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Chapter V A. Water Supply 501 General - Reference may be made to the following for provisions not contained in this Chapter. In case of any variation, the latter shall prevail. (1) Manual on water supply and treatment by Ministry of Urban Development, New Delhi 502 Preparation of Schemes for New Water Supply/Augmentation of Existing Water Supply -The preparation of schemes for new water supply/augmentation of existing water supply will involve collection of following data:- a) Justification for an improved or additional supply or new supply -This will include number of people to be covered, estimated consumption and basis of calculation; b) Nature, quality and quantity of existing supply and its source; c) Possible sources of additional supply and arrangements for its filtration, purification etc; d) Future requirements if known; e) Whether the supply will be metered, continuous or intermittent; f) Details of pumping arrangement and its cost. For collecting this data, preliminary survey, site investigation may be necessary. The investigation will involve yield test, check on quality of water etc. Necessary checklist for framing water supply proposals is given as Annexure 5.1. 503 Review of Water Supply Arrangements on the Railways:-Engineering Department officials should keep themselves posted with the information regarding rainfall, supply position from various sources and take suitable action to avoid any breakdown in supply of adequate water of proper quality. Every year the Divisional Railway Manager should conduct a Water Review meeting with all the branch officers and Civil Public Health Department if required, to review the adequacy of existing water supply, augmentation required, any other action to be taken for avoidance of emergency during summer months etc. Minutes of the meeting should be sent to the office of the Chief Engineer for information. Copy should also be endorsed to the Assistant Engineers and Section Engineers (Works) for necessary action. After the review meeting, the Divisional Engineer should submit necessary proposals for augmentation of water supply to concerned authorities wherever required and take further action. WATER SUPPLY 504 Data for Estimating Requirements of Water: The scale of daily supply may be computed on the following
* 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. B. OPEN WELLS 506 Preliminary Measures for Sinking a) Samples of strata and samples of underground water for chemical and bacteriological analysis should be obtained by trial-boring or sinking a test-well. This work should normally be carried out in the dry season. The Geological Department should, whenever possible, be consulted in regard to the strata and source at the proposed site. b) The yield of the test-well should be assessed by carrying out a recuperation test after pumping the water to below the "normal water-table" and plotting the results in the form of a diagram with draw down as abscissa and the inflow in litres per hour as the ordinate. 507 Determination of Size: (a) From the yield diagram, the diameter and depth of an open well should be arrived at on considerations of the maximum daily requirements, due allowance being made for the future demands. b) For the size of the open well, the following factors should be considered:- (i) The normal water table - This is the level at which water stands in a well which has not been pumped for 24 hours. This varies throughout the year; and (ii) The critical velocity of flow - The critical velocity of inflow is the maximum velocity of water passing through subsoil without disturbing the finer particles of the subsoil. In average conditions of subsoil, this velocity is between 750 mm and 1200 mm per hour and is obtained with a head of 2 metre to 3 metre. The safe yield of open wells is limited by the critical velocity and for practical purposes the yield may be obtained by multiplying the critical velocity by the area of the floor of the well. 508 Improving Yield in Open Wells b) In sandy soil- If the yield with a "drop" of 2 meters is insufficient, then a larger diameter well is needed. Alternatively, a tube well may be sunk in the open well to supplement the yield. Any increase in the "drop" will increase the "critical velocity" and "blowing" of the sandy soil and subsidence of staining may occur. c) In moorum and porous rock - If the yield is insufficient, it may be improved by deepening provided the lower strata is porous. This can only be ascertained by making a bore. Driving adits into sides of the well and providing a greater number of "weep-holes" would increase the yield. In porous rock the inflow may be slightly increased by holding up surface flow of the rainfall in the vicinity of the well. This may be effected by building a bund on the upstream side of the well. 509 Shallow Tube-Wells Tube-wells to a depth of 7.5 meters to 12 meters are found useful for tapping a shallow water-table. Where only small quantities of water are required, these are cheaper than open-wells and may be constructed at wayside stations, gang quarters and gate-lodges between stations if the water-table could be tapped at a reasonable depth. Quality of water of these wells is not reliable and�disinfection is essential. Shallow tube well can be operated either electrically or manually depending upon the convenience. At unimportant stations and wayside stations where water table is within about 10 metres of the ground level, hand pumps should be installed in colonies. Hand pumps have been standardized by Bureau of Indian Standards and standard hand pumps are available for installation. Sufficient number of spare parts for repair of hand pumps should be kept with the Section Engineer (Works) to attend to emergencies. C. DEEP TUBE WELLS 510 Consultation with Geological Department The Geological Department or Central Ground Water Board / Public Health Engineering department of the State Government should, be consulted wherever necessary, for proposals of deep tube-wells. Where the "normal-water-table" is at greater depth, it would be economical and preferable to sink deep tube-wells instead of open-wells. 