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WATER SUPPLY CHAPTER V d) Future requirements if known; A. WATER SUPPLY e) Whether the supply will be metered, continuous or intermittent;...

WATER SUPPLY CHAPTER V d) Future requirements if known; A. WATER SUPPLY e) Whether the supply will be metered, continuous or intermittent; 501 General - Reference may be made f) Details of pumping arrangement and to the following for provisions not contained in its cost. this Chapter. In case of any variation, the latter shall prevail. For collecting this data, preliminary survey, site investigation may be necessary. (1) Manual on water supply and The investigation will involve yield test, check treatment by Ministry of Urban on quality of water etc. Necessary checklist Development, New Delhi for framing water supply proposals is given as Annexure 5.1. (2) IS:1172 - 1983 503 Review of Water Supply (3) IS:10500 - 1991 Arrangements on the Railways: Engineering Department officials should keep (4) National Building Code of India themselves posted with the information regarding rainfall, supply position from (5) Manuals issued by local public various sources and take suitable action to health departments avoid any breakdown in supply of adequate water of proper quality. 502 Preparation of Schemes for New Water Supply/Augmentation of Existing Every year the Divisional Railway Water Supply -The preparation of schemes Manager should conduct a Water Review for new water supply/augmentation of existing meeting with all the branch officers and Civil water supply will involve collection of following Public Health Department if required, to review data:- the adequacy of existing water supply, augmentation required, any other action to be a) Justification for an improved or taken for avoidance of emergency during additional supply or new supply - summer months etc. Minutes of the meeting should be sent to the office of the Chief This will include number of people to be Engineer for information. Copy should also covered, estimated consumption and basis of be endorsed to the Assistant Engineers and calculation; Section Engineers (Works) for necessary action. b) Nature, quality and quantity of existing supply and its source; After the review meeting, the Divisional Engineer should submit necessary proposals c) Possible sources of additional supply for augmentation of water supply to concerned and arrangements for its filtration, purification authorities wherever required and take further etc; action. 131  WATER SUPPLY 504 Data for Estimating minimum basis unless otherwise justified by Requirements of Water: The scale of daily particular circumstances. Allowance should supply may be computed on the following be made for future development:- ________________________________________________________________________________________________________ Particulars Litres per day (a) Residential area Household consumption for.. 200 (Includes 45 litres required for Officers and staff per head.. flushing). (b) Office and workshop Offices per head.. 45 Workshops per head.. 30 (c) Station and platform Apron washing.. 10 per sqm Platform washing.. 5 per sqm. Passengers on railway station.. * 25 per passenger Washing of carriages on.. 3600 per carriage for BG washing lines.. 2600 per carriage for MG Cleaning of carriages on.. 500 per carriage platform Carriage watering.. **as per actual requirements. (d) Miscellaneous Gardens per hectare.. 22500 approx. of lawn area Hospital.. 450 per bed Fire Service.. Occasional Sumps and hydrants to be adequate for emergencies. ________________________________________________________________________________________________________ * Number of passengers for estimating requirement at a station shall be equal to passengers entraining at the station plus half of the passengers detraining. * * Quantity of water required for train originating station shall be equal to the full capacity of tanks for all the coaches. For trains scheduled for watering on other stations, only 75% filling capacity may be considered. 505 Capacity of Source - Ordinarily, in the summer season, sources should be able to supply in eight hours the quantity of water normally consumed in a day. 132  WATER SUPPLY B. OPEN WELLS In average conditions of subsoil, this velocity is between 750 mm 506 Preliminary Measures for Sinking and 1200 mm per hour and is obtained with a head of 2 metre to a) Samples of strata and samples of 3 metre. underground water for chemical and bacteriological analysis should be obtained by The safe yield of open wells is trial-boring or sinking a test-well. This work limited by the critical velocity and should normally be carried out in the dry for practical purposes the yield may season. The Geological Department should, be obtained by multiplying the critical whenever possible, be consulted in regard to velocity by the area of the floor of the strata and source at the proposed site. the well. b) The yield of the test-well should be 508 Improving Yield in Open Wells assessed by carrying out a recuperation test after pumping the water to below the "normal b) In sandy soil - If the yield with a "drop" water-table" and plotting the results in the form of 2 meters is insufficient, then a larger of a diagram with draw down as abscissa diameter well is needed. Alternatively, a tube and the inflow in litres per hour as the ordinate. well may be sunk in the open well to supplement the yield. Any increase in the 507 Determination of Size: "drop" will increase the "critical velocity" and "blowing" of the sandy soil and subsidence of (a) From the yield diagram, the diameter staining may occur. and depth of an open well should be arrived at on considerations of the maximum daily c) In moorum and porous rock - If the requirements, due allowance being made for yield is insufficient, it may be improved by the future demands. deepening provided the lower strata is porous. This can only be ascertained by making a b) For the size of the open well, the bore. following factors should be considered:- Driving adits into sides of the well and (i) The normal water table - This is providing a greater number of "weep-holes" the level at which water stands in a would increase the yield. well which has not been pumped for 24 hours. This varies throughout the In porous rock the inflow may be slightly year; and increased by holding up surface flow of the rainfall in the vicinity of the well. This may be (ii) The critical velocity of flow - The effected by building a bund on the upstream critical velocity of inflow is the side of the well. maximum velocity of water passing through subsoil without disturbing the finer particles of the subsoil. 