore at TTPP is dominated by an upper shore sandy belt and a spray zonewith coconut palms and maritime strand association. The maritime strand extends fromthe beach across a sandy road to a concrete drainage canal which borders the TTPP.

Plate 3-1: Left photograph of TTPP and maritime strand association looking north fromthe beach. Right photograph, view of upper sandy shore and beach looking east.

The Pra River estuary is located approximately 6 km east of Aboadze at Shama to theeast of TTPP. The Anankwari lagoon is located 1 km to the west of the Site.

Sea currents in the study area are dominated by the Guinea Current which is a countercurrent to the counter-clockwise circulation of the South Equatorial Current in the South

Atlantic. The prevailing currents are in a west to east direction, with the strongestcurrents occurring between May and July (Gyory et al ., 2005). During February toMarch and October to December currents weaken and a change in the trade windsproduces a reverse in the prevailing currents (Dr A.K. Armah, Pers. Comm, August2010). Merle and Arnault, (1985) also observed a current reversal as the westwardwind stress subsides during certain times in December, February and March. Thepresence of a sandbar at the mouth of the River Pra running to the west also indicates


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a west to east current on some occasions and maybe due to the irregular coastline alocal gyre may exist for a large part of the year (Acres, 1995).

The tidal range along the Ghanaian coast is relatively small; approximately 1 m on adaily basis and up to 2 m annually (Acres, 1995). There is a significant swell, generatedfrom the Southern Atlantic that arrives at the coast which results in several hundredmeters of surf zone.

3.1.1 Water Quality

The coastal waters experience seasonal changes at the surface and are characterisedby warm well-mixed water that extends from the surface to the depth of the thermocline(about 30 m to 40 m) (WAGP, 2004).

Average monthly beach seawater temperatures are shown in Table 3-1.

Table 3-1: Average annual beach seawater t emperature ( oC), Aboadze from monitoring byVolta River Authority, TTPP.

Month 2006 2007 2008January 25.5 26.5 25.4February 26.0 27.0 27.3

March 27.3 27.8 26.3 April 28.6 27.5 27.3May 27.5 27.5 27.6June 27.3 27.5 26.0July 24.4 25.6 24.3

August 24.3 23.8 22.7September 23.9 23.6 22.2

October 26.1 26.3 24.4November 29.2 27.0 29.3

December 27.8 27.3 29.8 Annual Average 26.5 26.4 26.0

Water quality studies undertaken for the WAGP in 2004 found high levels of tracemetals near the storm outfall from TTPP with lower levels at all other sites sampled inthe region. The highest levels recorded were for Aluminium (8.544 ppm), Lead (0.1174ppm), Vanadium (0.525 ppm), Iron (0.6194 ppm), and Magnesium (120.9 ppm).

Nutrient levels which govern productivity did not show any variation within the region(WAGP, 2004).

The BOD, COD and TOC levels ranged from 2.04 to 5.36 mg l -1, 56 to 160 mg l -1 and0.03 to 0.18 mg l -1 respectively in the vicinity of the TTPP.

3.2 Marine Ecology

3.2.1 Fisheries

Fish distributional information in the nearshore environment around TTPP has beendrawn from a number of sources including previous baseline studies for the WAGP(2004), from Acres (1995), and interviews with the Shama Canoe Fishing Council andlocal fisherman (2010).


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Over 100 fish species are known to frequent the Ghanaian waters the most abundantspecies are listed in Table 3-2.

Table 3-2: Key fish species.

Fish Species Common NameCynoglosses spp SolePseudotolithus spp Cassova fishBrachydeuterus auritus BurritoPornadays jubelioi BurroSardinella aurita Round sardinellaSardinella maderensis Flat sardinellaIllisha africana Long-finned herringTrichiurus lepturus Ribbon fishCarcharhiaida spp SharkPeueidae ShrimpManta birostrus Manta raySepia officinalis CuttlefishIstiophorus amaicanus SailfishNeothumus albacares Yellowfin tuna

Auxis thazord Frigate mackeralScomber japonicus Chub mackerelCaranx hippos Horse mackeralEngraulis encrasicolus AnchovyBalistes capriscus Grey triggerfishSelene dorsalis African moonfishPteroscion peli Boe drumSyacium micrurum Channel flounderGrammoplites gruveli Guinea flathead

Bothuspodas africanus African wide-eyesflounder

Trigla Lyra Piper gurnardSphyraena spp BarracudaEpinephelus spp GrouperLutjanus spp Snapper

The local fishery is extremely important to the local economy. Estimates in Acres,(1995) state it contributes 50% of the Districts artisanal catch, which itself contributesup to 5 % of the national catch. Agyepong et al. (1990) estimated that there were5,350 fishermen in the villages of Aboesi, Aboadze and Shama. In Aboadze, fishermenare attracted from throughout the country with the majority of people (up to 75%) in thevillage engaged in fishing, with men catching the fish and women smoking, processingand trading fish (WAGP, 2004).

