Urban Drainage Project (KCC) 3209

Urban Drainage Project (KCC)

INTRODUCTION

Removal of surface or subsurface water from a given area by natural or artificial means is

called drainage. The term is commonly applied to the removal of excess water by canals,

drains, ditches, culverts and other structures designed to collect and transport water either

by gravity or by pumping. The Drainage System may define as a branched network of

stream channels and adjacent land slopes, bounded by a drainage network and converging

to single channel at the outlet.

Excessive rainfalls often cause severe water logging in roads and streets that disturb the

daily life of urban people. This is a common phenomenon now a day in Bangladesh

known as Urban Flooding, as the cities have not grown and developed in a planned way.

Khulna City Corporation (KCC) provide drainage and sanitation facilities within the city

corporation boundaries. Section 85 of the Khulna City Corporation Ordinance, 1991

includes regulations on the drainage facilities. Section 85 (1) outline “ subject to any law

for the time being in force , the Corporation shall provide an adequate system of public

drains in city area and all such drains shall be constructed, maintained, kept, cleared and

emptied with due regard to the health and convenience of the public”.

OBJECTIVES OF THE STUDY

The objectives of the present study are as follows:

To identify the problems of existing drainage system of Khulna City Corporation

area.

To identify the community people’s perception about the problems

To identify possible solutions for the existing drainage system of Khulna City

Corporation area.

To suggest some measures for the improvement of the existing drainage system of

Khulna City Corporation area.

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STATEMENT OF THE PROBLEM

Large concentration of people in relatively small areas is recognized as an inevitable

historical process of urbanization. This process is continuing and predictions indicate that

by the end of this century, 51% of the world population will live in urban areas . In our

country, during various phases of urbanization of an area, various infrastructures are built;

these are mostly improvement of roads, provisions of power line, street light, supply water

etc and lastly the drain. However, urban drainage system should have priorities as it needs

extra space which is very difficult, after an area is being developed. Absence of proper

drainage system cause stagnant pool of water in urban areas. The stagnant water not only

creates discomfort to the inhabitants but it may also cause damage to adjacent structures

(Quabili, 1998).

COMMUNITY RESPONSE TO DRAINAGE PROBLEM

People’s response about existing drainage system and problems are listed below:

They are not satisfied with the existing drainage system,

They complain about irregular cleaning of pipes and manholes,

People of unplanned area complain about constructing high level roads than that of

houses,

They demand larger sewer system due to growth of multi storied buildings,

They claims about corruption of some employees of KCC for illegal sewer

connection,

They suggest government to take necessary steps to reduce sufferings of people.

During dry season there is no water logging or overflow problem. But during rainy season

unplanned area suffers much. Overflow from manholes creates nuisance. In unplanned

area, wastes from road side kitchen markets are often dumped into drains and manholes.

Planned area is free from this problem. Since in unplanned area storm sewer also serves

domestic waste water there is high potential to degradation of water quality in retention

reservoirs.

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CONSTRAINTS OF DRAINAGE SYSTEM MANAGEMENT

Management of drainage system of an area depends on many factors such as social,

economical, geographical, administrative, environmental and political. Major constraints

of management recognized in this study are:

- inefficient administration and manpower;

- insufficient development fund;

- political biasness and instability;

- corruption in responsible authority;

- no coordination among concerned public service authorities;

- lack of long term land use planning;

- frequent change in plans, etc.

EXISTING DRAINAGE SYSTEM

Survey of a large number of households in Khulna city shows that about 68 percent of the

households have no planned drainage facilities in and round their premises while only 32

percent have some sort of drainage facilities.

The existing drains in KCC area are discharging into the nearby khals, rivers, low-lying

areas and beels. The existing drainage network within KCC area is shown in the following

table.

Table: Existing Drains in KCC

Area Length (Km) Type of Drain

Pucca (Km) Semi Pucca (Km) Kutcha (Km)

KCC 528.12 64.08 51.79 380.75

There is no underground storm water drainage system in Khulna City. Concrete box

culverts are being used for road crossing only. The existing drainage facilities in the fringe

and sub-urban areas are inadequate and unsatisfactory. The major KCC areas in the town

is not subject to direct flooding from the Bhairab-Rupsha river, but the low-lying areas

situated on the western and southern part of KCC are flooded by the rain water and tidal

effect during monsoon season .