133  WATER SUPPLY 509 Shallow Tube-Wells - 511 Stages of Work for Sinking Tube-wells to a depth of 7.5 meters to 12 a) Trial boring- meters are found useful for tapping a shallow water-table. Where only small quantities of (i) During sinking of pipes, samples of water are required, these are cheaper than strata are examined for yield and open-wells and may be constructed at wayside samples of water taken for analysis stations, gang quarters and gate-lodges between stations if the water-table could be (ii) From the results obtained, the area tapped at a reasonable depth. Quality of water of strainer necessary for the of these wells is not reliable and disinfection quantity of water required and the is essential. strata in which the strainers should be located are decided upon Shallow tube well can be operated either electrically or manually depending upon the b) Samples of water for analysis-For a convenience. large water supply, water should be drawn from as great a depth as possible to eliminate At unimportant stations and wayside the danger of bacteriological contamination stations where water table is within about 10 which can be expected in water drawn from metres of the ground level, hand pumps should the upper strata. Water drawn from deep be installed in colonies. ground is likely to be bacteriologically pure. Hand pumps have been standardized As the water obtained from deep wells by Bureau of Indian Standards and standard may contain certain dissolved impurities, the hand pumps are available for installation. chemical analysis of water to determine its Sufficient number of spare parts for repair of suitability for drinking is always necessary and hand pumps should be kept with the Section samples should be sent to the Divisional Engineer (Works) to attend to emergencies. Medical Officer for test. C. DEEP TUBE WELLS c) Tube-well installation- Initially the casing pipes are sunk to required depth. 510 Consultation with Geological Strainers and plain pipes of tube-well proper Department - are then lowered to correct depths. The Geological Department or Central In suitable cases, pebbles or gravel is Ground Water Board / Public Health let down between the casing pipes and the Engineering department of the State tube-well as shrouding during casing-pipe Government should, be consulted wherever extraction. This is essential when the strainers necessary, for proposals of deep tube-wells. are located in fine sand. Where the "normal-water-table" is at greater depth, it would be economical and preferable Brass, galvanized iron, special alloy to sink deep tube-wells instead of open-wells. steel, high density polythene or PVC and metal combined strainers of the requisite size with 134  WATER SUPPLY gravel/sand shroud may be used. The total When the disks are further lowered down and area of the openings in the screen should be if the well pipe is not truly vertical, the wire such that the velocity of inflowing water is will deviate from the centre and that shall be sufficiently low to avoid disturbance to the indicated at the top of pipe. smaller particles of the water bearing stratum. Absolute verticality is ideal but a d) Testing yield of tube-wells.- A tube- deviation of 100mm per 30 metres of boring is well should be tested for yield by experienced generally acceptable where submersible staff of the tube well organization of the pumps are not to be installed. Railway. IS:2800-1979 may be referred where necessary. 513 Failure Of Wells And The Remedial Measures - 512 Checking Verticality of Tube Wells- The clogging of wells by sand or by Tubewells must be perfectly vertical. A corrosion or encrustation of the screen may simple method is to use plumb disk. Two disks reduce the yield substantially. The wells may made out of 3mm thick steel plate are be readily cleaned of sand by means of a sand connected together by a rod of 25mm diameter pump or bucket but if the strainers are and 3 metre long tightened with the help of corroded, they must be pulled out, cleaned or nuts at the ends. Some holes are punched in renewed or replaced. plates to facilitate immersion in water. A knob is fixed on the top nut to which a thin steel Method of surging, use of dry ice or wire is attached.The disk is suspended into chemical treatment by using acids, chlorine, the tube by the wire passing over a pulley on polyphosphates may be used for treatment a tripod. against clogging. Following table gives types of well clogging problems and recommended When the disk is lowered into the treatment : pipe,the wire is exactly in the centre of pipe. WELL CLOGGING PROBLEMS AND ITS SUGGESTED TREATMENTS ____________________________________________________________________________________ Problem Treatment recommended ____________________________________________________________________________________ 1. Clogging due to fine Sodium hexametaphosphate50gm/litres depending on the capacity of sand, clay and silts well bore be left therein for 24 hours.The same should be followed by surging, jetting with chemical mix or normal development till well is freed from clogging 2. Chemical clogging Hydrochloric acid or sulphuric acid with inhibitor are added to the well 3. Bacterial clogging Chlorine has been found to be effective in loosening this type of clogging Calcium hypochloride should be used to form solution which is introduced in well in a small polythene pipe. 200 gms. of hypochloride is required at 70% concentration for 1000 litres of water 135  WATER SUPPLY 514 Disinfection of Wells - areas requiring attention. Loss of capacity due to the deposition of silt in reservoir may impair Newly constructed wells as well as those the usefulness of the reservoir within a few after repairs have to be disinfected by heavy years. It may be minimized by erosion control, dosages of chlorine. Bleaching powder is reservoir operation and desilting works. There generally used for this purpose. are various commercially available organic compounds which when spread on the water D. IMPOUNDING RESERVOIRS surface form a monomolecular film, which reduces evaporation. Seepage can be reduced 515. Governing factors - by making cut off wall beneath the dam. The water weeds in the reservoir should be The catchment area, its characteristics controlled by suitable methods such as and the rainfall decide how much water would dragging and underwater cutting. Algicidal be available for storage. A contour plan of the treatment by using suitable Algicide may be neighborhood of proposed dam facilitates the adopted to control algae in reservoir. It is decision of the height of the dam and decides preferable to initiate the treatment in the early whether or not there is sufficient storage stages of algae growth. capacity for the amount of water needed. Losses by evaporation and absorption should E. INFILTRATION GALLERIES AND be assessed. Expert agencies should be WELLS consulted where necessary. 