Turkey - Istanbul Sewerage Project

Document of The World Bank i i FOR OFFICIAL USE ONLY Report No. 3836a-TU STAFF APPRAISAL REPORT TURKEY ISTANBUL SEWERAGE PROJECT May 3, 1982 Regional Projects Department Europe, Middle East and North Africa Region This document has a restricted distribution and may be used by recipients only in the performance of their official duties. Its contents may not otherwise be disclosed without World Bank authorization.  CURRENCY EQUIVALENTS (As of December 1981) k Currency Unit - Turkish Lira (TL) US$1.00 - TL 130 TL 100 - US$0.77 MEASURES AND EQUIVALENTS 1 millimeter (mm) - 0.04 inches (in) 1 meter (m) - 3.28 feet (f) 1 kilometer (km) - 0.62 miles (mi) I square meter (m2) - 10.8 square feet (sq. ft.) I hectare (ha) - 10,000 square meters or 2.47 acres (ac) I square kilometer (km2) - 0.386 square miles (sq. mi.) I liter (1) - 0.26 US gallons (gal) 1 liter per capita per day (1/cd) - 0.26 US gallons per capita per day (gcd) I cubic meter (m3) - 35.3 cubic feet (cu. ft) ABBREVIATIONS AND ACRONYMS ISKI - Istanbul Water Supply and Sewerage General Directorate DSI - The State Hydraulic Works IB - Iller Bankasi (Bank of the Provinces) YSE - Directorate for Roads, Water and Electricity ISI - Istanbul Water Authority Four Drainage Areas - Yenikapi, Kabatas, Uskudar and Kadikoy-- Kartal FISCAL YEAR January 1 - December 31  FOR OFFICIAL USE ONLY TURKEY ISTANBUL SEWERAGE PROJECT STAFF APPRAISAL REPORT J Table of Contents Page No. I. SECTORAL CONTEXT ....... .......................... I Country Background ............................... I Sector Organization and Development .............. I Water Supply and Sewerage Service Levels ......... 3 Service Levels Objectives ..... ................... 3 Sector Investment Program ................ . . ....... 4 Previous Bank Involvement ... 5 II. POPULATION, SECTOR SERVICES AND DEMAND IN PROJECT AREA .......... ......................... 5 Project Area ....... ................. 5 Population Projections ..... ............... 6 Population Served and Standard of Water and Sewerage Services in Project Area . . 6 Existing Sewage Disposal Systems and Receiving Water Bodies .......................... 8 Demand for Services ...... ............... 8 III. THE PROJECT ...................................... 9 Genesis ............................... 9 Sewerage and Sewage Disposal Master Plan ......... 9 Project Objectives ....... ........................ 10 Technological Aspects ............................ 11 Project Composition and Description of Project Components ............................................ 11 Cost Estimates ........ ........................... 13 Project Financing ....... ......................... 15 Project Implementation ...... ..................... 15 Procurement .... .................................. 17 Disbursements .................... ................ 17 This project was appraised in December 1981 and the report was prepared by Messrs. Aziz Kassab, Lars Rasmusson and J.A.C. Guy Prenoveau. This document has a restricted distribution and may be used by recipients only in the performance of their official duties. Its contents may not otherwise be disclosed without World Bank authorization.  - ii - Table of Contents (Continued) Page No. IV. FINAINE .19 Past and Present Performance .19 Tariffs .19 Future Financial Performance ................. 20 Monitoring System........... ..... 21 V. THE IMPLEMENTING AND OPERATING AGENCY .22 ISKI's Creation .22 Organizational Structure .22 Staffing .22 Training .23 Accounting, Billing and Collection .24 Audit .24 Insurance .25 VI. ECONOMIC ANALYSIS AND PROJECT JUSTIFICATION 25 Economic Analysis .................., ,, 25 Average Long-Term Incremental Costs .26 Project Impact on Poverty Group and Affordability Analysis .26 Project Merits and Justification .27 Project Risks ........ . 