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There are 6 regulators and 8 sluice gates which drain out storm water from KCC area. The

10-vent sluice gate located at Alutala performs major drainage function of the Khulna

City. Out of these, 4 regulators drain out storm water into the Rupsha River and the other

two regulators drain into the Khudir Khal, the upstream of Gollamari River.

DRAINAGE CONDITION OF KCC

Wastewater is flow within drain. But the drainage condition is not well served. Only 45%

of the drains are well served, 52% poor served and 3% vulnerable conditions. But about

3112776 gallon per day (URDP, 1999) wastewater flows by the drain.

CONDITION OF DRAINAGE FACILITIES IN KHULNA CITY

45%

52%

3%

Well served

Poor served

Vulnerable

Figure: Drainage facilities condition of Khulna City.

EXISTING DRAINAGE PATTERN

The topographical features, existing internal network of khals and the river system in and

around the Structure Plan area shows the following five drainage zones:

a. Long and Narrow Strip of Flat Highland along both Sides of the Bhairab

and Rupsha River (Right Bank).

There is a long and narrow strip of flat highland along the Bhairab and Rupsha

River and stretching along northwest to southeast direction; this strip consists

of KCC core and urbanizing area.

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The ground elevation of this narrow strip decreases sharply towards west and

south direction and gradually turns into a flood plain and swampy lands/beels

comprising flat and low-lying areas, criss-crossed by numerous tidal rivers

and channels.

The drainage water is discharged into the Bhairab and Rupsha River through

BWDB sluices/ regulators lying on the embankment cum road. The drainage

and flood protection works of this area are the responsibility of the LGED and

BWDB and covered by the STIFPP and BWDB Flood and Bank Protection

Projects.

b. Strip on the Eastern Side of the Bhairab and Rupsha River (left bank)

These areas are drained through natural drains, borrow-pits and ground

profiles sloping towards adjacent low-lying areas/flood plain and ultimately

into the outfall river/khals, viz., Bhairab, Rupsha, Atharbanki, Atai,

Majudkhali, etc. These areas comprise the fringe area of the town.

c. South and South-eastern Area on the Left Bank of Rupsha, Kazibacha

River

These are fringe areas and drained through numerous tidal creeks, low-lying

areas/beels and flat land situated in the flood plain of the major rivers, which

ultimately drained into the adjacent Rupsha, Kazibacha and Atharbanki rivers.

d. Western Part of the KCC Area along Left Bank of Gallamari River and

Khudir Khal.

The western part of KCC between Daulatpur and Kazibacha river is drained

by the upstream of Gallamari river or Khudir khal and downstream of

Gallamari river and ultimately through a regulator at Alutala which discharges

into the Kazibacha - Rupsha river. A small part of the catchment area

adjoining Khulna University area on the right side of the Gallamari river used

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to drain by two BWDB sluices, but now drains towards west and into the

lower Sholmari river due to occurrence of siltation problem in the Gallamari

river and Khudir khal.

e. Northwestern Part of KCC and Structure Plan Area, Western Part of the

Structure Plan Area.

This catchment may be subdivided into two areas:

i. North and northwestern part of structure plan area between Daulatpur,

Phultala.

ii. Middle and southwestern part of the structure area between upper and lower

Sholmari river on the west (left bank of Sholmari river) and Gallamari

river/Khudir khal on the east (right bank of Gollamari and Khudir).