519 Infiltration Gallery - 516 Storage Capacity - These are constructed in water bearing strata. The gallery obtains its water from water The storage capacity depends on the bearing strata by various porous drain pipes. height of the dam and contours of catchment A collecting well at the downstream end of behind. Due allowance should be made for the gallery serves as the sump from where losses due to seepage, evaporation and silting. the infiltrated supply is pumped out. The gallery laid perpendicular to the flow of sub- surface water yields maximum quantity. Quality of water is normally reasonably good 517 Cracks in reservoir walls - and only disinfection may be required. Cracks that may occur in reservoir walls 520 Infiltration Well - should be grouted, with fine cement grout/ resins. They should be kept under observation. Infiltration wells are usually sunk in series in the banks of river. They are generally 518 Reservoir Management - constructed of masonry with open joints. The infiltration wells in turn are connected by Problem of silting, evaporation losses, porous pipes to a collecting sump (jack well). seepage and algae troubles are some of the 136  WATER SUPPLY There can be large yield of water all the pumps and to maintain sufficient depth from these wells. Quality of water varies with of water to avoid air entry during draw down. quality of water in river, depth, and distance of well from river bank. The suction pipe should be as short and straight as possible. Any bends or elbows 521 Radial Collector Wells - should be of large radius. As a general rule the sizes of the suction pipe should be of one Radial collector well consists of a or two sizes greater than the nominal size of cylindrical well of reinforced concrete the pump. Alternatively the suction pipe should construction, 4-5 metre in diameter going into be such that the velocity is about 2m/s. Where the water bearing medium to as great a depth bell mouth is used, the inlet of the bell mouth of the substrata as possible. In the collector should be of such size that the velocity at the wells the radial pipes which are slotted steel bell mouth is about 1.5 m/s. The suction pipes normally 200mm to 300mm diameter are strainer should have net open area equal to driven horizontally at about 7 meters below three times the area of the suction pipe at the water table in the well. The length of the least. steel pipes will be determined by the requirement of water and yield of the aquifer 523 Water Supply from Outside i.e. the water bearing medium in the subsoil. Sources - The drain pipes are made of short lengths of pipes 2.4 metres each which are welded to When water is obtained for railway each other. The pipes are driven horizontally purposes from the Public Works Department, by means of suitable pin jacks placed in the the Municipality or a private body, the well. agreement should clearly specify:- Desanding operation is required to be (a) term or duration of agreement; done after driving of the radial pipes. Desanding is done by inserting another tube (b) rate of payment for water; into the drain tubes and blast of compressed air to separate the fine particles of alluvium. (c) mode of measurement and location The radial collector wells have higher efficiency of meters etc, of drawing the ground water compared to ordinary wells. This type of wells are able to (d) maximum and minimum quantities obtain high yields of water depending on the to be supplied daily; strata and depth of submergence. This is normally provided in alluvial beds of major (e) minimum pressure to be maintained rivers. in the mains at points of supply; 522 Intake Arrangements - (f) in case of bulk supply, point or points at which water is to be Detailed consideration is necessary for supplied; the design of intake to prevent vortex formation to obtain uniform distribution of the inflow to 137  WATER SUPPLY (g) in case of distributed supply, details 35000 litres per hour. of the layout of distribution mains and conditions for extensions or d) Vertical spindle deep well turbine extra connections. pumps are suitable for tube wells of large size; they are easy to operate and have a high Copies of such agreements should be efficiency. They should be used in tube wells available in the Divisional Engineer's and which are free from grit and where competent Assistant Engineer's offices. supervisory staff are available, as adjustments during repairs require skilled attention. F. PUMPS Submersible pump is suitable for 524 Types and Selection of Pumps comparatively smaller installations. It consists of an electric motor and pump both a) The types of pumps in general use submerged in water; the vertical spinning shaft are reciprocating, centrifugal, airlift and is dispensed with, the water being pumped vertical spindle deep well turbine pumps. through a vertical pipe. Hydraulic rams are useful and economical in perennial streams for supply of comparatively e) Pumping units should be so selected small quantities of water. that they could be operated continuously at rated load, as the units are operated most b) Reciprocating pumps have nearly a efficiently at the rated load. uniform efficiency over a large range and therefore greater flexibility in operation. f) Pumping capacity should not exceed Reciprocating pumps may be duplex, triplex the yield of the source, so as not to damage or quadruplex accordingly to the number of the strata through which water filtrates into water-cylinders and are suitable for pumping the source. from open wells. They are, however, not suitable for tube-well operation as the 525 Pump Installation - intermittent suction has a damaging effect on the strainers. While installing a pump, the following points should be paid attention: c) Centrifugal pumps are efficient, economical and require little attention. The a) the foundation should be sufficiently suction lift is, however, limited as in the case strong to absorb vibrations and to of reciprocating pumps. form a permanent, rigid support for the base plate. The foundations shall In tube-wells where centrifugal pumps be designed for the loads as per cannot be installed sufficiently close to the IS:2974 Part IV - 1979. water-table, airlift pumps may be used. Their efficiency is, however, low and should not b) the suction lift, which should be normally be used for capacities in excess of made as low as possible; the greatest suction-lift that may be 138  WATER SUPPLY expected at sea-level is about 7 526 Driving Units - metres. The driving unit may be an electric motor, c) the suction pipe should be air-tight, or an oil engine. Where power is available:- laid with as few bends as possible and equipped with foot-valve. (i) the prime mover should preferably be an electric motor, being d) near the pump, a non-return economical; (reflux)valve and a delivery valve (sluice or butterfly valve) should be (ii) the stand-by where provided may provided. The non-return valve be an electric generator so that in should be between the pump and case of failure of electric supply, the delivery valve. The size of the pumping is assured. valve should match the size of pipe. (iii) Where power is not available, oil e) the delivery pipe shall be of such engines may be used. size that the velocity of water is about 2.5 m/s. (iv) Non-return valve at the discharge pipe, supplemented by a sluice f) a dismantling joint must be valve shall not be closed while the provided between the pump and the pump is running. valves. The design of the dismantling joint should be such 527 Capacity of Pumping - that no pull or push is transmitted to the pump. The pumping system should be capable of supplying:- g) Sufficient space for generating sets should be available in the pump (a) In 12 hours or less, the normal house to locate the pump, motor, quantity required in 24 hours; valves, pipes, control panels in a rational manner with easy access (b) In 16 hours or less, the present and with sufficient space around for maximum quantity required in 24 the maintenance and repairs. The hours; minimum space between two adjoining pumps or motors should (c) In about 20 hours, the estimated be 0.6 m for a small or medium units maximum future requirements in and 1.0 m for large units. 