RJPUBLIC OF TUNISIA
GREATER TUWIS SEWERAGE PROJECT
ENVRONMENTAL ASSESSMENT SUMMARY
Public Disclosure Authorized TABLE OF CONTENTS
1. The ProjectScope ......
2. The Project Description ......
3. The Project Cost Estimates...... ii
4. The Environmental Review and Assessment ...... ii
5. Summary or Environmental and Social Impacts ...... iii Public Disclosure Authorized 6. Mfitigation Plan...... iv The TunisWest Treatment Plant . . . v The Sud Miliane Treatment Plant . .... vi
7. The Reuse of Treated Waste Water ...... vii
P. Conclusions ...... viii
LIST OF ANNEXES
Public Disclosure Authorized 1. MAP: IIBRDNo.27729 2. MAP: IBRD No.27730
/1 J f f Public Disclosure Authorized REPUIBLIC OF TUNISIA
GREATER TUNIS SEWERAGE PROJECT
ENVIRONMENTALASSESSMENT
SUMMARY
1. Proiect Scone.
1.1 The proposedproject covers the reorganization,expansion and rehabilitationof the Greater Tunis Seweraee System in order to cope with the growing demand for sewerageup to the year 2011.By then the populationis expectedto havegrown from the present 1.8 millionto 2.5 million.The service level is expected to increase from the present 75% to 95% of the populationbeing hooked up to the sewer svstemby then. As the expansion of the greater Tunis urban area will be mostly to the west, it will be necessaryto createa new westernsub-basin, subdividing the city in four sub-basins. The new westem basin willhave its own sewage treatmentplant, situatedat Attar, outside the city limnitsand withinthe area wheretreated sewagecould be used for irrigation.The other three basins, the southern, central and northem ones, are in need of expansion and rehabilitationonly. The project will be executed by ONAS (the National Sewerage Agency).
2. Proiect Description
2.1 The proposedproject includes:
i. The constructionof a waste water treatment plant (WWTP) for the western basin of Tunis. The WWTP, of the activated sludge system,will have a capacityto treat the sewageof 700,000 populationequivalent. The main complex is situated at Attar, just after the divide with the Mornag basin. A sewage collectioncenter, with a pre-treatment consistingout of sand and grit removal facilitiesand a pumpingstation will be situated at a low site on the shore of the Lac Sedjoumi. A double pressure main will transpon the sewage from the collectioncenter to the WWIP;
ii. The expansionand rehabilitationof the 'Sud-Maliane"sewage treatment plant in the southernbasin of Tunis. The capacitywill be increasedfrom 300,000 to 600,000 populationequivalent, applying the same extended aerationtreatment procedure;
iii. The restructuringof the western Tunis sewage collectionsystem, in order to divert part of the sewageto the new WesternTunis treatmentplant; iv. The strengtheningof the southern Tunis sewage collectionsystem and the connectionof the villageof Mornag to the "Sud-Meliane"treatment plant;
v. Theextension of the northernTunis sewagecollection system and a liaison conduit of 4 km between the northern Tunis and 'Cherguia"treatment plants, replacingan open canalthat obstructs groundwater drainageof the Soukra plain in the Arianalake;
vi. The rehabilitationand resizingof the sewage collectionnetworks of central Tunis and northernTunis (La Goulette and Le Kram),to prevent salty groundwaterintrusion;
vii. The strengtheningof all secondary sewer systems;
viii. Theconstruction of seven pumpingstations;
ix. The constructionof a pilot project for ground water rechargewith purified sewage after tertiarytreatnent;
x. The acquisitionof miscellaneoussewer maintenanceequipment;
xi. Theacquisition of a mobilelaboratory type of sewagetreatment plant; and
xii. Miscellaneousstudies and research work.
3. Proiect Cost Estimates
3.1 Total project cost (includingthe costing of the mnitigationplan) is estimatedat DT 154 million(USS 144 million),with a direct and indirect foreign exchangecomponent of DT 93 million (US$ 87 million).Identifiable taxes and duties amount to about 11% of total cost.
4. The Environmental Review and Assessment
4.1 The proposed project has been reviewed, screened, and proposed for Category A, consistent with the provisionsof Operational Directive 4.01, Annex E, "Environmental Assessment." Preparation for this project was comprehensive,encompassing a Sector EnvironmentalAssessment (SEA) and Project SpecificAssessment (PSA) for each of the WWTPsproposed for the Greater Tunis area. The EnviromnentalAssessment was carried out by a consortium of foreign and Tunisian consultants, financed under a Japanese (PBRD) Grant. The studies, which were done in close cooperation with the Tunisian Authoritiesand the WorldBank, were carried out in two phases. The first phase , the SEA provideda qualitativeframework on the situation of waste water managementand
GREATERTUNIS SEWERAGEPROJEC ENVIRONMENTALASSE5SMENT SUMMARY DALILATADJEROUNI DECEIER 5.1996 iii
disposaland how it could be improvedfor future investmentsin the field.The second phase coveredthe specificassessments related to the proposedproject. These assessments were based on studies,field work, and public consultationwith the differentconcerned populationgroups and withthe many institutionsinvolved. In addition,ONAS is required by law to undertake an EnvironmentalImpact Assessment in conformity with the requirementsof the ANPE( the National Agencyfor EnvironmentalProtection).
4.2 Both the SEA and PSAs showed that numerouspositive impactswill arise from this project, ranging from those related to public health to those directly affecting the economy. Such effects are generallyassociated with the provisionof sewage treatment facilitiesto a sizablepart of a capitalcity, with coverage of more than a millioninhabitants equivalent;an increaseof 30,000 connectionsto the sewer network; and protection of vulnerablereceiving waters from polluting discharges. Other substantialbenefits concern the agriculturesector, since the proposed project will includethe reuse of treated waste water for irrieation and other purposes related to the protection and preservation of groundwater resources.Few negative impacts associated with the project have been studied.These are relatedto the constructionand operationof the treatmentfacilities and the rehabilitationof the seweragesystem. Detailed environmentalanalysis along with a plan to mnitigatethe identifiednegative impacts were discussed and approved by the Governmentof Tunisia.These mitigation measures will be madepart of the enviromnental strengtheningand educationalprogram to be developedwithin the scope of this project. The projectwill not cause any resettlementdue to constructionof proposedfacilities.
