Storm Water Drainage System (Subject area: Environmental Environmental Engineering)
Prepared by: Guided by: Name: Ankit Balyan Khabete
Mrs. Anjali
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 Balyan U06CE065
Table of Contents
Abstract……………………………………………………………… …………………………….1 Introduction What is Stormwater…………………………………………………… ……………1 Stormwater Pollution……………………………………………………… ……….2 Storm Drain…………………………………………………………… …………………2 Ancient History………………………………………………………… ………………3 Stormwater Management Site Analysis………………………………………………………… …………………..4 Adjoining properties……………………………………………………… …………4 Public safety…………………………………………………………… ……………….4 Estimating Stormwater Runoff………………………………………………………….5 Stormwater Drainage System in Surat………………………………………………7 Case Study: Increasing the Storm Water Drainage Capacity of Mithi River in Mumbai……………………………………………………………… ……………….8 Conclusion………………………………………………………… ……………………………11
References………….. ………………………………………………………………………… 11
ABSTRACT STORM STO RM WATER WATER DRAINA DRAINAGE GE REFERS REFERS TO THE NETWORK NETWORK OF THE DRAINS 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 URBAN FLOODS FLOODS EXPER EXPERIEN IENCED CED IN SURAT, SURAT, MUMBA MUMBAII AND OTH OTHER ER INDIAN 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 CAPABL CAPABLE E OF MEETI MEETING NG NATURE NATURE’S ’S WORST WORST POSSIB POSSIBLE LE DEMAND DEMANDS. S. IT IS A DEVELO DEVELOPIN PING G AREA AREA IN THE FIELD FIELD OF ENVIRO ENVIRONM NMENT ENTAL AL ENGINE ENGINEERI ERING NG 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 also be used used to appl apply y to wate waterr that that orig origin inat ates es with with snow snowme melt lt or runo runoff ff wate waterr from from overwa overwater tering ing that that enters enters the stormw stormwater ater system system.. Stormw Stormwate aterr that that does does not not soak soak into 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 one relat related ed to the the volu volume me and and timi timing ng of runo runoff ff water water (flo (flood od cont contro roll and and wate water r supplies), and
•
The other related related to poten potentia tiall contam contamina inants nts that that the water water is carryin carrying, g, i.e. i.e. water water pollution.
A storm drainage system is a network of structures, channels and underground pipes that carry storm water (rain water) to ponds, ponds, lakes, streams and rivers. rivers. The network 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 groundwate groundwater, r, or supplies supplies stream baseflow baseflow in dry weather. weather. Pollutants Pollutants entering surface waters during during precipitatio precipitation n events events are termed as polluted 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 water drains 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 overla overland nd flow flow paths paths should should be identi identifie fied d and retaine retained. d. Where Where modifi modificati cations ons to these 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 containing underground underground pipes can operate operate as overland overland flow paths during during intense intense rainfall 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 method for estimating 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 stormwater 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 Pavement: Asphaltic and concrete Brick Roofs Lawns And Sandy Soil: Flat, 2 percent Average, 2 to 7 percent Steep, 7 percent Lawns, heavy soil: Flat, 2 percent Average, 2 to 7 percent Steep, 7 percent
COEFFICIENT OF RUNOFF
0.70 – 0.95 0.70 – 0.85 0.75 – 0.95 0.05 – 0.10 0.10 – 0.15 0.15 – 0.20 0.13 – 0.17 0.18 – 0.22 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 poi point nt.. It is desi desirab rable le to use use a sing single le coef coeffic ficie ient nt of runo runoff ff for for the the enti entire re area. area. Such a dimensionless coefficient (termed a weighted coefficient of runoff) C w, can be calculated using
Cw =
……………………………………………………………………………… …………………………………………………… …………………………
eqn (3)