Interviews with the Shama Canoe Fishing Council indicates that the majority of fishingoccurs offshore (greater than 3 km from the shore). The methods and locations offishing vary seasonally. Between May and September many local fisherman travelwestwards from Shama, transiting offshore past TTPP. The key species fished areSardinella spp. which are caught using fine meshed drift nets. When Sardinella spp are


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not as prevalent, fishermen target a large range of other species (e.g. tuna) and travelwest, east and south from Shama in search of offshore fishing grounds.

No significant fishery resource is known to exist nearshore (within 3 km of the coast)around TTPP. The WAGP which comes ashore several hundred metres to the west ofthe plant has a fishing exclusion zone extending 1 nautical mile (1.8 km) east and westof the pipe which runs offshore some 15 km. Some seasonally dependant fishing doesoccur around Shama Bay; cassava fish, shrimp, ribbonfish and lobster are all caught.

Acres (1995) identified shrimp fishing grounds in waters 20 to 50 m deep(approximately 8 km offshore) south east of Shama Bay. It is likely that shrimp will usethe sheltered bay at Shama as a nursery area.

West of Shama Bay is a length of rocky shoreline where lobsters are common, whichare then sold on to market at Sekondi and Takoradi, or exported. There is no lobsterfishing either bordering the proposed site, or close by in the Anankwari Estuary. Crab,shrimp and shellfish are known to be harvested in coastal lagoons and river mouths,but in the area this is confined to around the Pra River, 7 km from TTPP.

The Sherbro Bank, located about 1.5 - 2 km south of the high water mark near theTTPP (within the nearshore area) is an area of rocks approximately 2 km 2 whichpotentially provides a valuable fish and benthic community. The Roani Bank is of asimilar sized rocky outcrop located 4 km south of TTPP and within the offshore area.These areas are likely to contain a rich diversity of organisms including damsel fish( Abudefdut saxatilis ), surgeonfish ( Ophioblennius atlanticus ), and large parrot fish(Pseudoscarus hoefleri ) (Acres, 1995).

Worthy of note because of the commercial value is the sardinella fishery. The majorpart of this fishery is located offshore (circa 15 km) although sardinella larvae and

juvenile may come inshore to feed (Acres 1995). From July to September the majorupwelling provides the most productive fishing season with the round sardinella(S.aurita ) and flat sardinella ( S.maderensis ) the dominant species.


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Figure 3-3: Map showing key sardinella spawning areas.

Overexploitation during the 1970s is likely to have lead to decline in round sardinellastocks. Additionally, it is thought that demersal species catches are higher than issustainable to maintain stock levels (Mensah and Koranteng, 1988). Increasing fishingactivities combined with industrial and domestic pollution has caused a significantdecrease in fish stocks (Hens and Boon, no date given) whilst excessive fishingpressure has been recorded for bigeye grunt ( B.auritus ) (Bannerman and Cowx, 2002).In Aboesi catches are declining, attributed to the increasing numbers of trawlersoperating in the area. During the off-season fishing effort tends to concentrate on theshallower nearshore areas such as lagoons and estuaries. During this period pressureon spawners and young fish can reach levels that are unsustainable. This is increasingpoverty in the village and surrounding area exacerbated by the increasing cost offishing equipment.

3.2.2 Benthic Habitat

The sandy wave swept coast around TTPP is a hostile marine environment onlycolonised by a limited number of species. During a biotope survey conducted byJacobs in August 2010 only the ghost crab ( Ocypoda cursa) and several species ofpolychaete were observed.

Two areas of intertidal rock are present within the vicinity of TTPP. The first to the westof the site is man-made and provides protection to the WAGP. The second areadirectly in front of the TTPP is approximately 300 m 2 (Plate 3-2). This intertidal area islikely to extend subtidally by several hundred metres and may form the edge of theSherbro Bank which the WAGP crosses. A number of mid and low shore transects


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were surveyed during August 2010. The results show a diverse community of green(e.g. Ulva fasciata, Enteromopha flexuosa ), brown ( Basispora africana ), the encrusting Ralfsia expansa ) and red seaweeds ( Centroceras clavulatum ); snails ( Littorina spp);anenomes; urchins ( Diadema spp); and, limpets ( Siphonaria spp). In the rockpoolscrabs, fish and a sea cucumber were recorded. Surveys for the Acres report (1995)found barnacles ( Chthamalus spp), limpets ( Siphonaria spp, Fissurella spp) and thegastropod ( Nerita atrata ) dominant in the intertidal rocky zone. Algae were lesscommon although the brown algae, Basispora africana , and blue-green algae wereobserved. The algae on the rocky shores are likely to serve as important microhabitatsfor epifauna and fish.

