Storm Water Drainage System(Subject area: Environmental Engineering)

Prepared by: Guided by:

Name: Ankit Balyan Mrs. Anjali Khabete

B. Tech IV (Civil) Prof, CED, SVNIT,Surat

Roll no:U06CE065

Year: 2009-10

CIVIL ENGINEERING DEPARTMENT

S.V.NATIONAL INSTITUTE OF TECHNOLOGY,

SURAT-395007

CERTIFICATE

This is to certify that “Mr. Ankit Balyan” of B Tech IV semester

7th has satisfactory completed his seminar report on “Storm Water Drainage

System in Surat” during academic year 2009 – 2010.

Signature of guide: Signature of:

Head of Department

DATE: 11/11/09

CIVIL ENGINEERING DEPARTMENT

S.V.NATIONAL INSTITUTE OF TECHNOLOGY,

SURAT-395007

ACKNOWLEDGEMENT

I take opportunity to express my deep sense of gratitude and

indebtedness to “Prof. Anjali Khambete” in Civil Engineering department,

S.V.N.I.T, Surat for her valuable guidance, useful comments and co-operation

with kind and encouraging attitude at all stages of the experimental work for the

successful completion of this work.

I am also thankful to S.V.N.I.T, Surat and its staff for

providing this opportunity which helped in gaining knowledge and to make this

Graduate report successful.

Thank You Ankit BalyanU06CE065

Table of Contents

Abstract…………………………………………………………………………………………….1Introduction

What is Stormwater…………………………………………………………………1Stormwater Pollution……………………………………………………………….2Storm Drain………………………………………………………………………………2Ancient History…………………………………………………………………………3

Stormwater ManagementSite Analysis……………………………………………………………………………..4Adjoining properties…………………………………………………………………4Public safety…………………………………………………………………………….4

Estimating Stormwater Runoff………………………………………………………….5Stormwater Drainage System in Surat………………………………………………7Case Study: Increasing the Storm Water Drainage Capacity of Mithi River in Mumbai……………………………………………………………………………….8Conclusion………………………………………………………………………………………11References…………..…………………………………………………………………………11

ABSTRACT

STORM WATER DRAINAGE REFERS TO THE NETWORK OF THE DRAINS

LAID FOR THE PURPOSE OF CARRYING AWAY THE EXCESS RAIN WATER,

STREET WASHINGS AND ROOF WASHINGS, SO AS TO CLEAN THE ROADS OF

THE STATIONARY STAGNANT WATER. IN THE BACKDROP OF THE RECENT

URBAN FLOODS EXPERIENCED IN SURAT, MUMBAI AND OTHER INDIAN

CITIES THE ROLE OF THE STORM WATER DRAINS HAS ASSUMED A VERY

CRITICAL ROLE IN THE URBAN LANDSCAPE. A LOT MORE ATTENTION IS

BEING GIVEN TO THE DEVELOPMENT OF PROPER DRAINAGE NETWORKS

CAPABLE OF MEETING NATURE’S WORST POSSIBLE DEMANDS. IT IS A

DEVELOPING AREA IN THE FIELD OF ENVIRONMENTAL ENGINEERING

TODAY AND A LOT OF WORK IS BEING DONE IN DEVELOPING

SUSTAINABLE URBAN DRAINAGE.

INTRODUCTION

WHAT IS STORM WATER?

Stormwater is a term used to describe water that originates during precipitation events. It may

also be used to apply to water that originates with snowmelt or runoff water from

overwatering that enters the stormwater system. Stormwater that does not soak into the

ground becomes surface runoff, which either flows directly into surface waterways or is

channeled into storm sewers, which eventually discharge to surface waters.

Stormwater is of concern for two main issues:

one related to the volume and timing of runoff water (flood control and water

supplies), and

The other related to potential contaminants that the water is carrying, i.e. water

pollution.

A storm drainage system is a network of structures, channels and underground pipes that carry

storm water (rain water) to ponds, lakes, streams and rivers.  The network consists of both

public and private systems.

