Guidelines for Submersible Pump Set for Bore well, Tube well & Dug well (Open well)

UNIVERSITY INSTITUTE OF TECHNOLOGY, RAJIV GANDHI PROUDYOGIKI VISHWAVIDYALAY, BHOPAL GUIDELINES ABOUT SUBMERSIBLE PUMP SET FOR BORE-WELL/TUBE-WELL/DUG-WELL/OPEN-WELL

1 |16 P a g e R e p o r t P r e p a r e d & S u b m i t t e d b y : S a n t o s h K K h a r o l e

How to select capacity of Submersible Pump for a bore well? How does one calculate required HP of submersible pump required for a particular application, what all factors should be taken in to consideration? Q. (1): The bore well is 600 feet in depth, with 40 feet casing done. It is 6" diameter bore well. Location near RGPV Campus Bhopal. Q. (2): A 6.5 inch bore well of 410 ft. depth and the yield is more than 5 inch. The daily water consumption is 7000 litres and the water needs to be pumped to 5th floor building. Could you suggest the type of submersible pump I should choose and what is the necessary HP and the number of stages? What company should I go for? Q. (3): A bore well was dug in our apartment. The water was struck at a depth of 615 ft. and digging was stopped at 715 ft. as water pressure was high to continue drilling. The bore well digger estimated 2.5 - 3.0" flow of water. As yield is good, what is the HP and number of stages the submersible pump would require to pump water to ground level pump? The total length of piping will be 680 ft. Q. (4): A dug an open well which is 6 ft. wide and 42 ft. deep. I need to pump the water to a slope height of 80 ft. from the ground level. Since the total height including the depth of well is found to be 120ft (80ft+42ft), 0.5HP pump should be good enough. Provide proper protection to motor like overload & dry run protection while installing, so that the pump will last long. Q. (5): I would like to install a suitable capacity immersion pump to my bore well in a village near Vellore. The depth of the bore well is 680 ft. I am looking for competitive offers from service providers along with complete design specification for the same. Would appreciate if the contact details of Texmo agency at Vellore can be shared if any. With regards, Q. (6): I have 4 machines installed in our factory. Each of the machines need 6500 litres per hour. That's a total of 26,000 litres needed per hour by single pump supply. Pipe line is already fixed. The dia is 65mm, head 20 meters, horizontal length 200 feet. I need submersible motor capacity for this. Q. (7): I request an immediate comment/advice. We have recently drilled a bore well in Bangalore and have installed a Kirloskar 3 HP submersible pump at a depth of 330ft. Water is assessed at 2.5". For the first 24 hours, the water release was good, but then all of a sudden it stopped. On investigation it was noted that the cable connected with the pipe, which had a slag at the surface end became very tight indicating that it had been pulled down. Perhaps the pump seems to have slipped out of its installed point and thus dragging the electric cable and thus making it tight at the surface. The Panel indicates current, but there are no signs of motor running/ water coming out. We are in a bad situation. Please help/advise. Ans. (1): Your bore well must have a diameter of 6&1/2" in order to make smooth passage for a 6 inch submersible pump. However 4" pumps are also available in the market. Your bore well is 600 feet deep but you have not mentioned about the drill time discharge measured by the driller during drilling, which is necessary for choosing appropriate pump. Moreover the drawdown is another factor for correctly choosing the pump. However, at least the discharge during drilling or after completion of drilling is required. For example if your bore well's final discharge is around 7200 litres/hour, then you have to choose a 2 HP pump and 6



to 8 Staged one to provide a lift of around 48 to 64 meters. The discharge, head and HP/KwH chart of different pumps are available with your Pump dealer. [By Nirad Ch. Nayak, Scientist, Central Ground Water Board (CGWB, Bhubaneswar] Based on depth of bore well and discharge in inches, the local dealers supply the submersible pump set (not standard or efficient without BIS mark). The HP of the pump set or depth of installation of pump set may not be as per well characteristics hence create problems while pumping is under progress. If the capacity of the pump set is more and pump setting is in low depth, after few minutes of pumping the water level may go below the pump setting. If the pump setting is quite deep the discharge may be very low. Hence correct details regarding discharge and total head are necessary to select the correct size (HP) of pump set and pump setting in the bore well. Then how to get the details of discharge and total head before actually installing pump set in a bore well. (1). The organizations involved in groundwater survey and construction of bore wells-after completion of well, conduct the yield test or step draw-down test to arrive at correct discharge, total head and specific capacity etc. Taking the values of discharge and total head, the HP of pump set will be selected. The pump set should be selected which is efficient and consumes less power. (2). It is advisable to provide discharge and total head of wells existing in the mandal area periodically by groundwater departments just like the Meteorological departments provide rainfall data to local authorities, so that common public can utilise the data for selection of pump sets. (3). In the absence of above, the discharge and total head data of neighbouring wells having same depth and rock formations may be utilized for the selection of pump set. We should insist the pump dealer to suggest the pump set based on discharge and total head and pump should have BIS standard. Well reputed brands may be purchased having BIS standard. (4). There is a necessity of establishing pumping test units and consultancy services in every district so as to provide correct suggestions regarding the drilling of bore wells, selection of pump sets etc. So far it is observed that only AFRO organization is rendering such services. You can calculate the HP, Pump Efficiency of submersible pump as 'BHP of Pump' as follows: (1) Water Horse Power (WHP) = Discharge (lt. /sec.) X Total Head (m) / 76 [Total Head (for Submersible Pump) = Total Delivery Head = Pumping Water Level below Ground level + Delivery Head above ground level] (2) Bowl/Break Horse Power (BHP) = Water Horse Power / Pump Efficiency [Note: Suction Head = 0, for submersible pump Pumping Water Level below groundwater level = water level below ground level (before pumping) + Steady State Drawdown (during pumping)] [By S. Halder, Assistant Engineer (Agri- Irri), Water Investigation & Development Department Government of West Bengal, Manohar S. Halder] A 6” bore well submersible pump set normally works on 3-phase, 380 volts, and 50 Hz power supply. The type of submersible pump set you have to select depends primarily on your water requirements and the extent to which your bore well meets those requirements. In the absence of information on the non-pumping and pumping levels of water in your 600-feet bore well, you may assume a lift against a head of 550 feet. A radial flow submersible pump set with 10 to 15 HP and 25 to 35 impeller stages is best suited for this purpose. Depending on the yield of the bore well, discharge ranges from around 5,000 to 15,000 litres/hour through a 1½” to 2” delivery pipe.

