Leaky drainage infrastructure of the capital city

Ershad Kamol
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Photo: Star

WHENEVER the monsoon approaches, many areas of Dhaka go under water. Even after a moderate rain, one third of the areas in the capital city remain waterlogged due to faulty drainage system. For the passengers and residents of the areas, it is sheer agony. The problem also creates unavoidable crisis for office-goers. Most of the rickshaw drivers refuse to go to the asked for destination. And those who agree ask almost double the fare. The stagnant water in the canals is a perfect breeding ground for mosquitoes and other insects.

But the city does not have any master plan for its drainage system. The infrastructure related to the drainage system has been developing in an unplanned way by four government agencies on ad hoc basis with the aim to mitigate immediate crisis even without co-ordinating with other agencies. As a result the drainage system is absolutely in a mess, though the city is surrounded by rivers and gifted with natural canals and other water bodies.

The urban drainage system in Dhaka consists of a complex network of drains -- both open and underground. The roadside drains flow into bigger drains, which carry sewages and storm water into canals. These canals collect storm water runoff and carry into the rivers. Dhaka city is protected by a flood protection embankment on its three sides. And only the eastern side of the city is still unprotected.

Since its inception in 1968, Dhaka Water Supply and Sewerage Authority (Dwasa), the responsible government agency, planned to introduce a separate drainage system (for storm water and sewage) in the city. So far it has only 110 square kilometres of sewerage and 150 square kilometres of drainage lines, which are inadequate to say the least. Dhaka Wasa has only one sewage treatment plant at Pagla with a capacity of 0.12 million cubic metres per day, which is only 10 percent of the total sewage generated in the city. But because of inadequate, separate sewage lines, the treatment plant is using one third of its capacity. As a result, untreated domestic and industrial sewage of the canals are drained out into the river, which eventually pollutes the water bodies.

Greater Dhaka has an area of 350 square kilometres, while DWasa has only a service area of 140 square kilometres, which includes 10 km of box culvert and 65 km of open channel. There are 245 km of pipe drain and 3 pump stations with a capacity of 54.4 cumec and estimated storm water generation of 140 cumec.

In fact, the drainage system of Dhaka was defective and inadequate even during the British colonial period. An administrative report in 1882-83 notes, “The drainage system of the city was defective when the city area was around 20 km only. The main outlets mostly run north and south and fall into the river and the khals, which pass through the heart of the town. There are some pucca and large number of kutcha drains on road and lane sides. But their fall is mostly defective as the streams are slow in carrying water into outlets.” (Dhaka Municipality Administration Report, 1882-83, reproduced in a document, A City and its Civic Body. (A centenary publication of Dhaka Municipality, 1966), quoted from Mott MacDonald, 1993.

The city planners and engineers concerned blame this messy situation on the encroachment on the drainage canals and retarding pond areas by various interest groups, inadequate drainage conveyance facilities, disrupted drainage catch pits and connections, inadequate pumping facilities, lack of coordination in management of facilities by various agencies, change of drainage pattern due to land development or other human interventions and in some areas insufficient cleaning of drainage passages.

The drainage system in Dhaka was first established in 1923. Over the years many studies for an adequate drainage system was initiated. A full-scale sewerage master plan was formulated in 1968 by the Department of Public Health and Engineering. As a follow up, several other organisations and agencies had carried out several studies taking financial and technical support from the developing partners in 1976, 1978, 1981, 1983, 1985 and again in 1987.

The FAP 8A and FAP 8B studies, conducted in early nineties, focused on flood action plan for Dhaka city and it also covered action plan for drainage improvement in Dhaka city. The Institute of Water Modelling study titled “Study of Drainage Master Plan for Dhaka City” was aimed at assessing the present drainage conditions (2004) and recommend drainage improvement plan based on limited data collection, analysis and study of past drainage studies, particularly the FAP studies. However, the drainage situation in a mega city like Dhaka is still far from being satisfactory, a fact that is acutely evident during periods of even moderate showers. It is a system that is, in a word, bizarre.

Photo: Star

Of the existing 54 canals, only 19 canals of the western part of Dhaka are under the jurisdiction of Dwasa. Of the remaining seven canals, five canals of that part of the city are under the National Housing Authority and DCC is the authority for the other two canals. All the 17 canals of the eastern part of the city are still under the jurisdiction of Deputy Commissioner's Office. The 11 canals of the DND area are under the jurisdiction of Bangladesh Water Development Board.