28 VII. AGREEMENTS REACHED AND RECOMMENDATIONS .28 ANNEXES Annex I - Table 1: Salient Data and Service Levels - Table 2:. Design Data - Table 3: Project Cost Estimates - Table 4. Project Cost Estimates Contractwise - Table 5: Estimated Schedule of Disbursements - Table 6: Opening Balance Sheet as of December 31, 1981 - Table 7: Income Statements - Table 8: Table of Sources and Applications of Funds Statement - Table 9: Balance Slheet - Table 10: Operating andl Financial Monitoring Indicators - Table 11: Proposed Tariff Schedule for 1982 - Table 12: Average Imacremental Cost Calculation  - iii - Table of Contents (Continued) Annex 2 Major Assumptions Used in Financial Projections Annex 3 Additional Information Available in Project File CHARTS Chart No. 23569 Project Implementation Schedule Chart No. 23570 ISKI Organization MAP S IBRD No. 16225 Istanbul Sewerage Project Greater Istanbul Municipality Master Plan Proposal and Drainage Zones IBRD No. 16226 Istanbul Sewerage Project Yenikapi Drainage Zone Existing and Proposed Sewerage and Sewage Disposal Systems  * X - S ^  TURKEY ISTANBUL SEWERAGE PROJECT STAFF APPRAISAL REPORT 16 I. SECTORAL CONTEXT Country Background 1.01 The total population of Turkey in 1980 was about 45 million with 24 million (56%) and 21 million (44%) living in urban and rural areas res- pectively. The population growth rate, which during the period 1970-1979 averaged about 2.5% (4.1% for urban and 0.3% for rural areas), is projected to gradually decrease and the population is estimated to reach about 58 million by 1990. Istanbul /l and Ankara are the two largest cities in the country with about 3.2 million and 1.9 million people respectively, or 21% of the total urban population. 1.02 The country's total area is about 780,600 km2 with 97% in Asia and 3% in Europe. In physical terms it may be broadly divided into three regions: (i) the 7,200 km long coastal region, with precipitation exceeding 600 mm per annum, is the most industrialized and developed area; (ii) Central Anatolia, an arid plateau with precipitations between 250-300 mm, is sparsely settled and less developed than the first region; and (iii) Eastern Anatolia, a mountainous region with a harsh climate, is the least developed. 1.03 Water resources are abundant with only minor areas of scarcity. Underground water is generally available in large quantities. Sector Organization and Development 1.04 Traditionally, the provision of water supply and sewerage services has been the responsibility of municipalities and village councils. How- ever, the local bodies have lacked the financial resources and, except for a few major cities, the technical capabilities for discharging this function. Thus, planning, design and construction of new systems have been gradually absorbed by three central government organizations, which were originally established as advisory and financing agencies. These organizations are: (a) The State Hydraulic Works (DSI) in the Ministry of Power and Natural Resources which is the agency responsible for national water resources and is concerned with water supply development /1 Refer to previous Istanbul Municipality (para. 2.04).  -2- for towns with a population exceeding 100,000, presently 27. DSI has its headquarters in Ankara and operates 21 regional offices. (b) Iller Bankasi (Bank of the Provinces (IB)) which is the autonomous corporation responsible for water supply development for towns with a population of less than 100,000 and for sewage disposal in all urban areas except Istanbul. IB has its headquarters in Ankara & and operates 16 regional offices. Its shareholders are the muni- cipalities. (c) The Directorate for Roads, Water and Electricity (YSE) in the Ministry of Rural Affairs and Cooperatives which is responsible for rural programs including the provision of community water supply, but excluding rural sanitation for which no agency has been specifically assigned. 1.05 As could be expected under the existing sector organization, scarce experienced staff had been dispersed sometimes creating serious gaps or unnecessary overlapping. Alternative sector arrangements had been con- sidered, in particular at the 1978 Conference on Planning and Development of Community Water Supply and Sanitation in Turkey. Major changes, how- ever, were not to be made until, by Executive Order of February 1981 sanctioned by law of December 1981, the new Government created greater municipal areas. This is expected to improve planning and implementation of municipal services. 1.06 With the creation of greater municipal areas in 1981, the water supply and sewerage services of the small municipalities were merged with those of the nearest large urban centers, such as Istanbul, Ankara, Izmir, etc. In the case of Istanbul, the water supply services of 24 surrounding municipalities were merged with those of ISI, the semi-autonomous Water Supply Authority established in 1933, while all sewerage services were vested into a municipal Sewerage Department. ISI was responsible for works operation and maintenance as well aLs for bulk supply for a score of small municipalities, while DSI has undertaken project preparation and implementation. 