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Every pump manufacturer provides a Head-Capacity curve or a Table to tell you how much water you can expect from what depth for a given HP and efficiency range. Obviously deeper you install a pump, less water it pumps. Please note that higher the HP you use does not mean that more water you get. Ideally, a pump should extract only that much water as much as the yield rate of the aquifer permits so as to maintain a steady state in the pumping water level. A submersible pump suitable for a 6” (inch) bore well, will have outer diameter of the main pump body (motor + pump) at about 5 and odd inches to allow necessary margin of gap for lowering and rotation of the pump. This outer Dia. of pump suitable for a 6” bore is already fixed by the pump manufacturers. Usually the Dia. of the rising pipe which brings water to the surface for a 10 HP pump is to the order of 2” – 3” depending on discharge. Also a pump lifts water depending on the speed, diameter and stages of the impellers which again the pump manufacturers decide. For a given discharge capacity, one needs more stages (counted by the number of rings in the pump body) as one goes deeper. Ideally a bore well should be tested for its optimal yield before selecting a pump. Such test is known as “Step Drawdown Test”. In this test a submersible pump is lowered at a suitable depth and the pump is run for a fixed time (say 1 hr.) in steps. In each step the pump is made to lift water at very low, low, medium and high discharge rates using a Glove Valve in the delivery pipe to maintain a constant discharge for the particular step. The drawdown (fall in the pumping water level) is measured during and at the end of each step (1 hr.). The discharge drawdown curve gives the optimum discharges of the well. AFPRO-Field Unit (www.afpro.org), Bangalore can do such test at a reasonable cost. You can also try to do this test while installing your pump as would be recommended by the local pump dealer. Lowering the pump at a suitable depth with sufficient submergence is important as the pumping water level usually falls depending upon the discharge rate of the pump and aquifer yielding capacity (permeability). Ideally a pump should extract water at such a rate so that the water level in the well stabilizes after some times and do not fall further. A pump running dry with lowering water level can burn out easily. To prevent this, you are advised to install a 1.0”-1.25” flexible PVC pipe in the bore well till the pump depth so that you can monitor the pumping water level using an electrical water level recorder at any time. The PVC guide pipe needs to the clamped at the top securely to prevent it from falling in to the bore hole. Finally, do not expect, your well to yield more than your neighbour’s well of similar depth. In fact you will join the groundwater extraction club feeding on the same aquifer albeit tap a few extra fracture zone due to a greater depth. With best wishes. Dr. Mihir Maitra. Consultant. Water Resources Q. (8): I drilled a bore recently and generally drillers cannot provide exact levels of bore well. They provide the approximate Discharge like 2", 3" pressure or something like that. I have a bore well with a depth of 350 feet. The fractured zone has been touched at 160'. But we have gone up to 350 feet expecting another zone. But we could not get it. The yield expected by the driller was 2" loose. Kindly guide us as to at what depth the submersible pump has to be installed and what is the HP of the pump and also how many stages pump to be installed.