Plate 3-2: Rocky ou tcro p sout h of TTPP

The WAGP (2004) study at sample sites from Takoradi included a total of 26invertebrate species, with abundances highest in the lower intertidal zone includingeight polychaeta species, nine crustacean species and six mollusc species. A higherdiversity of molluscs had been recorded previously, with up to 68 families (Edmunds,1978). It has been suggested that the lower diversity in the upper intertidal zone is dueto fewer niches (Armah and Amlalo, 1998).

There are limited data for meiofauna (e.g. smaller oligochaetes and crustaceans) ormicrofauna (e.g. amoeba, foraminiferans and ciliates) (National Biodiversity Strategyfor Ghana, 2007).

Benthic macrofauna for Ghanaian subtidal habitats have been described by variousauthors most recently by Evans et al (1993). These works describe a benthiccommunity of arthropods, molluscs, polychaetes, bryozoans and echinoderms. Insubtidal rocky area such as the Sherbro Bank, the sea urchin, Echinometra lucunter , iswidespread, whilst Arbacia lixula is present but less common. Brown algae species,Dictyopteris delicatula and Sargassum vulgare are found (Acres, 1995).


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On subtidal sandy substrates diversity is reduced due to scouring but polychaetes(Nerine spp) and crabs ( Ocypoda spp and Donax spp) are common (Acres, 1995).

Polychaetes were found to be the dominant group in the benthic community along theTakoradi subtidal area in the WAGP studies (2004). The most diverse site had over 50species recorded, over 40 of which were polychaetes. This site also had the highestdiversity scores (Margalef and Shannon-Weiner). Sedentary detritivores and filterfeeders dominated the polychaete fauna mostly species from the families; Maldanidae, Spionidae, Orbinidae, Cirratulidae, Lumbrinereidae, Onuphidae, Capitellidae and

Ampharetidae. Predatory polychaetes were mainly from the families; Eunicidae,Nephtyidae and Glyceridae (WAGP, 2004).

It should be noted that despite the high diversity in areas of rocky outcrops, evidence(Armah and Amlalo, 1998) suggests some species are declining along the Ghanaiancoast, such as the gastropod Cymbium sp and the spiny lobster Panulirus sp. Thereason for these declines is unknown but is occurring throughout West Africa and isprobably related to modern fishing activities (i.e. beam trawling) and variableoceanographic conditions (for example concurrent El Nio events). Other speciesappear to have disappeared completely from some localities, including the sea star,

Astropecten sp. which is prone to a wasting disease effecting populations in sub-tropical areas.

3.2.3 Plankton

The diversity and abundance of the planktonic community changes seasonally. Themain driving influence is the oceanographic regime. Offshore the phytoplanktoncommunity maintains a high diversity and low abundance during stratification, duringperiods of upwelling the diversity declines but numbers increase rapidly (Wiafe, 2002).The main seasonal upwelling mixes cold, nutrient rich lower layers with surface layers,enhancing productivity. It is this process that results in populations of phytoplanktonand zooplankton increasing (Minta, 2003). The timing of fish spawning means that fish

larvae and eggs can contribute significantly to this peak (Acres, 1995).During the WAGP surveys (2004) as many as 63 species of zooplankton wererecorded. The phytoplankton community was dominated by the dinoflagellate genus,Chaetoceros spp and also included Dinophysis acuta , known to cause diarrheticshellfish poisoning during blooms. The most common species of zooplankton was thecladoceran, Penilia avirostris (WAGP, 2004).

Dinoflagellates are the main components of the coastal water community during theupwelling, dominating in temperatures below 25 0C. Diatoms proliferate at other times(Anang, 1978).

There appears to be an underlying trend of declining zooplankton abundances along

parts of the Ghanaian coast. There is little evidence to support rising temperaturesalthough the large copepod, Calanoides carinatus , an important species in theplanktonic community, is sensitive to temperature above 23 0C (Wiafe et al , 2008).