S. Summan of Environmentaland Social Impacts
5.1 The proposedproject will improvethe qualityof sanitationservices, reduce envirommentalpollution and mitigate health hazards from waste water dischargesin the nationalcapital region through the facilitiesdescribed above. The most significantpositive and negativeimpacts that the projectwill generate are summarizedbelow.
5.2 Positive mnRacts: The constructionof the tetment faciitieswill have a strongpositive effect on the overallenvironment at each proposedlocation. It willprevent the intensenegative impacts on hman healthand urban nuisancesassociated with the dischargeof untreatedsewage directly into the environmentfrom the sewagecolector systemat discharge points and, hence, decreasethe exposure to waste water related diseases(e.g., gastro- intestinal)of the affectedurban population. The rehabilitationand constructionof new sewers willenhance firther the qualityof life in the urban areas, especiallyfor those settlementswith insufficientifrastucture networks and higher housing density. More than 150,000 low incomepopulation are expectedto directlybenefit from the project.
5.3 Therewill also be improvementof the water qualityin the streamsthat flow throughout the city. A major benefit is the protection ofthe groundwaterresources frorn
GREATERTUNIS SEWERAGE PROECr ENVIRONMENTALASSESSMENT SUMMARY DAULATAD3EROUNI DECES,M 5. 1996 iv
contaminationby untreatedsewage and the preservationof the marineenvironment and other vulnerablewater bodies (agoons, oueds and sebkhas)frcm furthereutrophization. As a result, economicbenefit wil occurin terms of increasedwater volumeof good quality,and increased fisheriesand tourismactivities along the coast nearTunis.
5.4 Furthermore,the treatmentfacilities will provide an opportunityto improvethe controlof the industrialdischarges through pretreatment and connectionto ONASsewers, as requiredby the tunisianlaw. For the Sud Melianeplant, potential industrieswith non- compliantwaste waters have alreadybeen identified.Whin the frameworkof the FODEP activity,these industfies will benefit from a programwhich has materializedin the construction of an industrialpretreatment unit that willbe connectedto the proposedplant.
5.5 Finally,it is worthnoting that the enviromentalaspect lays at the heart of the whole conceptionprocess of this project. It has, iteratively,influenced the design of the WWIP's,their site locations and the qualityand use of their by-products.Two majorelements around which this process has revolved are the protection of the environmentand the valorizationof the scarcewater resourcesthrough the reuse of the treatedwater. Indeed,in the caseof TunisWest' WWTP the flow of the eising seweragesystem, for a sizablepart of the coveredarea, willbe revertedto the newlyidentified westem basinwhere it willbe treated in the proposedWWTP. This, on the one hand, preventsthe efuent from being discharged intothe Gulf of Tunis,the sea and other vulnerableRWB. On the other hand, it offersthe advantageof usingthis effluentfor irrigationor rechargeof the groundwaterresources. Hence, generatingsignificant economic and socialbenefits.
5.6 ieeativeInpacts: Duringthe constructionand rehabilitationof the sewer network and the constructionof the treatmentfacilities, impacts of minor importanceand magnitudea- -. uectedto occur. Theseimpacts are tempomryand willinclude: disruption of trafficpattem in.; - ,vicedareas of the city, interferencewith other urban infastructures, disruptedaccess to residentialor/and other buildings,change in the landscapeOoss of vegetation),noise mnisances and air pollutiondue to dust formation. The projectactivities do not requireany involuntaryresettlement. During operationof the treatmentplants, some of these minorphysical imnpacts will continueto occur. It is, actually,the case for odor and gas emissionsand noise.
6. Miti2ation Plan
6.1 A detailedMitigation Plan was presented and approvedby ONAS,the Ministry of Environmentand ANPE. The Plan containsa list of al the possibleimpacts that could occur in this project during the diff-rent phases of the project inplemernationcycle, comprising:(a) rehabilitationand construction phase of the sewer networks; (b) the constructionphase of the treatmentfacilities; and (c) the operationphase of the plants. For eachofthe possiblesource of impactsor type of projectactivity, the natureof the impactis descibed and actionsfor remedy are listed. The responsibiliifesfor these actionsare defined andthe concemedagencies identified. An enronmental managementplan is also proposed.
GREATERTUNIS SEWERAGE PROJECT ENVIRONMENTALASSESSMNT SUMMARY DALILATADJEROUNI DEMBR 5,1996 v
6.2 A monitoringprogram is recommendedfor the sewer networksand the treatmentplants. In additionto what is currentlydone by ONAS, through its laboratories, specificmonitoring of the propertiesof both the influentand effluentwill be performedand assessedagainst the normsfor agriculturereuse. The use of the sludge as fertilizeris strongly recommended.The monitoringprogram will also continueto evaluate all possibleother impactson the environmentincluding ambient air, soils and vegetation,and the RWBs dow%nstreameffluents.
6.3 A programfor institutionalstrengthening of ONAS' technical,organizational and managerialcapacities is also foreseen.It will cover the regional departmentsand will includea GeographicInfornation Systemcomponent. Furthermnore,reinforcement of the existinginstitutional machinery is recommendedalong the linesof the SEA!sfindings.