511 Stages of Work for Sinking a) Trial boring- (ii) From the results obtained, the area of strainer necessary for the quantity of water required and the b) Samples of water for analysis-For a large water supply, water should be drawn from as great a depth as possible to eliminate the danger of bacteriological contamination which can be expected in water drawn from the upper strata. Water drawn from deep ground is likely to be bacteriologically pure. As the water obtained from deep wells may contain certain dissolved impurities, the chemical analysis of water to determine its suitability for drinking is always necessary and samples should be sent to the Divisional Medical Officer for test. c) Tube-well installation.- Initially the casing pipes are sunk to required depth. Strainers and plain pipes of tube-well proper are then lowered to correct depths. In suitable cases, pebbles or gravel is let down between the casing pipes and the tube-well as shrouding during casing-pipe extraction. This is essential when the strainers are located in fine sand. Brass, galvanized iron, special alloy steel, high density polythene or PVC and metal combined strainers of the requisite size with gravel/sand shroud may be used. The total area of the openings in the screen should be such that the velocity of inflowing water is sufficiently low to avoid disturbance to the smaller particles of the water bearing stratum. d) Testing yield of tube-wells.- A tube-well should be tested for yield by experienced staff of the tube well organization of the Railway. IS:2800-1979 may be referred where necessary. 512 Checking Vertically of Tube Wells- Tubewells must be perfectly vertical. A simple method is to use plumb disk. Two disks made out of 3mm thick steel plate are connected together by a rod of 25mm diameter and 3 metre long tightened with the help of nuts at the ends. Some holes are punched in plates to facilitate immersion in water. A knob is fixed on the top nut to which a thin steel wire is attached .The disk is suspended into the tube by the wire passing over a pulley on a tripod. When the disk is lowered into the pipe. the wire is exactly in the centre of pipe . When the disks are further lowered down and if the well pipe is not truly vertical, the wire will deviate from the centre and that shall be indicated at the top of pipe. Absolute verticality is ideal but a deviation of 100mm per 30 metres of boring is generally acceptable where submersible pumps are not to be installed. 513 Failure of Wells And The Remedial Measures The clogging of wells by sand or by corrosion or encrustation of the screen may reduce the yield substantially. The wells may be readily cleaned of sand by means of a sand pump or bucket but if the strainers are corroded, they must be pulled out, cleaned or renewed or replaced. Method of surging, use of dry ice or chemical treatment by-using acids, chlorine, polyphosphates may be used for treatment against clogging. Following table gives types of well clogging problems and recommended treatment: WELL CLOGGING PROBLEMS AND ITS SUGGESTED TREATMENTS
Newly constructed wells as well as those after repairs have to be disinfected by heavy dosages of chlorine. Bleaching powder is generally used for this purpose. D. IMPOUNDING RESERVOIRS 515 Governing factors The catchments area, its characteristics and the rainfall decide how much water would be available for storage. A contour plan of the neighborhood of proposed dam facilitates the decision of the height of the dam and decides whether or not there is sufficient storage capacity for the amount of water needed. Losses by evaporation and absorption should be assessed. Expert agencies should be consulted where necessary. 516 Storage Capacity The storage capacity depends on the height of the dam and contours of catchment behind. Due allowance should be made for losses due to seepage, evaporation and silting. 517 Cracks in reservoir walls Cracks that may occur in reservoir walls should be grouted, with fine cement grout/ resins. They should be kept under observation. 518 Reservoir Management Problem of silting, evaporation losses, seepage and algae troubles are some of the areas requiring attention. Loss of capacity due to the deposition of silt in reservoir may impair the usefulness of the reservoir within a few years. It may be minimized by erosion control, reservoir operation and desilting works. There are various commercially available organic compounds which when spread on the water surface form a monomolecular film, which reduces evaporation. Seepage can be reduced by making cut off wall beneath the dam. The water weeds in the reservoir should be controlled by suitable methods such as dragging and underwater cutting. Algicidal treatment by using suitable Algicide may be adopted to control algae in reservoir. It is preferable to initiate the treatment in the early stages of algae growth. E. INFILTRATION GALLERIES AND WELLS 519 Infiltration Gallery These are constructed in water bearing strata. The gallery obtains its water from water bearing strata by various porous drain pipes. A collecting well at the downstream end of the gallery serves as the sump from where 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 and only disinfection may be required. 520 Infiltration Well Infiltration wells are usually sunk in series in the banks of river. They are generally constructed of masonry with open joints. The infiltration wells in turn are connected by porous pipes to a collecting sump (jack well). There can be large yield of water from these wells. Quality of water varies with quality of water in river, depth, and distance of well from river bank. 521 Radial Collector Wells Radial collector well consists of a cylindrical well of reinforced concrete construction, 4-5 metre in diameter going into the water bearing medium to as great a depth of the substrata as possible. In the collector wells the radial pipes which are slotted steel pipes normally 200mm to 300mm diameter are driven horizontally at about 7 meters below the water table in the well. The length of the steel pipes will be determined by the requirement of water and yield of the aquifer i.e. the water bearing medium in the subsoil. The drain pipes are made of short lengths of pipes 2.4 metres each which are welded to each other. The pipes are driven horizontally by means of suitable pin jacks placed in the well. Desanding operation is required to be done after driving of the radial pipes. Desanding is done by inserting another tube into the drain tubes and blast of compressed air to separate the fine particles of alluvium. The radial collector wells have higher efficiency of drawing the ground water compared to ordinary wells. This type of wells are able to obtain high yields of water depending on the strata and depth of submergence. This is normally provided in alluvial beds of major rivers. 