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Ans.: To decide about the correct size of submersible pump set, the details regarding Discharge (LPS) Total Head i.e. pumped water level (Static water head + Drawdown) in metres to discharge point on ground level required. Discharge data of winter season and pumped water level date of summer season is necessary as these are the maximum values based on which we can calculate H.P of pump set. Other option is, take the data of discharge and total head of your bore well to pump dealer. By using pump curves, the dealer can suggest you the correct size of pump set. You have to select the pump set which consumes less power. To calculate the HP (precisely it is called BHP) of pump set, the following formula can be used. Q in LPS X Total Head in metres H.P. = ---------------------------------------- 76 X Pump efficiency The no. of stages can be calculated by dividing the total head by 4 metres (after deducting several losses, it is assumed single stage pump set can lift the water up to 4 metre which generally some manufacturers adopt) But if we consider the discharge of your bore well i.e. 2 inches (as reported by driller) it is very low. I am afraid within few minutes of pumping, the pumped water level may go down below pump setting, particularly during summer season. As per V-Notch method (at 90 degrees) at 2" the discharge is about 1LPS and 45 degrees the yield is still less. As per Drillers assumption - 2" means about 2 LPS. As no pump set is installed in bore well, I suggest you collect the discharge and total head (winter and summer respectively) data of your neighbouring bore wells having same depth and approach the pump dealer for correct size of submersible pump set. However, correct details regarding discharge and pumped water level data can obtain by carrying out step-draw-down test by trained professionals. In addition, the existing voltage conditions, variable discharge and Totaleasons causes under loading and overloading of motor which leads to more consumption of power and low power factor. In such conditions installation of L.T. Capacitor is necessary to safe guard your pump set. Can bore wells be drilled inside an existing well? Dry wells can be brought to use by drilling bore-wells inside them. It is mostly done in large wells used for irrigation purposes. Flexible rigs which have separate tripod and drilling head, can be used for drilled a bore-well inside an existing well if it is above 3m x 3m size to accommodate size of the rig and working space. These rigs are capable of drilling up to a depth of around 300 feet.

Which types of pumps are suitable for bore wells?

Jet, compressor and submersible pumps are the widely used pumps for domestic purposes in India. Jet

pumps which are installed above the ground level over or near the bore well are suitable for depths up to

150 feet. If the ground water is at lower depths submersible or compressor pumps are used.

Compressor pumps are suitable for low yielding bore wells and also they are easy to install and maintain

as they are installed at ground level. However, they are noisy and may also require frequent repairs.

As submersible pumps of 4” diameter which can work in single phase electricity connection are available

in the market now, these have become a preferred choice for domestic bore wells. They can be installed

for meeting higher water requirements. However, submersible pumps will be prone to frequent repairs if

they are installed in the bore wells containing heavy silt particles.



How to choose a right type and capacity of pump for a bore well?

Capacity of the pump to be chosen depends on the depth at which the pump/foot valve is to be installed

and the desired discharge. Based on the total depth of the bore well, the depth at which the pump is to

be installed (usually 10-25 feet above total depth of pumps) is decided.

The total head is determined using the depth of pump, overhead tank level and friction loss expected in

the suction and delivery pipes. Using the total head and the discharge desired, from the pump rating

curves for each models of pump manufactured by various companies, the right HP of the pump suitable

can be selected.

Is it necessary to obtain legal permission for drilling a new bore well?

Some states have implemented groundwater legislation acts which prevent drilling of bore wells without

the permission of Government Bodies in water scarce regions. However, some states allow only drilling

of drinking water bore wells without the need for obtaining permission. Therefore, it is advisable to explore

the details of it before drilling a bore well.

How to seal unused or defunct bore wells?

Sealing defunct or unused bore wells is essential to prevent contamination of ground water. If left open,

unused bore wells can lead to rapid contamination of the ground water as they allow contaminants directly

into the aquifers.

Good quality clay materials can be used to seal the bore well using different methods after removing the

casing pipe (details in the reference given at the end). In case it is not possible to take such measures,

cover the bore well properly using a well cap or provide adequate earthen cover over a concrete or stone

slab kept on the bore well.

Ensure not to allow entry of waste water or any external material inside an unused bore well. Alternatively,

unused or defunct bore wells can be used as rainwater recharge wells after providing proper filter

arrangements and intake arrangements around the well.

How to measure depth of water and total depth of existing bore well?

We can find the water level in a bore well from the ground by time calculating the time taken for a very

small stone (0.5 inch) to strike the water surface. All you need is a watch and a very small stone. Drop

the stone and note the time taken for it to strike the water surface. Multiplying with 9.8 (i.e. an object free

falling near the earth surface would travel 9m/sec due to gravity) to the time taken for the stone to strike

the water surface measured in seconds, we can get the water level depth in meters (Ex: for a 10 seconds

time, depth to water is – 9.8 x 10 = 98 meters) .

Repeat the exercise few times to get the correct depth.

A thin nylon rope longer than the depth of bore well firmly attached to a small sized stone (2 inches) or

metal ring (a small automobile bearing is ideal for this purpose) in one end is used for finding both the

water level and total depth of the bore well. While leaving the stone/metal block attached to the rope into

the bore well, when reduction in the weight of the stone is felt due to buoyancy of water after it strikes

water surface, mark the point on the rope and remove the entire portion of rope let inside the bore well

to measure for the water level from the ground.



Similarly, when you feel that the rope is not freely moving downwards from your hand once the stone

strikes bottom of the bore well, mark the point and measure for the total depth of the bore well after

removing the rope.