WATER -LOGGING AREAS DUE TO POOR DRAINAGE

Inundation and inadequate drainage in structural plan area are occurring due to localized

storm rainfall (internal flood) affecting drainage system. External flood is not likely to

occur since the structure plan area is situated in the tidal zone. The areas suffering from

drainage congestion has been identified during moderate to heavy rainfall. The inundated

areas associated with drainage congestion are mentioned below:

- Natun Bazar

- Rupsha

- Tutpara

- Shipyard areas

- East Bania Khamar

- Boyra

- Rayer Mohal

- Khan-A-Sabur road (infront of KDA building)

- Nodal Point of Khan Jahan Ali and KDA Avenue (nearby and surrounding

Royal Hotel)

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The reasons for water-logging have been identified as follows:

(i) Improper operation and maintenance of khals/drains,

(ii) Blockage in the existing khals/drains,

(iii) Absence of integrated network comprising secondary and roadside

drains,

(iv) Haphazard expansion of the regional settlements which obstructs the

natural drainage system,

(v) Uncontrolled and haphazard disposal of solid waste into the drainage

system,

(vi) Siltation in the drainage channels with consequent reduction of

discharge capacity.

FUTURE ASSESSMENT

There is no planned drainage system in the fringe areas of KCC as well as outside the

KCC area. The drainage scheme may be extended and taken up phase wise with the

progress of urbanization which depends on some factors, such as population growth, rate

of urbanization, extent of flood damage in the area, affordability of KCC and viability of

the project etc.

The need for improved drainage system will be greatly influenced by the physical

development of the Structure Plan area and a Drainage Master Plan will be needed for the

Structural Plan areas. The land use activities are guided by KDA; on the other hand KCC,

DPHE and LGED have their own drain improvement programs within and out side KCC

area. Therefore, a high degree of coordination is necessary between these organizations for

improvement of drainage network within the Structure Plan area.

The various projects of BWDB, LGED and KCC concerning flood protection works, river

bank protection works and drainage improvement works and a proposed Drainage Master

Plan will help solve many drainage problems.

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OUTLINES OF PROPOSED DRAINAGE IMPROVEMENT PLAN

Open drainage system is followed in Khulna as it is cheaper than piped drain and easy to

maintain. Piped storm water drainage system could not develop because it is expensive to

construct, operate and maintain such system and also beyond the present affordable limit

of KCC. The situation however, demands a comprehensive Drainage Master Plan with an

integrated network of drainage system for the Structure Plan area and a link-up with the

Secondary Town Integrated Flood Protection Project recently executed by the BWDB and

LGED and the existing drainage sluices and regulators constructed earlier by the BWDB.

The existing drainage system will provide a basis for a comprehensive drainage scheme in

which the khal network, pucca/kutcha drains and borrow-pits may be up-graded to act as

the main framework for improved and integrated as well as viable drainage system for the

Khulna City Structure Plan area which will serve the drainage need during the peak

monsoon period when the drainage stands critical.

Policy Drain/1 : Formulation of storm water drainage improvement plan

In order to develop a practical and affordable solution to the storm water drainage

problem, formulation of a drainage improvement plan for the areas which are not covered

by BWDB and STIFPP projects for storm water drainage may be proposed. For this

purpose the following tasks will be needed:

(i) topographical surveys of the area including levels of existing drains and

culverts

(ii) assessment of extent and frequency of flood damage to the flood affected areas,

(iii) design of primary and secondary drains, and retention areas required,

(iv) review of technical, environmental, institutional, economic and social

feasibility of the proposed works,

(v) planning of implementable phases

(vi) detailed design,

(vii) provision of adequate drainage reserves and right-of-way,

(viii) maintenance program including assessment of manpower requirements,

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(ix) funding mechanisms for construction phases and operation and maintenance of

the system,

(x) application of practical standards for storm water drainage,

(xi) selection of realistic return periods of rainfall and river water levels based on

the experiences from the STIFP and BWDB projects,

(xii) system design following existing drains and culverts as much as possible and

natural topography of the area, keeping land acquisition to an absolute

minimum.

It is very important to point out that the KCC should develop its ability to clean and

maintain the designed drainage systems. Therefore, institutional and technical

strengthening of the KCC and planned maintenance procedures will be an important factor

for any drainage improvement project.