1.07 The most important institutional reform, however, and one which may set the pattern for other urban areas, was initiated with the creation by Law 2560 of Novexnber 20, 1981, of the Istanbul Water Supply and Sewerage General Directorate (ISKI), as an autonomous entity responsible for the planning, design, construction, operation and maintenance of all water supply and sewerage facilities in Greater Istanbul. Of particular signi- ficance, the new law gives ISKI's General Council the right to set water tariffs and sewerage charges without, as in the past, having to seek prior approval of the Municipality or the Central Government. The new arrange- ments should enable ISKI to meet its financial obligations and to finance a gradually increasing share of its investments with internally generated funds (para. 1.18).  - 3- Water Supply and Sewerage Service Levels 1.08 Estimated water supply service levels (1979) are as follows /i: Urban Population Rural Population Total Population millions % millions % millions % Adequate supply 14.4 63 12.9 63 27.3 63 Inadequate supply 3.2 14 4.5 23 7.7 18 No public supply 5.3 23 2.8 14 8.1 19 22.9 100 20.2 100 43.1 100 Population with adequate supply are those served by public piped systems (either house connections or standpipes) and receiving a satisfactory service from quantity and convenience viewpoints. Inadequate supply means insufficiency and intermittence in water availability and distribution. 1.09 Sewer systems exist only in the major cities serving about 4.4 million people or 18% of total urban population. None of these systems include treatment, and only a few have adequate disposal facilities. Precarious sanitary conditions prevail, particularly in high density, low income, urban areas. 1.10 The insufficiency of sewage systems and the indiscriminate dis- posal of domestic and industrial liquid and sol-d wastes have caused serious deterioration of rivers and coastal sea waters increasing consider- ably the dangers of contaminating drinking water supplies. According to public health statistics, 38% of water samples tested (during 1977) were unsatisfactory from a bacteriological viewpoint. Water related diseases are endemic with outbreaks occurring annually. In 1977 the total recorded number of such cases exceeded 15,000 with 143 deaths. In 1970, a cholera epidemic in Istanbul caused 52 deaths, and was attributed to unsatisfactory sanitary conditions. Service Levels Objectives 1.11 The water supply and sewerage service level objectives as formu- lated during the 1978 Conference (para. 1.05) would be: (i) by 1990 the total urban and rural populations would be covered with adequate water supplies; (ii) by 1990 the total rural population would be covered with satisfactory excreta disposal facilities; and (iii) by 2000 total urban population would be provided with satisfactory sewerage and sewage disposal facilities. 1.12 The above objectives (para. 1.11) are ambitious and unlikely to be met in the time frame originally envisaged. The National Action Committee set up in connection with the U.N. Water Decade has established a number of /I Source: Community Water Supply and Sanitation, Rapid Assessment of Current and Prospective Sector Development, WHO, 1979.  - 4 - priorities. Their realization, however, will depend in large part on available financial and human resources. These matters will be addressed further in a sector study and during project supervisions. Sector Investment Program 1.13 The water supply and sewerage sector investments during the third Five Year Plan (1973-1977), which represented about 5.5% of total public investments, were divided between urban water supply, rural water supply and urban sewerage in the proportions 50%, 39% and 11% respectively. 1.14 The investment program for the fourth Five Year Plan (1978-1982), which represents about 3.5% of total public investments, shows that. (i) sector investments would be divided between urban water supply, rural water supply and urban sewerage in the proportions of 37%, 46% and 17% (actual for 1978-80, 45%, 35% and 20%) respectively; and (ii) the amounts allocated during the first three years represent about 80% of the funds requested. 