Checking water resource capability of unused bore well

I am planning to purchase a site which is containing a bore well. I want to know whether that borewell is

having water or not. The owners are saying they dug up to 700 feet and around 600 feet they got water.

Next to this site, people have got bore water at 400 feet and they are having enough water. We want to

check the water resources in this bore well.

Please advise how to check if the water is sufficient or not. 3 month old bore well, not used. Is

there anybody to check the bore well water resources?

What has to do is to get a pumping test or step drawdown test conducted in the bore well. The bore

well must have been drilled to a depth of 700 feet as the water-bearing fracture zone met at a shallow

depth in the nearby bore well of 400 feet was not met.

The depth to water level and depth of the bore well can be determined using a wetted tape. The local

sellers of deep-well pumps will be able to arrange for such testing. In a step drawdown test, water is

pumped at different rates (that is, so many litres per hour) by keeping the submersible pump at

different depths to know the actual quantum of water that could be safely pumped and the

resulting lowering of water level or drawdown. The test helps to know whether the bore well can

meet the water requirements of the land to be irrigated and the types of crops that could be grown

with the available water.

A simple solution: - By inserting a thin nylon rope tied a small stone/metal piece inside the bore well to

an anticipated depth, you can find out the water level and total depth of the bore well. You can easily do

this yourself.

Also, contact reputed vendors selling pumps who will be able to help in identifying the suitable solution

for your requirement.

How to identify a suitable site for bore well? Vertical Electrical Sounding is one of the very common geophysical methods used for domestic bore well exploration. However, sufficient open area around the location is needed for conducting the survey. Geologists charge around Rs.1, 500 to 5,000/- for identifying a bore well site. Other methods of geophysical survey are used in special cases and they are quite expensive. Local well diviners who use wooden sticks or magnetic blocks are also to some extent successful in identifying bore well sites. But this method may not be always reliable, especially in areas where the geological formation is critical. Is there a best suited time for drilling a bore well? As such there is no prescribed season for drilling a bore well if the location of site has adequate ground water potential. However, identifying a suitable site and drilling the bore well in summer months would give the worst possible scenario in the location at the point of time. Therefore, summer months are usually



preferred by some experts as the best suited period for drilling a new bore well. Also, as most agricultural sites can be accessed by drilling rigs only during summer months, they are usually available in these periods. What are the common methods adopted for drilling bore wells? Methods of drilling to be adopted depends on factors like suitability of a method for a particular type of geological formation (i.e. such as alluvial, boulder and hard rock), cost factors, diameter and depth of bore well and the purpose intended. Most commonly used types of drilling methods are; (1) Water Jetting - Shallow bores in alluvial formations (2) Augur Drilling - Shallow bores in alluvial formations (3) Calyx Drilling - Shallow bore wells in both hard rock and alluvial formation (3) Percussion Drilling – Deep bores in bouldery formation (4) Rotary Drilling - Most common method used for drilling large and deep bores in alluvial formations. (5) Down the Hole Hammering (DTH) Drilling – Most common method for drilling large and deep bore wells in hard rock formations. What is the standard diameter of bore wells drilled for domestic purposes? For domestic purposes, 4.5 and 6 inches diameter bore wells are usually drilled. While 4.5 inch is most commonly drilled bore wells for domestic purposes, 6 inch bore wells are drilled when higher yield is required for large apartments or buildings and also for agricultural purposes. Initially larger diameter bits are used to place the casing pipes up to the hard rock zone prior to drilling specified size of the bore well. How charges for drilling a bore well are usually calculated? Charges for drilling a specified size of bore well include: (i) Drilling cost per feet, (ii) Cost of casing pipe per feet, (iii) Cost of drilling and installation charge for casing pipe per feet, (iv) Flushing charges per hour for flushing the bore well after drilling and (v) Transportation charges of the rig to the site from nearest town per km. Drilling rates are sometimes charged in slabs for specified ranges especially when deep borewells are drilled. As drilling rates usually vary depending on the availability of rigs, local demand and site conditions, it is better to cross check with few drillers to get a competitive quote. What are the types of casing pipes used in bore wells? Currently, PVC pipes are very widely used as casing pipe. GI/Mild steel casing pipes which were used earlier are not being recommended due to the problem of corrosion. PVC casing pipes installed in bore wells must confirm to IS 12818: 1992 that governs the specification for un-plasticized PVC screen and casing pipes for bore well of the Bureau of Indian standard. This standard covers the requirements of ribbed screen, plain screen and plain casing pipes of nominal diameter 40 to 400 mm produced from un-plasticized polyvinyl chloride for bore-well for water supply. Slotted PVC casing pipes are used if aquifer yields through sandy zones to protect collapse of bore well side walls and to prevent entry of fine sand into the bore well which might clog the bore well. This requires



