Wells

Wells are excavations or wells created in the land by digging, pressing in or drilling to access groundwater and aquifers. Water from the wells can be pumped with different designs of pumps in manual or electric drive. Pumping water from household wells, can also be performed with buckets which are raised by hand or machine. Wells differ in depth, the character of the water level (the level of artesian water pressure and normal to the level of water below ground level) and water quality (thermal wells, mineral or drinking water

In the past, all wells were dug manually. They did not have an electric pump, and the water is pulled out with buckets or by mechanical pumps. They varied in size, but usually they were large enough that one or more people can fit in them. They were most often depths up to 60 meters. The walls are usually secured quarry stone or brick, to prevent the demolition, and to protect people who dig or occasionally enter into a well in order to clean it. However, in recent times dug wells have been performed by using larger diameter caissons. This type of well is abandoned because of the great risk of frequent accidents resulting in death of workers who perform or clean these wells. For these reasons, wells in recent time are mainly performed by drill rigs. This type is called drilled wells. Drilled wells are used for agricultural irrigation, water supply industry and settlements, dewatering of the mine, to draw of thermal, thermomineral and mineral water etc.

Pressed in wells are made very easily and cheaply. The only necessary thing is to determine the point where the well will be. Then, pipes are pressed into the ground at a given location. Previously, the pipe (usually galvanized 5/4" to 2") is drilled as a filter in a certain place, mainly at its lower end, so that water can enter the pipe. The lower end of the pipe has the shape of a spike, for easier pressing into ground. As soon as the pipe reaches the aquifer, pressing stops. A pump is mounted on the pipe and pumping of water can start. However, this type of well is spatially restricted to the terrains with aquifers which have extremely high filtration properties and a great amount of groundwater to a depth less than 9 m (mainly in plains along rivers). Given the diameter of the pipes, there is no possibility to place an electric pump into these wells, and their capacity is limited to the water needs of individual households.

Wells can be drilled by various manual or mechanical methods. In this way it is possible to achieve a much greater depth, even hundreds of meters. Drilled wells are lined with pipes (usually steel, galvanized, stainless steel, plastic, etc.). Drilling of wells starts with a larger diameter and is carried out until a certain depth, then drilling continues with chisel of smaller diameter. The well is lined with pipe smaller in diameter than the borehole. In the zone of the aquifer, lining is done using filter pipes which are made of different structures of perforated pipes (bridge-like, wired, slotted, multilayer, etc.), which enables the surrounding water to enter the well. The lower part of the pipe lining of wells (below the filter) has a sedimentation tank, usually with conical shape on end, for easier installation and cleaning. The ring like shaped space between pipe and borehole wall is filled with clay in the zone of pipe without filter and with granulated gravel packs in the zone of filters. Tampon of clay or cement mass in the space from the ground surface to the water table, has the function of impermeable barrier that prevents contamination of wells.

Answers to most frequently asked questions

I want to dig a well or to order digging or drilling of well - what should I do ?

Performing wells can be very risky, complex and dangerous job with an uncertain outcome. Since the phase of locating wells, the quality of performance, type of built-in material (wells filters), etc., the professional help is required . So do not hesitate to contact the professional (licensed) company that performes these kind of work. One of them is "IPIN" Institute of Applied Geology and waterengineering from Bijeljina. Experts in the field of hydrogeology will give you some advices, offers and recommend how to get to the desired goal.

If you hire professionals, you will eliminate most part of the risk in the results. Namely, after a field inspection of locations and insight into the geological structure of the field (geological and hydrogeological maps, results of previous studies of the area), experts can tell you, whether it makes sense to invest money in exploration or drilling of wells or you have only waterproof (anhydrous) rocks present on location. Of course, if the situation is favorable, access to geophysical studies, exploratory drilling, testing and analysis and finally the well is made. The absence of previous phases of research increases the risk in the results, but there are places/terrains where capacity and quality of future wells can be assumed with reasonable assurance, in that case performing of wells is accessed immediately. Agreement / arranging about performing of the well and selection of contractors should be performed according to the criteria that follow below.

How to arrange a good quality well with the contractor ?

If you do not have a desing for the well which is made and revised by a licences company for hydrogeological works, it would be better to follow these instructions:

1. Contract deal with licensed contractors only (proof for that is a decision of the Ministry of Industry, Energy and Mining or a record of a geological Inspector), which have reference to successfully performed works.

2. Make sure that users of the wells from the contracotr’s reference list are satisfied with the wells,

3. Never contract choosing the offer "per meter" of drilling, but ask from the contractor to propose a bill of quantity specifying the type and quantity of materials and the works which will be carried out, and then compare it with the instructions which are given below.