Policy Drain/2 : Phase-wise implementation of drainage improve-ment plan

Priority areas should be first identified during preparation of comprehensive topographical

surveys and drainage outline plan, through observed physical conditions, discussions with

the local residents, and detailed discussions with different authorities. Specific attention is

to be given to the improvement of the drainage systems in the town centre and in the

densely populated residential, commercial and industrial areas in the structural plan area.

The priority for the proposed works should be grouped into different priority levels for

phase-wise development.

The KCC Authority will confirm the local priorities and select the remaining improvement

works as Second Priority Works on the basis of availability of funds.

Pumping stations comprising high capacity pump should be installed for dual purpose, i.e.

drainage and irrigation in dry season.

More sluices with flap gates at outfall points on primary khals/river and in the existing

protective embankments to control backflow during high stages of rivers/khals

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Re-excavation, regarding, deepening, widening of drainage khals comprising the network

of khals should be done on priority basis.

Non-structural measures prescribed for site development and plinth levels of different

structures to be followed as prescribed.

The existing agricultural lands /lowlands lying in the fringe and semi-core areas of the

structural plan area is not only serving as good retention basins but also playing an

important role in decreasing magnitude of flood in the core/semi-core areas.

Further, it may be noted here that though urbanization is progress, but all the lands

including agricultural lands within the structural area will not be urbanized by the year

2020 and that some low and agricultural lands will exist beyond this period, which will

serve as storage basin/ detention pond and reduce magnitude of flood significantly in the

structural plan area during monsoon season.

Policy Drain/3: Improvement of environmental situation through improved drainage

system

Improvement in the drainage system will improve the environmental situation in the water

logged areas by eliminating stagnant water and associated problems like odors from

decaying solid wastes, insects, scams and disease vectors as well as the incidence of local

flooding due to rainfall.

Although the drains are intended to remove storm water, but they also receive sludge flow,

septic tank effluent and other locally contaminated water. For the above problem the

following mitigating measures may be taken :

(i) KCC will educate and take action against polluters;

(ii) Provide better sanitation for low-income and town center areas through construction of

pit latrines and public toilets respectively;

(iii) protect the outlet of drains by providing Oil and Silt Traps as necessary and Trash

Racks and Sumps in the drainage system to reduce cost of routine cleaning and

maintenance work;

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Policy Drain/4: Complementary non-structural measures to protect right of way and

other aspects

In addition to physical works program KCC should adopt complementary procedures and

policies in maintaining a proper drainage system within its jurisdiction. In the long run

these “non-structural measures” will improve the drainage situation and resolve the

drainage problems. The following non - structural measures are recommended:

a) Provide adequate funds in all annual budgets for carrying out routine

maintenance programs;

b) Identify, on the basis of the Drainage Improvement Plan, all areas where

existing main drains are located or will be required in future and enforce existing

legislation to prevent unauthorized development or encroachment on the drain alignments;

c) Identify, on the basis of the Drainage Improvement Plan, all low-lying areas

which are prone to regular flooding due to drainage congestion and cannot be

economically drained by gravity systems; inform residents and enforce building control

regulations to prevent development at levels which would be dangerous for future

residents;

e) Undertake a long range program to reduce the “source” of intrusion of sludge,

silt, garbage and effluent into the drainage system, thereby reducing the cost of the long

term maintenance operations, by : (i) prohibiting dumping of garbage into the drains by

enforcing regulations; (ii) providing convenient local collection points and more efficient

removal services; (iii) prohibiting dumping of night soil/wastes into the drains by

enforcing regulations and more efficient removal services; (iv) prohibiting direct septic

tank connections to the drainage system by enforcing regulations to prevent this; (v)

installing trash racks and sumps at convenient locations to facilitate collection of silts and

floating garbages;

(f) Introduce public information campaign to make people more aware of the

problems, hazards and unacceptable practices,

(g) Ensure proposed channel geometry to keep water way free from all unwanted

intrusion, encroachment etc.;

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Policy Drain/5: Operation and maintenance of drainage system

Operation and maintenance will comprise the following classified activities:

(i) Preparation

(ii) Maintenance

(iii) Rehabilitation and

(iv) Replacement.