6.4 Themain impacts and relatedmitigation measures for the treatmentplants are sumnarizedbelow:
The TunisWest Treatment Plant
E-missionof pollutedwater: The proposedproject will preventemission of raxvwaste water in the servedareas from currentlyovercharged plants to a very important extentand, hence improveconsiderably the sanitationof a sizablepart of the capitalurban areas. It wil also relieveSebkha Sejouni from tne curent dischargesand possibleflooding of its banks.However, it maypresent some risks. The majorone remainsthe dischargeof the effluentinto the environmentif the reuse option is not pursued. The plant is designedto produce a disinfectedeffluent with a qualityto meet the standardsfor irrigation. lt will however, contain high nutrient concentrationswhich will contribute to the ongoing accumulationof nutrientsir. the Gulf of Tunis. The latter, being highy vulnerableto eutrophization,this willcause further deterioration of the sea grass fieldsand bloomof algae. The effluentwill also affectthe Mejerdabut to a lesser extent than the Gulf of Tunis. It is estimatedthat the effluentwill increase by 1%the flow ofthis sectionof the Mejerdaadding to its alreadyrich load of nutrients.
MitiLation: The nutrientswill be removed,by meansof tertiauytreatnent, if the effluentis to be dischargedinto the ouedsand, in finalstage, into the Gulf Altematively, otherdestinations ofthe effluentwill be examined.
Emissionof waste: The plantwill also producean estimated90 m3 per day of stabilized,dried sewage sludge that willbe soldto farmersor elsetransported to a controlled dumpingsite. Constructionof a solid waste treatmentplant under study is proposedfor the closevicinity of El Attarsite.
Mtigation: The sludgeproduced so far by ONAS'eisting treatmentplants has been of good qualityand has been in high demand by farmers. However, irregular emissionsinto the sewersystems could drasticallychange its qualityas wellas the qualityof the
GREATERTUNIS SEWERAGE PROJECT ENVIRONMENAL ASSESSMENrSUMMARY DALILATADJEROUN DECEMBE,S.1996 vi
effluent,which in tum willbe damagingto the environmentand publichealth. ONASmonitors carefullysewage coLected at eachof its operatingWWTP's, through on-site laboratories and a sophisticatedcentral laboratory.
Emissionsinto the air: The waste water treatment plant wrillalso have local impacts in the forTnof odor and gas emissionsinto the ambientair as well as noise. At El Attar, odor will be emittedbe the sedimentationbasins causingnuisance up to 500 meters beyondthe plant'slimits. The methane-drivengenerator for aerationwil causeemission of NO, et CO2. A torch (5 m height)uill be neededtoo for flaringrmetane surplus.
Mfitlation: At the Sejouni plant, odor emissionswill be controlledby coveringthe equipmentand treatingthe air in a biofilter.In El attar, the site is isolatedand thereare no housesin the closevicinity.
UrbanPlannin Aspect: In additionto the alreadyexisting urban settlements in the vicirnityof the plant at Sejoumi,the area is planned,according to the provisionsof the MasterPlan , to be fiutherdeveloped into a residentialquarter wuffi average to highdensity.
Mitigation: It is foreseento installa bufferzone of no lessthan 500 meters aroundthe site to preventany negative impacts to the healthof the inabitants of the planned residentialdevelopment. Within the scope of this project,the Departmentof Urban Planning willbe notifiedin order to makleprovision for such measure into the MasterPlan, currently understudy.
The SudMeliane Treatment Plant
Emissionof poluted effluent: The effluentwill be dischargedinto the Oued Melianeand then into the sea. It will have an adverse effect on the marineecosystern if the nutients are not removed.
Mitization: Additionaltreatment is needed if the reuse programdoes not mateialz and the sea outfallsare unjustifiable.
Emissionof waste: It is estimatedthat the productionof sludgewill reach 38 m3 per day.In this area of Tunissouth, the sludgecurrently produced is beingused entirely by fmers.
Mitigation: If unused,the sludgewil be dumpedinto controlledlandfiDls.
Emissionof othernuisance: The plant willproduce regular emission of odor intothe air and noise.
Mitigation: The odor emissionwill be unacceptablewith the doublingof plant capacityin highlyurbanized area. In additionthe internationalsport complexwill be
GREATERTUNIS SEWERAGEPROJEC ENVONMETAL ASSESSMNT SUMMARY DALILATADJEROUN!l DECMBER5.1996 vii
locatedjust in front of the plant, across the road. Simple measuressuch as covering, evacuatingand treatingthe air uith biofilterswill be used.
6.5 PublicHearing and Communications:During Septemberand October 1996, ONIAS,in coordinationuith the Ministryof Environmentand ANPE,organized a public infornationprocedure in harmonywith legalrules. A seninar was heldwhere all the partics were invitedincluding community groups, professionalassociations, and non governmental organizations.The appraisalmission will assess the results of this procedure.The fill environmtal assessmentsreports are availablein the PublicInformation Center.
7. The Reuseof Treated Waste Water
7.1 Reuse Potentialin Tunis West: El Attar is located just over the water separationof the Mejerdariver basin with a large area of land suitablefor irrigation,located on the sides of the hillsoverlooking the Chaffrouvalley. This land (6,000to 8,000ha) is suitable for cultivationof fruittrees. Consultationwith the agriculturcdepartment proved that there are no technicaLsocioeconomic or culturalobstacles for effluent irrigationin this area. The activatedsludge treannent process coupled with disinfectonwill producean effluentwith a suitablequality for irrigation.
7.2 To be able to use the effluent,construction of a storagebasin and distribution works will be required. These should be the responsibilityof the agricultre sector. Preliminarystudies have located a suitablesite for a storagebasin closeto theplant. Increased storagecapacity, using the naturaldepressions of the landnearby the siteof the ,plantcould also be achievedat minimumcost. It is sought to make the effluentavailable for non-restrictive irnigationwher. the recon=nendedchanges in legislationare made. In the meantime,only restrictiveirrigation will be allowed- The fiu debit could be reused by 2011,creating up to 8,000ha and possiblyextending to the neighboringzone.