522 Intake Arrangements Detailed consideration is necessary for the design of intake to prevent vortex formation to obtain uniform distribution of the inflow to all the pumps and to maintain sufficient depth of water to avoid air entry during draw down. The suction pipe should be as short and straight as possible. Any bends or elbows should be of large radius. As a general rule the sizes of the suction pipe should be of one or two sizes greater than the nominal size of the pump. Alternatively the suction pipe should be such that the velocity is about 2m/s. Where bell mouth is used, the inlet of the bell mouth should be of such size that the velocity at the bell mouth is about 1.5 m/s. The suction strainer should have net open area equal to three times the area of the suction pipe at least. 523 Water Supply from Outside Sources When water is obtained for railway purposes from the Public Works Department, the Municipality or a private body, the agreement should clearly specify:- (a) term or duration of agreement; (b) rate of payment for water; (c) mode of measurement and location of meters etc, (d) maximum and minimum quantities to be supplied daily; (e) minimum pressure to be maintained in the mains at points of supply; (f) in case of bulk supply, point or points at which water is to be supplied; (g) in case of distributed supply, details of the layout of distribution mains and conditions for extensions or extra connections. Copies of such agreements should be available in the Divisional Engineer's and Assistant Engineer's offices. F. PUMPS 524 Types and Selection of Pumps a) The types of pumps in general use are reciprocating, centrifugal, airlift and vertical spindle deep well turbine pumps. Hydraulic rams are useful and economical in perennial streams for supply of comparatively small quantities of water. b) Reciprocating pumps have nearly a uniform efficiency over a large range and therefore greater flexibility in operation. Reciprocating pumps may be duplex, triplex or quardruplex accordingly to the number of water-cylinders and are suitable for pumping from open wells. They are, however, not suitable for tube-well operation as the intermittent suction has a damaging effect on the strainers. c) Centrifugal pumps are efficient, economical and require little attention. The suction lift is, however, limited as in the case of reciprocating pumps. In tube-wells where centrifugal pumps cannot be installed sufficiently close to the water-table, airlift pumps may be used. Their efficiency is, however, low and should not normally be used for capacities in excess of 35000 litres per hour. d) Vertical spindle deep well turbine pumps are suitable for tube wells of large size; they are easy to operate and have a high efficiency. They should be used in tube wells which are free from grit and where competent supervisory staff are available, as adjustments during repairs require skilled attention. Submersible pump is suitable for comparatively smaller installations. It consists of an electric motor and pump both submerged in water; the vertical spinning shaft is dispended with, the water being pumped through a vertical pipe. e) Pumping units should be so selected that they could be operated continuously at rated load, as the units are operated most efficiently at the rated load. f) Pumping capacity should not exceed the yield of the source, so as not to damage the strata through which filtrates into the source. 525 Pump Installation While installing a pump, the following points should be paid attention: a) the foundation should be sufficiently strong to absorb vibrations and to form a permanent, rigid support for the base plate. The foundations shall be designed for the loads as per IS:2974 Part IV- 1979. b) the suction lift, which should be made as low as possible; the greatest suction-lift that may be expected at sea-level is about 7 metres. c) the suction pipe should be air-tight, laid with as few bends as possible and equipped with foot-valve. d) near the pump, a non-return (reflux) valve and a delivery valve (sluice or butterfly valve) should be provided. The non-return valve should be between the pump and the delivery valve. The size of the valve should match the size of pipe. e) the delivery pipe shall be of such size that the velocity of water is about 2.5m/s. f) a dismantling joint must be provided between the pump and the valves. The design of the dismantling joint should be such that no pull or push is transmitted to the pump. g) Sufficient space for generating sets should be available in the pump house to locate the pump, motor, valves, pipes, control panels in a rational manner with easy access and with sufficient space around for the maintenance and repairs. The minimum space between two adjoining pumps or motors should be 0.6m for a small or medium units and 1.0m for large units. Space for control panels should be planned as per the Indian Electricity Rules. 526 Driving Units The driving unit may be an electric motor, or an oil engine. Where power is available:- (i) the prime mover should preferably be an electric motor, being economical; (ii) the stand-by where provided may be an electric generator so that in case of failure of electric supply, pumping is assured. (iv) Non-return valve at the discharge pipe, supplemented by a sluice valve shall not be closed while the pump is running. 527 Capacity of Pumping The pumping system should be capable of supplying:- (a) In 12 hours or less, the normal quantity required in 24 hours; (b) In 16 hours or less, the present maximum quantity required in 24 hours; (c) In about 20 hours, the estimated maximum future requirements in 24 hours. For small pumping systems, generally of capacity less than 15 million litres per day, two pumps (one duty and one standby of full capacity) should be provided. Alternatively, two duty and one standby, each of 50% capacity may be provided. Although this alternative would need larger space, it facilitates flexibility in regulating the water supply. Also in an emergency of two pumps going out of order simultaneously, the third helps to maintain at least partial supply. In the case of medium and large pumping stations , at least two standbys should be provided. Electrical department is responsible for installation and maintenance of electrical machinery/equipments. 528 Pump Horse Power The equation for pump horse power- Where P.H.P is the pump horse power (metric): (One metric horse power = 75 kilogram metres/Sec), H is the vertical height in metres from suction-level to highest point of discharge; L is the litres of water per minute and 'h' the head lost in friction in metres. 