STORM WATER POLLUTION

Because impervious surfaces (parking lots, roads, buildings, compacted soil) do not allow rain

to infiltrate into the ground, more runoff is generated than in the undeveloped condition. This

additional runoff can erode watercourses (streams and rivers) as well as cause flooding when

the stormwater collection system is overwhelmed by the additional flow. Because the water is

flushed out of the watershed during the storm event, little infiltrates the soil, replenishes

groundwater, or supplies stream baseflow in dry weather. Pollutants entering surface waters

during precipitation events are termed as polluted runoff. Daily human activities result in

deposition of pollutants on roads, lawns, roofs, farm fields, etc. When it rains or there is

irrigation, water runs off and ultimately makes its way to a river, lake, or the ocean. While

there is some attenuation of these pollutants before entering the receiving waters, the quantity

of human activity results in large enough quantities of pollutants to impair these receiving

waters. Polluted runoff from roads and highways is the largest source of water pollution in

coastal areas today.

Fig 1 Relationship between impervious surfaces and surface runoff

STORM DRAIN

A storm drain, storm sewer (U.S.), stormwater drain, drain (Australia and New Zealand) or

drainage well system (UK) is designed to drain excess rain and ground water from paved

streets, parking lots, sidewalks, and roofs. Storm drains vary in design from small residential

dry wells to large municipal systems. They are fed by street gutters on most motorways,

freeways and other busy roads, as well as towns in areas which experience heavy rainfall,

flooding and coastal towns which experience regular storms.

Fig 2. Different types of storm water drains

ANCIENT HISTORY

Since the era that humans began living in concentrated village or urban settings, stormwater

runoff has presented itself as an issue. Such dwelling styles can be generally related to the

Bronze Age when considerable amounts of impervious surface emerged as a factor in the

design of early human settlements. Some of the early incorporation of stormwater engineering

is evidenced in ancient Greece.

Archaeological studies have revealed use of rather sophisticated stormwater runoff systems in

ancient cultures. For example, in Minoan Crete approximately 4000 years before present cities

such as Phaistos were designed to have storm drains and channels to collect precipitation

runoff. At Cretan Knossos storm drains include stone lined structures large enough for a

person to crawl through.

An early specific example of stormwater runoff system design is found in the archaeological

recovery at Minoan Phaistos on Crete. Other examples of early civilizations with elements of

stormwater drain systems include early people of Mainland Orkney such as Gurness and the

Brough of Birsay in Scotland.

STORM WATER MANAGEMENT

Stormwater management is a fundamental consideration in the planning and design of urban

development. By considering stormwater management at the initial design phase it is possible

to ensure viable stormwater management solutions that are compatible with other design

objectives for the site.

SITE ANALYSIS

The site’s topography will have a significant impact on the layout design. This is because

stormwater drainage systems almost always rely on gravity. The layout of the development

must be configured so as to allow excess stormwater to be gravity-drained to a drainage

system. Topography will also affect runoff onto the site from surrounding properties. Existing

overland flow paths should be identified and retained. Where modifications to these are

unavoidable, they should be designed so as to maintain existing hydrological conditions.

Drainage easements, natural watercourses and flood prone land should also be identified and

considered in the design process. It needs to be borne in mind that drainage easements

containing underground pipes can operate as overland flow paths during intense rainfall

events. Buildings must be kept clear of drainage easements to ensure public safety and to

allow maintenance access. Consideration also needs to be given to local soil conditions.

Relevant factors include absorption capacity, erosion potential, soil salinity and the possibility

of soil contamination from past activities

ADJOINING PROPERTIES

One of the basic principles of stormwater management is to avoid adverse stormwater impacts

on other properties. Careful consideration must be given to controlling surface runoff and

subsoil drainage to adjoining properties. The redirection and concentration of stormwater

flows onto neighboring properties may constitute a ‘nuisance’ at common law, giving affected

owners a legal right of redress.

PUBLIC SAFETY

Stormwater runoff from rare and intense storm events can pose serious risks to life and

property. It is essential that the design of overland flow paths, on-site detention storages and

other stormwater management measures meet relevant safety criteria for pedestrians, vehicles

and property damage. Fencing and landscaping should be designed so as to minimize the

potential for overland flow paths to be obstructed during rare and intense storm events.

ESTIMATING STORM-WATER RUNOFF

Calculation of the rate of storm-water runoff is important in determining the size of inlets,

drains, sewers, etc. All portions of the storm drainage system must be designed to handle the

peak flow anticipated under certain design conditions.

