LIST OF TABLES4

LIST OF FIGURES4

ACKNOWLEDGEMENTS

ABSTRACT6

INTRODUCTION6

ENVIRONMENTAL IMPACT ASSESMENT FOR A SEWAGE TREATMENT PLANT FOR FLACQ

REGIONS10

1.0 Introduction10

2.0 Legislative Framework...10

2.1 The Environmental Protection Act 200211

2.2 The Town and Country Planning Act11

2.3 Noise Prevention Act 193812

2.4 The Waste Water Management Authority Act of 200012

2.5 Public Health Act 200812

2.6 Employment Right Act 200812

2.7 Maritime Zone Act Of 200513

2.8 Legal Register13

3.0 Description of the proposed project14

3.1 Primary Design Criteria14

3.2 Wastewater Characterization14

3.3 Proposed Method of treatment15

3.4 Design of Primary Settling tanks16

3.4A Parameters16

3.4.2 Design considerations16

3.4.3 Calculations17

3.5 Sludge Disposal18

3.6 Alternatives for eluent disposal20

4.0 Description of the existing environment21

4.1 Overview of Bassin Requins21

4.2 Climatic Conditions-21

4.3 Geological and hydrological conditions22

v.-

4.4. Aquatic Communities (Fauna and Flora)23

5.0 Identification of possible impacts24

5.1 Construction Phase25

5.1 A Anticipated Significant Impacts on Physical Environment25

5.1.2 Anticipated significant impacts on Biological Environment29

5.1.3 Anticipated Signiicant Impacts on Socio-Economic settings30

5.2 Operation Phase32

5.2.1 Anticipated Significant Impacts on Physical Environment32

5.2.2 Anticipated Significant Impacts on Biological conditions34

5.2.3 Anticipated Significant Impacts on Social-Economic conditions36

6.0 Mitigation Measures39

6.1 Construction Phase39

(5.7.7 Mitigation measures on Physical Environment39

6.1.2 Mitigation measures on Biological Environment43

6A.3Mitigation measures on Socio-Economic Environment43

6.2 Operation Phase44

6.2.1 Physical Environment44

6.2.2 Odour45

6.2.3 Sludge Storage46

6.2.2 Biological46

6.2.3 Socio-Economic settings52

7.0 Recommendations54

8.0 Conclusion55

9.0 References56

ANNEX57

LIST OF TABLES

Table 1: Summary of legislation and administrative ramework

Table 2: Summary of the climatology of the East of Mauritius Table 3: Noise levels of equipment

Table 4: Workforce of WWTP

Table 5: Employees working at the WWTP

Table 6: Standard for particulate matter

Table 7: Standard for onsite substances discharge Table 8: Noise exposure limits

Table 9: Pollutant Exposure limits

Table 10: Permissible limits for wastewater parameters

LIST OF FIGURES

Figure 1: General map of the proposed waste water treatment plant at Bassin Requins

Figure 2: Layout of the proposed facilities

Figure 3: Air Quality Standards

Figure 4: Map showing the B62 road

ACKNOWLEDGEMENTS

We would like to show our gratitude and heartfelt thanks to our lecturer, Mrs. Rana, who guided

throughout the completion of this report.

/

/

v

ABSTRACT

This report contains a detailed Environmental Impact Assessment for a wastewater treatment plant based at Bassin Requins, situated in the East of Mauritius.

The areas that will be beneiting rom this service is the East region comprising of only the major villages.

The wastewater treatment will comprise of primary to tertiary method of treatment so the treated efluent can be used for irrigation purposes for the golf courses around Belle Mare.

^

'

INTRODUCTION

Water is a fundamental ingredient of life. Houses, commercial buildings, educational institutions,

industries and in the agricultural sector consume water and produce waste water. Sanitary sewage is of domestic origin and its quantity depends on the number of people living in an area. Storm water comes rom catchments particularly rom roofs and roads and directly depends on the intensity and duration of rainfall. Industrial wastewater is the effluent delivered out of particular industries. Its quality depends upon nature of industry, raw materials used; manufacturing process .Wastewater is generally composed of water, pathogen, organic and

inorganic materials, big debris, emulsions and dissolved minerals.

