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by Ahmet SAMSUNLU, Bilsen BELER BAYKAL, Fatoş GERMİRLİ
Istanbul, which serves as a bridge between Europe and Asia, has been one of
the most attractive and exotic historical cities of the world. She has Seen
the capitol of many ancient civilizations including the Roman, Bizantian and
Ottoman Empires. With the start of the 20 th century, Istanbul has experienced
considerable urbanization and pollution problems due to the insufficient
infrastructure to host the heavy industrialization and population grow-tn.
Having a past of 2500 years, Istanbul has been the most crowded city of Turkey
as the leading commercial, industrial, cultural and artistic center of the country. Istanbul holds 12% of the population of Turkey and approximately 50% of the industry within its vicinity. In 1950’s the migration from Anatolia led to a rapid increase in the population of the city which has grown from about 1.000.000 in 1950 to about 7.000.000 in 1988. A natural consequence of these changes was an increase in the dimension of environmental problems, and the necessity of taking precautions to control the pollution became more and more apparent each day. Within the framework of environmental pollution and attempts for its control, the Golden Horn, called Halic in Turkish, has a unique place.
THE GOLDEN HORN
The Golden Horn, located in the heart of Istanbul, is an 8 kilometer estuary, 700 meters at its widest and 60 meters at its deepest points. It is in the European side of the city separating the districts of Beyoglu (one of the major shopping and entertainment centers and the ancient city . The Golden Horn was historically the symbol of old Istanbul. It has once been the entertainment center of the Ottoman Sultans itself and was heavily exploited for recreational purposes. However, at the beginning of the 20th century, industrialization in the district started to appear, and it has increased tremendously after 1950’s bringing together with it a vast group of pollution problems. Another contributor to the pollution was the residence areas which have increased parallel to the industries nearby.
Industrialization in this area does not seem proper due to a few reasons. First, the Golden Horn is at a location which is very close to the downtown district and also to major residential areas. The predominant winds are such that the air pollution created by the industries are dragged towards these areas. Secondly, in contrast to the Bosphorous, currents are not common in the Golden Horn and this region is more or less dormant. This leads to an accumulation of pollutants since there are no currents available for watercirculation.
Till the first part of 1980’s the shores of Golden Horn were exhausted with factories, manufacturers, various work premises and warehouses. Industrial establishments occupied 71% of the total of 170 hectars of the zone. 28 % of the area was used by shipyards and 8% by the warehouses. Almost all branches of industry were present in this district. Shipbuilding using one fifth of the area was followed by iron-steel and chemical industries. 40% of the total area was used by metal, electrical appliances and construction equipment, textile, food, lumber products and machinery manufacturers. The population equivalent for the industrial _plants has increased from 1.270.000 to over 2.000.000 in the ten years between 1962-1972. The daily industrial liquid waste was approximately 200 tons. Of this, 67% the wastes of the chemical industry, 27% washing water, 4% cooling water, and the rest other wastewaters. Also a considerable amount of solid wastes were discharged into the Golden Horn daily.
ATTEMPTS FOR THE CONTROL OF POLLUTION
In early 80’s Istanbul was named the pilot area in tourism in the country. Attempts and rennovations that will promote touristic activities were heavily encouraged. Among the first efforts to fulfill this purpose were the removal of tanneries and ship building industries from their conventional locations and the preperation of the Golden Horn Project. In order to control pollution generally in Istanbul and specifically in the Golden Horn, Istanbul Water and Sewerage Administration (ISKI) has started a comprehensive project named the Metropolitan Istanbul Sewerage Project. For the realization of this project, British, Swiss and Turkish companies worked in collaboration with each other under the sponsorship of ISKI. Financial assistance was provided from International Bank for Reconstruction and Development (World Bank) and European Settlement Fund and the project was a good example of international cooperation.