1.15 A comparison between the 1973-1977 and the 1978-1982 investment plans indicates that rural water suipply and sewerage are getting increased priority over urban water supply, and that the sector's share of total public investments is decreasing. During 1973-81, sector investments for water supply and sewerage in the Istanbul Municipality represented about 8% and 1% respectively of total country sector investments. The budget allocations are inadequate compared to the needs of the sector and their proportional reduction would be caused by the competing demands from other sectors considered more important for the country's economic recovery. 1.16 The sector investments have been planned in five year increments rather independently by the different sector agencies (para. 1.04) and although budgets have been prepared, the utilization of the funds could be improved by better inter-agency coordination. Capital investments have been financed by Government grants or low interest rate loans, which in the past have seldom been repaid. 1.17 Except in the major cities, water tariffs have been insufficient to even cover operating expenses. Sewer connection charges have been levied but sewage disposal service has so far been free. Thus operational and maintenance costs for sewerage and sewage disposal systems and to a certain extent also for water supply systems have been covered by municipal budget allocations. 1.18 It is the Government's intention to enable the sector entities to become financially viable through appropriate tariff levels for water supply and the introduction of sewerage charges. Water Supply and Sewerage entities are also expected to finance a gradually increasing proportion of their investment requirements through internal cash generation.  -5- Previous Bank Involvement Prior Bank involvement in the sector consists of. (a) Loan 844-TU of June 30, 1972 for US$37.0 million to the Government and passed on to the former Istanbul Water Administration (ISI) for the expansion of the Istanbul water supply system. The loan was fully disbursed as of March 1982 and the Project Completion Report is under preparation. The project implemented by ISI was substantially delayed due to institutional and financial constraints,and ISI's difficulties in attracting and retaining competent staff. The additional water supply provided under the project helped to maintain a relatively good level of service which is expected to improve considerably as leak detection and other improvements under way start yielding results. More importantly, the project contributed to institutional development in the establishment of ISKI as an autonomous entity responsible for the Greater Istanbul Municipality area (para. 1.07). This will facilitate the rational planning, execution and financing of water supply and sewerage services. The experience gained from the implementation of the Water Supply Project has been incorporated in the proposed project to ensure timely execution and financing arrangements. (b) IDA Credit 324-TU of June 30, 1972 for US$2.3 million for the preparation of master plans and studies for urban development programs in Istanbul. This Credit partly helped to prepare the Camp-Tek-Ser report on sewerage and sewage disposal (para. 3.01) and review the master plan for sewage disposal in the Istanbul area. (c) Loan S-15TU of December 12, 1979 for US$6.0 million to the Government and passed on to TKI (National Turkish Coal Board) to develop methods of manufacturing smokeless fuel from lignite, and to investigate other possible technologies which may provide a cleaner fuel in order to reduce air pollution in Ankara. This project is still in the early implementation stage. II. POPULATION, SECTOR SERVICES AND DEMAND IN PROJECT AREA Project Area 2.01 Istanbul, the capital of the former Byzantine and Ottoman Empires and one of the oldest historical cities of the world, is the foremost cultural, industrial and economic center of Turkey.  - 6 - 2.02 Industrial growth started on the European side around the Golden Horn and later spread to the Bakirkoy area in the direction of the airport along the northe'rn shore of the Sea of Marmara. On the Asian side of Istanbul, industrial growth has concentrated mainly in the Kartal area, away from the densely populated areas. Greater Istanbul's industrial growth has been accompanied by heavy migration and accelerated proliferation of large squatter settlements (Gecekondus). Map IBRD 16225 shows an outline of the Greater Istanbul area. 2.03 The physical component of the project will mainly be located in the area of the medieval walled city, the most densely populated area of Istanbul. This area is bounded by the old city wall to the West, the Golden Horn to the North, the Bosplhorus to the East, and the Sea of Marmara to the South. Population Projections 2.04 Population projections as prepared by the Istanbul Master Plan Bureau through the year 2000 have been shown separately for previous Istanbul Municipality, 24 surrounding municipalities and Greater Istanbul Municipality (para. 1.06). Istanbul 24 Surrounding Greater Istanbul Average Annual Year Municipality M!lunicipalities Municipality Growth Rate --------------Poplation ( '000)------------ % 1975 2,547 1,185 3,732 -'4.1 1980 3,122 1,449 4,571 3.5 1985 3,405 1,981 5,386 3.0 1990 3,632 2,637 6,269 2.6 2000 3,930 3,909 7,839 These projections take into account existing master plans for urban devel- opment, and other factors such as growth potential, land availability and industrial development. Population Served and Standard of Water and Sewerage Services in Project Area 2.05 The population served by water supply and sewerage facilities as of 1980 are summarized below. Annex 1, Table 1 shows more detailed data regarding sewerage services.  -7 - Istanbul 24 Surrounding Greater Istanbul Municipality Municipalities Muncipality '000 % '000 % '000 % Water Supply. - connections 2,872 92 1,150 79 4,022 88 - standposts 94 3 188 13 282 6 - own supplies 156 5 III 8 267 6 Waste Disposal; - connections 1,967 63 362 25 2,329 51 - septic or hold- ing tanks 1,155 37 1,087 75 2,242 49 2.06 Pertinent comments on the existing water supply systems may be summarized as follows: (i) the water supply is obtained from 4 major and about 10 minor surface water sources with a maximum production capacity of 900,000 m3/day; (ii) the proportions of domestic and industrial/commercial consumption and unaccounted-for water, are about 42%, 18% and 40% /1, respectively; (iii) the water availability at domestic connections averages about 100 1/cd; and (iv) the water supply is intermittent in about 15% of the supply area and operation and maintenance standards can generally be described as inadequate. The production capacity could be considered as sufficient for the time being while the water distribution facilities need to be improved and extended. 2.07 The major components of the existing sewage systems are as follows: Istanbul 24 Surrounding Greater Municipality Municipalities Istanbul Municipality Connections (nos) /2 300,000 87,910 387,910 Laterals (km) /3 1,500 1,000 2,500 Interceptors (km) 150 50 200 Map IBRD 16226 shows major existing sewerage works in the Yenikapi drainage area (para. 3.05). 2.08 The sewage systems are concentrated in centrally located high density areas while holding and septic tanks are more prevalent in fringe less densely populated areas. The older sewers were combined for sewage and storm water, but since 1960 separate sanitary sewers have been laid. Innumerable and inadequate holding and septic tanks, antiquated sewers and /1 Unaccounted-for water is the difference between water produced and water sold. It includes inaccuracies in water metering, non-metered water used at public hydrants, standpipes, illegal connections and leakages. /2 Based on number of household connected. /3 Secondary sewage systems.  - 8 - lack of proper maintenance equipment, combine to make the operation of the systems expensive and difficult. The Istanbul Municipality has so far not been able to operate its system satisfactorily. 2.09 Accurate data on sewerage coverage of different population groups are not available, but the lack of satisfactory sanitation is particularly prevalent in high density and in squjatter areas (para. 2.02). Existing Sewage Disposal Systems and Receiving Water Bodies 2.10 The Greater Istanbul area is divided into 14 major drainage zones with sewage flowing by gravity to the nearest receiving water body. The outfall mains end close to the shorelines, which (except in the Bosphorus) provide limited dispersion and causes extensive shore pollution. The problem is aggravated by indiscriminate solid waste disposal. 2.11 About 90% of the effluents goes into the Golden Horn and the Sea of Marmara and 10% into the Bospihorus. About 80% of industrial waste is discharged into the Golden Horn and along Bakirkoy into the Sea of Marmara, the remaining 20% is discharged in the Bosphorus and the Asian side of the Sea of Marmara. 