The most widely used method for estimating peak storm-water runoff is called the rational-

formula method. This formula assumes (a) that the rate of storm-water run-off from an area

is a direct function of the average rainfall rate during the time that it takes the runoff to travel

from the most remote point of the tributary area to the inlet or drain, (b) that the average

frequency of occurrence of the peak runoff equals the average frequency of occurrence of the

rainfall rate, and (c) that the quantity of storm water lost due to evaporation, infiltration, and

surface depressions remains constant throughout the rainfall.

The coefficient of runoff is a coefficient which accounts for storm-water losses attributed to

evaporation, infiltration, and surface depressions. The peak value of the flow rate Q of storm-

water runoff is estimated using the following equations:

Q = CIA ft3/s ……………………………………………………………..eqn (1)

Q = m3/h ……………………………………………………………....eqn (2)

Where C = coefficient of runoff

I = rainfall rate for a specified rainfall duration and average frequency of occurrence,

in/h (cm/h)

A = tributary area to the inlet or drain, acres (m2)

CHARACTER OF SURFACE COEFFICIENT OF RUNOFF

Pavement:

Asphaltic and concrete 0.70 – 0.95

Brick 0.70 – 0.85

Roofs 0.75 – 0.95

Lawns And Sandy Soil:

Flat, 2 percent 0.05 – 0.10

Average, 2 to 7 percent 0.10 – 0.15

Steep, 7 percent 0.15 – 0.20

Lawns, heavy soil:

Flat, 2 percent 0.13 – 0.17

Average, 2 to 7 percent 0.18 – 0.22

Steep, 7 percent 0.25 – 0.35

Table 1 Typical values for the coefficient of runoff

A given site may have areas with different coefficients of runoff all draining to a common

point. It is desirable to use a single coefficient of runoff for the entire area. Such a

dimensionless coefficient (termed a weighted coefficient of runoff) Cw, can be calculated using

Cw = ……………………………………………………………………………… eqn (3)

where A1, A2, and An are the area in acres (m2), and C1 , C2 , and Cn are the corresponding

coefficients of runoff of the individual tributary areas to a common point. A weighted

coefficient of runoff must be calculated for each segment of the stormwater drainage system.

In the design of a storm-water drainage system, runoff must be transported as fast as it is

received, unless specific provisions are made for ponding of the excess runoff which the

storm-water drainage system cannot handle. Determination of the rainfall rate to be used for

design purposes involves an evaluation of the potential damage which could occur as a result

of flooding. If the potential damage from flooding is high, the selection of an average

frequency of occurrence of 50 or 100 years may be warranted. If the potential damage from

flooding is rather slight, the selection of an average frequency of occurrence of 5, 10, or 25

years may be appropriate. In many cases, the local authority having jurisdiction will determine

the average frequency of occurrence to be used in the design of storm-water drainage systems.

STORM WATER DRAINAGE SYSTEM IN SURAT

After the floods of 2006, a lot of attention has been given to the improvisation of the storm

water disposal system of Surat with a goal to ensure such huge quantities of water can be

easily handled in the future. Till 2005, Surat had total storm water drainage lines of 275 kms.

Since 2006, under the “Jawarharlal Nehru National Urban Renewal Mission” these have been

proposed to increase upto 491 kms to include the new areas that have been added to the city

since. This project also includes improving the capacity of the existing storm water drains to

handle flood situations better.

The project aims to achieve following goals:

There will be protection of mankind and other living organisms from flooding

There will be protection of major equipments and infrastructure from being getting

damaged due to floods.

To protect loss of man hours, business hours of working people and increase

productivity, thereby enhancing economic growth in the area.

To quickly remove the stagnant water as soon as possible so that epidemic can be

avoided and make the pavement free to resume traffic

The new areas where the work of laying of new storm water lines is being carried out in Vesu,

Pal Palanpore and the new eastern areas. The total project cost of the entire work in progress

is Rs 450 crores which have been approved by the government. The projected completion date

is Dec 2010. The entire upgradation is expected to be over by 2012. Surat Municipal

Corporation has taken a major initiative to replace secondary drain pipes with 1400mm

diameter pipes. Another area of concern that would be addressed in the new upgradation

process is to have storm water drains along all smaller side roads which previous did not have

these drains. This will reduce the burden on the main roads as previously this water was

diverted to the drains on the main roads leading to overflowing drains on the main roads.