detailed study by Geologists to decide slot size and at what depths these have to be provided along with gravel packing around the casing pipe. What is well development? (i) Flushing and Over Pumping Well development is the process by which a bore well is cleaned and the permeability of the bore well is increased by removing fine materials like sand, clay deposits and rock cuttings accumulated in bore wells and gravel packing provided around well screens. Usually it is done by over pumping water in the bore well or flushing the bore well with adequate air pressure. In hard rock areas, flushing is done after the drilling process for at least 2-3 hours by using compressed air before drilling is stopped. Most of the drillers avoid this as it is an additional task. This is an important process that must be finally performed before completion of the drilling process at any given site. Well development is also carried out to bore wells which are facing reduction in water yield over a period of time to increase its yield. The reduction in yield can be due to clogging of pores spaces by silt and mineral deposits. Flushing using air pressure or over pumping the bore well are the methods normally employed to improve the yield of such bore wells. (ii) Bore Blasting Bore blasting is a technique which is used for opening up of fracture zones of borewells located in hard rock areas. Around 14 to 230kg explosives are used depending upon the depth at which the blast is to (www.indiawaterportal.org) be carried out. It is usually carried out when a drilled bore well is dry and there is a potential to obtain water by opening up fissures in the rock at the specific site. This method could also affect very existence of the bore well therefore taking professional help is must for choosing this method. (iii) Hydro-fracturing As the term suggests, it is applying water under high pressure for the creation, propagation and cleaning of fractures and fissures deep in the rocky layer of the earth. Creation or extension of the fractures is done using very high pressure water pumped into the bore well with pressures reaching as high as 3000 PSI (pounds per square inch). Hydrofracturing is one way of cleaning the blockage in the fissure and releasing water back into the bore wells. Hydro-fracturing can also open up the bore well to new fissures in the immediate vicinity not previously tapped by the bore well. A borewell camera is used to identify the fracture zones inside the borewell prior to the process. Hydro-fracturing is an expensive process which is normally adopted by Government Water Supply Departments. Recently, in Bangalore a private agency is involved in providing such services. They can be contacted at; (a) Mr. P.Ganesh, Managing Director, Fractech Equipment {p} Ltd, E-mail- [email protected], [email protected] (b) Parvatha Industrial complex, Ganganna circle, Jalahalli, Bangalore -560 013. Phone: 28384732, Subramaniam- 9443150582 How to determine yield of a bore well while drilling?

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Usually V-Notches (a metal plate/wooden board with V shaped slot on top) are used by bore well drillers for determining yield of a bore well during the bore well drilling process. To measure the flow, water coming out of the bore well during drilling process is allowed to flow through an earthen barrier created around the site is fixed with a V-notch temporarily. Drillers won’t be inclined to do so as this is an additional task they have to do. Based on their experience, they tell the rough yield which may not www.indiawaterportal.org be always correct. Yield of a bore well is usually referred in inches (i.e. depth of water flowing over the notch). Refer the website http://www.lmnoeng.com/Weirs/vweir.htm to calculate water yield for various types of weirs and the depths of water measured over them (your computer should have java to support the program). How yield of an existing bore well can be determined? Yield of a bore well can be determined by conducting a step drawdown test, in which water is pumped at different rates (that is, so many litres per hour) by keeping the submersible pump at different depths to know the actual quantum of water that could be safely pumped and the resulting lowering of water level or drawdown. The test helps to know whether the bore well can meet the water requirements. Usually, reputed pump dealers can conduct such tests at a fee before deciding to purchase a pump. Such tests are necessary for large settlements like apartments to arrive at very suitable pumps which can provide huge quantities of water needed. Bore well not giving sufficient water 1. The bore well yield may not be equal to or above that of pump suction rate. Try reducing delivery rate 2.The sand could have sunked in blocking free flow of water. Immediately after the water flow stops, try measuring the water level depth from ground level and this will give you an idea of rate of water recharge from the bottom. How to minimise the delivery rate of pump. Once we ran it on low voltage it gave us 1 inch water for 5-7 minutes I think there are 2 possible things in this matter 1 is the bore well contractors fooled us by saying we got at least 2-2.5 inches water or the water which we got at 270 feet was blocked by the sand as the base of the bore is now at 250 feet when we measured it with rope and chain. Now we are in touch with some experts who will probably come this Friday and will suggest us some solution till then I request experts in this forum to give your valuable inputs. From the image I deduce that the water flow is either blocked / choked or little. The "throw" seems to be less. I think the flow would have been farther initially and dwindled after a short while towards the point of exit of the delivery pipe. You can use a reducing coupler of suitable size (2.5" to 1 " or 2 " to 1 " depending upon the current delivery pipe size) to build sufficient pressure in the delivery line. You had posted that the bore well was drilled to a depth of 340 feet and now you measure up to 250 feet only. This clearly shows that sand has caved in. I don't know the size of the suction / casing pipe you have used. You may ask the drillers to clear the sand up to 340 feet and send in a lesser dia PVC pipe up to the bottom of 340 feet. This lesser dia. pipe may be used as suction pipe .Of course this will send the sand along with water but the bore hole will not be blocked.