7.3 Reuse Potentialin Sud Meliane: For the existingplant of Sud Meliane,the reuse has currentlyattained 40 percentof the identifiedirrigable land (fruitand olivetrees), counting1000 ha and locatedin the closevicinity of the site. This low percentageis due to the defectivestate of the irrigationirastructure in place. Investmentsneed to be done to renew and/orrehabilitate this infrastructure. This could result in an increasein the presentpotential of reuseto a higherpercentage and openup the possibilityof extending the currentirrigation area by another400 ha, that havealready been identified.
7.4 Basedon the resultsof this first experience,though promisingconclusions on the potentialof the reuse practicein this area could not yet be drawn. A studyneeds to be conductedto shed somelight on this matter. The discussionswith the AgricultureDepartment regardingthe potentialfor the whole project(existing and extension)suggest that the area is rather sensitiveand confirmthe need for fiuiher study to explore the possibilities.The economicfeasibility of reuse in this area has also to be established. As the cost of irrigation water fromthe CanalCap Bon, used in this area, could prove to be a seriouscompetitor to treatedwater.
GRATER TUn SEWERAGEPROJECr ENVIONM ENTALASSESME SU "Y ALATAD=OU DEE 5.1996 viii
S. Conclusions
8.1 The environmentalreview concludes that the proposed projectwill generate overwhelminglypositive emironmental, social and economicimpacts. With its mitigation measures,the projectdoes not presentnegative environmental consequences. The mitigation plans stress the importanceof projectplanning during the differentimplementation phases, institutionalstrenghening and technicalperformance. ONAS, ANPE and the M,inistryof Agriculturewill oversee and evaluate,for their respectivepart, the complianceand the effectof theseplans. They willalso ensureproper coordination during implementation of theseplans.
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REPUBtLCOF TUNISIA
GREATERTUNIS SEWERAGE AND REUSE PROJECT
STAFFAPPRAISAL REPORT
Euvir l Asswae and Miduitl Plan
1. INTRODUCTION
1.1 Under dhe environmentalguidelines of the World Bank (Operaonal Directive 4.01), the GreaterTunis Sewerage Project has been classifiedas a CategoryA projecLThis report is an enmvronentalmview which mmarizes the environmentalimpacts of the proposedproject and providesrecomndons for impactmitigation under Amex C of the Directive.
1.2 Project Comonents The project, focussingmainly on the Tunis area, consistsof the following:
Sewerage TreaumentFacilities:
* The constructionof a wa te water treamtent plant in the Tunis West area for a capacity of 850,000 inhabitarts equivalent.
* The doubling of the capacity of the existing WWTfPof Sad Meliane in the southern part of Tmis by additional treaten capacity of 375,OODinhabitants equivalent
Rehabilitationand Exnion of Sewerage Networks:
* The reortion of the existing sewerage network of Tunis West area in order to revert a sizable part of the waste water flow to the new basin.
* The sgthenin of the primay networkof Tunis south and the constmctionof a liaison pipebetween the WWTP's of CotiereNord and Chutan
* The constuctionof sevenpumping stations.
1.3 The preparaionof thepmject has benefittedfrom a comprehensiveenvironmental study.The Sectral Envirmntal Assment (SEA)has provideda qualitativeframework on the situationof wastewater _magementanddisposal and how it couldbe imprved, not only in the ANNEX 10 Pagc 2 of 16
scopeof the projectat handbut also for futureinvestment in this tield. The ProjectSpecific Assessments(PSA) havc exarnined the difterenh site location alternatives, determined the design of the treabnentprocess for eachof theplants for the selectedlocations and identifiedthe related environmentalimpacts and possible mitigation measres. In additionto thiscnvironmental analysis, ONAS is requiredby Tunisianlaw to undertakean environmenalassessment to satisfythe requirementsdefined by ANPE..
1.4 This environmentalreview is basedon resultsof the environnentalassessments (PSA's)undertaken for eachof thetreatnent plants pmposed. the technical studies and the findings of thepre-appraisal mission. A seriesof technicalmeetings were hcd with ONAS, ANPE, the concerneddepartments in the respectiveministries of Environmentand Territorial Planning, and Housingand Equipmentand Agriculture to discussthe different alternatives of projectdesign and theirrespective impacts on theenvironment. Another series of meetingswere conducted with the Consultantswho undertookthe SEA and PSAs.A numberof field visits to investigatethe potentia problensof thesites were also made.
2. DESCRIPTIONOF PROJECT
2.1 TbeWaste Water TreatmentPlant of TunisWest
2.1.1 The projectenvisaged for thearea of TunisWest has been designed to reachfull capacityby theyear 2011. Theamount of collectedwaste water is estimatedat 59,000cubic meter perday with a pollutionload of 34,000BOD5. It will comprisethe constmction of:
(a) a primarytreatment plant at thedischarge point, includinga majorpumping station on theshore of SebkhaSejoumi;
(b) a secondarytreatment plant on a site nearthe village of El Attar located7,5 kan westuphill of theSejoumi site; and
(c) a pressurepipe for wastewater between the plant in Sejoumiand the plantat El Auar.
The treatmentforeseen is theactivated sludge process after prinmry sedimentation. The methane pmduced by the anaerobicdigester for sludge mineralizationwill be used in the treatmentplant makingit self-sufficientin energyrequirement.
2.1.2 AlsDenvisaged are the constuction and rehabilitationof 213 km of sewerage systems,allowing for 20,000 new hook-ups.For some parts of theexisting systems, the direcdon of flow will be revertedfrom existingovercharged treatment plants of CotiereNord and Choutrana to the proposedTunis West plant. The plant as described will cover a large area of the capital ANNEX 10 Page3 of 16 serving850,000 inhabitants equivalent; making it one of the largesttreatment plants in Tunisia.The achievablehook-up rale is estimatedto reach 75 percent. The type of treaumentchosen is the activatedsludge pmcess with anaerobicdigeston of sludgeand cnergyrecovery.