It has been observed that Chaetognaths are sparse most of the year, but becomeprolific September to November. Thaliaceans, mainly Thalia democratica , becomeprolific only in December and July, and Appendicularians are often abundant in Juneand October (Thiriot, 1977 cited in WAGP, 2004)).


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3.2.4 Marine Mammals and Reptiles

There are a few records of dolphins and whales spotted along the coastline of Ghana(WAGP, 2004) with the majority of sightings are offshore (>3 km for the coast). Asurvey by Waerbeek and Ofori-Danson (1999) recorded six cetacean species:humpback whale ( Megatera novaeangliae ), sperm whale ( Physeter macrocephalus ),dwarf sperm whale ( Kogia simus ), bottlenose dolphin ( Tursiops truncatus ), clymenedolphin ( Stenella clymene ) and rough-toothed dolphin ( Steno bredanensis ). However, athorough study of by-catch data confirmed there were at least 18 species along thecoast of Ghana (Van Waerebeek et al , 2009).

Table 3-3: Dominant marin e mammals in Ghanaian waters

Mammal Species Common Name

Tursiops truncatus Bottlenosed dolphin

Stenella clymene Clymene dolphin

S. longirostris Spinner dolphin

S.attenuata Pan-tropical spotted dolphin

Steno frontalis Atlantic spotted dolphin Deiphinus capensis Long beaked common dolphin

Lagenodelphis hosei Frasers dolphin

Steno bredanensis Rough toothed dolphin

Grampus griseus Rissos dolphin

Pepononcephala electra Melon-headed whale

Physeter macrocephalus Sperm whale

Ziphius cavirostris Cuviers beaked whale

Megaptera novaeangliae Humpedback whale

Worthy of note because of the vulnerable classification under the International Unionfor Conservation of Nature (IUCN) is the West African manatee. This species mainlyoccurs in large rivers and coastal waters. No species have been recorded from theRiver Par, 6 km from the TTPP; the main populations are located around the VoltaEstuary and Abby Lagoon (over 200 km to the west of the TTPP)

Sea turtles are protected under Memorandum of Understanding ConcerningConservation Measures of Marine Turtles of the Atlantic Coast of Africa, 1999 (WAGP,2004). Along the Ghanaian coastline the main nesting periods are generally from lateJuly through to December, with peaks in November (Armah et al , 1997). Six speciesare known to occur along the Ghanaian coastline; loggerhead, olive ridley, Kempsridley, green, hawksbill and leatherback. There are no known nesting sites aroundTakoradi, the closest being at Princes Town, approximately 30 km west of Takoradi(Irene Heathcote, Pers. Comm., Ghana EPA 2010).

3.2.5 Lagoons

Two open lagoons occur within the vicinity of TTPP; the Anankwari Lagoon,approximately 1 km to the west and the Pra River estuary, approximately 6 km to theeast. Open lagoons are associated with larger river mouths, systems which tend to bemore stable, functionally predictable with higher diversity because of the influence ofthe sea. Due to the continued transport of nutrients from the terrestrial environment,


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estuaries and coastal lagoons are generally highly productive ecosystems. This isreflected by the recognition of the importance of Ghanas open lagoons for migratingseabirds (Ntiamoa-Baidu and Gordon, 1991).

Waders and terns are especially abundant in Ghanaian lagoons, some with numbers ofinternational importance, contributing to >1% of the east Atlantic Flyway population(Ntiamoa-Baidu, 1991). Abundances are especially high between August and March(inclusive), peaking in November and December, although this does vary betweenspecies. Lowest densities tend to occur in May, June and July. A bird survey of fourGhanaian wetlands revealed important migratory and breeding sites with a total countof 51 species. Whilst these were larger Ramsar designated wetlands, it does suggestthat other wetland sites, such as the Anankwari Lagoon and the Pra River estuary, willbe important ecologically (Gbogbo, 2007).

Wetlands are especially important as nutrient rich habitats for fish spawning andnursery grounds (Wuver and Attuquayefio, 2006) and Ghanas coastal wetlands havelong been acknowledged as important habitats for fish spawning and nursery grounds(Ntiamoa-Baidu and Gordon, 1991).

At Aboadze there is a Cyperus articulatus-dominated wetland (Oteng-Yeboah, 1994,cited in WAGP 2004) near to TTPP. During the wet season, the entire wetland areabecomes flooded and joins the nearby Anankwari Lagoon, located to the southwest.This allows for a cross transport of materials bi-directionally between the freshwaterand the sea and contains diverse and varied biota (WAGP, 2004). During flooding thewetland receives effluent from the T1 RO plant and sewage from nearby settlementshowever this does not appear to impact on the ecosystem. Levels of certain metals(e.g. aluminium, lead, vanadium and magnesium) have been noted as being highernear the TTPP discharge point compared to areas further away although again thisdoes not appear to be at a level to impact on the ecology (WAGP, 2004)

Sardinella larvae and juveniles use the estuaries, for example the River Pra, forforaging (Acres, 1995). Four species of mullet have been recorded from a tidal lagoon

to the west of the proposed site (Blay, 1994).