8 percent extra for incrustation in the case of cast iron pipes may be allowed while calculating PHP. The relation between the pump horse power and the indicated horse power or brake horse power of the engine working the pump depends on the type of engine and type of pump and their efficiency. G. AQUEDUCTS AND PIPE LINES 529 Conveyance of Water from Source a) Gravity conduits should be accurately set out to the necessary gradient and covered to prevent contamination; they should be provided at the lowest point with a scour sluice and with manholes not farther apart than 250 meters and at all bends and changes of gradient. b) For pressure mains, galvanized screwed pipes upto 80 mm diameter may be used; for diameters over 80 mm, cast iron spigot and socket or reinforced concrete or suitable asbestos pipes should be used as per relevant BIS specification. c) Cast iron pipes.- First and Second class cast iron pipes in stock when used should be treated with a suitable solution in order to reduce corrosion and encrustation. Owing to liability to tuberculation and encrustation, it is not economical to use cast iron pipes of 80 mm diameter or less. When arriving at the diameter of a cast iron pipe, calculations should be based on data for old pipes unless it is positively known that the pipes will not be required to serve for more than two years. d) Concrete pipes: Concrete pipes are best suited where pressure is low and danger of shock is small. These are not to be used for pressures above 50 metres head of water. For greater pressures, hume/steel pipes are to be used. Reinforced concrete pipes used in water supplies are classified as P1( P2 and P3 with test pressures of 2.0, 4.0 and 6.0 kg/cm2 respectively. For use on gravity mains, the working pressure should not exceed 2/3 of the test pressure. For use on pumping mains, the working pressure should not exceed half of the test pressure. Generally concrete pipes have corrosion resistant properties similar to those of prestressed concrete pipes (PSC) although they have their own feature which significantly affect corrosion performance. Concrete pipes are made by centrifugal spinning or vibratory processes. Centrifugally spun pipes are subjected to high rotational forces during manufacture with improved corrosion resistance properties. While RCC pipes can cater to the needs where pressures are upto 3.0 kg/cm2 And C.I. and steel pipes cater to the needs of higher pressures around 24 Kg/cm2, the PSC pipes cater to intermediate pressure range for which the metallic pipes are expensive while RCC pipes would not be suitable. PSC competes economically with steel for pipe diameters of 600 mm and above. The PSC pipes are ideally suited for water supply mains where pressures in the range of 6 Kg/ cm2to 20 Kg/cm2 are encountered. e) PVC pipes have the advantages of resistance to corrosion, lightness of weight, toughness, rigidity and ease of installation. PVC pipes are cheaper and do not get pitted or corroded in service. They are resistant to a wide range of chemicals. They have good elastic properties and resistance to deformation resulting from earth movements in buried conditions. Thermal retentivity of PVC is very low compared to metals. PVC pipes are available in various sizes ranging from 20mm to 315mm and stand working pressures varying from 2 to 10 kg per cm square. The use of PVC pipes above ground is not encouraged for the reason that the decomposition of the plastic material is accelerated by the ultra violet light and frequent changes in temperature. The deterioration results in discoloration, surface cracking and ultimately rendering the pipe unfit for use. PVC pipes are not suitable for hot water supply systems. Hitherto Gl pipes have been in predominant use in water supply systems. Now pipes with specific improved characteristics are available. f) Steel pipes: Steel pipes can be adopted conveniently where changes in relative ground levels are there and are very suitable for laying in grounds liable to subsidence. Where high dynamic loading is expected, pipes are joined by flexible joint. Judicious method of laying and joining may be used i.e. either flexible joint made of white lead and spun yarn or welding the plain ended pipes (refer IS 5822-1986). 530 Pipe Laying and Fitting of Valves and Meters a) The following instructions should be followed: - (i) For a gravity line, the pipe line may follow the contour of the ground so long as frequent and abrupt changes in gradient are avoided, and it is well below the hydraulic gradient under conditions of maximum discharge. (ii) Keep the top of pipe at least 0.5 metres below ground surface and where severe frost occurs, the cover is at least 1 metre. The bed of the trench shall be finished to an even gradient/level and filled with soil rammed in 150 mm layers. (iv) Lay spigot and socket pipes with sockets facing the direction from which the water will flow. (v) Carry pipes across deep depressions or marshy places on pillars or props. (vi) On steep hill-sides, anchor the pipes to prevent sliding of pipes downslope In vertical position, use pipes with flanged ends and bolts as far as possible. (vii) Close the open end of the last pipe at the end of the day's work. (viii) Test the pipe line with water pressure in sections before the trench is filled in. b) Pipe lines should be fitted, where necessary with:- (i) Air valves of proper size and pressure rating at summits. (ii) Reflex (non-return) valves at the foot of all ascending parts of a main. (iii) Scour valves at depressions on the main for clearing sediment and emptying the pipes. (iv) Sluices as necessary in order to divide the main into convenient sections for repairs. (v) A ball cock at the discharge end of a gravitational main when the discharge into a tank or reservoir is to be automatically controlled. A ball cock must only be used at the end of a pumping main if there is a safety or relief valve on the main. (vi) Meters as required. c) The covers and glands of all valves should be removed, packing adjusted, spindles and gates examined and the whole assembly refitted in free and perfect order before installation. 531 Quality of Water It should be ensured that the water supplied is clear, potable, free from pathogenic organisms and odour. Water should be of reasonable temperature and free from minerals which could produce undesirable physiological effects. The physical and chemical Standards as per Annexure 5.2 may be adhered for drinking water supply. 