4. Check how much space the contractor needs for the organization of the site (access road for the transport of machinery to the location of the well, the area around the location of the wells), and request that the terrain is restored back to its original state after the completion of the works.

5. Insist on the application of drilling without the use of bentonite drilling mud because it reduces filtration characteristics of near-well area and its capacity (the amount of water you can get) of a future well.

6. The diameter of the well pipe should not be less than the diameter of the flange of the pipe to the pump, as well as the maximum diameter of the pump and its engine with a cable that you plan to install into the well, but it should be at least 5 cm larger, and sometimes even that is not enough depending on the calculations of water movement and the expected capacity of the well.

7. The diameter of the well pipe should be at least 5 cm (in wells with pipe diameter to 200 mm), 10 cm (in wells with pipe diameter over 200 mm) larger than the outer diameter of the well and filter pipe which is to be installed.

8. The relation between the aperture of the well filter to the total developed area of well filter pipe should be optimally over 20% in order to reduce the critical input speed, avoid high turbidity and blasting of the well, as well as to increase the optimal capacity of the well.

9. Pebbly backfill (optimal composition of quartz) of uniform grain size, size depending on the size of the grain formation (in sandy layers usually 1-4 mm and in gravel typically 4-8 mm) must be installed in the annular space of the well in the interval of well filter installation, i.e. the depth of the aquifer from porous rocks (gravel, sand or cracked, cavernous solid rock masses). In areas with prevailing coarse gravels with pebbles, granular backfill filter can be omitted providing that certain elaboration of appropriate materials is done. Also, in aquifers with cracked porosity type, omission of the backfill is usual, but only if cavernosity is not distinct, and the cracks are not filled with fine-grained fractions that may eventually lead to kolmiranja in the zone of backfill and near-well zone.

10. A buffer of clay material, bentonite or cement mass is built into the annular space of the well, from the surface of the terrain to the depth of maximum 0.5 m above the well filter in order to prevent penetration of polluted water from the surface.

11. Development (winning of the near-well zone) and rinsing of the well should be performed using an appropriate method, depending on the type of rock material of the aquifer (airflifting with sectional flushers, clipping or some other method). Rinsing solely by pumping a pump is not sufficient for the development of the well, because it a near-well zone cannot be cleaned of fine-grained material which reduces the capacity of the well and eventually leads to rapid deterioration or "aging" of the well, blasting, increased turbidity, reducing its capacity and duration. In the course of developing and rinsing of the well it is necessary to measure the turbidity of water by terrain turbinometer and the content of sand by Imhoff tank. Development and rinsing of the well is completed when the well water containst sand in the amount less than 0.5 ml/m3 of water and turbidity is below 1 NTU ° scale.

12. Test pumping of the well should be carried out in two phases. The first phase, the so-called step-test of short pumping of the well with three different capacities without interruption (from smaller to larger), then the long-term test pumping which is to be performed for a minimum duration of 36 hours for wells that draw water from gravel-sandy layer on the plain next to a river flow. If it is a well that draws water from solid rock masses with distinct fracture-cavernous porosity type, then the minimum length of pumping is 168 hours straight. Reducing the length of pumping leads to a risk of getting incorrect data on the capacity of the well, the choice of pump and inadequate regime of pumping during using of the well.

13. Sampling of water from the well is done by a qualified person at the end of the pumping test with a required sample conservation using an method (using chemicals), and measurement of unstable parameters on site is a must (pH, oxygen content, temperature, turbidity, sand content). Water sampling for microbiologic analysis is performed in sterilized bottles by an expert, following procedures required for this type of analysis.

14. Contractor is required to present you a report upon the completion with information about the performed work in textual form, showing the characteristics of the aquifer, lithologic and technical characteristics of the well in textual and graphical form with the results of measurement of the water level and the capacity at testing time and test pumping of the well, calculations of optimal capacity of the well and hydraulic parameters of the well and hydrogeological parameters of the aquifer, and the results of water quality analyses.

How to determine where and when to drill a well ?

You will have to determine the location of your well. As part of the work in making wells for companies and settlements, we do a free estimation of the terrain and will be glad to assist in determining the most appropriate location for your well. It is necessary to consider the available area, as well as geological and hydrogeological characteristics of the terrain. The location has to be accessible to equipment used for drilling wells. Drilling rigs with their equipment have an approximate working height of 8 to 12 m during performing of the well. “IPIN” Ltd. owns a drilling rig that has a low working height (4 m) for drilling wells. You have to take into account the power lines, trees and steep climbs and especially the possible danger of mines (the possible presence of minefields in former war zones). It is important to provide evidence of regulated property issues on the location of drilling, transport roads and work areas.