Wastewater is treated irst before it is disposed in rivers and seas. It is usually done in a waste water treatment plant. The objective of a waste water treatment plant is to reduce the concentration of specific pollutants to the level at which the discharge effluent will not adversely affect the environment or pose health threat. In Mauritius, we have 19 treatment plants, the main one being at St Martin, Grand Baie, Baie Du Tombeau and Montagne Jacquot.

Most oten, before the construction a treatment plant or any project, the promoters require an environment impact assessment (EIA) permit. The EIA is an assessment of the possible impacts that a proposed project may have on the environment, consisting of environment, social and economic aspects. It ensures that decision makers whether or not to proceed with the project. The EIA is reinforced by the Environment Protection Act 2002 which helps in the protection of the environment assets of Mauritius and Sustainable development.

LITERATURE REVIEW Sewage treatment

Sewage treatment is a process where contaminant rom wastewater and household sewage is removed by chemical and biological processes. Its objective is to produce an environmentally safe effluent and solid waste (sludge) that is safe for disposal or reuse. Using advanced

technology it is now possible to treat wastewater back to drinking water standards.

Note: Singapore is the only country to re-use sewage efluent for drinking purposes Process Overview

Sewage is collected and transported by a network of pipes to the treatment plant. Sewage treatment is typically subject to federal regulations and standards.

Sewage treatment generally involves three main stages:

Primary treatment involves temporarily in a quiescent basin where large particle can settle to the bottom and are removed

Secondary treatment include removal of dissolved and suspended biological matter using indigenous micro-organism in a supervised environment

Tertiary treatment can be defined as anything beyond primary and secondary treatment

s

prior to disposal into a ragile and sensitive environment or or drinking purposes

Choosing Location for Treatment plant

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When a site for a waste water treatment plant is to be set up, it is preferable to choose a site which is considerably away from residential areas. Even if most of the treatment plant components are odor tight, in an aesthetical point of view these kinds of sites are chosen

Besides it is usually chosen at low-level grounds. With a treatment plant at low-level most of the water is likely to low to the treatment plant by gravity. This means that less pumping will be necessary making the project more economical.

7|

Moreover location of the site with respect to the eluent disposal must also be considered. There are two main method of eluent disposal:

Land disposal

Disposal in sea or ivers

Satisfactory disposal of wastewater is dependent on its treatment prior to disposal

Forecasting population growth over the years

According to the Statistics Mauritius (under the aegis of the Ministry of Finance and Economic Development) website, whenever a population growth need to be forecasted over the years, a growth rate of 1.18% per annum shall be taken into account.

Px(l + r)n

Where, P is the current population

r is the growth rate

n is the number of year which needs to be

forecasted

^/

Environmental impacts

Any development irrespective of the nature of the type of work, scale and scope will generate impacts. They can be either direct or indirect impacts both qualitatively and quantitatively in terms of the physical aspects of the environment, namely land use, soil and geology, lora, fauna, air quality, water quality, noise, visual aesthetics and the landscape. The impacts could also be positive or negative or a mixture of both depending on the nature and complexity of the project.

Apart rom the impact on the physical environment development will have a significant impact related to the socio-economic aspects, which include the effects on employment and traic. An

8

assessment of the likely impact of the project on these environmental components has been carried and elaborated in subsequent sections

Mitigations

Mitigation in legislative terms is the principle that a party who has suffered or caused any adverse impact has to take reasonable actions to minimize the amount of the loss suffered. For the development of a wastewater treatment plant, we shall take into account the concerns which have been expressed rom the developments in recent years. Subsequently substantial investments shall be expected in the mitigation of the general hostile impacts such as odour mitigation, noise mitigation, reduction of landscape use, visual impact mitigation and traic disruption. The adoption of a good management practices and speciic environmental control

measures will mitigate these impacts.V.

