Last week the whole city was submerged after a rainfall thatlasted only a few hours. Has anybody given it a thought that why the entirecity got inundated during the recent rains. All this is due to the lack ofpublic awareness and lack of civic sense among the people. The drainage systemcan never be designed for “ZeroSubmergence”. It’s beyond the design norms. As such there are some areas whichcome under submergence during heavy downpour due to their topography, but thisphenomenon is purely temporary as the situation normalizes within few hoursafter the rains stop. It clearly indicates that there is no defect in thedrainage system. This kind of phenomenon is observed in the metropolitan andcosmopolitan cities like Delhi, Mumbai, Kolkata & Chenai. However somesubmergences take a serious turn due to blockade of drains which is due to theusers of the drainage system i.e. the population of that particular area. Ithas been observed that whatever the rubbish is generated in homes either in theform of faecal matter or polythene bags or any other organic or inorganicrefuse, is dumped into the drains which every now and then result in theblockade of drains. Even the Green Sewer which has been designed for hugedischarge and has a big enough section of waterway, gets choked occasionallyand it requires to spend a considerable amount of money & manpower forremoval of such blockades and making the drainage and sewerage systemfunctional. Such situations can easily be avoided if the people in general becomeaware about their civic duties and the Government in particular takes stringentmeasures to stop such reckless use of drains. An important measure to be takenup is to impose a whole hearted ban on the use of polythene which has become anenvironmental hazard and being non-biodegradable often lead to chocking ofdrains thereby rendering drainage system non-functional. Also emphasis needs tobe laid for the construction of a separate sewerage system in all the areas inorder to meet the requirement of people on this account and to provide properhygienic conditions. Moreover in order to avoid prolonged submergences it isessential to augment the existing dewatering stations in order to enhance theirfunctionality due to increased demands also it will be necessary to replace theworn out machinery at these pump stations.
Before discussing the present scenario of drainage system inthe Srinagar city in particular and that of the valley in general, we mustunderstand the function of a drainage system and differentiate it from that ofa sewerage system. The essential principle of any type of land drainage is toprovide an open, adequate, and readily accessible channel through which thesurface or subsoil water can flow. For this purpose open ditches are sometimes used,but these are not always satisfactory because they may become choked withsediment and vegetation. Underground drains are thus usually employed toovercome this problem.
Drainage means removal of surface or subsurface water from agiven area by natural or artificial means. The term is commonly applied to theremoval of excess water by canals, drains, ditches, culverts, and otherstructures designed to collect and transport water either by gravity or bypumping. A drainage project may involve large-scale reclamation and protectionof marshes, underwater lands, or lands subject to frequent flooding. Such aproject usually involves a system of drainage ditches and dikes; often pumpsare required to raise the water into the drainage network.
In cases of large-scale drainage it is essential to improvethe discharge capacity of natural channels to protect adjacent properties andto upgrade the ditches and channels that convey the runoff from drainagesystems to the improved channels. Such connecting drains commonly follow thenatural surface drainage pattern of the area, intercepting the normal surfacerunoff that takes place during periods of excessive rainfall.
In draining comparatively flat land, common practice is tolay along one side of the plot a main drain to which a number of transverselaterals are connected. The laterals are often set parallel to the main drain,coming together to join it at the lower end of the field. Local conditions ofsoil and terrain govern the spacing of laterals and the depth at which they areplaced. To prevent water from higher ground from reaching lower areas,catchment or interception drains are frequently built. They consist of ditchesor underground drains, placed across the slope, that catch water and carry itaway before it reaches the low ground.
The drainage in the Srinagar city poses a particularproblem, since parts of the city are lower than the river and adjacent lakearea thus to drain out the area, the system needs to be provided with thedewatering stations having effective and adequate pumping equipment with properbackup in order to meet the power failure which is frequently experienced inthe valley. The drainage system constructed already in the city of Srinagarenvisaged the disposal of drainage water in to the natural drainage channels& wetlands identified by the flood control department for the purpose. Thedisposal of the drainage water thus has to be into the natural drainagechannels or wet lands as is done in many other countries and even in United States.Where gravity flow is impossible, the water from the drainage system is pumpedaway into streams or canals, the level of which is often higher than that ofthe drained land.
Though, as reported in the news item, it is a fact that only20-30% of the city is covered by the drainage system, yet it is far fromreality that the drainage system where it exists is inadequate beingconstructed during Bakshi era. The drainage system of any area is designed onthe basis of catchment area of that particular system with an assumption of arainfall intensity of 8-10mm per hour taking appropriate runoff coefficientdepending upon the topography of the area. Since the land use at most of placeshas changed in the city outskirts the runoff coefficient adopted for designingany drainage system is likely to change thus there always remains scope for upgradation of the drainage system. However it does not hold good for the citycentre area such as the area from Tagore Hall to Kaka Saria including HSHStreet Sahheed Gunj etc and from Maulana Azad Bridge to Budshah chowk includingResidency Road and Lal chowk, as the topography of this area has not changedmuch since the construction of drainage system in this area. The area has aneffective drainage system with sufficient number of dewatering stations andnetwork of drains sufficient enough to cater to the surface runoff for which ithas been designed.