In any case, quantities of water cannot be guaranteed just by observing the surface. We use the experience of our research geologists and hydrogeologists, we use geological maps and data on the results of previously performed geological surveys of the wider area, as well as knowledge of the geological and hydrogeological structure of your area to help you determine the best location for your wells.

We are able to drill your well in all weather conditions if there is access to the site. The best time for drilling is before you start building your object (a building or factory). It is the best time to perform the well as this gets you your own water, which is essential at the time of construction. It also provides water for heating and cooling of the building using the heat in the ground (using heat pumps), for washing, cleaning and testing installations under pressure while building your building or factory.

How deep will be my well ?

The depth of the well will depend on the geological and hydrogeological structure of the area. Well water comes from underground aquifers. Aquifers are present in the underground at varying depths. The role of the aquifer is to accumulate groundwater in order to release them, that is, so that certain amount of groundwater can be drawn from them. These are mostly gravel and sand layers, fractured and cavernous limestones, fractured dolomite and other porous rocks. Because of these differences, the depth of the well is finally determined after the completion of the drilling, but in some terrains it may be assumed, without further research work.

Can you determine the amount of water (capacity wells) ?

Unfortunately, there is no way to determine in advance the amount of water (capacity) of the well or the water quality until the well has been performed. The quality of the well water cannot be determined before the pump has been installed in the well and some test pumpings have been carried out with the corresponding measurements on-site, sampling, sample preservation and laboratory analyses. However, in many cases, we can estimate the quality of water in advance thanks to great experience and known hydrogeological and hydrochemical conditions in your area. Sometimes, this may affect your decision to enter the process of drilling the well or quiting the field works. During the process of performing the well, we are able to provide you with bills of quantity and a quality development budget so that the maximum possible amount of water is provided from the aquifer. After completion of the well and performed laboratory analyses, we are able to inform you about the quality of the water from your well.

Can I repair or rehabilitate my old well?

If there has not been any serious damage of well casing (pipes and well filter), it is possible to revitalize the well. This can be checked by underwater recording and a proposal for the rehabilitation of the well can be made. If the diameter of the well pipe construction is bigger, a repair of the well with damaged filter frame is sometimes possible by installing a new pipe and filter construction of a smaller diameter along with the physical-chemical revitalization of the old pipe construction and near-well zone. Do not hesitate to contact specialized contractors for this type of work (IPIN Institute) and request an offer.

How much water do I need ?

Personal use and consumption, irrigation systems, fire safety, swimming pools and spas are some specific spending needs that you should consider when determining the necessary amount of water for regular water supply. Experience indicate that it is necessary to provide 380 liters per person a day. Our experts can help you in estimating the required amount of water.

How big or powerful pump do I need for my well ?

Each water system has dimensions which depend on several factors. For determining the dimensions of the pump it is important to consider the following: the depth of the well, well capacity which is determined according to the criteria of allowable deductions and critical input speed, static water level in the well (before turning on the pump), dimensions of the well pipe and a solution of a supply system with the position of the tank. If these parameters are known, it is possible to determine simension of the well pump for your water supply.

Why my well does not have enough water and why my pump often cuts out because of low level in the well ?

Inadequate - improper performance of the well can result in insufficient capacity or poor results of quality analysis due to:

a.) Inadequate drilling method,
b.) Bad characteristics of well pipe and / or filter construction,
c.) Inadequate method or short duration of development and rinsing of the well,
d.) Insufficient time for testing the well or non-applying the speed input criteria when determining the capacity of the well.

Do I need to install any equipment for conditioning of water (filtration, softening, disinfection) ?

The movement of water through pores in different rock masses dissolves minerals present in the formation which the water is in contact with. Water contains many mineral salts that are by origin from the formations through which it passes on its way to your well. Various filters and water softening systems are added for the separation of different particles and mineral salts from water. Regarding your question, after installing pumps with auxiliary equipment, testing and quality analysis, we will be glad to recommend some of the necessary equipment for disinfection, filtration or water softening, if this is required in your terrain.

Why is the water from my well blurry, or polluted ?

Contamination of well water (or bad results of water quality analysis) usually means the following:

- It is necessary to clean and revitalize the well (if it has worsened compared to the previous period),
- Inadequate location of the well,
- Mutual connection of the underground flow with the location of pollutants,
- The lack of cementation of the opening column,
- Inadequate sampling of water for water quality analyses.

Why water from my well has a lot of sand ?