ENVIRONMENTAL IMPACT ASSESMENT FOR A SEWAGE

TREATMENT PLANT FOR FLACQ REGIONS

1.0 Introduction

The Republic of Mauritius intends to construct a new waste water treatment plant in the region of

Flacq, under the National Sewerage Master Plan. As part of this regime, the Government of Mauritius is planning to modernize the system of treatment of waste water and provide the inhabitants with the facility of sewerage for the major villages governing the district of Flacq.

In regard of this matter, an Environmental Impact Assessment (EIA) will consider all the laws and guidelines that can be applied for the construction of a new waste water treatment plant. EIAs are important to consider prior to approval and design phase, so as to ensure that all the conditions regarding the protection of the environment are met and that the construction of the project will not cause any damage to the surroundings.

The proposed site is called Bassin Requins and is found near the coastal region of Poste de Flacq and is a location whereby no activities are conducted except for pig-rearing. The fact this region has, since many years, been used for pig rearing, no urban expansion and no tourism activities have been developed.

Near the proposed site is found Belle Mare Golf club and Le Prince Maurice hotels, and Riviere

du Poste de Flacq river.

2.0 Legislative Framework

u

Legislation is a law which has been proclaimed by a governing body. Before an item of legislation becomes a law it is known as a bill. Legislation can have many purposes; to regulate, to approve, to forbid, to fund, to sanction, to grant, to declare or to restrict in order to promote sustainable and economic development in the country. Our National environment legislation consists of the legislations, standards, regulations, institutions and administrations adopted to control activities damaging to the environment. This chapter describes the relevant legal tools of the laws and regulations concerning the construction of a treatment plant.

10

2d The Environmental Protection Act 2002

Similarly in Mauritius an institutional and legislative policy for environmental protection has

been established primarily rom the National Environmental Action Plan (NEAP) which has been prepared by a joint Government/World Bank team in 1988. The Environmental Protection Act of 2002 is one of the major products of the NEAP. The Environmental Protection Act of 2002 provides a legal ramework to the protection and management of the environment in the country. As speciied in the Act a National Environmental Commission was founded to establish national goals and objectives and enforce policies and priorities for the protection of the environment.

The Commission must oeuvre in such a way so as to:-

Set national ambitions and objectives and establish policies and precedence for the protection of the environment

To protect the environment and promote all its elements such as water, air and land in a sustainable manner, as well as to monitor the measuring of these elements and their components.

To prohibit the admission of harmful and hazardous substances, costing a way or embedding them in the State's lands.

Assess progress by public departments viewing it in an environmental aspect.

Ensure synchronization and collaboration between public departments, local authorities, and other government organizations engaged in environmental protection programmes. Issue directions and recommendations to public department

Supervise and evaluate the activities of public departments involved in the protection and management of the environment.

2.2 The Town and Country Planning Act

The Town and Country Planning Act ^yas established in order to set out a planning ramework

for new development. The Act allows development permits to be allocated for developments. National Physical Development Plan was prepared in 1993/94 to provide a ramework for

meticulous local development planning and control. The Board is the sole authoity allowed to grant permit for development of land. The Board has the authority to grant permit to conditions as they may deem it or may simply refuse permission for development. Liable to the Minister's

111

approval, the Board can also appoint a planning committee that shall furnish the board with information concerning the future planning needs and nature of development.

23 Noise Prevention Act 1938

Noise is one of our major environmental problems which is giving rise to lots of public

complaints, due mainly to juxtaposition of residential, religious, commercial and industrial activities. The Act declares that noisy activities related to construction such as demolition of a building, excavation or illing of land and use of heavy machines require prior authorisation from the local authority if such activities are carried out before 7 am or ater 7 pm on any day.

2.4 The Waste Water Management Authority Act of 2000

The Waste Water Management Authority Act of 2000, explicitly, provides the ruling classes of

the Waste Water Management Authority (WMA) as an institution responsible of the wastewater sector in Mauritius. These codes provide guidelines about the power of the authority over the design and installation of the water system and septic tanks.