2.12 The water flows from the Aegean Sea through the Dardanelles, the Sea of Marmara and Bosphorus to the Black Sea as a bottom current. Conversely a surface current witlh lower water salinity flows from the Black Sea to the Aegean Sea. 2.13 The Golden Horn receives a significant domestic and industrial pollution load, which in its inner portion far exceeds the dispersion and assimilative capacity of the water body and results in anaerobic condi- tions. Because of comparatively strong currents, the effluents discharged into the Bosphorus are better dispersed. Surface currents bring polluted water from the Golden Horn and the Bosphorus into the Sea of Marmara. 2.14 The Sea of Marmara with its attractive shorelines constitutes the best recreational area for the Istanbul population, but the water quality is gradually deteriorating with increasing population and effluent dis- charge. Water samples taken at public beaches frequently show unacceptable levels of coliform bacteria content. Demand for Services 2.15 Although the production and distribution capacities of the water supply system have recently been extended (para. 1.19), the population increase has been such that they are still inadequate to meet medium-term requirements. Extension of the sewage networks has not kept pace with the increased water supply; neither has any provision been made for appropriate waste disposal facilities. The decision to concentrate at present on the extension of sewerage services and on pollution reduction accurately reflects current priority. Subsequently, investments will be made for the augmentation of water production and distribution facilities.  - 9 - III. THE PROJECT Genesis 3.01 Two comprehensive sewerage and sewage disposal master plan studies have been carried out for the Greater Istanbul area, i.e., the Damoc report and the Camp-Tek-Ser report completed in 1971 and 1975 respectively. In 1978 it was decided to up-date the Camp-Tek-Ser study, to further evaluate some alternative technical proposals and to include detailed engineering for three major drainage areas - Yenikapi, Kabatas and Uskudar (Map IBRD 16625). Consultant, Nedeco (Holland), was appointed at the end of 1979 and the work was mainly completed by end-1980. Concurrently detailed engineering was prepared for the Kadikoy-Kartal drainage area by a local consultant (Tek-Ser) engaged by Iller Bankasi (para. 1.04). 3.02 The Nedeco study was financed in part by a US$ 0.5 million advance from the Bank Project Preparation Facility approved August 18, 1978. Sewerage and Sewage Disposal Master Plan 3.03 Map IBRD 16225 shows drainage areas and major sewerage and sewage disposal works as proposed to be executed during the master plan period (through 2020). Data on population and cost estimates (including engi- neering and contingencies) for those drainage areas (referred to as the four drainage areas) that have been subject to detailed engineering (para. 3.01) are as follows; Cost Estimates Population ('000) (US$ Millions Drainage Areas 1995 2020 Equivalent) Yenikapi 1,735 2,065 210 Kabatas 1,035 1,140 160 Uskudar 424 500 30 Kadikoy-Kartal 1,477 1,400 100 /1 4,671 5,105 500 3.04 The implementation of proposed works in the four drainage areas, because of financial and project implementation constraints, have been phased out taking into account considerations such as: (i) the extension of secondary sewage networks has precedence because of significant associated health benefits; and (ii) since the Sea of Marmara is extensively used for recreational purposes, the reduction of pollution in this area has higher priority than in the Bosphorus and the Golden Horn, which establishes priority of Yenikapi and Kadikoy-Kartal over Kabatas and /1 Refers to pre-treatment works and outfall main only.  - 10 - Uskudar. However, alternative technical solutions still remain to be elaborated for the Kadikoy-Kartal pretreatment works and pumping station (para. 3.01). 