2.1.3 Ske Selection: The site selectionpmcess for die locationof this treatment facilitywas basedon three majorfactors: (a) the tradidonalcost-benefit analysis for optimizationof the choices both from the environmentaland the economicfeasibiliy standpoints; (b) he recommendadonsmade by the SEA and the provisionsof the planningtools in exercise;and (c) the potentialfor reuseof treatedwater (see paragraph3.4 of this annex). Four site locationswere analyzedand on the completionof this pmcess. the altemativedescribed (in para 2.1.1) was selected. The site and the wholecircuit of the effluent,which was inspectedin the field, presents the best locationmainly due to:
* the effluentwill have a longerroute beforereaching the sea. This has the advantage that more nutrientswill be naturallypurified;
* the potentialfor tated water reusefor agricultureis the gratest with the possibility of crating 6.000 to 8,000 ha of newlyirrigated land ( para 5.1- 5.2);
* the site is large and isolated,and presentsalong the effluentroute the potentialfor naturalstorage of the teated water for reusein agriculture;and
* lack of conflictingland uses.
2.1.4 The primarysite of the plant is locatedon SebkhaSejoumi. The latter, mostlydry except where unteated waste water is discharged.occasionally floods the residentialareas on its banksduring rainy weather. A protectiondike is pojected in the mne where the plant is plannod. The land, a lot of 10 ha, is publiclyowned and is in the processof being transfenredto ONAS. The whole ara is denselyurbanized with a numberof substandardsettlements. In the southemdirection is te villageof Sidi Hassineand in the other directions,the site is surroundedby busy roads(MC 37). Beyondtm roadsto the North lie the residentialareas and some light industriesto the west. The secondarysite at El Attar is a farmlandcultivated (cereals) by a public owned cooperadve. The land area needed for this part of the plant amountsto 100 ha. The nearest housesare at a distanceof 800 meters in the villageof El Attar. It is a semi arid area with saline, unusableground water.
2.2 The Waste Water TreatmentPlant ol TunisSou
2.2.1 The plannedtreatment plant of Tunis Southhas been conceivedas an extensionof the existingplant of Sud Melian,. It has boen designedto reach full capacityby the year 2011, when the amountof collectedwaste water is estmatedat 60.000 m3 per day with a pollutionload of 30,000 per day BOD5. The site of the current plant is sufficientenough to harbor the proposed ANNEX 10 Page4 of 16
extensionwhich will doubleexisting capacities. The achievablehook-up rate is estimatedat 75 percent.It will becomposed of:
(a) a pumpingstation and a pressurepipe of 4 kIn;
(b) therehabilitation of thesewer system of BenArous, currently overcharged; and
(c) a secondtreatment unit alongside, and identical to theexisting one using the same oxidationditch treatment system, as it hasbeen proven most feasible.
3. SUMMARYOF ENVIRONMENTALAND SOCIAL IMPACTS
3.1 The proposedproject will improvethe quality of sanitationservices, reduce environmentalpollution and mitigate health hazards from wastewater discharges in the national capitalregion thiough the facilitiesdescribed above. The nmstsignificant positive and negative imnpactsthat the project will generateare summarized below.
PositiveImpacts
3.2 The constructionof the treatmentfacilities will have a strongpositive effect on the overallenvironment at each proposedlocation. It will prevent the intense negativeimpacts on hunmanhealth and urban nuisancesassociated with the dischargeof untreatedsewage directly into the environmentfrom the sewage collectorsystem at discharge points and, hence, decrease the exposureto waste water relateddiseases (e.g., gastr-intesinal) of the affectedurban population. The rehabilitationand constructionof new sewers will enhance further the quality of life in the urban aras, especiallyfor those settlementswith insufficientinfrasucture networksand higher housingdensity. More than 150,000low incomepopulation are expectd to directly benefitfrom the project.
3.3 There will also be improvementof the water quality in the streams that flow thoughout the city. A major benefit is the pmtection of the groundwater resourcesfrom contaminationby unteated sewage and the preservationof the marine eniromnmentand other vulnerablewater bodies (lagoons,oueds and sebkhas)from further eutrphization. As a result, economicbenefit will occur in termisof increasedwater volume of good quality, and increasd fisheriesand tourismactivities along the coast near Tunis.
3.4 Furhermore, the treatmentfacilities will provide an opporunity to improve the controlof the industrialdischarges thrugh preteamen and connectionto ONAS sewers, as requiredby the tunisianlaw. For the Sud Melianeplant, potentialindustries with non-compliant waste wats havealready been identified.Within the frameworkof te FODEP activity, dtw ANNEX 10 Page 5 of 16 industrieswill benefitfrom a programwhich has materializedin the constructionof an industrial pretreatmentunit thatwill be connectedto the proposedplant.
3.5 Finally, it is worth noting that the environmentalaspect lays at the heart of the whole conceptionprocess of this project.It has. iteratively,influenced the design of the WWTP's. their site locationsand the qualityand use of their by-products. Two majorelements around which this processhas rvolved are the protectionof the environmentand the valorizationof the scare water resourcesthrough the reuseof the treatedwater. Indeed,in the caseof Tunis West' WWTP (pam 2.1.1 to 2.1.3) the flow of the existingsewerage system, for a sizablepart of the covered area, will be revertedto the newly identifiedwestem basin whereit will be treatedin the proposed WWTP. This, on the one hand, preventsthe effluentfrom beingdischarged into the Gulf of Tunis. the sea and other vulnerableRWB. On the other hand, it offers the advantageof using this effluentfor irrigationor rechargeof the groundwaterresources (par 5.1-5.4). Hence, generating significanteconomic and sociawbenefits.
NegativeImpacts
3.6 Duringthe constructionand rehabilitationof the sewer networkand the construction of the tr=m t facilities,impacts of minor importanceand magnitudeare expectedto occur. These impactsare tempomryand will include:disruption of trafficpattem in the servicedareas of dte city. interferencewith other urban infrastructures.disrupted access to residentialor/and other buildings,change in the landscap (loss of vegetation), noise nuisancesand air pollutiondue to dust fonration. The project activitiesdo not require any involuntary esttlement. During option of the treatmentplants, someof these minorphysical impacts will continueto occur. It is, actually.the case for odor and gas emissionsand noise.