24 hours. Space for control panels should be For small pumping systems, generally planned as per the Indian Electricity Rules. of capacity less than 15 million litres per day, two pumps (one duty and one standby of full capacity) should be provided. Alternatively, 139  WATER SUPPLY two duty and one standby, each of 50% to prevent contamination; they should be capacity may be provided. Although this provided at the lowest point with a scour sluice alternative would need larger space, it and with manholes not farther apart than 250 facilitates flexibility in regulating the water meters and at all bends and changes of supply. Also in an emergency of two pumps gradient. going out of order simultaneously, the third helps to maintain at least partial supply. b) For pressure mains, galvanized screwed pipes upto 80 mm diameter may be In the case of medium and large used; for diameters over 80 mm, cast iron pumping stations , at least two standbys spigot and socket or reinforced concrete or should be provided. Electrical department is suitable asbestos pipes should be used as responsible for installation and maintenance per relevant BIS specification. of electrical machinery/equipments. c) Cast iron pipes.- First and Second 528 Pump Horse Power - class cast iron pipes in stock when used should be treated with a suitable solution in The equation for pump horse power- order to reduce corrosion and encrustation. P.H.P.= L(H+h) Owing to liability to tuberculation and 4560 encrustation, it is not economical to use cast iron pipes of 80 mm diameter or less. When Where P.H.P is the pump horse power arriving at the diameter of a cast iron pipe, (metric): (One metric horse power = 75 calculations should be based on data for old kilogram metres/Sec.), H is the vertical height pipes unless it is positively known that the in metres from suction-level to highest point pipes will not be required to serve for more of discharge; L is the litres of water per minute than two years. and 'h' the head lost in friction in metres. d) Concrete pipes: Concrete pipes are 8 percent extra for incrustation in the best suited where pressure is low and danger case of cast iron pipes may be allowed while of shock is small. These are not to be used calculating PHP. The relation between the for pressures above 50 metres head of water. pump horse power and the indicated horse For greater pressures, hume/steel pipes are power or brake horse power of the engine to be used. working the pump depends on the type of engine and type of pump and their efficiency. Reinforced concrete pipes used in water supplies are classified as P1, P2 and P3 with G. AQUEDUCTS AND PIPE LINES test pressures of 2.0, 4.0 and 6.0 kg/cm2 respectively. For use on gravity mains, the 529 Conveyance of Water from Source working pressure should not exceed 2/3 of the test pressure. For use on pumping mains, a) Gravity conduits should be accurately the working pressure should not exceed half set out to the necessary gradient and covered of the test pressure. 140  WATER SUPPLY Generally concrete pipes have corrosion deterioration results in discoloration, surface resistant properties similar to those of cracking and ultimately rendering the pipe unfit prestressed concrete pipes (PSC) although for use. they have their own feature which significantly affect corrosion performance. Concrete pipes PVC pipes are not suitable for hot water are made by centrifugal spinning or vibratory supply systems. Hitherto GI pipes have been processes. Centrifugally spun pipes are in predominant use in water supply systems. subjected to high rotational forces during Now pipes with specific improved manufacture with improved corrosion characteristics are available. resistance properties. f) Steel pipes: Steel pipes can be adopted While RCC pipes can cater to the needs conveniently where changes in relative ground where pressures are upto 3.0 kg/cm2 and levels are there and are very suitable for laying C.I. and steel pipes cater to the needs of higher in grounds liable to subsidence. Where high pressures around 24 Kg/cm2, the PSC pipes dynamic loading is expected, pipes are joined cater to intermediate pressure range for which by flexible joint. the metallic pipes are expensive while RCC pipes would not be suitable. Judicious method of laying and joining may be used i.e. either flexible joint made of PSC competes economically with steel white lead and spun yarn or welding the plain for pipe diameters of 600 mm and above. The ended pipes (refer IS 5822-1986). PSC pipes are ideally suited for water supply mains where pressures in the range of 6 Kg/ 530 Pipe Laying and Fitting of Valves cm2 to 20 Kg/cm2 are encountered. and Meters e) PVC pipes have the advantages of a) The following instructions should resistance to corrosion, lightness of weight, be followed : - toughness, rigidity and ease of installation. PVC pipes are cheaper and do not get pitted (i) For a gravity line, the pipe line may or corroded in service. They are resistant to follow the contour of the ground so a wide range of chemicals. They have good long as frequent and abrupt elastic properties and resistance to changes in gradient are avoided, deformation resulting from earth movements and it is well below the hydraulic in buried conditions. Thermal retentivity of gradient under conditions of PVC is very low compared to metals. PVC maximum discharge. pipes are available in various sizes ranging from 20mm to 315mm and stand working (ii) Keep the top of pipe at least 0.5 pressures varying from 2 to 10 kg per cm metres below ground surface and square. The use of PVC pipes above ground where severe frost occurs, the is not encouraged for the reason that the cover is at least 1 metre. The bed decomposition of the plastic material is of the trench shall be finished to an accelerated by the ultra violet light and even gradient/level and filled with frequent changes in temperature. The soil rammed in 150 mm layers. 