532 Water Samples for Analysis Whenever the quality of water from any source of supply or from taps is to be tested and samples are required to be collected by the Engineering staff, the following procedure should be followed:- a) Sterilized glass-stoppered bottles available with the Divisional Medical Officer should be obtained. Bottles separately available for bacteriological or chemical examination have to be appropriately used. The paper cover of the stopper should be removed just before taking the sample. The stopper should be removed just before filling the bottle and replaced immediately after. The stopper should be held from the top while the bottle is being filled. Contamination while filling the bottle must be avoided. There should be no external contact with the mouth of The bottle or the part of the stopper that goes into it. The bottle should be filled to about 25mm below its neck. b) When samples of water are taken from a tap, the mouth of the tap should be heated by a spirit lamp for 3 minutes. Water should then be allowed to flow for 5 minutes before the sampling bottle is filled. c) If the sample is to be obtained from a tank or a reservoir or a river, the unopened bottle is to be held in water about 300 mm below the surface and away from the edge without disturbing the bed. The stopper should then be removed, the bottle withdrawn when full, a few drops of water poured out and the stopper replaced and tied down. d) Well water should be collected by lowering the bottle (tied with a piece of weight) into the well by a string attached to the neck-; the stopper should be removed by another string tied to it and the bottle filled in with water, not from the surface but from a point a metre or two above the bottom of the well. If collected from a tube-well with a pump, the water should be allowed to flow for about 20 minutes. e) Bottles containing samples of water should be properly labeled, packed around with ice and saw-dust and sent without any delay to reach the Divisional Medical Officer. Satisfactory packing and expeditious dispatch are essential for a proper bacteriological examination. 533 Method of Treatment The aim of water treatment is to produce and maintain water that is hygienically safe, clean and potable in an economical manner. Treatment should ensure the desired quality at the end points of consumption. The method of treatment to be employed depends on the nature of raw water and the desired standards of water quality. The unit operations in water treatment constitute aeration, flocculation (rapid and slow) and clarification, filtration, disinfection, softening, deferrization, defluoridation and water conditioning. Different combinations are possible to achieve the required quality of water. The choice of any particular sequence of treatment will depend not only on the quality of the raw water available but also on the comparative economics of alternative treatment steps to get desired quality. In the case of ground water storage which are well protected, where the water has turbidity below 10 NTU and water is free from odour and colour, plain disinfection by chlorination is adopted before supply. Where ground water contains excessive iron, dissolved carbon dioxide and odorous gases, aeration followed by flocculation and sedimentation, rapid gravity or pressure filtration and disinfection may be necessary. Conventional treatment including pre-chlorination, aeration, flocculation and sedimentation, rapid gravity filtration and post-chlorination are adopted for highly polluted surface waters laden with algae or other micro organisms. Water with excessive hardness will need softening by conventional method or by ion exchange method. 534 Disinfection of Water - Water treatment processes described in paragraph above remove micro organisms to varying degrees. For utmost safety of water for drinking purposes, disinfection of water has to be done to remove disease producing organisms before it enters distribution system. Disinfection is also required to prevent contamination of water during its transit from the treatment plant to the place of its consumption. The efficiency of disinfection depends on the nature of disinfectants. For treatment on larger scale, chlorination is generally used as treatment for disinfection. Chlorine can be applied in water by using bleaching powder, chloramines or as free chlorine gas. A minimum of 30 to 60 minutes contact time must be provided before delivery of water to the consumer. Utmost care shall be taken for storage and use of disinfectants. All safety precautions as laid down in relevant codes shall be taken. Sufficient number of chlorinators in working conditions should be available with the Inspectors of works. To decide the quantity of chlorine to be added Inspector of works should find out breakpoint chlorination and accordingly chlorinate the supply. 535 Residual Chlorine Minimum residual chlorine available at the farthest end shall be 0.2 mg per litre. However, where distribution is long and complex it may be difficult to maintain the minimum residual value and in such cases re-chlorination may be carried out in the distribution system. During monsoon months or if specific complaints are there, super-chlorination more than 2 ppm of chlorine may be resorted to effectively get rid of bacteria. The Section Engineer (Works) should frequently check the concentration of residual chlorine at the consumer point by orthotolodine test. In this test 100 ml of chlorinated water sample is collected in the test tube. 1 ml of orthotolodine solution is added to it. The colour formed is noted, value of the residual chlorine is directly determined by comparing the colour so obtained with the standard chart of colours of non-chlorine residuals. Divisional Engineer should ensure sufficient number of equipment with all the field units. I. HIGH-LEVEL STORAGE 536 Storage Capacity Normally, the storage capacity should be equal to the higher of the following figures:- a) With efficient stand-by pump:- (i) One-quarter the maximum water consumption in 24 hours (ii) One-third the normal water consumption in 24 hours b) Without stand-by pump:- (i) One-third the maximum water consumption in 24 hours. (ii) One-half the normal consumption in 24 hours. Local conditions should however be considered when deciding on the storage capacity, Each tank may be partitioned to facilitate cleaning or repairs.