3.3 Terrestrial Ecology

From previous studies, about 20 species of herpetofauna, 50 species of birds, and 19species of mammals were recorded in the vicinity of the thermal plant (WAGP 2004).

Six herpetofaunal species are of international conservation significance, out of whichone species, Kinixys homeana (hinged tortoise) is designated data deficient (DD) onthe IUCN Red List of Endangered Species. The other five species, Chamaeleo gracilis (chameleon), Varanus niloticus (Nile monitor), V. exanthematicus (savanna monitor),Python regius (royal python), and P. sebae (African python) are listed in Appendix II by

CITES. These five species were all in the Aboadze/Takoradi area during the WAGPsurveys in 2004.

None of the 50 bird species known to occur in the Aboadze area are of internationalconservation significance, but 14 species are of national conservation significance (fourare listed on Schedule I, and 10 on Schedule II). Out of the four Schedule I species,Milvus migrans (black kite) and Neophron monachus (hooded vulture), were recordedin the survey, while two out of the 10 Schedule II species, Lonchura cucullata (bronzemanikin) and Ploceus cucullatus (village weaver) were also recorded (WAGP, 2004).


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Six of the 19 mammal species are of international conservation significance. Three ofthese, Crocidura oliveri (white-toothed shrew), Cephalophus maxwelli (Maxwell'sduiker), and Neotragus pygmaeus (royal antelope), are categorised on the IUCN RedList of Endangered Species (WAGP, 2004).

Generally, by the nature of the vegetation, the more coastal areas tend to have lowerspecies diversity and abundance than areas further inland, where biodiversity may beenhanced by the presence of rare or endemic species, which are more vulnerable toenvironmental change. Habitat disturbance in coastal areas therefore poses relativelyless danger to biodiversity than disturbance in the more inland areas (WAGP, 2004).

3.4 Landscape and Visual

This section describes the existing landscape and visual character of the TTPP siteand study area, taking into account the changes that have already occurred as a resultof T1 construction and the ongoing development of T2.

3.4.1 Landscape Character

The TTPP site lies on relatively flat land that from sea level rises to 50 m at a distanceof 4 km inland. The landscape character of the area has been disturbed by previousdevelopment at the TTPP. The site itself was originally regraded and levelled for theconstruction of T1 in the late 1990s, and ongoing development of T2. The surroundingstudy area is predominantly open with scattered trees.

Landscape planting associated with the construction of T1 and T2 has already beenimplemented. This included replacement planting of palm trees along the beach sectionthat was previously cleared during the construction of the LCO (light cycle oil) supplypipeline and the seawater intake/discharge pipelines. These measures have served tosignificantly reduce the original impacts of TTPP on the landscape, but TTPP still formsa distinctive feature within the surrounding, more natural, landscape.

3.4.2 Visual Aspects

Given the largely flat topography of the general surrounding area, the overall aestheticquality, and that T1 and T2 currently comprises numerous large scale buildings andhigh features, (in particular, the 40 m stacks and the transmission pylons and lines) theexisting visual impact of TTPP can be described as adverse.

3.5 Airborne Noise

The existing noise levels relate to T1 in full operation in combined-cycle and T2

operating in open-cycle mode. The southern boundary noise levels are within theapplicable 70 dB limit which is applicable considering that this boundary is not adjacentto residential areas. Following expansion of T2 to combined-cycle operation thebaseline noise levels at the boundary could increase if T2 were to have cooling towers(rather than once-through cooling as proposed), due to the noise generated by thecooling tower fans and by the spray of water in the cooling tower. Noise levels areaddressed in more detail in the Environmental Update for the T2 Expansion Project.


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3.6 Social

TTPP lies within the Shama Ahanta East District. The nearest settlement is Aboadze,1.5 km immediately to the east of the site. A further 1.5 km east is Aboesi. Most of thelocal population lives in scattered village communities or single family units. Within thecommunities of Aboadze and Aboesi it is estimated that 75% of the male workforce arefishermen. These settlements are nationally important fisheries relying on a 23 monthupwelling period, with operations reduced to subsistence levels outside this period.