141  WATER SUPPLY (iii) Provide air valves at all summits a gravitational main when the and scour valves at all sags. discharge into a tank or reservoir is to be automatically controlled. A (iv) Lay spigot and socket pipes with ball cock must only be used at the sockets facing the direction from end of a pumping main if there is a which the water will flow. safety or relief valve on the main. (v) Carry pipes across deep (vi) Meters as required. depressions or marshy places on pillars or props. c) The covers and glands of all valves should be removed, packing adjusted, spindles (vi) On steep hill-sides, anchor the and gates examined and the whole assembly pipes to prevent sliding of pipes refitted in free and perfect order before downslope In vertical position, use installation. pipes with flanged ends and bolts as far as possible. H. WATER TREATMENT (vii) Close the open end of the last pipe at the end of the day's work. 531 Quality of Water - (viii) Test the pipe line with water It should be ensured that the water pressure in sections before the supplied is clear, potable, free from pathogenic trench is filled in. organisms and odour. Water should be of reasonable temperature and free from minerals b) Pipe lines should be fitted, where which could produce undesirable physiological necessary with:- effects. (i) Air valves of proper size and The physical and chemical Standards pressure rating at summits. as per Annexure 5.2 may be adhered for drinking water supply. (ii) Reflex (non-return) valves at the foot of all ascending parts of a 532 Water Samples for Analysis - main. Whenever the quality of water from any (iii) Scour valves at depressions on the source of supply or from taps is to be tested main for clearing sediment and and samples are required to be collected by emptying the pipes. the Engineering staff, the following procedure should be followed:- (iv) Sluices as necessary in order to divide the main into convenient a) Sterilized glass-stoppered bottles sections for repairs. available with the Divisional Medical Officer should be obtained. Bottles separately (v) A ball cock at the discharge end of available for bacteriological or chemical 142  WATER SUPPLY examination have to be appropriately used. delay to reach the Divisional Medical Officer. Satisfactory packing and expeditious dispatch The paper cover of the stopper should are essential for a proper bacteriological be removed just before taking the sample. The examination. stopper should be removed just before filling the bottle and replaced immediately after. The 533 Method of Treatment - stopper should be held from the top while the bottle is being filled. Contamination while filling The aim of water treatment is to produce the bottle must be avoided. There should be and maintain water that is hygienically safe, no external contact with the mouth of the bottle clean and potable in an economical manner. or the part of the stopper that goes into it. Treatment should ensure the desired quality The bottle should be filled to about 25mm at the end points of consumption. below its neck. The method of treatment to be employed b) When samples of water are taken from depends on the nature of raw water and the a tap, the mouth of the tap should be heated desired standards of water quality. The unit by a spirit lamp for 3 minutes. Water should operations in water treatment constitute then be allowed to flow for 5 minutes before aeration, flocculation (rapid and slow) and the sampling bottle is filled. clarification, filtration, disinfection, softening, deferrization,defluoridation and water c) If the sample is to be obtained from a conditioning. Different combinations are tank or a reservoir or a river, the unopened possible to achieve the required quality of bottle is to be held in water about 300 mm water. The choice of any particular sequence below the surface and away from the edge of treatment will depend not only on the quality without disturbing the bed. The stopper should of the raw water available but also on the then be removed, the bottle withdrawn when comparative economics of alternative full, a few drops of water poured out and the treatment steps to get desired quality. stopper replaced and tied down. In the case of ground water storage d) Well water should be collected by which are well protected, where the water has lowering the bottle (tied with a piece of weight) turbidity below 10 NTU and water is free from into the well by a string attached to the neck; odour and colour, plain disinfection by the stopper should be removed by another chlorination is adopted before supply. string tied to it and the bottle filled in with water, not from the surface but from a point a metre Where ground water contains excessive or two above the bottom of the well. If collected iron, dissolved carbon dioxide and odorous from a tube-well with a pump, the water should gases, aeration followed by flocculation and be allowed to flow for about 20 minutes. sedimentation, rapid gravity or pressure filtration and disinfection may be necessary. e) Bottles containing samples of water should be properly labeled, packed around Conventional treatment including pre- with ice and saw-dust and sent without any chlorination, aeration, flocculation and 143  WATER SUPPLY sedimentation, rapid gravity filtration and post- 535 Residual Chlorine - chlorination are adopted for highly polluted surface waters laden with algae or other micro Minimum residual chlorine available at organisms. the farthest end shall be 0.2 mg per litre. However, where distribution is long and Water with excessive hardness will complex it may be difficult to maintain the need softening by conventional method or by minimum residual value and in such cases ion exchange method. re-chlorination may be carried out in the distribution system. 534 Disinfection of Water - Water treatment processes described in paragraph During monsoon months or if specific above remove micro organisms to varying complaints are there, super-chlorination more degrees. For utmost safety of water for than 2 ppm of chlorine may be resorted to drinking purposes, disinfection of water has effectively get rid of bacteria. to be done to remove disease producing organisms before it enters distribution system. The Section Engineer (Works) should Disinfection is also required to prevent frequently check the concentration of residual contamination of water during its transit from chlorine at the consumer point by orthotolodine the treatment plant to the place of its test. In this test 100 ml of chlorinated water consumption. The efficiency of disinfection sample is collected in the test tube. 1 ml of depends on the nature of disinfectants. For orthotolodine solution is added to it. The colour treatment on larger scale, chlorination is formed is noted, value of the residual chlorine generally used as treatment for disinfection. is directly determined by comparing the colour Chlorine can be applied in water by using so obtained with the standard chart of colours bleaching powder, chloramines or as free of non-chlorine residuals. Divisional Engineer chlorine gas. A minimum of 30 to 60 minutes should ensure sufficient number of equipment contact time must be provided before delivery with all the field units. of water to the consumer. I. HIGH-LEVEL STORAGE Utmost care shall be taken for storage and use of disinfectants. All safety precautions 536 Storage Capacity - as laid down in relevant codes shall be taken. Normally, the storage capacity should be Sufficient number of chlorinators in equal to the higher of the following figures:- working conditions should be available with the Inspectors of works. To decide the quantity a) With efficient stand-by pump:- of chlorine to be added,Inspector of works should find out breakpoint chlorination and (i) One-quarter the maximum water accordingly chlorinate the supply. consumption in 24 hours (ii) One-third the normal water consumption in 24 hours 144  WATER SUPPLY b) Without stand-by pump:- manner that these are readily visible. (i) One-third the maximum water 538 Float Gauges and Scouring consumption in 24 