537 Maintenance and Cleaning of Storage Tanks a) For the inspection, maintenance and painting of steel-work, action should be taken as detailed in the Indian Railways Bridge Manual. b) Tanks used for the storage of drinking water should be rubbed and cleaned at such intervals as specified by the Divisional Engineer. The cleaning of water tank and disinfection should be carried out as per recommended procedure. Tanks used for the storage of water for locomotive and carriage washing purposes should be scrubbed and cleaned at least once in six months. Reports on cleaning of tanks should be submitted to the Assistant Engineer by the Section Engineer (Works) who shall maintain a register with complete particulars for the purpose. The periodical reports should include information regarding the condition of external and internal painting and corrosion, if any. The dates of cleaning and of both external and internal painting should be painted on one side of the staging in such a manner that these are readily visible. 538 Float Gauges and Scouring Sluices Every high level storage tank should be provided on the outside with a float gauge with a scale marked in metres divided into 5 parts to indicate the water level in the tank. Every storage tank whether at high level or at ground level should be provided with a sluice at its sill level to facilitate the cleaning of the tank. 539 Protection Against Pollution - High service storage tanks, for drinking water in particular, should be locked and provided with gauze wire to obviate pollution by birds and growth of algae. J. DISTRIBUTION OF WATER 540 Distribution System The distribution system is important in a water supply scheme for wholesome and adequate supply of water at required pressures in sufficient quantity. The distribution accounts for 40 to 70% of the outlay of the water supply scheme. Proper provision of configuration of pipes, pumping arrangements, and location of valves and pipe specials are very important and adequate attention should be paid to the functional and hydraulic purposes to be served by the system. For general convenience of distribution, a grid where different mains are interconnected is recommended. This system facilitates supply of water to any point from two directions. The tree system of distribution will be adequate only in small water supply distribution system on wayside stations. 541 Layout of Distribution Systems - Distribution systems should be laid out in the form best suited to conditions at site. The economical diameter of a pipe-line is based on considerations of head-losses and velocities under conditions of maximum flow including fire demand. The design of the distribution system should be based on the maximum estimated daily consumption being supplied in 10 to 16 hours as may be prescribed. A diagram of mains, branch mains and distributaries should be prepared and on it the points of supply, the lengths of pipes and the reduced levels of all junctions noted. Starting at the end farthest from the points of supply, the supply in litres per minute that each pipe must be able to accommodate, is worked out for its length and noted on the diagram. From the heads and longitudinal sections, the diameters are arrived at; a reserve of at least 3 metres head should be ensured at the tail-end of every service line under conditions of maximum discharge. 542 Rising Mains not to be Used for Distribution The tapping of a rising main for purposes of distribution shall be strictly prohibited. Where, for engineering construction purposes, such a course may be justified as a temporary expedient, e.g. in order to save long lengths of service pipe-lines, a control valve must be fitted on the connection. 543 Separate Supplies for Drinking and Other Purposes Where there are separate mains for drinking water and water for other purposes, it should be ensured that when any junctions or branches are laid, the two supplies may not get connected. The economics of having a separate distribution system for water unfit for drinking purpose vis-a-vis the treatment cost of that water and supplying through the single distribution system has to be worked out in relevant cases and a proper choice made. Water unfit for drinking purpose can be in many cases economically used for purposes such as carriage washing, washing aprons, platforms etc. 544 Service Pipes from Mains The per capita rate of water supply indicate only the average consumption of water per day. To take into account fluctuation in consumption due to season, month, day, and hour, the average demand should be multiplied by a peak factor for purpose of designing distribution system. A peak factor of 2.5 is recommended. The number and size of service pipes that can be supplied from a properly designed distribution-main may be assumed as shown below; exceptional cases will depend, however, on actual conditions:-
To avoid dead ends, the main shall be arranged in a grid formation or in a network. 545 Residual Pressure - Distribution maintaining the capacity of pipe line and system should be designed for the following cleaning of pipe lines, minimum residual pressures at ferrule points:
Distribution system should not ordinarily be designed for residual pressures exceeding 22 m. Multi-Storeyed buildings needing higher pressure should be provided with boosters. 546 Preventive Maintenance - Preventive Maintenance of water supply distribution pipe lines assures the twin objectives of preserving the hygienic quality of water in the distribution mains and providing conditions for adequate flow through the pipe lines without leakages. Two of the main functions in the management of preventive aspects in the maintenance of mains are assessment, detection and prevention of wastage of water from pipe lines and cleaning of pipe lines. 547 Protection Against Pollution Near Sewer and Drains a) Horizontal Separation - A water main should be laid such that there is at least 3 m separation, horizontally from any existing or proposed drain or sewer line. If local conditions prevent this lateral separation, a water main may be laid closer to a storm or sanitary sewer, provided that the main is laid in a separate trench, or on an undisturbed earth shelf located on one side of the sewer at such an elevation that the bottom of the water main is at least 0.5 m above the top of the sewer. b) Vertical Separation - In situations where water mains have to cross house sewer, storm drain, or sanitary sewer, it should be laid .at such an elevation that the bottom of the water main is 0.5 m above the top of the drain or sewer with the joints as remote from the sewer as possible. This vertical separation should be maintained for a distance of 3 m on both sides measured normal to the sewer or drain it crosses. 