4. MITIGATIONPLAN
4.1 The mitigationplan on pages7 to 15 of this annex, presentsa detailedlist of all the possible impacts tha could occur in tis project during the different phases of the project implementationcycle, comprising:(a) rehabilitationand constructionphase of the sewer networks; (b) the constructionphase of the treatmentfacilities; and (c) the operationphase of the plants. For each of the possiblesource of inpacts or type of projectactivity, the nature of the impact is describedand actionsfor remedyare listed. The responsibilitiesfor these actionsare defined and the concened agenciesidentified. An enviromnentalmanagement plan is also proposed.
4.2 A monitoringprogram is recomnded for the sewer networksand the treatnent plants(mitigation plan). In additionto what is currendydone by ONAS, thomughits laboratDries, specific monitoringof the pmperties of both the influent and effluent will be performed and assessedagainst the nonns for agriculturereuse. The use of the sludge as fertilizer is strongly ANNEX 10 Page 6 of 16
recomendedThemonitoring program will also corntnmeto evaluateall possibleother impawts on the environmentincluding ambient air, soils and vegetation,znd the RWBsdownstream effluents.
4.3 A program for institutionalstreghening of ONAS' technical,organizational and managerialcapacities is also foreseen.It will cover the regionaldepartments and will include a Geographic InfonmationSystemn conmponent. Furthemiore, reinforcenient of the existing institutionalmachinery is recomnmededalong the lines of the SE' findingsas describedin pam 1.10 to 1.15 of the SAR.
4.4 The main impacts and related mitigationmeasures for the treatment plants are sunmarizedbelow:
The TunisWest Treatment Plant:
Em'issionof pollutedwater: The proposedprojerct will prevent emiission of raw wastewater in the served areas from currendy overchargedplants to a very imiportantextent and, hence, improve considerablythe sanitationof a sizablepart of the capita urban areas. It will also relieveSebkha Sejouniifromn the current dischargesand possibleflooding of its banks. However, it may present somierisks. The major one rmains fth dischargeof the effluent into the enviromnmentif the reuse optionis not pursued. The plant is designedto producea disinfectedeffluent with a qualityto meet the standardsfor irrigation. It will, however. contain high nutrient concentrationswhich will contributeto the ongoingaccumulation of nutrientsin the Gulf of Tunis. The latter. being highly vulnerableto eutrophization,this will cause furthe deteriorationof the sea grass fields and bloom of algae. The effluentwill also affectthe Mejerdabut to a lesser extent tha the Gulf of Tunis. It is estimattedthat the effluentwill increasreby I1%the flow of this sectionof the Mejerdaadding to its alreadyrich loadof nutrients.
Mitigatio: The nutrientswill be removed,by means of tertiary treatment,if the effluentis to be dischargedinto the oueds and, in final stage, into the Gulf. Alternatively,other destinationsof the effluentwill be examnined.
Emnissionof waste: The plant will also producean estimated90 ff3 per day of stabilfized,dried sewage sludge tha will be sold to fanners or else taranportedto a controlled dumipingsite. Consinuctonof a solid waste trament plant under study is proposed for the close vicinity of El Attar site.
Mititaton The sludge producedso far by ONAS' existingtratmuent planits has been of good quality and has been in high demand by farmers. However, irrgular emlissionsinto the sewer systms could drasticallychange its qualityas well as fth qualityof the effluent,which in turn will be damagingto the environmientand public health. ONASmonitors carefully sewage collected at each of its operatingWWTP's, throughon-site laboratories and a sophisticate centrallaboratory. ANNEX 10 Page 7 of 16
Emissionsinto the air The wastewater treamientplant will also have localimpacts in the fonn of odor and gas emissionsinto the ambientair as well as noise. At El Attar, odor will be eiitted by the sedimentationbasins causing nuisance up to 500 metersbeyond the plant's limits. The meane- driven generatorfor aertion will cause enissionof NOxet C02. A torch(5 m height) will be neededtoo for flaringmethane surplus.
Mitigation: At theSejoumi plant, odor enissions will be controlledby coveringthe equipment and teating the air in a biofilter.In El attar, the site is isolatedand there are no houses in the close vicinity.
UrbanPlanuing Aspect: In additionto the alreadyexisting urban settlementsin the vicinityof the plant at Sejounii,the area is plazned. accordingto the provisionsof the MasterPlan , to be furtherdeveloped into a residentialquarter with averageto highdensity.
Mitigation: It is foreseento instal a buffer zone of no less than 500 metrs aroundthe site to preventany negativeinipacts to the healthof the ibitants of the plannedresidential development. Withinthe scope of this project, theDeparmet of Urban Planing will be notified in order to makeprovision for such measureinto the MasterPlan, curently under study.
TheSud MelianeTreamt Plant
Enissionof pollutedeffluent The effluentwill be dischargedinto the Oued Melianeand then into thesea. It will have an adverseeffect on the marineecosystem if the nutrientsare not removed. Midgation Additionalteamen is neededif thereuse progam does not materializeand the sea outflls are unjustifiable.
Enissionof waste: It is estmated that theproduction of sludgewill reach38 m3per day. In this aea of Turis south, thesludge currendy produced is beingused entirelyby famiers.
Mitigation: If unused,the sludge will be dumpedinto controlledlandfills.
Enission of other nuisance: The plant will produce regular emissionof odor into the air and noise.