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The bore was drilled to the depth of 340 feet but after 280 or as soon as we got water there was layer of white sand in which they drilled till 340 feet hoping to get stone layer again but there was no stone down there so they stopped drilling, I think as soon as they brought out their equipment the bore must have caved in after 270-280 feet as that layer was that of white sand. The casing is of 6'1/2 inches after that bore is of 6' inches and the GI pipe line from pump to the top is of 2' inches. In the image u are seeing 2' inch 20 feet GI pipe after the bend. Luckily today i got to know that the drilling contractors have come near our village so i contacted him to which he is now saying to me that u were there that day and you saw the water coming yourself and there must be no water now so what can i do. So i asked him to meet me tomorrow and provide me the solution for the same or flush clean the bore. As per the description of the construction of your bore well & as per the running time of the submersible Pump set installed in your bore well, I would want you to understand the following aspects for helping you take the appropriate measures with your bore well water problem - Always water coming into the bore well, in stream, comes from up to down i.e. that water in the aquifers flows to the lower elevation in the bore well & maintain its level (STATIC LEVEL) in the bore well. For efficient pumping, pump must be installed below the Dynamic Water Level (refer fig. Below)



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If no water level electrodes or level switches are installed, the water level may be drawn down to the suction interconnector of the pump and the pump will then draw in air. Long-time operation with water containing air may damage the pump and cause insufficient cooling of the motor. In your case, the depth of the bore well available is 250 feet & I suppose that you must have installed your pump set at 200 feet, the Kirloskar Pump 05 HP, 08 Stage - which you had mentioned shall deliver the following quantities at respective Heads (H) in Mtrs 76(H) - 60 (LPM), 69(H) - 120(LPM), 60(H) - 160(LPM), 54(H) - 180(LPM), 31(H) - 240(LPM), 15(H) - 270(LPM). Considering the friction loss we may assume that you are able to pump 150 LPM with your pump installed at 60 metres depth, i.e. if your pump runs for 5 minutes at every 30 minutes you are able to get 1500 Litres per Hour i.e. 36,000 Litres in 24 hours duration time. Suggestion for Solution to your requirement - 1. As your bore well is caved in because of the sandy formation & also you did not find any confined formation i.e. rocky formation up to 340 feet depth, I would suggest that, you may not incur any further expenses on flushing the bore well or trying to lower the less diameter screen pipe up to the bottom of the bore well i.e. 340 feet, which would be a very costly affair, instead, u must install the level sensors in the bore-well for automization of the pump set & u may also try to reduce the off time period of the pump set to up to 20 minutes to increase the cycle of pumping in an hour, to get maximum water quantity in an hour. 2. You may control the flow by fixing a ½" dia. ball valve at the discharge nozzle of your GI pipe, & connect it with the flexible hose pipe to return the ½" flow back into the bore-well for the prolonged continuous flow of water. I hope the above given suggestions shall help you with your requirements. May you have any further queries, please feel free to contact us at any time. YASH D SHAH Mobile: 08652810004 What should be the water quality in the drinking water bore wells? Water Quality is an important measure to be analysed in bore wells. The IS Code 10500:1991 governs the water quality standards for drinking water. Chemical and bacteriological parameters of the water in a bore well can be analysed by taking the water samples to a water quality labs. Government water supply and geological departments have such labs in every district and city. Reputed private labs also conduct such tests at a fee. India Water Portal has a section which provides a comprehensive list of water quality labs in India as well. Usually bore wells constructed in hard rock areas are free from bacteriological contamination if due precautions like proper installation of casing pipes and avoiding stagnation of water around bore wells is taken care off. If any strong smell or heavy froth forms in the bore well water, it could be due to entry of sewage/contaminated water. Chemical parameters such as iron, fluoride, TDS, arsenic and nitrate are some very important parameters to be normally analysed as they occur in ground water depending upon the geological formations. Other parameters such as pesticides, cadmium, etc., can be assessed on specific cases where such contamination is suspected (for details, go through the links given in reference).

http://www.indiawaterportal.org/blog/2008/05/20/water-testing-labs-informationrequired/

http://www.indiawaterportal.org/blog/2008/05/20/water-testing-labs-informationrequired/