hours. Sluices- (ii) One-half the normal consumption in Every high level storage tank should be 24 hours. provided on the outside with a float gauge with a scale marked in metres divided into 5 parts Local conditions should however be to indicate the water level in the tank. considered when deciding on the storage capacity. Each tank may be partitioned to Every storage tank whether at high level facilitate cleaning or repairs. or at ground level should be provided with a sluice at its sill level to facilitate the cleaning 537 Maintenance and Cleaning of of the tank. Storage Tanks 539 Protection Against Pollution - a) For the inspection, maintenance and High service storage tanks, for drinking water painting of steel-work, action should be taken in particular, should be covered and provided as detailed in the Indian Railways Bridge with gauze wire to obviate pollution by birds Manual. and growth of algae. b) Tanks used for the storage of drinking water should be rubbed and cleaned at such J. DISTRIBUTION OF WATER intervals as specified by the Divisional Engineer. The cleaning of water tank and 540 Distribution System - disinfection should be carried out as per recommended procedure. Tanks used for the The distribution system is important in a storage of water for locomotive and carriage water supply scheme for wholesome and washing purposes should be scrubbed and adequate supply of water at required pressures cleaned at least once in six months. in sufficient quantity. The distribution accounts for 40 to 70% of the outlay of the water supply Reports on cleaning of tanks should be scheme. Proper provision of configuration of submitted to the Assistant Engineer by the pipes, pumping arrangements, and location of Section Engineer (Works) who shall maintain valves and pipe specials are very important a register with complete particulars for the and adequate attention should be paid to the purpose. The periodical reports should include functional and hydraulic purposes to be served information regarding the condition of external by the system. For general convenience of and internal painting and corrosion, if any. distribution, a grid where different mains are interconnected is recommended. This system The dates of cleaning and of both facilitates supply of water to any point from external and internal painting should be two directions. The tree system of distribution painted on one side of the staging in such a will be adequate only in small water supply 145  WATER SUPPLY distribution system on wayside stations. 543 Separate Supplies for Drinking and Other Purposes - 541 Layout of Distribution Systems - Distribution systems should be laid out in the Where there are separate mains for form best suited to conditions at site. The drinking water and water for other purposes, economical diameter of a pipe-line is based it should be ensured that when any junctions on considerations of head-losses and or branches are laid, the two supplies may velocities under conditions of maximum flow not get connected. The economics of having including fire demand. The design of the a separate distribution system for water unfit distribution system should be based on the for drinking purpose vis-a-vis the treatment maximum estimated daily consumption being cost of that water and supplying through the supplied in 10 to 16 hours as may be single distribution system has to be worked prescribed. out in relevant cases and a proper choice made. A diagram of mains, branch mains and distributaries should be prepared and on it the Water unfit for drinking purpose can be points of supply, the lengths of pipes and the in many cases economically used for purposes reduced levels of all junctions noted. Starting such as carriage washing, washing aprons, at the end farthest from the points of supply, platforms etc. the supply in litres per minute that each pipe must be able to accommodate, is worked out 544 Service Pipes from Mains - for its length and noted on the diagram. From the heads and longitudinal sections, the The per capita rate of water supply diameters are arrived at; a reserve of at least indicate only the average consumption of 3 metres head should be ensured at the tail- water per day. To take into account fluctuation end of every service line under conditions of in consumption due to season, month, day, maximum discharge. and hour, the average demand should be multiplied by a peak factor for purpose of 542 Rising Mains not to be Used for designing distribution system. A peak factor Distribution - of 2.5 is recommended. The tapping of a rising main for purposes The number and size of service pipes of distribution shall be strictly prohibited. that can be supplied from a properly designed Where, for engineering construction purposes, distribution-main may be assumed as shown such a course may be justified as a temporary below; exceptional cases will depend, however, expedient, e.g. in order to save long lengths on actual conditions:- of service pipe-lines, a control valve must be fitted on the connection. 146  WATER SUPPLY Diameter of service pipes Distribution Main 15mm 20mm 25mm Number of service pipes 40mm 12 6 3 50mm 20 10 6 65mm 39 20 10 80mm 65 32 18 90mm 88 43 24 100mm 115 56 32 To avoid dead ends, the main shall be arranged in a grid formation or in a network. 545 Residual Pressure - Distribution cleaning of pipe lines. system should be designed for the following minimum residual pressures at ferrule points: 547 Protection Against Pollution Near Sewer and Drains Single storey building - 7m a) Horizontal Separation - A water main Two storey building - 12 m should be laid such that there is at least 3 m separation, horizontally from any existing or Three storey building - 17 m proposed drain or sewer line. If local conditions prevent this lateral separation, a Distribution system should not ordinarily water main may be laid closer to a storm or be designed for residual pressures exceeding sanitary sewer, provided that the main is laid 22 m. Multi-storeyed buildings needing higher in a separate trench, or on an undisturbed pressure should be provided with boosters. earth shelf located on one side of the sewer at such an elevation that the bottom of the 546 Preventive Maintenance - water main is at least 0.5 m above the top of the sewer. Preventive Maintenance of water supply distribution pipe lines assures the twin b) Vertical Separation - In situations objectives of preserving the hygienic quality where water mains have to cross house of water in the distribution mains and providing sewer, storm drain, or sanitary sewer, it should conditions for adequate flow through the pipe be laid at such an elevation that the bottom of lines without leakages. Two of the main the water main is 0.5 m above the top of the functions in the management of preventive drain or sewer with the joints as remote from aspects in the maintenance of mains are the sewer as possible. This vertical separation assessment, detection and prevention of should be maintained for a distance of 3 m on wastage of water from pipe lines and maintaining the capacity of pipe line and 147  WATER SUPPLY both sides measured normal to the sewer or d) The maintenance and periodical drain it crosses. cleaning of all storage tanks. 