Total funds for the project was estimated to be USD 547.000.000; USD 218.000.000 from foreign and USD 329.000.000 from local sources. The Golden Horn project is planned to serve 5.000.000 people in the future.
In an attempt to protect Istanbul’s existing water resources and to be able to bring a radical solution to the sewerage problems, the city was divided in
into eleven separate drainage/catchment areas. Various treatment plants, either as pretreatment or full biological treatment facilities, were planned at different locations within the city.
THE SOLUTION FOR THE GOLDEN HORN
As a major subproject of the Metropolitan Istanbul Sewerage Project, the Golden Horn task was started. The first step was to notify the housing and business units on the shores of the Golden Horn to move elsewhere. The Is¬tanbul Metropolitan Municipality lead the action by immediately stopping its activities of certain facilities in the region. Wholesale food and fish markets, repairs workshops, rowboat manufacturers and the slaughter houses among others were moved to their new destinations. Meanwhile, expropriations were effectuated. Planning and construction to replace the old bridge which was an additional obstacle to water circulation have been started in collaboration with west Germany and Japan.
The Golden Horn Sewerage Project, a map of which is given in Figure 1, is actualized in two parts:The Southern Golden Horn and the Northern Golden Horn Projects.
– The Southern Golden Horn Project
This project will serve an area of 2,000,000 people, which is approximately one third of Istanbul’s population: in 10,000, hectare zone. Later in the future, it is planned to provide service for 3,000,000.
Within the framework of the project, 11 km. of open cut interceptors with diameters between 1,200 mm and 2,800 mm; and 6,5 km of tunnel interceptors with diameters between 2,200 mm and 2,800 mm were built. Furthermore, a 2×2,000 mm diameter force mains 2.4 km long, a 1,600 mm diameter sea outfall 2×1,180mm long-at discharge depth of 60m. were also constructed.
The system is planned to intercept a total of 1.600.000 cubic meters of wastewater per day via three interceptors.
The pretreatment plant is located at Yenikapi and comprises of influent and effluent pumping stations, course and fine screens, and grit chambers. The pretreated wastewater is then discharged into the Marmara sea. The current capacity of the plant is 864,000 cubic meters per day to be increased to 1.600.000 cubic meters per day in the year 2000.
The phases below were followed within the context of the project:
1. Construction of interceptors in open cut,
2. Construction of interceptors in tunnels,
3. Contruction of pumping stations and the pretreatment plant,
4. Procurement and installation of electrical and mechanical equipment of pumping stations and the pretreatment plant,
5. Construction of the sea outfall.
The Southern Golden Horn system was put in operation in the summer of 1988.
The water in the Golden Horn was circulated by the Southern Golden Horn System, and there is a notable improvement in quality.
— The Northern Golden Horn Project.
This project will serve a current population of 1.000.000 people but is planned to provide service for 2.000.000 in the future in a region of 6500 hectares.
The Northern Golden Horn Project is planned to be completed in 1990. A total of 17 km of interceptors (4km open cut and 13km Tunnels), a pretreatment plant similar to the one in the Southern Golden Horn System with an initial capacity of 855,000 cubic meters per day and a final capacity of 1.100.000 (in the year 2020); and a sea outfall that will discharge the pretreated wastewater into
the bottom currents of the Bosphorous at a depth of 70 meters will be constructed. A similar scheme of constructional phases will also be handled for this part of the project.
As a closing remark, it may be stated that the Golden Horn project has been one of the leading efforts to save the environmental pollution in Turkey. The former mayor of Istanbul, Mr. Bedrettin Dalan, who has played a prime role in its actualization has been given the United Nations Environmental Program Award in 1987 for his success in environmental protection. There is an apparent improvement in the water quality of the Golden Horn. Pictures I and 2 are presented herein to give the reader a feel of the change.
Ahmet Samsunlu is Professor and Chairman of the Environmental Engineering Department at Istanbul Technical University, Bilsen Beler Baykal and Fatoş Germirli are research assistants in the same department.