4 Impact Assessment

4.1 Construct ion Phase Impacts

The construction activities that will be discussed in this section relate to those whichpose a threat to the marine and terrestrial environment. Construction activities at thesite posing a potential threat to the environment will be localised and are associatedwith construction of the intake structures, pumping station and laying the CW conduits.

Prior to any construction works, method statements should be produced detailing fullconstruction methodologies and construction activities and a ConstructionEnvironmental Management Plan (CEMP) should be produced and adhered to in orderto minimise and mitigate the impact of the construction activities where possible.

An environmental and engineering options appraisal was carried out for the CW intakesystem which highlighted potential design and location options (Jacobs, 2004). Thepreferred option is to construct a low velocity side entry (LVSE) intake (Figure 2-2)where water is abstracted 90 o degrees to the current. The intake will be located in awater depth of around 13 m avoiding the Sherbro Bank where possible. At this time ithas not been determined where the LVSE intake structure will be constructed, howeverit is thought likely that it will be constructed on-land, floated out and sunk into position.Two separate intake pipes will lead from the intake structure and run parallel ashorebefore reaching the onshore intake chamber of the seawater pump house for T1 andT2.

Two discharge pipes, one from T1 and one from T2, will follow the same route as theintake pipes and discharge CW via diffusers approximately 1.2 km offshore, in waterdepth of approximately 8.5 m.

The laying of the intake and outfall conduits and structures will involve dredging,onshore and nearshore trenching, nearshore piling and possibly onshore sheet piling.

Although rock is visible in the surf zone underwater blasting is not anticipated at this

stage.

4.1.1 Noise and Vibration

Activities involved in the construction of the CW system will produce noise abovebackground which may impact marine (i.e. fish and marine mammals and reptiles) andterrestrial species (i.e. birds, mammals and reptiles). Anthropogenic noise is a genericterm that refers to any man-made sound or vibration which intrudes into the naturalenvironment and which can mask a biologically useful sound (a signal) or cause other


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harm. Noise can be sensed in the form of sound (measured as changes in pressure) orvibration (measured e.g. as changes in particle velocity). Any object vibrating in air orwater will generate vibrations caused by oscillations of the particles of the medium andconcomitant pressure waves. Thus while measured separately, they coexist.

A sound or vibration is defined in terms of its frequency (pitch) and amplitude (level orloudness). Frequency is measured in Hertz [Hz] (1 Hz = 1 cycle per second), amplitudeis measured in units of velocity, e.g. millimetres per second (mms -1), but is oftenexpressed in decibels (dB) in biological applications. Responses to sound are speciesspecific as each has its own range of frequencies over which it can hear and its ownhearing sensitivity. In humans sounds above 20 kHz are considered to be ultrasonic i.e.above human frequency range. For most fish, sound above 1 kHz is ultrasonic. Formarine mammals such as dolphins, sound below 1 kHz is not audible as they typicallyhear between 1 and 100 kHz (Nedwell et al . 2004).

Underwater noise can mask a biologically useful sound (a signal), disturb the naturalbehaviour of the animals, impair hearing or cause injury and death. Such noise sourcesinclude piling, shipping, dredging, drilling and earth works.

Of the activities proposed, impact piling is considered to produce the greatest noise.Sound levels generated during piling operations are variable and depend on themethod, frequency and duration of piling. A report by Nedwell and Edwards (2004)summarised sound levels produced during impact piling and vibropiling operations.Underwater sound levels recorded during piling operations in the UK ranged between130 and 150 dBre1Pa at a distance of 400 m

Studies of pile driving activity on an offshore windfarm construction site recorded atemporary drop in acoustic activity of porpoises during piling operations. However, theactivity returned to baseline levels three to four hours later. Temporary avoidance ofthe area was also observed up to 15 km from the piling noise although no observationswere made at a greater distance (Thomsen et al ., 2006).

In marine and terrestrial mammals, exposure to sound levels above absolute hearingthresholds can result in either a temporary threshold shift (TTS), when hearingsensitivity returns to normal after temporary loss, or a permanent threshold shift (PTS),when hearing is lost permanently. Reliable information on the levels of sound whichcause damage in mammals is not available and therefore it is common practice toapply human Damage Risk Criteria (DRC) (Richardson et al. , 1995). Humans exposedin air, to continuous sound levels 80 dB above their absolute hearing thresholds arelikely to suffer TTS and eventual PTS (Hammond et al. , 2006). Applying Damage RiskCriteria (DRC) to marine mammals it would be predicted that at low frequencies (