Operation is related to drains involved in carrying out activities in the field of

conservancy, collection and disposal of solid wastes from drains. Maintenance relates to

maintenance of equipment and drains. Rehabilitation and replacement relate to provision

of rehabilitation work and replacement of equipment. KCC should develop a routine

preventative maintenance program for the drainage systems so that the structural

improvements will provide a lasting benefit. It is, therefore, recommended that the KCC

develop a comprehensive conservancy program for maintenance of drainage system which

is maintenance activities and scheduling of these activities, methods and equipment,

staffing needs and any appropriate re-organization which may be necessary.

The following guidelines may be followed for development of staffing and equipment for

a preventative maintenance program:

a) Drains should be cleaned regularly;

b) One cleaner/sweeper should be provided for every 50 m of primary/secondary

drains, 150 m of tertiary/local drains per day (i.e. 1.5 km primary/secondary drains or 4.50

km of tertiary drains per month supervisors should be provided at the rate of 1 jamadar for

each 10 sweepers, and 1 sanitary inspector for each 4 jamadars;

c) adequate equipment should be provided for efficient operation of the cleaning

crews, including wheel barrows and miscellaneous hand tools for each drain cleaner, 3 ton

dump truck (s) for waste transport and disposal (garbage truck will serve on demand), and

pump (s);

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RECOMMENDATIONS

In some specific KCC and outside KCC areas, there are some low-lying areas, which are

subjected to waterlogging during and after heavy rainfall in a year between August and

October. The depth of stagnant water varies from 0.25 to 0.35 m and usually lasts for 3.0

to 5.0 hours from place to place. The waterlogging situation is likely to further aggravate

in the years to come with growing urbanization. The prime causes of this water-logging

are as follows:

(i) Lack of cleaning and maintenance of the khals/drains,

(ii) Unplanned and inadequate drains in the existing drainage system,

(iii) Obstruction and encroachments in the khals/drains and drainage paths,

(iv) Lack of construction and integration of tertiary, secondary and primary drains,

(v) Non existence of drains in different places.

The following recommendations may be made for future Drainage Improvement Plan:

Proposed drainage system should be designed to discharge most of the storm

run-off by gravity flow; pumping is necessary when gravity flow will not work

and when the water level at outfall is higher than the drain water level.

Existing khals constitute the storm water run-off delivery system.

Timely undertaking of drainage issues and improvement plan in the structural

plan area are to be considered as timely venture to formulate an investment

project to reduce sufferings of the residents.

Any proposed drainage improvement plan should be justified technically,

economically and socially. Priority program should be recommended for

implementation. The program after implementation will mitigate major

drainage problems in the core and semi-core area where the density of

population varies from high to medium.

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For improvement of drainage condition, improvement in respect of solid waste

management and household sanitation is considered to be vital. As such, these

components should be included in any proposed drainage improvement project.

KCC should take immediate steps to remove the unauthorized structures like

earthen barriers; small culverts etc. from the drainage paths/khals and ensure

clear right-of-way.

KCC should execute any drainage improvement project as implementing

agency. If KCC is lacking in planning and detailed design works for

implementing this project, it will need the assistance and supports of local

consultants for detailed design and implementation support. This will develop

the skill of manpower of KCC through transfer of technology and training.

Any proposed drainage improvement plan should be exchanged with other

utility organization to avoid any overlapping and duplication. As such, a high

degree of close co-ordination with DPHE, BWDB, LGED, PDB and other

utility organizations should be maintained during the project implementation

stage so that disruptions to services of these utility organizations do not take

place.

Cost of the drainage improvement project should be funded as grant to KCC or

by Aid giving agency because the KCC is not in a position to implement this

project from its own resource.

KCC should involve community/NGO in cleaning and maintenance of the

drainage and environmental sanitation activities.

KCC should improve significantly in revenue collection and efficiency in

financial management so that KCC can properly maintain the drainage system.

If possible the knowledgeable NGO could be employed for accurate

assessment of individual KCC residents.

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Pipe drain may be suggested where road is narrow and where there is no space

for roadside drain.

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Documents

Urban Drainage Project (KCC) 3209