Case Study: Increasing Storm Water Drainage Capacity of Mithi

River and Mumbai City drains

The Mithi River flows through the city of

Mumbai and forms a principal channel to

discharge storm water and sewage. This

Sound Practice pertains to the widening

and deepening of the Mithi river and other

city drains in a scientific and well planned

manner. This is intended not only to

increase their discharge capacity but also

to prevent flooding in low-lying areas

adjoining the river by reducing gradients of

the Mithi river in its’ upper reaches. The

storm water drainage for the Mithi river

catchment areas has been disrupted due to

the encroachment of hutments in large

numbers, storage facilities, processing industries, workshops and scrap yards situated along

the banks of the Mithi River that make it difficult even to delineate its path. Direct discharges

of untreated sewage, wastewater from the unauthorized settlements, and industrial effluents

along the river’s course are a cause of concern.

Following the damage caused by severe floods in Mumbai in 1985, the BRIMSTOWAD

Project was initiated by the Municipal Corporation of Greater Mumbai (MCGM).Engineers

and Researchers, under this project, studied the storm water drainage system of Mumbai in

detail and submitted a report in 1993 to MCGM giving suitable recommendations, but they

largely remain unimplemented. Mumbai was again hit by a more disastrous flood in 2005,

which necessitated a fresh study on increasing storm water drainage capacity of the Mithi

river and other city drains. Central Water and Power Research Station (CWPRS), Pune –

Central Government’s Principal Hydrological Research Institute, conducted 1-D

Mathematical Model and Desk Studies for mitigating floods of the MIthi river and submitted

its reportwith suitable recommendations in January, 2006.

The Storm Water Drainage (SWD) system of Mumbai comprises a hierarchical network of

roadside surface drains (about 2000 km length, mainly in the suburbs), underground drains

and laterals (about 440 km length in the island city area), major and minor channels (200 km

and 87 km length, respectively) and 186 outfalls, which discharge all the surface runoff into

rivers and the Arabian Sea. Of the 186 outfalls, there are 107 major outfalls in city, which

drain to Arabian Sea directly, 4 at Mahim creek and 4 at Mahul creek. There are 29 out-falls

in western suburbs draining directly into sea while 14 drain into Mithi river which ultimately

joins Mahim creek.

The location of the Mithi river is an important administrative boundary that divides the

City and the Suburbs. Flooding in the river has direct or indirect implications for

disrupting traffic on five transport corridors; Central Railway Main Line, Central Railway

Harbor Line, Western Railway Line, Western Express Highway, and Eastern Express

Highway.

The intensity of flooding following the unprecedented rainfall of 944 mm recorded at Santa

Cruz airport on 26th July 2005 led to the submergence of large areas adjoining the Mithi river

to an alarming extent which caused disruption of the abovementioned corridors of railways

and surface transport. The reduced flood discharge capacity of the river may have worsened

the situation.

Following the flooding in 2005, the MMRDA asked the CWPRS, Pune was to undertake

hydrological study, whose report was submitted in January 2006.

Results and Recommendations of the Technical Report submitted by CWPRS, Pune

The first two segments, which have an origin to Jogeshwari and Vikhroli Link Road to

Sir MV Road have Steep Slopes, they provide a swift discharge of water eliminating the

chances of flooding. The downstream segments, however, have flat slopes and hence

may cause flooding. Presently, a maximum of 50 m3/s discharge can be accommodated

in the downstream courses of the river without causing any spill over. But the discharge

corresponding to 50 yr rainfall (382.5 mm per hour) or 100 yr rainfall (418.3 mm per

hour) averaged throughout the stream length will cause a severe flood in the

surrounding areas.

In order to mitigate floods, following remedial measures are recommended by CWPRS,

Pune:

(a) Bandra Kurla Complex (BKC) area

1. Providing a dredged channel of 60 m width from -2 m (with respect to Mean Sea

Level or MSL) contour in the sea to Mahim Causeway bed level (dredged to -1

m) and removing existing rock over-crops.

2. Widening of the waterway from Mahim Causeway to Dharavi Bridge to 100 m.

3. Widening of the bed width from the existing 175 m to 200 m between Dharavi

Bridge and CST Bridge.