548 Carriage Watering System - e) The maintenance of all pipe lines and specials, hydrants and water- On all new watering stations, carriage taps in station yards and colonies, watering arrangement shall be by side filling. fire hydrants at stations, goods The rate of flow at delivery end on hydrant sheds and loco sheds. shall not be less than 100 litres per minute. The diameter of pipe, general arrangement of f) The maintenance and periodical pipe line, spacing of wheel valve and height testing of all water meters wherever shall be as per standard drawing issued by installed. The testing should be RDSO. carried out at least once a year. It is preferable to have separate g) The periodical testing and joint- overhead tank of required capacity for carriage recording of consumption in meters watering. at such points where supply to the railway is made by outside bodies. K. MAINTENANCE AND OPERATION OF h) Wastage and leakage detection WATER SUPPLY INSTALLATIONS survey should be carried out and action taken to reduce the losses. 549 Engineering Department's Responsibilities- 550 Mechanical Department's Responsibilities The Engineering Department shall be responsible for:- a) The Mechanical Department will be responsible for the erection, maintenance and a) The adequacy of water supply at all operation of diesel oil pumping plants at all sources, permanent and auxiliary. pumping stations. b) The despatch of samples of water b) The Mechanical Department will be if so required to be done, from responsible for the operation and maintenance water supply sources, storage- of carriage-watering and carriage-washing tanks or taps for chemical and hydrants. bacteriological analysis to the Medical Department. 551 Electrical Department's Responsibility c) The maintenance and operation of water purification plants. a) All planning,installation maintenance and operation of electrical pumps shall be done by electrical department. 148  WATER SUPPLY b) All water coolers provided in offices The Assistant Engineer shall ensure that and stations shall be cleaned once a month to water supply plan is corrected as and when prevent contamination. Water coolers shall there is any addition or modification in pipeline. be disinfected properly before putting into use. Wherever the laying/modification to the existing pipe line is done through contractual 552 Inspections by Assistant Engineer agency, a certificate in the measurement book and Staff shall be recorded while entering the final measurements to the effect that necessary a) The Assistant Engineer and Section changes in the plans have been incorporated. Engineer (Works) should frequently inspect In case of Construction Organization all water supply installations and pipelines and implementing any water supply scheme or ensure their maintenance in efficient condition. augmenting the existing scheme, a copy of The Section Engineer (Works) should be the water supply plan shall be handed over to equipped with an adequate imprest of Open Line as and when the scheme is materials such as pipes and specials and completed. water taps of requisite sizes and the necessary tools to facilitate immediate 554 Water Purification Works attention on repairs as and when required. b) Storage-tanks for drinking water and a) Periodical analysis of water - Samples for flushing purposes over offices, bungalows of raw, filtered and sterilized water from filter- and quarters should be inspected frequently plants should be sent for examination and by the Section Engineer (Works) and their certification once a month or as may be cleanliness ensured. Complaints from prescribed to the Divisional Medical Officer residents should be promptly attended to. who will advise, if deemed necessary, on the appropriate dosage of the coagulant or the 553 Water-Supply Plans - sterilizing agent. Reports on water analysis received from the Divisional Medical Officer Up to date plans should be maintained in should be carefully filed, the action taken on the Chief Engineer's, Divisional Engineers', each report being recorded. Samples for Assistant Engineers' and Section Engineer chemical examination should be sent for (Works) Offices of every water supply system testing once in six months or once before showing the source, pumps and pumping monsoon and once after monsoon. particulars, rising mains, storage tanks and capacities, the distribution mains, service b) Maintenance of water works - Detailed pipes, hydrants and taps. The diameter and instructions in regard to the maintenance and type of pipe-lines should be clearly indicated operation of filtration and chlorinaton plants on the plans and on the longitudinal sections. at each installation shall be issued by the Chief Engineer. It should be ensured that- Where there are separate supplies for drinking and other requirements, the (i) the plants, in general, with their respective systems should be shown on the ancillaries are maintained in a plan in different colours or on separate plans. perfectly sanitary and hygienic 149  WATER SUPPLY condition; in the Inspection Register maintained for the purpose. He (ii) aeration of raw water is effected by should follow the course of water spraying through the air, cascading from the point of intake and through over obstacles. the different treatment stages to the point of delivery to the distribution (iii) the sedimentation tanks or basins mains and arrange to remedy are drained at such intervals as defects noticed. prescribed; AEN should arrange for a joint (iv) coagulants, either in the form of dry detailed inspection by Section powder or in aqueous solution, are Engineer (Works) of the pumping added in the correct proportion machinery once a year as may be according to the turbidity of raw prescribed alongwith the staff of the water; Mechanical/Electrical Department and ensure prompt compliance to (v) the filters are cleaned and washed repairs or replacements required. with pure water at such intervals as prescribed; (ii) The Assistant Engineer should check the following:- (vi) the filtered water is sterilized either by adding liquid chlorine or - Stock account showing bleaching powder strictly to the transactions of stores dosage specified. - Log book for filtration plant (vii) disinfectants are stored properly and all safety precautions are taken d) Inspection by Divisional Engineer - The Divisional Engineer should inspect the The water works staff in-charge shall water works in every detail once a year and strictly adhere to the prescribed rules. A copy record his notes in the Inspection Register of the detailed instructions on the operation of maintained for the purpose. plant and purification process should be available at each installation together with the e) Inspection Register - An Inspection duty-lists of the staff posted there. Register should be maintained at each water purification work to enable every Inspecting c) Supervision by Assistant Engineer Officer of the Engineering and Medical Departments to record notes. Prompt action (i) The Assistant Engineer shall on inspection notes shall be ensured. inspect each installation once in three months and record his notes HHHHHHH 150  WATER SUPPLY ANNEXURE 5.1 Para 502 CHECK LIST FOR WATER SUPPLY SCHEME 7. Whether future requirement has been NAME OF THE SCHEME : taken into account ? B. SOURCE OF WATER DIVISION : 1. Whether quantity/ yield available is sufficient to meet the requirement ? SCHEME APPROVAL DETAILS : 2. Have the tests for quality of water been done ? _____________________________________ 3. Are the test results satisfactory ? (For YES/NO Stds. of quality of water refer Annexure _____________________________________ 5.2) A. ASSESSMENT OF DEMAND 4. Whether any treatment is required to bring down the various impurities within 1. Is this a new scheme or augmentation to permissible range ? the existing arrangement ? 