548 Carriage Watering System On all new watering stations, carriage watering arrangement shall be by side filling. The rate of flow at delivery end on hydrant shall not be less than 100 litres per minute. The diameter of pipe, general arrangement of pipe line, spacing of wheel valve and height shall be as per standard drawing issued by RDSO. It is preferable to have separate overhead tank of required capacity for carriage watering. K. MAINTENANCE AND OPERATION OF WATER SUPPLY INSTALLATIONS 549 Engineering Department's Responsibilities The Engineering Department shall be responsible for:- a) The adequacy of water supply at all sources, permanent and auxiliary. b) The despatch of samples of water if so required to be done, from water supply sources, storage-tanks or taps for chemical and bacteriological analysis to the Medical Department. c) The maintenance and operation of water purification plants. d) The maintenance and periodical cleaning of all storage tanks. e) The maintenance of all pipe lines and specials, hydrants and water-taps in station yards and colonies, fire hydrants at stations, goods sheds and loco sheds. f) The maintenance and periodical testing of all water meters wherever installed. The testing should be carried out at least once a year. g) The periodical testing and joint-recording of consumption in meters at such points where supply to the railway is made by outside bodies. h) Wastage and leakage detection survey should be carried out and action taken to reduce the losses. 550 Mechanical Department's Responsibilities a) The Mechanical Department will be responsible for the erection, maintenance and operation of diesel oil pumping plants at all pumping stations. b) The Mechanical Department will be responsible for the operation and maintenance of carriage-watering and carriage-washing hydrants. 551 Electrical Department's Responsibility a) All planning installation maintenance and operation of electrical pumps shall be done by electrical department. 552 Inspections by Assistant Engineer and Staff a) The Assistant Engineer and Section Engineer (Works) should frequently inspect all water supply installations and pipelines and ensure their maintenance in efficient condition. The Section Engineer (Works) should be equipped with an adequate imprest of materials such as pipes and specials and water taps of requisite sizes and the necessary tools to facilitate immediate attention on repairs as and when required. b) Storage-tanks for drinking water and for flushing purposes over offices, bungalows and quarters should be inspected frequently by the Section Engineer (Works) and their cleanliness ensured. Complaints from residents should be promptly attended to. 553 Water-Supply Plans Up to date plans should be maintained in the Chief Engineer's, Divisional Engineers', Assistant Engineers' and Section Engineer (Works) Offices of every water supply system showing the source, pumps and pumping particulars, rising mains, storage tanks and capacities, the distribution mains, service pipes, hydrants and taps. The diameter and type of pipe-lines should be clearly indicated on the plans and on the longitudinal sections. Where there are separate supplies for drinking and other requirements, the respective systems should be shown on the plan in different colours or on separate plans. The Assistant Engineer shall ensure that water supply plan is corrected as and when there is any addition or modification in pipeline. Wherever the laying/modification to the existing pipe line is done through contractual agency, a certificate in the measurement book shall be recorded while entering the final measurements to the effect that necessary changes in the plans have been incorporated. In case of Construction Organization implementing any water supply scheme or augmenting the existing scheme, a copy of the water supply plan shall be handed over to Open Line as and when the scheme is completed. 554 Water Purification Works a) Periodical analysis of water- Samples of raw, filtered and sterilized water from filter-plants should be sent for examination and certification once a month or as may be prescribed to the Divisional Medical Officer who will advise, if deemed necessary, on the appropriate dosage of the coagulant or the sterilizing agent.- Reports on water analysis received from the Divisional Medical Officer should be carefully filed, the action taken on each report being recorded. Samples for chemical examination should be sent for testing once in six months or once before monsoon and once after monsoon. b) Maintenance of water works - Detailed instructions in regard to the maintenance and operation of filtration and chlorinaton plants at each installation shall be issued by the Chief Engineer. It should be ensured that- (i) the plants, in general, with their ancillaries are maintained in a perfectly sanitary and hygienic condition; (ii) aeration of raw water is affected by spraying through the air, cascading over obstacles. (iii) the sedimentation tanks or basins are drained at such intervals as prescribed; (iv) coagulants, either in the form of dry powder or in aqueous solution, are added in the correct proportion according to the turbidity of raw water; (v) the filters are cleaned and washed with pure water at such intervals as prescribed; (vi) the filtered water is sterilized either by adding liquid chlorine or bleaching powder strictly to the dosage specified. (vii) disinfectants are stored properly and all safety precautions are taken The water works staff in-charge shall strictly adhere to the prescribed rules. A copy of the detailed instructions on the operation of plant and purification process should be available at each installation together with the duty-lists of the staff posted there. c) Supervision by Assistant Engineer (i) The Assistant