The Board is responsible for:

Carrying out, monitoring, supervising, maintaining, managing, and controlling wastewater work.

Promoting treatment and reuse of wastewater.

Handling researches and studies on the wastewater sector

Safeguarding resources to inance operations and maintenance

/

Monitoring pollutions due to wastewater treatmentx/

2.5 Public Health Act 2008

The Law stipulates: The Ministry of Health shall supervise the water of Sewage system and the

sewage system networks and the internal installations and the refinement stations in coordination with other concerned Departments, and according to its own legislations, in order to ensure the presence of health standards and conditions, so that no harm could reach the public health.

2.6 Employment Right Act 2008

The Employment Right Act was issued to regulate the relationship between the Employer and

the Employee. The Act afirms that any contract or any term in any contract between both parties that contradicts the labour law is considered invalid. Employment contracts can be limited or

^

12

unlimited contracts, the law has specified the speciic conditions for each. According to labour law, it is not allowed to employ any foreigner workers without prior consent rom the Ministry of Labour. The work permit should not exceed one year and can be renewed for extra years.

2.7 Maritime Zone Act Of 2005

The Maritime act was introduced in 2005 in order to make necessary controls in thecontiguous

zone to prevent and punish infringement of the customs, fiscal, immigration or sanitary laws within Mauritius, its archipelagic waters, internal waters and territorial sea. The Act also states that solely the Prime Minister has the right to make regulations to provide for the authorization for any construction, operation or the laying of pipelines or cables in the exclusive economic zone

2.8 Legal Register

A summary of legislation and administrative ramework applicable during both phases

(construction and operation) is shown in the Table below:

Legislation

The Environmental Protection Act 2002

The Town and Country Planning Act

Noise Prevention Act 1938

The Waste Water Management Authority Act

of2000

Public Health Act 2008

Employment Right Act 2008

The Maritime Zone Act of 2005

Responsible Authority

Ministry Of Environment

Ministry Of Public Works And Housing

Ministry Of Environment

Ministry Of Environment

Ministry Of Environment

Ministry Of Labour

Ministry of Fisheries

Table 1: Summary of legislation and administrative ramework

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13

3.0 Description of the proposed project

3.1 Primary Design Criteria

The new wastewater treatment plant at Bassin Requins is to be designed for the inhabitants for part of the Flacq regions (Centre de Flacq, Bon Accueil, Montagne Blanche, Camp Ithier, Lallmatie, St Julien, Bonne Mere, Poste de Flacq, Bel Air, several hotels around Belle Mare), and in view for the future population estimate for the next 20years. This will allow adequate time for design and completion of the project.

According to the Statistics Mauritius (under the aegis of the Ministry of Finance and Economic Development) website, Flacq district comprises of approximately 90,000 inhabitants and each km of land is occupied by 614 inhabitants and projecting a growth rate of 1.18% for Flacq region over a period of 20 years, it is thought that around 140,000 heads will beneit rom the sewerage system, making provision for the growth rate.

Note: The area of land that will beneit of the project is taken about 150Km2

Present industries in the area include hotel, food processing, ishing industry, stone crushing plant. No industries (MIDA Industrial Site, DBM Industrial site or sugar factories require sewage system. Thus, the domestic portion of the wastewater stream dominates the flow volume and the wastewater characteristics can be considered representative of typical domestic sewage for this region.

Storm water has been assumed that it will not signiicantly affect the treatment operations because of the climatic conditions over the Flacq region (See Section 2.2). The per capita water usage in the above mentioned Flacq regions has been estimated to be 200L per day (average water usage value used by the Central Water Authority). A design low of 35000 cubic metre per day has therefore been selected for Flacq district. This is based on 200 L per capita per day consumption rate, and includes an allowance for both industrial flows and iniltration.

3.2 Wastewater Characterization

For design purposes, a biochemical oxygen demand (BOD) of 250 mg/L and total suspended solids (TSS) of 300mg/L has been used, with a flow of 35,000 m3/day.