Dwasa is facing such problems with many government agencies including the DCC, Roads and Highways, DESA, complains the high official of the Drainage Department.

Besides Dwasa, the DCC has installed open drains and underground drains which carry a huge volume of untreated domestic sewage into the canals. Rajuk constructs drainage system with support from Wasa. On the other hand, Water Development Board maintains the canals in the DND areas and sluice gates of the embankments.

Another major cause of narrowing down of the canal channels is dumping of solid wastes. Because of a lack of dumping facilities, people dump solid wastes into the canals as well as other drainage outlets.

Prescribed and funded by World Bank, ADB and Japan International Cooperation Agency (JICA), four major canals -- Dholai Khal, in to box culverts in the mid 1980s. Such conversion has virtually killed these canals, since the Drainage Department of DWasa is not equipped with machinery to clean the huge length of box culverts. As a result, the city centre becomes awfully waterlogged.

Of late, Dwasa has initiated a master plan for its drainage system funded by World Bank, which is providing continued support to improve the drainage system and mitigate water pollution. The project has already begun and is expected to be completed in next four years.

"It's the major part of a 11.60 billion taka 'Water Supply and Sanitation Project' funded by World Bank and ADB," informs a high official of Dwasa, "However, the project is basically focused on drainage and sewage system: Updating Sewerage Master Plan of Dhaka City, and Preparation of Detailed Design and Bidding Documents for Priority Works for Existing Sewerage System of Dhaka City."

"It will not be just a master plan targeting next fifty years. Some pilot projects and renovation works are also included with the project. We will renovate the existing drainage and sewage system, construct new drainage lines, create two permanent pumping stations with retention ponds at Kamalapur and Rampura and install sewerage treatment plant."

However, the high official is in doubt about the completion of the project because, first of all, the current situation is very complex. They are still in dilemma whether the donor agency will continue funding and whether people will actively discharge their responsibilities.

"In the areas where Wasa does not have sewerage lines, people must use septic tanks. However, violating the Rajuk's law, people drain the domestic wastes in the drainage system. On the other hand, industries inside Dhaka do not also use any treatment plant and discharge wastes into the canals," the high official added.

However, the engineers concerned demand that the government should shun its foot-dragging on the matter and take immediate steps to implement the following recommendations.

Recommendations for the improvement of drainage system in Dhaka:

1. After carrying out a comprehensive study on the existing drainage system, its expansion and rehabilitation are necessary.

2. Sewer lines should be separated from storm water drainage system.

3. Steps have to be taken to prevent disposal of waste into the drainage lines and canals.

4. Adequate solid waste disposal system should be made available to the city dwellers.

5. Need for improving pumping facilities.

6. All flood proofing structures would require proper maintenance and should be manned by adequate personnel for operation during monsoon under definite guidelines.

7. All internal drainage and flood control infrastructures should be handed over only to Dhaka WASA for operation and maintenance.

8. The city flood and drainage management should collaborate with Bangladesh Water Development Board for weather and flood forecasting system for early warning and preparatory activities.

9. RAJUK should ensure that the development of eastern Dhaka is carried out under a Master Plan, which would integrate land use plan with that of service utilities like, storm-water drainage, water supply and sewerage.

10. RAJUK should develop and implement building codes, which would clearly give direction for preserving drainage facilities in city areas, most importantly, in low-lying areas. Natural canals of the eastern part are to be protected from land grabbers and encroachers by the DC office. To ensure that the khash (Government) lands and natural canals are not be given to the private developers on lease. If already given, that has to be cancelled.

11. A central high-powered coordination committee should be formed to coordinate activities of all agencies engaged in providing city utility services.

12. Create public awareness about the necessity for conservation and protection of the manmade or natural drainage facilities.

13. Benchmarks need to be established throughout the city area, so that construction and rehabilitation of drainage facilities could be done against a common reference level.

14. Electric pumps with mobile sub-stations should replace all diesel pumps. Standby generators would ensure lesser interruption to pump operations.

15. The problem of DND area is complex. The only outlet from the area is the DND drainage channel, which falls into Shitalakhya River at Sarulia. The capacity of the drainage pumps is limited, which needs to be increased. The drainage channel leading to the pump house needs to be protected from encroachment. Two additional pumping stations, one at Adamjinagar and the other at Pagla, are recommended. The drainage channels needs to be re-excavated to increase their conveyance capacity.
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A journalist associated with the STAR Magazine.

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