3.05 The Project, to be executed as a first stage extension of the master plan during the period 1982-1987, would basically cover the Yenikapi drainage area and would be composed of: (i) extension of secondary sewage networks mainly to be concentrated to the Yenikapi drainage area to achieve optimum population coverage (para. 6.07) ind utilize proposed sewage intercepting and disposal facilities; and (ii) sewage intercepting and disposal facilities including interceptors along the Golden Horn (Alibeykoy) and the Sea of Marmara (Sarayburnu-Bakirkoy), a t:unnel (Fatih) connecting the Alibeykoy interceptor to the pre-treatment works, pre-treatment works and pumping stations at Yenikapi, pumping mains and a submarine out- fall main at Ahirkapi. The project would cover about 60% of projected water supply and sewerage sector investments in Greater Istanbul Municipality during the project implementation period 1982-1987. Project Objectives 3.06 The major project objectives would be: (i) to extend and improve ithe coverage of sewerage services, by reha- bilitation and extension of the secondary sewage systems to about 60% of the total population in the Greater Istanbul Municipality covering about 70% of the low income group; (ii) to improve the environmental conditions by the reduction of the amount of sewage being discharged along the shorelines of the Golden Horn and the Sea of Marmara by the construction of a sewage intercepting system; (iii) to provide satisfactory sewage disposal by the construction of pre-treatment facilitiess and a deep submarine outfall main; (iv) to improve the institutional capacity in project preparation and implementation, operation and maintenance, and financial manage- ment by the developmenit of a suitable organization; and (v) to assure financial self-sufficiency by the introduction of adequate water supply and sewerage charges. 3.07 The project would also aim at developing for the Istanbul area, and for the country as a whole, procedures for pollution control. For this purpose, industrial wastewater and oceanographic surveys would be carried out (para. 3.30). 3.08 The project would provide a pattern for sewerage and waste dis- posal system operation which would be adaptable to other urban areas and would thus have an impact on overaLl sectoral development.  - Il - Technological Aspects 3.09 The sub-division of the Greater Istanbul area into drainage zones follows the topography, which is also a determinant in the possible loca- tion of sewage outfall points. The design of outfall mains and preceeding sewage treatment works is interrelated. A high degree of sewage treatment would enable use of a short and shallow outfall main while the opposite would apply to a low degree of sewage treatment. The latter solution has been found the most economical. After pre-treatment, the sewage effluent would be dispersed at the mouth of the Bosphorus in the bottom current (para. 2.13) through a submarine outfall main equipped with diffusers to be laid at a maximum water depth of about 50 m. Through this arrangement, an initial dilution of about I to 100 will be achieved, which, because of the significant flow will increase rapidly enabling a natural treatment process to take place without causing environmental problems. The Bosphorus pro- vides significantly better conditions for effluent discharge than the Sea of Marmara and any discharge into the Golden Horn should ultimately be avoided. 3.10 Comparative studies have been carried out between combined and separate outfalls for the Kabatas and Yenikapi drainage areas with the latter solution evaluated as the most economical. Interceptors to be laid in open cut trenches have also been evaluated as less expensive and more suited to the local conditions than the alternative construction of tun- nels. A short tunnel (Fatih) to be constructed in rock material will, however, be required to connect the Alibeykoy interceptor to the pre- treatment works. The Archeological Commission, when reviewing the proposed works, concurred that the construction of a short tunnel would minimize archeological implications and would be preferable to an open cut trench. The pre-treatment plant in Yenikapi has been sited in the industrial zone next to a solid waste landfill in order to minimize nuisance to adjoining neighborhood. 3.11 The design basis for interceptors, pre-treatment works and outfall main is shown in Annex 1, Table 2. The interceptors, with overflow cham- bers along the shorelines of the Golden Horn and the Sea of Marmara, are designed for four and two times the average dry weather flow respectively, which takes into account the assimilative capacities of the receiving water bodies. The Yenikapi drainage area is expected to reach its saturation capacity regarding population density by early next century and the project components have been designed for the ultimate requirements. 