V

14

3.3 Proposed Method of treatment

Only one method of treatment of sewage was considered and that is the conventional method,

consisting of the preliminary treatment, primary, secondary treatment, which will be followed by the tertiary treatment of the wastewater.

The individual processed include:

Preliminary Treatment - Removal of large solid materials delivered by sewers that could obstruct flow through the plant or damage equipment.

Primary Treatment- Ater removal of the coarse materials, sewage passes to sedimentation tanks, which aim to remove the settleable by gravity.

Secondary treatment- The secondary treatment process aims to reduce the BOD exerted by reducing organic matter. This is mediated, primarily, by a mixed population of heterotrophic bacteria that utilize the organic constituent for energy and growth.

Tertiary Treatment- Tertiary and/or advanced wastewater treatment is employed when

specific wastewater constituents which cannot be removed by secondary treatment must

be removed. This will be done so as the wastewater could be used as water for irrigation

purposes, for the nearby golf courses at Belle Mare.

A large number of biological unit operations are available to achieve the aerobic oxidation of BOD. All operations can be classified on the basis of their microbial population, into either ixed ilm or dispersed growth processes. Fixed ilm reactors have bioilms attached to a ixed surface where organic compounds are adsorbed into the bio ilm and aerobically degraded. In suspended (e.g. activated sludge) growth reactors the microorganisms mix reely with the wastewater and are kept in suspension by mechanical agitation or mixing by air diffusers.

15 1 ? g e

3 A Design of Primary Settling tanks

3.4.1 Parameters

Discharge Q = 35,000m3/day

BOD=250mg/L

TSS= 300mg/L

3.4.2 Design considerations

1. Overlow rate or surface loading rate is 15 to 35 nrVm /d for average low and 40 to 50

m /m /d for peak flow. Overflow rate must be checked both at average flows and peak flows.

2. Detention time: The rate of removal of BOD and SS is maximum during the irst 2 to2Vi

hours of settling and thereater decreases appreciably. Longer detention time beyond 4

hours may affect the tank performance adversely due to setting in of septic conditions,

particularly in tropical climates. Experience has shown that a detention period of 2 to 2lA

hours for primary settling tanks and VA to 2 hours for secondary settling tanks will

produce the optimum results.

3. Weir loading: Weir loading influences the removal of solids in sedimentation tank,

particularly in secondary settling tanks where flocculated solids are settled. For all

primary and secondary settling tanks, in all cases except in the case of secondary tanks

for activated sludge process, weir loading not greater than 100 m3/d/m for average low is

recommended. For secondary settling tank in activated sludge or its modiications, the

weir loading shall not exceed 150 nrVd/m.

4. Performance: Primary sedimentation of domestic sewage may be expected to

accomplish 30 to 45% removal of BOD and 45 to 60% removal of suspended solids.

16

3.4.3 Calculations

Discharge of sewage Q = 35,000 m3/day

Q3S000

Plan area of tank A = = = 700 in2

Assuming L = AB

L x B = 4B2 = 700

B = 13.2 = 14m

But B must not be greater than 6m (scrapping becomes dificult otherwise) Therefore, 5 PST must be provided.

700

4B2=

B = V35 = 5.92 = 6

Therefore L = 4 x 6= 24

Assuming a depth of 4m,

, NV24

Detention time (t) = =3 x 24 x 6 x 5 x = 1.87 hours

Q

Length of Weir

Weir Loadinq rate =

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Major industrial and commercial activities are located to the east and west of the proposed treatment plant. The major tourism activities are located at Belle Mare and a few others at Poste La Fayette. The nearest hotels are Le Prince Maurice and Le Touressrok; each ofthem having their own waste water treatment plant and discharging the treated effluent into the nearby seas or

used as water for irrigation purposes.