where A1 , corresponding ing , A2 , , and An are the area in acres (m 2), and C 1 , C 2 , and C n are the correspond coeffic coefficien ients ts of runoff runoff of the indivi individua duall tribut tributary ary areas areas to a common common point. point. A weight weighted ed 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 floodi flooding. ng. If the potent potential ial damage damage from from floodi flooding ng is high, high, the select selection ion of an averag averagee 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 years may may be appr approp opri riat ate. e. In many many cases cases,, the the loca locall auth author ority ity havi having ng juri jurisd sdict ictio ion n will will determ determine ine the average average frequen frequency cy of occurr occurrenc encee to be used used in the design design of storm-w storm-wate ater r 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 proposed to increase upto 491 kms to include 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 prot protec ectt loss loss of man man hour hours, s, busi busine ness ss hour hourss of work workin ing g peop people le and and incre increas asee 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 Dec 2010 2010.. The The enti entire re upgr upgrad adat atio ion n is expe expect cted ed to be over over by 2012 2012.. Surat Surat Muni Munici cipa pall Corporation has taken a major initiative to replace secondary drain pipes with 1400mm diameter diameter pipes. Another Another area of concern that would would be addressed addressed in the new upgradation 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 discha discharge rge storm storm water water and sewage sewage.. This This Sound Sound Practic Practicee pertai pertains ns to the wideni widening ng and deepening deepening of the Mithi river and other city drains in a scientific and well planned mann manner er.. This This is inte intend nded ed not not only only to increase their discharge capacity but also to prev preven entt floo floodi ding ng in lowlow-ly lyin ing g areas areas adjoining the river by reducing gradients of the Mithi river in its’ its’ upper upper reaches reaches.. The storm water drainage for the Mithi river catchment areas has been disrupted due to the the encr encroa oach chme ment nt of hutm hutmen ents ts in larg largee numbers, numbers, storage facilities, facilities, processing processing industries, industries, workshops workshops and scrap yards situated 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 river and other other city city drains drains.. Central Central Water and Power Researc Research h Statio Station n (CWPRS), Pune – Cent Centra rall
Gove Govern rnme ment nt’s ’s
Prin Princi cipa pall
Hydr Hydrol olog ogic ical al
Rese Resear arch ch
Inst Instit itut ute, e,
cond conduc ucte ted d
1-D 1-D
Mathematical Model and Desk Studies for mitigating floods of the MIthi river and submitted its reportwith suitable recommendations re commendations 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) respectively) and 186 outfalls, 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, directly, 4 at Mahim creek and 4 at Mahul creek. There are 29 out-falls 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 intensity of flooding following following the unpreceden unprecedented ted 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 CST Brid Bridge ge (Ch (Ch.. 5.8 5.88 8 km) km) fro from m +2 m to 0.67 0.67 m
•
Air India India Colo Colony ny (Ch. (Ch. 7.05 7.05 km) km) from from +3.11 +3.11 m to +1.0 +1.0 m
•
Airp Airpor ortt (Ch. (Ch. 9.38 9.38 km) km) from from +6.1 +6.15 5 m to to +4 m
•
MV Roa Road d (Ch. (Ch. 10. 10.47 47 km) km) fro from m +8.1 +8.12 2 m to to +6.3 +6.35 5m
•
Aarey Aarey Dairy Dairy Foot Foot Over Over Bridg Bridgee (Ch. (Ch. 12.18 12.18 km) km) from from +12.7 +12.75 5 m to +10 +10 m
•
Jogesh Jogeshwari wari-Vik -Vikhro hroli li (Ch. (Ch. 14 km) km) from from +20.25 +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 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 recommendations
The City City Admini Administr strati ation on acting acting swiftl swiftly y on recomme recommenda ndatio tions ns accepte accepted d most most of them 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 system is beneficial 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 caused due to the long standi standing ng stagna stagnant nt water water which which become becomess a breedi breeding ng ground 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, Coombes, Water Sensitive Sensitive urban design design in the Sydney Region, Region, Lower Hunter Hunter and Central Coast Regional Environmental Management Strategy, 2002 5. Hiedem Hiedeman an L. David, David,PE, PE,CIP CIPE, E, StormStorm-Wat Water er Draina Drainage ge Syste Systems ms in Practic Practical al Plumbi Plumbing ng Engineering, American Society of Plumbing Engineers, 1998 6. Surat Municipal Corporation, Drainage Department, Surat 7. http://en.wikipedia.org/wiki/Stormwater