Engineer shall inspect each installation once in three months and record his notes in the AEN should arrange for a joint detailed inspection by Section Engineer (Works) of the pumping machinery once a year as may be prescribed alongwith the staff of the Mechanical/Electrical Department and ensure prompt compliance to repairs or replacements required. (ii) The Assistant Engineer should check the following:- - Stock account showing transactions of stores - Log book for filtration plant d) Inspection by Divisional Engineer -The Divisional Engineer should inspect the water works in every detail once a year and record his notes in the Inspection Register maintained for the purpose. e) Inspection Register- An Inspection Register should be maintained at each water purification work to enable every Inspecting Officer of the Engineering and Medical Departments to record notes. Prompt action on inspection notes shall be ensured. CHECK LIST FOR WATER SUPPLY SCHEME
YES/NO A. ASSESSMENT OF DEMAND 1. Is this a new scheme or augmentation to the existing arrangement ? 2. Has total demand been assessed ? 3. Whethertotal demand includes domestic needs, workshop, offices and station requirement ? 4. Whether fire demand if any, Loss & Wastages and variation in demand has been considered ? 5. Whether demand has been calculated separately for treated and untreated water ? 6. Has the financial viability been considered for providing one distribution system with filtered water vis-a-vis, separate distribution systems for treated and untreated water ? 7. Whether future requirement has been taken into account ? B. SOURCE OF WATER 1. Whether quantity/ yield available is sufficient to meet the requirement ? 2. Has the tests for quality of water been done? 3. Are the test results satisfactory ? (For Stds. of quality of water refer Annexure 5.2) 4. Whether any treatment is required to bring down the various impurities within permissible range ? 5. Has the sanitary survey of area surrounding the available water source been carried out to estimate the possible pollution or contamination of water from such source ? 6. Has the line of treatment been decided consistent with quality of water required ? 7. Whether there is accessibility to the site of proposed source of water ? 8. Is there any need for development of communication system ? 9. Is the controlling device of intake located at a place which is accessible even during floods ? 10. Is there provision for pitching on the down stream and upstream portions of canal near intake? C. PUMPING AND STORAGE OF RAW WATER 1. Has the selection of size and pipe material for raw water mains been done ? 2. Is direct pumping from the source feasible ? 3. Is there any need for storage of raw water ? 4. If so, is the storage capacity adequate ? 5. Has the requirement of the pumps and their capacity been calculated based on 1.5 times the average daily demand? 6. Has the standby arrangement been made for auxiliary power unit (generally diesel type) and stand-by pumps ? 7. Is there provision for proper structure 'required for housing the Pumps and Pump Operator ? 8. Has the provision been made for ".adequate extra space for additional pump if required ? 9. Is there separate adequate space for storage of diesel and other spares ? 10. Has the arrangement been provided for lifting of pumps or stair case in case the pumps are provided at lower level than the prevailing ground level ? 11. Is door of the pump house wide enough to enable pumps to be taken out for repair or replacement? 12. Has the provision been made for fire fighting equipment appropriate to hazard likely in the pump house and storage space of diesel? D. ARRANGEMENTS FOR PURIFICATION AND TREATMENT 1. Has the line of treatment been decided ? 2. Does the layout of the entire scheme fulfill the requirement of the line of treatment? 3. Is aeration unit exposed to the prevailing direction of wind ? 4. Is sedimentation unit designed with 5. Is there feasibility of regular supply of sand required for replenishing the sand of filter? 6. Has the requirement of chlorination been assessed based on the quality of water and longest length of supply pipeline in the distribution system ? 7. Is water softening required to remove the permanent hardness, if any ? 8. Is recarbonation plant necessary (in case of Lime Soda process or softening), if so, is it provided before filtration unit ? 9. Has the method of chlorination been finalised keeping in view the availability of equipment and constant supply of chlorinating material ? 10. Is there any other impurity to be removed ? 11. Has the provision of small laboratory including equipment for testing of water required at filtration plant been made? E. STORAGE AND DISTRIBUTION OF TREATED WATER 1. Has the location of pump house been finalised taking into account the availability of power and requirement of the operator ? 2. Is it feasible to utilise the same staff for filtration unit and for operating the pumps in pump house ? 3. Has the capacity and number of pumps required been calculated based on quantity of water, pumping hours, total head and various losses? 4. Is there provision for auxiliary power supply and stand by pumps ? 5. Has the location of the storage tank been finalised considering the topography and major areas of consumption ? 6. Are distribution mains designed for the maximum hourly demand on the day of maximum consumption ? (2.5 times the average demand) 7. Has the layout for the pipeline for, distribution system been finalised ? 8. Does the layout of pipeline take into account future expansion plans for the colony? 9. Have the dead ends been avoided in the layout of the pipe line ? If unavoidable, is there provision for hydrants to act as washouts ? 10. Has the pipeline layout been provided with the provision for controlling water supply timings for different areas if required, by operating minimum number of valves? 11. Is there any requirement of air valves ? If yes, have they been located at points which are close to or above the hydraulic gradients ? 12. In case of buried pipe line, has it been proposed min. 2m above the sewer line ? 13. Has the testing of leakage been contemplated? STANDARDS OF QUALITY OF DRINKING WATER PHYSICAL AND CHEMICAL STANDARDS
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