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Impacts of noise on fish are less understood, however studies in the UK on protectedmigratory fish species, such as Atlantic salmon ( Salmo salar ), have been undertaken. Itis thought that fish are more at risk of pressure pulse rupturing the swim bladder, whereone exists, than effects on their hearing (Vagle, 2003). Nedwell et al (2003) undertookexperiments on caged fish (brown trout, Salmo trutta ) during both vibro-piling andimpact piling. Cages were placed at varied distances from the piling, from 25 m to400 m away, with a control cage located approximately 10 km from the site. Two typesof behaviour were investigated; startle reactions and fish activity level. The studyconcluded that there was no evidence that trout reacted to impact piling at a distance of400 m, no evidence that trout reacted to vibro-piling at an even closer range, and noevidence of gross physical injury to trout at the monitoring range of 400 m.

Only fish located in the vicinity of pile driving activities during construction are predictedto be at risk of injury. Fish, by their nature are highly mobile and therefore able to moveout of areas where acoustic disturbance is occurring, limiting the likelihood of physicalinjury. Therefore, only minor impacts are predicted on fish species in the immediatevicinity of piling activities and no significant impacts further afield. The impacts will onlyexist for the construction period.

Potential impacts on the terrestrial environment will be where the intake and outfallconduits come ashore and cross wetland areas bordering the TTPP site. Airbornenoise and physical disturbance is likely to displace wildlife during construction activitieshowever no significant impact is predicted and wildlife will return once constructionnoise and physical disturbance has ceased.

Redundant onshore cooling system structures may be demolished, although this hasnot yet been confirmed. If demolition does take place, it is predicted that this couldhave a minor short-term local noise and dust impact.

Redundant off-shore intake and outfall structures will be left in situ and will thereforehave no construction phase impact.

Noise levels are addressed in more detail in the EIS Update prepared for the consentapplication being made for the T2 Expansion Project (Jacobs 2010a).

4.1.2 Habitat Loss / Gain

Laying of conduits and intake/outfall structures will result in damage to marine benthicand terrestrial habitats along the route corridor. Onshore this will include the clearing ofthickets and shrubs. Much of this onshore area has previously been cleared for theoriginal seawater supply conduits for the cooling towers at T1 and the WAGP. Anaccess road has also been created running in parallel to the TTPP drainage channel.

Although sensitive receptors have been identified in the general area during the WAGP

surveys this was to the west of the TTPP site. The terrestrial ecology in-front of theTTPP, along the proposed route corridor, is limited in its ecological value. In additionthe corridor is narrow (circa 50 m) and therefore potential impacts will be limited.Mitigation measures are proposed in the following section to minimise any potentialimpacts.

Where temporary habitat loss occurs, as a result of the activity footprint, re-colonisationby flora and fauna from surrounding areas is expected to be rapid following completionof activities. However, an initial loss of marine benthic and terrestrial communities iscertain to occur although the ecological value both within the sandy intertidal and


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subtidal area and along the onshore corridor is very limited. No significant impact ispredicted outside of this corridor.

4.1.3 Increased Suspended Solids and Turbidity

Any works causing increased turbidity or increased suspended solids loading may havenumerous impacts for example, affect foraging cetaceans, smother benthic fauna,affect the feeding ability of fish or cause a reduced gill function. However, increasedlevels of turbidity and suspended solids from construction will be temporary due tomixing by wave action and currents and therefore will be spatially limited.

Background turbidity levels are naturally high around Takoradi due to bed currents anda large surf zone which re-suspends sediment. Due to the small scale of worksprogrammed, compared to the vast sea area, any re-suspension of sediment from theworks will not significantly increase turbidity and any increases would be localised towithin 50 m for example. Currents will disperse re-suspended sediment quickly so thatlevels would not be detectable above background levels. For these reasons it isexpected that the small amount of re-suspension of sediment will be of negligibleimpact on the water quality and have no significant impact on the aquatic ecology.

4.1.4 Pollut ion from Construction Activities

Accidental release of pollutants (e.g. of oil or fuel from barges laying the conduits) mayhave a major significant effect on local ecology either through direct mortality,destruction of habitat or a change in water quality. The scale of impact would dependon the nature of the pollutant, duration and extent. The main pollution sources are likelyto be fuel, oil, on-board spills and wastewater from engines and other machinery. Bilgewater often has a high biological/chemical demand for oxygen (BOD/COD) andcontains pollutants such as dissolved solids, oils and other chemicals (Schmidt, 2000).