How to choose a right type and capacity of pump for a bore well? Capacity of the pump to be chosen depends on the depth at which the pump/foot valve is to be installed and the desired discharge. Based on the total depth of the bore well, the depth at which the pump is to be installed (usually 10-25 feet above total depth of pumps) is decided. The total head is determined using the depth of pump, overhead tank level and friction loss expected in the suction and delivery pipes. Using the total head and the discharge desired, from the pump rating curves for each models of pump manufactured by various companies, the right HP of the pump suitable can be selected. Can an existing bore well be deepened to increase the yield? Deepening an existing bore well to a greater depth is undoubtedly cheaper than constructing a new bore well as there will be saving on the installation of casing pipe and lesser depth of drilling. However, drilling companies may be reluctant to deepen existing bore wells and therefore it is necessary to identify the one willing to take up such a work. Exact saving that can be achieved in developing an existing well over drilling a www.indiawaterportal.org new well can be known by obtaining quotations from the drilling company for the two works. However, it is better to consult a Geologist to know the feasibility of finding adequate quantity of groundwater in the location deciding upon deepening the bore well. Can an existing bore well be recharged for increasing its yield? It is preferable to take up recharge measures such as recharge wells/bore wells around the site of a bore well used for drinking purposes rather than putting rainwater directly into it. To maximise the benefit, it is always advisable that the entire neighbourhood is encouraged to take up recharge measures to benefit all the wells in the area. In case the bore well itself is being used for recharging, proper filtering arrangements for removing silt particles and also proper piping system for allowing the only rainwater water from clean roof catchments inside the well without damaging the side walls is essential. Bore well drilling: My Experience - Let's divide the whole process into 5 stages. Stage 1: Realization Stage 2: Deciding on the point Stage 3: Drilling Stage 4: Cleaning up the mess Stage 5: Getting the water Stage 6: Future planning. Our apartment was constructed 5-6 years ago and we have 2 bore wells for 75 flats. At the time when the apartment was constructed, there was no water shortage in our area (Basvanagar), hence our builder decided to go for only 2 bores at 450 feet. Unfortunately, both the bores are 10-15 ft. apart and at same depth. So when the things went wrong, both the bores went dry at the same time. Stage 1: Realization In the summer of 2010, we for the first time realized that underground water that we had been pumping out so happily is not unlimited. One fine day our bore well just went dry. This happened in the month of June 2010. We then thought, never mind, let’s call tanker guys. This was the time when we realized that it is easier to buy petrol tanker but not water tanker. Irrespective of how much money we were ready to throw, none of the tanker guys agreed to come. Reason: They were already running at full capacity supplying water to other apartments. Then it dawned upon us that the whole area where we


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are located has become very dry in the last 5 years...all thanks to mindless drilling and pumping. Luckily for us, we finally managed to get 3-4 loads of water for 75 flats for the next few days. Within a week it started raining and our bore well again started functioning. Two things we learnt from stage 1. A. Water is very precious. (It’s certainly not free as most of the peoples in my apartment used to think). B. Rainwater harvesting. If regular rains can help us get water for 6-8 months harvesting all the water (and if done by everyone) will certainly help us in the long run. Stage 2: Deciding on the point. We started putting in our efforts on two fronts. First was rainwater harvesting and another was to increase the depth of existing bore wells. Rainwater harvesting project is still WIP (work in progress). To deepen the existing bore well, we called some consultants. We came to know that since both these bores are situated in the basement, there is not enough space to get the drilling truck. We can do some gas pressure drilling but then it can be done only up to the depth of 500ft. Moreover it costs double of the regular drilling. So then our focus shifted to drill a new bore. For this the first thing was to find a place to drill. A little research revealed that there are 3 prominent ways to do this. a. A coconut guy. b. A wooden L shaped rod guy. c. A geologist, and d. Some service based on GPS points and satellite imagery of that location. Among these, d is most scientific and most unreliable of all. (Take a hint from our weather forecasting services) Among the remaining 3, (c) a geologist guy seemed to be the most scientific. However, under pressure from senior citizens and other wise men of our society, we decided to call in a coconut guy. He gave us 3 points. At the end of the day, the impression I got was, it’s all eyewash! He charged us INRs. 500 for his services. Next we researched for the bore well company. After a few consultations we finalized on Kannan bore wells. We called them to visit the site and discuss the modalities with us. There manager visited our apartment and we finalized on a date and time to start drilling. He also suggested a geologist to mark the drilling point for us. Costs for his services were INRs 750. Since it was not much and we were not very sure about the methods used by coconut guy, we decided to go the scientific way. The geologist's methods were a bigger eyewash when compared to coconut guy. However, he also suggested a point very near to our coconut guy's point. Since all these points were in the general area where we anyway wanted to drill our bore well, we decided to drill at the point given by coconut guy. Stage 3: Drilling Drilling costs vary from location to location. It depends on the general nature of soil in your area. Price will also vary for the width of the bore well. We got the estimates for 6.5 inch bore only. We got quotations from 2-3 companies and the rates were more or less same. Cost of drilling increase with the depth. The best quotation that we got was INRs. 63 for first 250 ft. and INRs. 10 increment for every 100 ft. up to 550 ft. Then the increment is INRs. 20 up to 750 ft. and then its INRs. 30 up to 1000 ft. Maximum legal limit to drill is 1000 ft. So the estimate was like INRs. 63 0 - 250ft