5. Has the sanitary survey of area 2. Has total demand been assessed ? surrounding the available water source been carried out to estimate the possible 3. Whether total demand includes domestic pollution or contamination of water from needs, workshop, offices and station such source ? requirement ? 6. Has the line of treatment been decided 4. Whether fire demand if any, Loss & consistent with quality of water required ? Wastages and variation in demand has been considered ? 7. Whether there is accessibility to the site of proposed source of water ? 5. Whether demand has been calculated separately for treated and untreated 8. Is there any need for development of water ? communication system ? 6. Has the financial viability been 9. Is the controlling device of intake located considered for providing one distribution at a place which is accessible even during system with filtered water vis-a-vis floods ? separate distribution systems for treated and untreated water ? 151  WATER SUPPLY 11. Is door of the pump house wide enough 10. Is there provision for pitching on the down to enable pumps to be taken out for repair stream and upstream portions of canal or replacement? near intake ? 12. Has the provision been made for fire C. PUMPING AND STORAGE OF RAW fighting equipment appropriate to hazard WATER likely in the pump house and storage space of diesel? 1. Has the selection of size and pipe material for raw water mains been done ? D. ARRANGEMENTS FOR PURIFICATION AND TREATMENT 2. Is direct pumping from the source feasible ? 1. Has the line of treatment been decided ? 3. Is there any need for storage of raw 2. Does the layout of the entire scheme water ? fulfill the requirement of the line of treatment ? 4. If so, is the storage capacity adequate ? 3. Is aeration unit exposed to the prevailing 5. Has the requirement of the pumps and direction of wind ? their capacity been calculated based on 1.5 times the average daily demand ? 4. Is sedimentation unit designed with coagulation ? 6. Has the standby arrangement been made for auxiliary power unit (generally diesel If yes, has the feasibility for supply of type) and stand-by pumps ? coagulant and cost been considered while deciding to go in for coagulation 7. Is there provision for proper structure vis-a-vis only plain sedimentation with required for housing the Pumps and Pump increased capacity of sedimentation Operator ? unit ? 8. Has the provision been made for 5. Is there feasibility of regular supply of adequate extra space for additional pump sand required for replenishing the sand if required ? of filter ? 9. Is there separate adequate space for 6. Has the requirement of chlorination been storage of diesel and other spares ? assessed based on the quality of water and longest length of supply pipeline in 10. Has the arrangement been provided for the distribution system ? lifting of pumps or stair case in case the pumps are provided at lower level than 7. Is water softening required to remove the the prevailing ground level ? permanent hardness, if any ? 8. Is recarbonation plant necessary (in case 152  WATER SUPPLY of Lime Soda process or softening), if finalised considering the topography and so, is it provided before filtration unit ? major areas of consumption ? 9. Has the method of chlorination been 6. Are distribution mains designed for the finalised keeping in view the availability maximum hourly demand on the day of of equipment and constant supply of maximum consumption ? (2.5 times the chlorinating material ? average demand )] 10. Is there any other impurity to be 7. Has the layout for the pipeline for removed ? distribution system been finalised ? 11. Has the provision of small laboratory 8. Does the layout of pipeline take into including equipment for testing of water account future expansion plans for the required at filtration plant been made ? colony ? E. STORAGE AND DISTRIBUTION OF 9. Have the dead ends been avoided in the TREATED WATER layout of the pipe line ? 1. Has the location of pump house been If unavoidable, is there provision for finalised taking into account the hydrants to act as washouts ? availability of power and requirement of the operator ? 10. Has the pipeline layout been provided with the provision for controlling water 2. Is it feasible to utilise the same staff for supply timings for different areas if filtration unit and for operating the pumps required, by operating minimum in pump house ? number of valves ? 3. Has the capacity and number of pumps 11. Is there any requirement of air valves ? required been calculated based on If yes, have they been located at points quantity of water, pumping hours, total which are close to or above the hydraulic head and various losses? gradients ? 4. Is there provision for auxiliary power 12. In case of buried pipe line, has it been supply and stand by pumps ? proposed min. 2m above the sewer line ? 5. Has the location of the storage tank been 13. Has the testing of leakage been contemplated? 153  WATER SUPPLY ANNEXURE 5.2 Para 531 STANDARDS OF QUALITY OF DRINKING WATER PHYSICAL AND CHEMICAL STANDARDS ________________________________________________________________________________ S.No. Characteristics Requirement Permissible limit (Desirable limit) in the absence of alternate source ________________________________________________________________________________ (1) (2) 3 4 ________________________________________________________________________________ 1. Turbidity (NTU scale)5.0 10 2. Colour Haten units 5.0 25 3. Taste and odour Unobjectionable --- 4.Ph value 6.5 to 8.5 No relaxation 5. Total dissolved solids(mg/l) max. 500 2000 6. Total hardness as CaCo3(mg/l) max. 300 600 7. Chlorides as Cl2(mg/l) 250 1000 8. Sulphates as SO4 (mg/l) max. 200 400 9. Fluorides as F (mg/l)max. 1.0 1.5 10. Nitrates as No3 (mg/l)max. 45 100 11. Calcium as Ca (mg/l)max. 75 200 12. Iron as Fe (mg/l)max. 0.3 1.0 13. Zinc as Zn (mg/l)max. 5.0 15.0 14. Mineral Oil (mg/l)max. 0.01 0.03 15. Copper as Cu (mg/l)max. 0.05 1.5 Toxic materials 16. Arsenic as As (mg/l)max. 0.05 No relaxation 17. Cadmium as Cd (mg/l)max. 0.01 -do- 18. Lead as Pb (mg/l)max. 0.05 -do- 19. Residual free chlorine (mg/l)max. 0.2* --- ________________________________________________________________________________ Source :Indian Standard - Drinking water - specification (First Revision) IS:10500 - 1991 by BIS *When protection against viral infection is required, it should be min. 0.5 mg/l. 154