3.6 Alternatives for efluent disposal

Two methods of effluent disposal were considered:

Land disposal

Discharge in the Bras de Mer Requins

Discharge into Riviere du Poste river

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Due to lack of available land and nearby hotels, land disposal was rejected and the most convenient one remains discharge into the Bras de Mer Requins because the seaside is neither considered as a bathing area nor is considered to have endemic fauna or flora and is not a preserved lagoon or a marine park in the East.

20

4.0 Description of the existing environment

4.1 Overview of Bassin Requins

Bassin Requins is found on the coast of the East of Mauritius near the East Coast of Mauritius,

and is one among the various places around the island that is used for pig farming. This area is not occupied by any inhabitants and is an undeveloped plot. The nearest Road Development Authority "owned" road is the B62 road, which means there is no oicial access to this area. The discharge area is found at about 2Km away rom Bassin Requins, with a decreasing slope (See Annex for contour map).

This makes Bassin Requins a suitable site for a wastewater treatment plant, that is away rom any houses and since it is a remote place, there is no cultural or religious heritage nearby. As for the design of the pipeline carrying wastewater, a gravity main can easily be used for the sea outfall.

The discharge area, Bras de Mer Requins, the nearest discharge area rom the proposed site, is not used for any recreational purposes, except rom leisure fishing by the local inhabitants. Therefore, there is no health hazard when the treated wastewater will be discharged into the seas.

4.2 Climatic Conditions

The country has two seasons; a warm humid summer extending from November to April and a

relatively cool dry winter from June to September.

Mean summer temperature is 24.7C and mean winter temperature is 20.4 C.

Long term mean annual rainfall (1971 -2000) over the Island is 2010 mm. The wettest months are February and March. The driest month is October.

The climatology of the district of Flacq is as summarized in the following table.

MonthMean maximum

Temperature (C)

January28.8

February28.7

March28.6

Mean wind speedAverage rainfall

(Ka/h)(mm)

8.0261.3

9.1334.1

9.6231.2

21

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April27.69.1240.0

May26.29.3167.7

June24.610.8104.0

July23.712.3102.5

August23.811.7104.9

September24.311.270.1

October25.411.062.2

November27.110.182.0

December28.29.1201.8

Table 2: Summary of the climatology of the East of Mauritius

(Source: Mauritius Meteorological Services website, http://metservice.Intnet.mu.climatc-

scrvices/climatc-or-mauritius.nliD). V-

4.3 Geological and hydrological conditions

Volcanic deposits which formed Mauritius, through three basaltic lava flows, greater than 3.5

million years ago, greater than 500,000 years ago and greater than 100,000 years ago,

respectively, dominate the geology of Mauritius. The soil of Bassin Requins mostly belongs to the Lowland Latosolic Reddish Brown Prairie soils.

The surface drainage pattern of Mauritius has been classiied into major drainage areas with permanently lowing rivers and minor drainage areas, which lie between the major ones.

The Riviere Francoise North and Riviere du Poste East are fed principally rom groundwater originating in the Nouvelle Decouverte area. Riviere du Poste, in addition to its natural low, receives water rom Riviere Francoise (North) via Constance Canal as well as rom G.R.S.E via Sans Souci canal.

To the east of Riviere du Poste is the minor drainage area, which is similar to the Plaine des Roches minor catchment.

The next drainage area, Riviere Seche East is also fed rom groundwater originating in Nouvelle Decouverte and Quartier Militaire, lowing underground between Fayence and Montagne Blanche, to appear at Clemencia as Riviere Seche.

22

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4.4. Aquatic Communities (Fauna and Flora)

A satellite view of the efluent discharge area (Bras de Mer Requins) indicates that the coral reef

is a barrier one which is found away rom the mainland and which is separated by a deep channel or lagoon.

The Bras de Mer Requins is dominated by species such as mammals, reptiles, bony fishes, cartilaginous ishes, molluscs, echinoderms, corals, mangroves, seagrass, chlorophyceae, and phaeophyceae.

However, according to a report of the State of the Environment in Mauritius clearly indicates the deterioration of the coastal and marine environment; the fouling of seas due to industrial effluents, sedimentation, erosion of shores, decrease in ish production among others.