Mitaion: The odor emiissionwill be unacceptablewith te doublingof plant capacityin highly urbanzd area In additon theinternational sport complexwill be locatedjust in frontof theplant, acrss the road. Simple meawressuch as covering,evacuating and treatingthe air with biofilters will be used. ANNEX 10 Page 8 of 16
5. THE REUSEOF TREATEDWASTE WATER
5.1 ReusePotential in Tunis West El Attar is locatedjust over the water separtion of the Mejerdariver basinwith a large area of land suitablefor irrigation,located on the sides of the hills overloolingthe Chaffrouvalley. This land (6,000 to 8,000 ha) is suitablefor cultivationof fnrit trees. Consultadonwith the agnculturedeparment proved that there are no technical,socio- economicor culturalobstcles for effluentirrigation in this area. The activatedsludge treatment processcoupled with disinfectionwill producean effluentwith a suitablequality for irrigation.
5.2 To be able to use the effluent,constuction of a storagebasin and distributionworks will be required. These shouldbe the responsibilityof the agriculturesector. Preliminarystudies have locateda suitablesite for a storagebasin close to the plant. Inclreasedstorage capacity, using the naturaldepressions of the land nearbythe site of the plant could also be achievedat minimumcost. It is soughtto make the effluent availablefor non-restietive irrigationwhen the reconmended changesin legislationare made. In the meantie, only restrictiveirrigaion will be allowed. The ful debit could be reused by 2011, creaing up to 8,000 ha and possibly exmendingto de neighborngzDne.
5.3 Reme Potental in Sod Meian: For the existingplant of Sud Meliane, the reuse has currmly tained 40 percentof the identifiedirrigable land (fnuitand olive trees),counting 1000 ha and locatedin the close vicinityof the site. This low percentageis due to the defectivestate of the irigation iraiu in place. Invetments need to be done to renew andior rehabilitatethis infrastructure.This could result in an increase in the present potential of reuse to a higher pentage and open up the possibilityof extending the current irrigadonarea by another 400 ha, that have alreadybeen identified.
5.4 Basedon the resultsof this firt experieice, thoughpromising, conclusions on the potenial of the reuse pracdce in this area could not yet be drawn. A study needs to be conductedto shed somelight on this matter. The discussionswith the AgricultureDepartment regarding the potential for the whole project (exising and extension)suggest that the area is raer sensitiveand confinn the need for furter studyto explore the possibilities.The econoiuc feasibilityof reuse in this area has also to be established. As the cost of irrigationwater from the Canal Cap Bon, used in this are could prove to be a seriouscompetitor to reated water. ANNEX10 Page9 of 16 6 CONCUSIONS
6.1 The envirorwnmt review concludes Xa the proposed project will generate ovwhenlminglypositive environmental, social and economicimpacts. With its mitigation meaures,the project does not presentnegative enviromnental cons s. The mitigationplans stressthe importanceof projectplaning duringthe differentimpleenion phases,instituional strengteing and wechnicalperfonnance. ONAS, ANPE and the Ministryof Agriculturewill overseeand evaluate, for theirresective part, thecompliance and the effect of theseplans. They willalso enase propercoordination during implementation of these plans. ANNEX 10 Page 10 of 16 7. MITIGATIONPLAN
Actvite and Origns of En as Maon Measures - I__ Rehabiatio DandCOof the Sew_ragNetwork 1. site r _ (beforeand after) Pisive aets Ao/R bilis
* excavationof tweches @ inprovementof rads w ONASwill ensre works conditions do not take place at night @access to undevelopedareas r minimi dust formaion * openingaccess roads by meansof water spraying Negative nmpacts w minimizeareas of * rehabilitationof mads and de-vegetationand restorethe pathways @ increasednoise levels, lands ter completionof mudand dust works 0 disruptionof accessto w work out acceptable homes alternative tansport 0 localtraffic patterns and routing tr ort routesdismupted r ONASwill makesure that 0 deteriorationof the dtesemeaes are adheredto landscapeand the visual during implemention as part aspectsof the affected of the enforcemn of the areas utilityand buildingcode (refleced in the bidding documents) 2. Constructionand Instlation Phase Positive mss A=
@Creation of employment w Same set of actionsas § generationof local above * nstLation of sewersand revenues(supply of e impactstied to storageof pressuremins materis and services) buildingmaterials and * storageand tansport of equipmentcould be avoided matrials NegativeImts though siteplanning * constuion of pumVing 0 same set of impacs as stations above * waste angment 0 risk of waste water spills ANNEX10 Page 11 of 16 andcontaination e obstructionof roads,side- walksby thestorage of site materialsand equipment.