Then what went wrong that entire city came under submergenceand remained water logged for hours together which created panic among thebusiness community and the inhabitants of these areas? All this is experienceddue to choking of drains and large scale siltation of the drainage system whichhas reduced the carrying capacity of these drains. During the devastating deluge of the city inSeptember 2014, the water remains stagnant in most of the area for more thantwenty five days and the entire silt load transported by the flood water fromthe mountainous region got accumulated in the drains thereby rendering theentire drainage system dysfunctional which resulted in the inundation of citydue to rain water on 29/03/2015. and many times thereafter including on24/07/2019 the drainage system been rehabilitated and cleaned properly by wayof de-silting of the network of the drains and if the worn out and damagedmachinery during floods been replaced the storm water of the rains on would nothave worried the populace as the entire storm water could have been dischargedinto the outfalls through the effective network of drains.
After the devolution of municipal functions to MunicipalCorporation, Urban Environmental Engineering Department has been reduced to oneSewerage Division in Srinagar and one Sewerage Sub Division in Jammu. The otherDivisions which were taking care of the Drainage sector have since been givenunder the Administrative control of either the Municipal corporations or urbanlocal bodies of Srinagar and Jammu Divisions. However some areas like Buchwaraand Khanyar which were previously looked after by the Drainage Divisions weretransferred to the Sewerage Sector. Since no sewerage system existed in theseareas, the existing Drains are being used as sewers. As indicated earlier thesedrains transport with them a huge amount of trash which not only overloads the onlyexisting treatment plant but also results in the frequent blockades in thetrunk sewers in which these drains culminate. Though the drainage and thesewerage system have different functions to perform yet it has been observedthat both the Drainage and the sewerage system of the city perform samefunctions, otherwise the drainage system meant for taking care of the stormwater would have been dry during the dry weather and the sewerage system meantto take care of the sewage would not overflow during the rains. The groundreality is that the area under the administrative control of UEED is named asSewerage and that under the administrative control of Municipal Corporations isgiven the name as drainage though both the systems perform identically the onlydifference is that the discharge taken care of by UEED is first taken to STPBrari Numbal for treatment which makes the treatment plant overloaded owing toits capacity for treating Sewage flow only. As a result, there is always a dualcontrol on the drainage as well as sewerage system.
To overcome this problem, there seems to be only solutionand that is to provide a separate sewerage system so that the people open thehouse connections into the sewers in order to dispose the night soil andkitchen waste which contains the chemicals due to excessive use of soap. Thesewage needs to be treated before its disposal into water bodies. It needs tobe borne in mind that the urbanization has had profound effect on aquaticenvironment of the city of Srinagar. During urban development vegetation isremoved and replaced by roads, car parks, drive ways and roof tops that areimpervious to rainfall. Unable to percolate into soil, rainfall becomescompletely converted into runoff. Furthermore the impermeable surfaces associatedwith urban development are often contaminated by a variety of gross pollutantssuch as detergents, trace metals, hydrocarbons, nutrients, pesticides andherbicides. Due to the topography of the vale of Kashmir in general and that ofSrinagar city in particular the storm water while flowing down the streets orthe road on its way picks up gross pollutants like dirt lawn clippings, petwaste, salt, lawn chemicals, field fertilizers, oil grease etc. This water andthe pollution load it carries generally go into the storm water drains of thearea and from there to the nearest stream, river or the water bodies withouttreatment. Studies have determined that up to 70% of our surface pollution iscarried along by the storm water. This pollution load not only results in thesiltation of these water bodies but also cause the eutrophication of the waterquality of these water bodies. Thus keeping in view this fact the concept ofdischarging the storm water discharge directly into the water bodies without anytreatment is mediocre and thus not perceptible.
The concept of a separate system for the storm waterdrainage keeping in view the huge operational cost of the treatment plants, canprove a success only if both the system i.e. Drainage system and the Seweragesystem coexist so that the storm water, grey water and the black water is takencare of simultaneously. Otherwise as experienced form the present scenario ofthe existing utilities on this account the sewerage system is being used asdrainage system as well which results in its overloading of sewers andtreatment plant and thus the desired results are not achieved. Similarly wheresewerage system does not exist, the existing drains are being used for thedisposal of sewage as well and since the drainage discharge is disposed inexisting water bodies without treatment, it results in large scaleeutrophication of these water bodies thereby making their condition abominable.
In most of the areas topography does not permit a separatesystem thus in these areas it will not be possible to segregate sewage from thestorm water/drainage owing to the congested population and closely builthouses, narrow lanes and by-lanes. As indicated earlier the city of Srinagarhas observed a yawning sprawl in its limits and a number of new colonies havecome up in an unscientific and haphazard manner. The service roads in thesecolonies are so narrow and do not have sufficient width to accommodate thebasic utilities like water supply distribution pipes, electric poles, telephonecables etc. thus it will not be possible in these colonies to have a separatesystem as the width of these lanes and by lanes do not permit to lay sewers aswell as drains separately. To overcome this problem it is suggested to convertthe existing drainage system where ever it exists into the combined system asthe dry weather flow is almost negligible as compared to the storm water flowand can always be taken care of by the storm water drains. This can be achievedby employing the technique of Trench less rehabilitation of existing system.This technique is the modern technique and has many advantages. Also it issuggested to adopt a combined system in all existing colonies which have comeup in unscientific way. However in new areas which shall be strictly developedon scientific grounds, separate system can be adopted.