Bras de Mer Requins is one among several seaside in Mauritius, where there has been massive deterioration of the coastal and marine environment. No activities, except rom ishing can be noticed in that area.

As for the environment near Bassin Requins, no fauna or lora or any endemic species of animals

or plants have been identiied.v

23 j ri ~i -

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5.0 Identification of possible impacts

Any development irrespective of the nature of the type of work, scale and scope will generate

impacts. They can be either direct or indirect impacts both qualitatively and quantitatively in terms of the physical aspects of the environment, namely land use, soil and geology, lora, fauna, air quality, water quality, noise, visual aesthetics and the landscape. The impacts could also be positive or negative or a mixture of both depending on the nature and complexity of the project.

Apart rom the impact on the physical environment development will have a significant impact related to the socio-economic aspects, which include the effects on employment and trafic. An assessment of the likely impact of the project on these environmental components has been carried and elaborated in subsequent sections.

During the construction phase, the following environmental and social aspects were identified as signiicant:

1) Impacts on Physical Environment

Air Quality

Noise

Land Visual

2) Impacts on Biological Environment

Fauna

Flora

Pest nuisance

3) Impacts on Socio-Economic settings

Cultural resources

Employment

Traffic and transportation

24 I F a 2 e

During the operation phase, the following environmental and social aspects were identified as signiicant:

1) Impacts on Physical Environment

Air Quality

Noise

Water quality & quantity Land Use and Landscape

2) Impacts on Biological Environment

Pest nuisance

Marine life

3) Impacts on Socio-Economic settings

Employment

Trafic and transportation

5.1 Construction Phase

5.1.1 Anticipated Significant Impacts on Physical Environment

5. L L1 Noise

Noise is traditionally deined as unwanted sound that interferes with normal activities in a way that reduces the quality of the environment.

Increases in noise associated with construction activities will temporarily impact local residents of Poste de Flacq in the project area. There are no hospitals, schools or other public facilities

within the project area that would be adversely affected by construction noise.

The impact rom noise generated during the construction phase on the surrounding properties/land uses located along the line of the sewers is likely to be significant at different times throughout the construction period. The project work would be far rom residential and

25 | P a g a

During the operation phase, the following environmental and social aspects were identified as signiicant:

1) Impacts on Physical Environment

Air Quality

Noise

Water quality & quantity Land Use and Landscape

2) Impacts on Biological Environment

Pest nuisance

Marine life

3) Impacts on Socio-Economic settings

Employment

Trafic and transportation

5.1 Construction Phase

5.1.1 Anticipated Significant Impacts on Physical Environment

5. L L1 Noise

Noise is traditionally deined as unwanted sound that interferes with normal activities in a way that reduces the quality of the environment.

Increases in noise associated with construction activities will temporarily impact local residents of Poste de Flacq in the project area. There are no hospitals, schools or other public facilities

within the project area that would be adversely affected by construction noise.

The impact rom noise generated during the construction phase on the surrounding properties/land uses located along the line of the sewers is likely to be significant at different times throughout the construction period. The project work would be far rom residential and

25 | P a g a

commercial establishments. Therefore, the noise sensitive receptors to the site are the houses, commercial premises along roads, schools, and a hospital.

Common construction activities will include truck traffic, heavy machinery movement and hauling of construction materials. Rock is known to be present in many parts of the project area and rock excavation and use of pneumatic rock breaking equipment will also generate severe noise impact.

These higher noise levels may have significant and negative health impacts on staff working within the construction site.

The following table gives an idea of the noise levels generated by typical construction equipment.

EquipmentAverage Noise Level (dB)

Bulldozers80

Backhoe82

Bobcat75

Crane76

Dump Truck88

Jack Hammer90

Table 3: Noise levels of equipment

Given that the nearest receptors are at least1 km away rom the construction site, the noise

pressure levels are within acceptable levels during day and night. The overall noise level will be

higher during the day time compared with the night time.

Mitigation measures will have to be applied accordingly.

5.1.1.2 Air Quality

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