3. User HookUps PositiveIbmacts A;i o lc or throughsite and time * excavationon streetsand § inmprovementof sanitary planning,in-4 -ne worksand, sidewalks. andhealth conditions therefore,disnrption of § creationof local householdactivities could be employment minimie. * installationof home-to- strut conduits. NegativeImpats wONASwill ensure ta contracrs willmake pmper @disuption of household provisionsof thesemeawres. activities 3 accessto homesand buildingsdisrupted
4. M_w____ PositiveImpacts ______
* sewerrepairs @ geneaion of local e Tine andsite planning to rvenues andenmployment minmMiedisriptions * maitance of electic Personneltraining mechanicalequipmen NesaiveIn restoredamage done t otherinfrastucture * leaksand spills e increasedday time e applyemrgZency and nuisances(noise, dust,traffic safetyprocedures andaccess disrption) wONASwill assume taining of persomneland the applicationof abovemeasums alongwith the municipalities for otherifras ures. WasteWater Treatment Plan Consrction Phae
IPositive Actions/Rsonsibilities ANNEX10 Page 12 of 16 or Sameset of acwionsas * pretreatmentplant on the @ generationof local std above, in addition: bankof SebkhaSejouni evenuesand emnployment e specificbuilding *•teamentplant a El attar Negaive mpact regulaons fordis Wpeof soil existare appliedas wellas * In additonto this, Avhat 3 risksof constructiondebris properprovisions against the wasdescribed above in the dumpedin theSebkha risk of fboding siteprparation and ® soilof Sebkha'sbank ew makesure that the debris constructionphases for the couldengender stability are not dumpedinto the sewernetork applies. problems alreadysensitive Sebkha @ potentialflooding of the w ONASto makeprovision Sebkha'sbank of theseitems in the bidding documentsand e ONASand the Municipalitycontrol tie issue of wastedischarge. Waste waw Treatment Plant Operation Phase 1. PyKi EuvirolrAit _ Forboth WWTP's .Poitive IOpacts or the sewersand pipes Undeoumd Water planmedor to be rabilitated 0 proectionof undegrund in the projectwill be made waterand impmvment of and in3talledwith high * sewernetwork quality waprofness to mimize any Q imprve publichealth and leakint the aquifers * theWWTP itself, eaviromnentconditions especiallythe drying beds The sameapplies to the NegativeInwacts buildingand isallations of * thedischage of tread the plants. waterin the environment @ possibleleaks and conmintionn wONASis in theprocess of * infilation though fhe completnga computer mmscof treatd water ® waterproofWWTP assistedsystem for the installationsis a deterinant mageme of thesewer factorfor contamnationrisk network. of groundwater e ONASand Ministry of @ contminationthroughthe Agriculaur makepwrvisions infrastructurfor to rnuinze infiltralions a
ANNEX 10 Page 13 of 16
reuse(conduitsand basins) and diroughinfrast re for l afterirrigation taed waterreuse (pipe cortions, waterproof 0 in caseof dischargein the materials) environment,possible aquifer contamsinaton e ONASwill makesure that levelsof nutrientskept very lowin caseof dischargein te environment.In TunisWest, azoteconcentration would be keptlower dtan 25mg/I
sofae Waters Positive s Actios/
@the project will reduce e in theabsence of sea * SebkhaSejomni considerablythe impat on the outfal, additionaltretment Sebkhain the wastewater forthe removalof P andN of theTuis Westarea will be is essential. evertedto t plant e Thisrisk is to be @ theproject will reduce mmi by meansof considerablythe inpact on the sunity precautions * the Lac Sud lac Sud sincethe waste waters incorpod in the designof of theTunis South area, te plantsand a sounddaily arentdy dischargedin the monitoringprocess during [wcwill be tated in Sud operaion. Meliame.
Neative bcpaM e-r Thisimpact will be eiminatedby mans of 0 in caseof disharge in the mriary eunen¢ ONASis * the gulf of lTnis Gulf, there is risk of reponsible for this task eutrpr ion itluding nu testingto be ANNEX 10 Page 14 of 16
- Accidentaldisfutioning nmonitoredby ANPE. in the pumpingstations and pressuremains or/and emergencysitations could cause spillsor voluntary dischargein de Sebkha,in OuedSud Meliae and the enviromnentwith potential healthhazards
0 in the absenceof reusefor TunisWest, die dischargeof m Other receivingwater the effluentwill flow in the bodies oueds downstrem the Gulf, csng additionalpolluton.
Air luiutioland Other PoIdtve AIpincts Acsons/
* Odor emissions @Quality of the ambientair e This willbe controlledand will be impmvedby the minimid by covering the projectin all the residential sourcesof odors and treating areasto benefitfrom the the capturedair form ese sewera infrastructure. sourcesby a biofilter.This also requirs sound Neat Imaagement of the plant.
* noiseand vibrations @ In the WWTP siteand its wNoise will be reducedby vicinity, the odors will be plawingthe relatedequipment inevitable.This is quite into insulatedbuildings. importantfor Sud Meliane ONASalready being in an urbani2Warea and madeprovision to incorporate in view of the projectedsport tis nmsure in fte design. facilityin the closevicinity. B Urbanpla meae to 0 The impats of NO%,SO2 be enforcedin the form of a and C0 are not very buffer zone arund the plant importantdue to the low along withvegetatiors to * Odwerenummissions concertationmitigate dhse impnts, the visualnuisance and risk for contamation. ANNEX 10 Page 15 of 16
0 In caseof concentrion of w ONASwill trace backthe pollutantsin the sludge, there sourceof pollutantsand take is risk of soil contami-nation appropriatemeasres. Sludge whenused for agricultureor to be disposedof in controlled otherrisks whendisposed of. landfills. EnvironmentalManagement
Moz,koru of the WWTP Nrfonnance
Neaativebcts Actions/R * for operationof all poposed tretment units. § AlthoughONAS has set up w introducethe monitoringof a decentralizedsystm at the te pzameters:N-Kj, pH, plant levelwith a labomtory alklinity, greasymaterials, ting daily measuremn of MES, gaz formaion and the the differenttreamt drinage systemsof the diying operations,monitored by the beds (min 1/moth). Regionaland central e The waterquality of the laboratories,these additional matration basinto be stepsare recommended: monitoredby ONAS/Agriculturefor the relatedparmets. e Reportingsysten of this monitoringactivity to be established.ONAS to request detailedmonitoring plan for each plant as partof plant design e ANPE to controlthe results and make owmchecks 3 to 4 times/year. e ONASconcened personnelto uwdergotraining for soundmmaagemnt of treabent_ plants waterBodies
Negative ~~Acdions ANNEX 10 Page 16 of 16
* The waterbodies 0 potendialnegative impacts e ONASwill take measums downstram from the of the effluentson the to monitorthe impactsof the dischargepoint receivingbodies in case of dischargeof the effluents * Soilsand vegetationthat dischargewithout appropriate outsidethe plant boundariesin receivethe effluent. treament, especiallyfor those coordinadonwith ANPE, and classifiedas veryvulnerable the Healthand Agriculture authoritieswith a reporting systemand proposalsfor _remedial actionswhen needed. Conceptionof Trement or ONASto cooperatewith the concerneddepartments of Agriculture,PublicHealth, EnvironmentMinistries and localauthorities to determine the systen of tneament of each new plantproject and its desiredlocation.
m U nlR0.^