4. Widening of Vakola Nalla from the earlier designed width of 40 m to 60 m.

5. Deepening of bed level at Mahim Causeway to -1 m and at CST Bridge to +0.67

m.

(b) Upstream of BKC area

1. Widening of existing bed from CST Bridge to MV Road to 100 m.

2. Widening of existing bed from MV Road to Jogeshwari – Vikhroli Link Road to 60

m

3. Widening of existing bed from Jogeshwari – Vikhroli Link Road to Morarji Nagar

to 40 m.

4. Deepening of existing bed levels:

• CST Bridge (Ch. 5.88 km) from +2 m to 0.67 m

• Air India Colony (Ch. 7.05 km) from +3.11 m to +1.0 m

• Airport (Ch. 9.38 km) from +6.15 m to +4 m

• MV Road (Ch. 10.47 km) from +8.12 m to +6.35 m

• Aarey Dairy Foot Over Bridge (Ch. 12.18 km) from +12.75 m to +10 m

• Jogeshwari-Vikhroli (Ch. 14 km) from +20.25 m to +18 m

All the suggested cross sections of Mithi River upto Ch. 10.5 km need to be provided with

slopes of 1 : 1.5. Further upstream upto Morarji Nagar, the required slope is 1 : 2. All the

suggested measures taken together would roughly double the discharge capacity the River.

Additional Recommendations

Moderating the river course by replacing existing sharp bends with longer gentler

bends.

Providing Non-return valves for cross drains.

Providing Regular maintenance and dredging.

Providing smooth transition for waterways near bridges.

Action taken by the City Administration on these recommendations

The City Administration acting swiftly on recommendations accepted most of them and

directed Mumbai Metropolitan Region Development Authority (MMRDA) and Municipal

Corporation of Greater Mumbai (MCGM) to take the necessary action. The work was divided

in two parts. The 11.84 km upstream stretch from Vihar Lake to CST Bridge was given to

MCGM and the critical downstream part of the remaining 6 km was undertaken by MMRDA.

The downstream stretch was more critical due to flat slopes and nearness to sea and was

further divided into two phases by MMRDA:

Phase 1: It involves de-silting and widening of the stretch. The time frame decided for

this was 1 March 2006 to 30 June 2006 and is now finished. The amount sanctioned

for the work was Rs. 30 crores.

Phase 2: It is planned for the post-monsoon period from 1 Oct 2006 to 30 June 2007

with a budget of Rs. 100 crores (subject to variation after post monsoon study). It will

involve dredging, widening, construction of retaining wall, beautification and building

of service roads.

CONCLUSION

Surat is one of the fastest growing cities in the country today. With its rapidly changing urban

infrastructure, it is a city on the rise. However, Surat has always faced the problem of flooding

over the period of time in recent history with the worst flood ever coming in 2006. Lessons

need to be learned from the past experiences and they have to be learned fast. A good storm

disposal system has to be put in place to match the rapid strides in urban development that

Surat has made over the years. The attention has shifted to this very critical area and the work

of rebuilding it has already begun.

A good and efficient storm water drainage system is beneficial is more ways than one. It not

only saves a lot of life and property on the day of the floods but also prevents epidemics

caused due to the long standing stagnant water which becomes a breeding ground for

mosquitoes and insects. Surat lost a lot of money in the 2006 floods, a better and more

efficient storm water drainage system can save another such situation from arising in the

future.

REFRENCES

1. Stanley W. Trimble (2007) Encyclopedia of Water Science, CRC Press, 1586 pages ISBN

0849396271

2. Hogan C. Michael, "Phaistos Fieldnotes." The Modern Antiquarian (2007)

3. Schueler, Thomas R. "The Importance of Imperviousness." Reprinted in The Practice of

Watershed Protection. 2000. Center for Watershed Protection. Ellicott City, MD.

4. Peter Coombes, Water Sensitive urban design in the Sydney Region, Lower Hunter and

Central Coast Regional Environmental Management Strategy, 2002

5. Hiedeman L. David,PE,CIPE, Storm-Water Drainage Systems in Practical Plumbing

Engineering, American Society of Plumbing Engineers, 1998

6. Surat Municipal Corporation, Drainage Department, Surat

7. http://en.wikipedia.org/wiki/Stormwater