3.12 The various project components recommended for implementation represent least cost solutions at a discount rate of 10%. The design cri- teria used are appropriate. Project Composition and Description of Project Components 3.13 The project would include the following major components-. (i) laterals and collectors, about 285 km; (ii) interceptors, 26 km; (iii) tunnel, 2.4 km; (iv) pre-treatment works with in and outlet pumping stations (eight pumps); (v) pumping mains, 2.3 km; and (vi) submarine outfall main, 2.0 km. Sewer connections are not included in the project since related costs are borne directly by the customers, which is standard practice.  - 12 - 3.14 The project would also cover: (i) consulting services and/or technical assistance for project martagement and construction supervision; identification and preparation of future projects for development and extension of water supply and sewage disposal facilities; initial supervision of the concrete pipe manufacturing; financial, accounting, tariff and training matters; (ii) industrial wastewater and oceanographic surveys for pollution control; (iii), laboratory facilities and operational and maintenance equipment for water supply and sewage systems including water leak detection equipment and meters; and (iv) the establishment of a regional training center. 3.15 The following works are also planned to be executed in the Greater Istanbul Municipality during the project implementation period outside the scope of the project; (i) water production facilities, transmission and distribution mains; and (ii) laterals and collectors, about 300 km. The water distribution and sewage networks will be executed mainly in areas to be developed and the costs will basically be covered by developers and con- sumers. 3.16 Population projected to be served by sewer connections during the project period (Annex 1, Table 1) are: Greater Istanbul 24 Surrounding Istanbul Municipalitz Municipalities Municipality Population served (by 1987) - nos. ('000) 2,577 884 3,461 - % of total population 74 40 61 Additional population served during project period - nos. ('000) 520 390 /I 910 - % of total population (1987) 15 18 16 3.17 The interceptors along the Golden Horn and the Sea of Marmara are designed for maximum carrying capacities of about 5.5 m3/s and 6.5 m3/s, respectively. Pre-treatment works, pumping stations and sub- marine outfall main have consequently been designed for a maximum discharge of about 12 m3/sec. 3.18 Interceptors will consist of concrete pipes up to a size of 2000 mm and culverts where larger capacities are required. The proposed outfall main is expected to be of steel pipes but alternative proposals will be considered at tendering. 3.19 The major functions of the pre-treatment works will be to elimi- nate coarse material from the influent through screening and to reduce sand content, floatables and grease material through settling and aeration. /I This population refers mainly to new areas to be developed.  - 13 - This will reduce the amount of deposits that would otherwise occur in the outfall main and immediately downstream of the diffuser openings as well as the possibility of surface water pollution by rising floating materials. Cost Estimates 3.20 Annex 1, Table 3 shows a breakdown of the cost estimates which are summarized below: % of Grand Local Foreign Total Local Foreign Total Total -------TL Million------- -US Million Equivalent- Basic Costs Secondary Sewage System 3,181.1 167.7 3,348.8 24.47 1.29 25.76 12 Alibeykoy Interceptor 2,084.8 1,122.6 3,207.4 16.04 8.63 24.67 11 Bakirkoy-Sarayburnu Interceptor 572.3 63.7 636.0 4.40 0.49 4.89 2 Fatib Tunnel 247.7 743.1 990.8 1.90 5.72 7.62 3 Yenikapi Pretreatment Works, Pumping Stations and Pumping Mainst - Civil Works 2,503.9 1,072.5 3,576.4 19.26 8.25 27.51 13 - Mechanical and Elec- trical Equipment 226.5 2,038.4 2,264.9 1.74 15.68 17.42 8 Submarine Outfall Main 2,379.8 1,586.6 3,966.4 18.31 12.20 30.51 14 Water Supply and Sewage Systems Operational and Maintenance Equipment 390.0 585.0 975.0 3.00 4.50 7.50 3 Land Acquisition 139.1 - 139.1 1.07 - 1.07 1 Sub-Total 11,725.2 7,379.6 19,104.8 90.19 56.76 146.95 67 PROJECT MANAGEMENT AND CONSTRUCT ION SUPERVISION 247.0 299.0 546.0 1.90 2.30 4.20 2 CONTINGENCIES Physical 1,459.6 876.7 2,336.3 11.23 6.75 17.98 8 Price 3,854.5 2,414.1 6,268.6 29.65 18.57 48.22 22 Sub-Total 5,314.1 3,290.8 8,604.9 40.88 25.32 66.20 30 TOTAL 17,286.3 10,969.4 28,255.7 132.97 84.38 217.35 99  - 14 - % of Grand Local Foreign Total Local Foreign Total Total -------TLMml ion