Whatever the source, the spillage of any polluting material from shipping orconstruction plant associated with construction, could result in entry of toxic materialinto the marine environment. Although the level of impact could be severe (dependingon the quantity and toxicity of the spilled material), the ultimate sink for insoluble solidswill be the benthos and studies have shown that sediment-dwelling, benthiccommunities can be impacted heavily by petroleum hydrocarbon contamination (e.g.Kingston, 1992). The exact locations where any spilt material is incorporated into theseabed will depend on whether it first enters the water column or lands directly onto thebenthos. Although any impact associated with the spillage of contaminants could havea potentially long-term impact on benthic habitats the extent of the impact will beinfluenced by the nature of the receiving environment. The distance over whichmaterial entering the water column is distributed will be related to local currents, tidalstate, water depth and settling velocity of material.

Given the currents and extent of the surf zone around Takoradi, any such materialsentering the water column are likely to be rapidly diluted and dispersed. There aresome valuable habitats within the vicinity of TTPP for example, Sherbro Bank.However, construction activities will be away from this area which would be upstreamof the prevailing currents therefore preventing any major significant impacts on theSherbro Bank. Benthic areas in the vicinity of the conduits are impoverished with asubstrate consisting predominantly sands, supporting few invertebrates. There is littlefishing activity in the area, suggesting fish are unlikely to be impacted directly fromconstruction activity. In addition, fish, mammals and reptiles are mobile and therefore


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able to avoid any pollution should there be any incidents. Mitigation measuresproposed in the following section provides measures to limit any impact from accidentalspillage.

4.1.5 Introducti on of Non-Native species

Many marine habitats are prone to invasion by exotic marine species from vesselsinvolved in international trade and the availability of vectors for species varies withprevailing shipping routes. Construction activities may potentially increase the risk ofintroducing non-native, invasive species through increased ship travel from areasoutside of the Gulf of Guinea.

The most frequently cited vector route is by transport as viable pelagic larvae or as juveniles in ballast water. A lesser known route is the transportation as adults in hullfouling. Generally one of the limiting factors to invasive species is prevailingtemperature conditions. Ships originating from temperate waters will carry exoticspecies adapted to a cooler climate. The significantly higher temperatures found in thetropical Gulf of Guinea will mean it is extremely unlikely that any species fromtemperate waters will gain a competitive advantage over locally occurring nativespecies. The biggest risk, therefore, will be from ships travelling from other tropicalregions outside the Gulf of Guinea.

However, there are now international measures in place for exchanging or sterilising ofballast water and advances in anti-fouling products have significantly reduced the risk.Therefore no significant impact is predicted as a result of non-native species beingintroduced.

4.1.6 Transportation

Delivery of general construction material will put considerable pressure on the existingroad network around TTPP. Despite the fact that the access roads around the TTPPsite are in good condition, there will be some unavoidable disruption to traffic flow andincreased risk of vehicle accidents and injury to pedestrians.

If HDPE pipes were to be used, their delivery would not affect local road links. Thepipes are extruded at their manufacturing plant in Norway. They are then floated inlengths are up to 500 m, and towed to site from Norway. They would remain floatingoffshore until installation. The landward of the pipe will be anchored onshore and theremaining length of pipe will be flooded in a controlled manner to bed on the pipetrench at the sea floor.

It is understood that the intake structure would be constructed on land before beingfloated out and sunk into position. Local road traffic disruption could therefore

potentially occur.

4.1.7 Landscape and Visual

The construction of the pumphouse will have negligible landscape and visual effectsgiven the absence of sensitive receptors and the fact that this activity will take placeadjacent to the southern TTPP boundary, adjacent to existing infrastructure. Thepower plant includes buildings, heat recovery boilers, etc., which are considerably tallerthan the proposed pumphouse.


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The intake and outfall conduits will be buried from the intertidal zone to thepumphouse. Depending upon how this is undertaken, there may be localised, short -term, minor landscape and visual effects. However the beach area through which thisconstruction activity will take place is isolated, with no existing sensitive receptors.

A beach resort is planned approximately 3 km to the west of the TTPP site, betweenEsupon and the Anankwari River, and, although some development has taken placethere, it is not clear when this development is scheduled for completion. Given itsdistance from TTPP, it is considered that the proposed CW works will have no impacton this resort.

4.1.8 Social

TICO and VRA have considerable experience in managing construction relatedimpacts on the local population; having been involved in the TTPP development forover 10 years.

There are expected to be no significant effects on local community infrastructure as aresult of the CW system construction. Significantly lower numbers of constructionworkers will be required than was the case for T1 and T2 development: for whichappropriate ar

takoradi cooling report

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