INRs. 73 250 - 350ft INRs. 83 350 - 450ft INRs.93 450 - 550ft INRs.113 550 - 650ft ....and so on. Apart from this we need to pay for the pipes that will go into the bore. Putting in pipe is must for the first few 100 ft. as this is loose soil and will slowly fall into the bore. After that if the ground is solid enough you may not need pipe linings. We finalized on the dates and gave the advance cheque around 1 week in advance. The drilling was scheduled for a Saturday 6 AM and was supposed to take around 12 hrs. to drill down to 1000 feet. In line with its established reputation, Kanan bore well's equipment reached our premises only 18 hrs behind schedule. On Saturday night, they just setup there equipment and left it as is. I must admit they do have an impressive array of drilling equipment...all automated! The work started at sharp 5.45 AM on Sunday morning. For the first 100 ft. a 10 inch drill bit was used. This was changed to 6.5 inch drill. The loudest noise was made by the drill when it went thru the concrete surface. After this all the noise was from the generator. At 5.48 am a police personal from HAL police station was there at our gate...to collect his share, very impressive. I must say. He informed me that someone complained about the noise coming from our apartment. I informed him that as per Supreme Court guidelines we can do this work between 6am and 11pm. I know we are 15 minutes early, but if you insist, we will hold the work for 15 more minutes and then start. (PS: I have no idea of any such SC directive...it was just a fluke statement!) Any way, he just demanded some tea money...which I handed over to him, but not before telling him that last month even I had complained about the noise made from a flat in opposite apartment and even after 4 hrs nobody came to check it! His facial expressions were worth watching!! Anyway, coming back to bore well drilling. We hit the first signs of water at 120ft. Next hit was at 415ft and thereafter absolutely nothing. The water yield of bore well is measured in inches. A 1-2 inch yield is considered good for 4 - 5 houses. For big apartment complexes a yield of 4 inches is considered good. Now, how is this yield measured? Bore well companies have a wooden board, with a V cut on one side. With all the water coming out. After a few hours of drilling, they create a dam kind of structure (using the silt that has come out) and put this wooden board at one end. Then they measure the height of water flowing out of the V. Hence the yield is determined. Anyway, we drilled all the way down to 1000ft. The most confusing part was that for almost until 500ft the supervisor was telling us that what water we have got is nothing, at 600-700ft we will get a lot more. But then, when by 800ft we got nothing else, he started saying that the yield that we are getting is very good and he just can’t help it as we have hit a rock formation, hence no water. And by evening he was suggesting us that we must put in PVC pipes all the way down to 1000ft as the soil is kind of lose. The total estimate to put the pipes was INRs. 140 per running ft. These were all contradictory statements, hence we decided to leave the things as is for now. They finished there drilling work by 11pm, collected there money and left all the muck as it is. Stage 4: Cleaning up the mess: Next task was to get a tractor guy to clean up the mess. It took them 6 loads to remove all the mud and slush. This will give you an idea of how much stuff come out of the bore...apart from water.



Stage 5: Getting the water up This task took us to SJP Road. Crompton Greaves, Kirlosker, V-Guard, Texmo are some of the favourite brands of the bore well motors available there. Each shop has their own favourite and will try to sell you one brand over the other. Bore well motors, as any other electrical motor are either single phase or 3 phase. In layman's terms 3 phase motor will be able to give you more water per hr when compared to single phase motor. This difference is about 50% more. 2nd attribute of bore well motors is Stages. Each stage is capable of pushing up the water by 22ft and push the water along horizontal surface by 66 ft. Since we had decided to put our bore well at 600ft depth, a 40 stage motor was recommended for us. Since our yield is not much, a single phase, 40stage motor is what we decided on. The expected output was 60 LPM (litres per minute), with 1.5 inch pipe thickness. We decided to go for Texmo brand as this was the only brand giving us 2 yrs. warranty. Rest all were 1 yr. warranty. Next is the pipe and wire. The defacto standard in wires is finolex 4mm sq wire. Water pipes also come in various flavours. Quality of pipe is measured in kg/sq.cm. A pipe with a strength of 12.5 kg per Sq.cm was recommended to us. The price difference between a 8kg/sq.cm and a 12.5kgpercmsq pipe is almost 100%, so this is one place where these shop owners will make a killing. All the recommendations that we were following were given to us by a relative of one of the residents of our apartment. Hence, we trusted him fully. Rishi, Raksha are few of the prominent brands. Motor costed us INRs. 21k. Pipe was at INRs. 70 per ft. and wire was INRs. 73 per sq. ft. Another point to note is that all the prices quoted in SP road are pre-tax. The shop owners are not in habit of informing you this until the bill is made. So always add 13.5% to whatever price they are quoting. The motor was delivered and installed at our premises within 24 hrs. Currently, it is taking our 20k lt sump around 5 hrs to fill up to 90%. So effectively we are getting around 3600 litres of water per hr. This is in line with the arithmetic told to us by the motor guy in SP road. Stage 6: Future planning: Rain water harvesting. We intend to implement a complete setup by end of March this year. Will create a new thread on my experiences with that project soon.

References:

India Water Portal – Ask a Question (Bore wells section)

Hand Book on Bore well – Bureau of Indian Standard (BIS), Govt. of India (GoI).

Guidelines For Sealing Groundwater Wells – WRMD, GNFL

Water Quality Implementation Manual – Department of Drinking Water Supply , GoI

Water Well Manual.

Documents

Guidelines for Submersible Pump Set for Bore well, Tube well & Dug well (Open well)