This can be achievedby making for the people at helmaccountable and for which the Environmental Engineering Department (UEED) needsto be revived for the effective management of sewerage and drainage systemwhich needs to reverse the decision of transferring drainage Divisions bothcivil and Mechanical into the control of Srinagar Municipal Corporation afterdevolution of municipal functions. Thereby transferring these Drainage Divisionsboth Civil and Mechanical back under the administrative control UrbanEnvironmental Engineering Department (UEED) after reorganizing the Departmentas there is need of one Sewerage and Drainage Division in every Districtkeeping in view the urban agglomeration.
Recommendations:-
1. UrbanEnvironmental Engineering Department (UEED) needs to be restored to predevolution position of 2005 by way of immediate transfer of Drainage Divisionsboth Civil and Mechanical in Srinagr and Jammu to Urban EnvironmentalEngineering Department with the creation of one new drainage and sewerageDivision in each District.
2. Topographyof the entire area for which the drainage system is being proposed need to besurveyed, its slope and terrain need to be accurately mapped by using latestmapping technologies.
3. Availablehydraulic head in the system up to highest flood level of the river or waterbody which will serve as disposal need to be established.
4. Geotechnicalsurvey of the area need to be conducted so that the details of ground waterdepth and its seasonal fluctuations affecting construction of the drainagesystem form infiltration, and structural design (uplift considerations) pointof view are established. Also the soil bearing capacity and type of soil strataexpected to be met during construction need to be evaluated for each basin/area. The concept report lacks this part. It is, thus suggested that theconsultants should conduct the geotechnical surveys and incorporate this partin the final DPR and all the structures should be designed in accordance withthese survey reports.
5. In orderto ameliorate the situation and to reprieve the public from the sordidatmosphere due to water logging, the existing drainage net work needs to beextended to all the new colonies with proper dewatering stations where everrequired with the pumping equipment of fuller capacity and sufficient enough tocater the design discharge of these areas. Consultants should as such includethe grey water content while calculating the design discharge.
6. Theexisting system needs to be revamped by way rehabilitating thedamaged/non-functional portion of the system. Moreover The sewer appurtenancessuch as manholes, lamp holes, street inlets, catch basins, flushing tanks,storm-relief chambers, grease- traps etc should be proposed to be introduced atrequired place in the existing system, proposed to be rehabilitated as thepresent system lacks these devices which are otherwise necessary to assist inthe efficient operation of the system.
7. The wornout machinery need to be replaced in all the existing dewatering stationswherever required. Also the existing under capacity dewatering stations need tobe augmented by supplementing them with the additional pumping equipment. Allthe dewatering stations need to be fed from the essential service feeder of thepower supply for their uninterrupted functioning. Also arrangements need to bemade for the backup in case of power failure which is frequently observed inthe valley. Such provisions need to be incorporated in the project cost.
8. Since thestorm water and both black water and the grey water need to be treated beforetheir discharge into the water bodies in absence of the separate system forDrainage and sewerage, it will be expedient to have a combined system with CSOmechanism for its treatment in order to reduce the operational cost of thetreatment plants during the heavy downpours/Storms. It will be important tomention here that as per the available rainfall data it has been observed thatthe Srinagar city experiences 55 numbers of rainy days on an average during theyear. This implies that for more than ten months of the year the combinedsystem will carry dry weather flow only. For rest of period the storm watercombined with the waste water will be regulated to a combined treatmentfacility. This method will not overload the dry weather treatment facilitywhich will have to work for about ten months of the year thus saving energy andrunning cost.
9. As thestorm water and the grey water need minor treatment and break more quickly thanthe black water, Possibility of adopting sustainable drainage system need to beexplored where ever wherever applicable in order to reduce the number ofconventional treatment plants and thus the operational cost on account oftreatment of the drainage discharge.
10. Whereverpossible construction of retention basins and detention basins need to beproposed to remove the pollutant load from the drainage discharge before itsdisposal into water bodies in order to avoid eutrophication and siltation ofthese water bodies.
11. The sewagecollection (House connections) should be made through the closed pipes insteadof open surface drains to avoid entry of garbage into the sewer lines whichotherwise may result in the blockade of the sewers.
12. As far aspossible all proposed drains need to be kept covered with RCC slab to avoidtheir misuse by way of dumping garbage and other household waste into thesedrains as has been observed commonly. This will also keep the drainage systemin a better state of hygiene.
13. Alldesigns shall have to be in accordance with the norms as laid down in themanual of sewerage and sewerage treatment prepared by Central Public Health andEnvironment Engineering Organization (CPHEEO).
(Er. Mehraj -u- DinBhat is Executive Engineerster Water Supply Mas Plan Division Srinagar