A common cause of sand in well water of drilled wells is excessive use of a stronger pump than the optimal capacity of the well, negative pump working mode (insufficient reservoir area on water supply and frequent switching the pump on and off) or poor and inadequate installation of filter construction (filters of small porosity) and also poor development and rinsing after casing of the well, "decay" of well filter, determining the optimal capacity of the well without the use of "criteria of critical input speed," etc. Maybe you can recognise some of these causes and solve the problem. In any case, this is a reason to call hydrogeologists.

How do I perform cleaning or revitalization of wells?

The application of chemical agents, the possibility of damage to well’s structure, necessary special equipment for underwater recording, airlifting, measurement, preparation and dosing of chemicals and control analyses all require specialized contractors. Cleaning and rehabilitation (rehabilitation or recovery) of wells is performed by specialized companies which are licensed for work in the field of geology and hydrogeology. One of them is "IPIN" Institute for Applied Geology and Hydroengineering from Bijeljina, so do not hesitate to contact us if you are thinking about revitalizing an industrial well or water system well for settlements and cities.

Should I ask for a water quality analysis to be done ?

Testing the water quality should be done if you are not satisfied with the response to some of the following questions:

- What does it taste like? (maybe salty, lužinast, like metal, bitter, etc.)
- Are there any problems with the smell of water? (musty smell, the smell of an egg, the smell of oil, methane, chemicals, etc.)
- Are there any visual problems with the water? (is there any sludge or mud, are there any stains, is there a milky appearance, greenish, black or yellowish colour, etc.)
- Is the well in the vicinity of any pollutants? (a landfill waste, a storage of chemicals or discharge of chemicals, sewage, industrial landfill, sludge, agricultural facilities, etc.)

The EPA (United States Enviromental Protection Agency) recommends testing home water wells at least once a year.

Hydrogeologists interpret the condition of wells, the condition of the aquifer that is drained by the well, the need for revitalisation and cleaning of the well, as well as some other causes that may lead to deterioration in the quality of well water, so do not hesitate to ask them if you have any questions.

Which analyses of the well water can I perform ?

Depending on how much money you want to spend on the analysis, you will determine the level of physical-chemical analysis of water. Physical-chemical analysis of a sample of water can cost anything from € 50 to more than € 1,000.00 and these analyses are mostly performed for new sources of urban water supply facilities. Apart from these detailed complete analyses, there are basic physical-chemical analysis of water, as well as expanded or periodic physical-chemical analyses. "IPIN" Ltd. performs physical-chemical analyses of groundwater in its own laboratory and we can determine 44 parameters of quality on site.

For the purposes of microbiological examination of water samples, the so called bacteriological analyses in authorized institutes and the Institute of Public Health (http://www.phi.rs.ba/) are being performed. These analyzes are significantly cheaper than physical-chemical analyses of water.

What determines the total price of my well ?

The price depends on many factors, so never contract the drilling by only considering the lowest price "per meter of drilling". This option will get you a deeper "hole" for less money, and it will not get you a good well, because the contractor will try to save some materials and works that follow the drilling, which is financially even more than double, compared to the cost of drilling.
The well depth, the type and kind of casing, the kind of well filters, distance from the well to the point of water draining, the availability of electric energy on the site, the method and duration of flushing, development and testing the wells by test pumping, the analyses types and the level of processing of final report will significantly determine the aggregate unit price that varies from BAM 20 to BAM 15,000 per meter of a completed well.

How do I choose a company that drills wells ?

You need to consider many factors. When selecting a contractor for drilling the wells, never make a decision based only on the lowest price. Make sure that the contractor of the well (company) holds a license, that is, whether it meets the requirements of the Law on geological research and whether the company is safe to perform the planned works properly. You should check the reputation and experience of the contractor. You can do this by checking the contractor's reference list and how satisfied the customers are with some of the performed wells. Also, you should check the guarantees that the contractor gives. You should also check whether the employees in the company that performs the well have appropriate education or training (engineers, geologists and drillers).

What are the requirements on the entity level (Republic of Srpska) before performing the well and what are the requirements before using the well ?

1. Prior to the commencement of performing the home wells for one's own usage, mandatory provision of water management agreement is not prescribed and nor is the approval for the concession by the relevant ministry.

2. For wells that are used for water supply of facilities of companies and settlements, systems for agricultural irrigation of legal entities, mine drainage, exploitation of slightly mineralized, mineral and thermal waters (spas, aqua parks, swimming pools), for bottling, extraction of gas and mineral resources, it is necessary to provide the following (can be ordered from "IPIN" Ltd.):

a) Before the commencement of work on performing the well
- Project of detailed hydrogeological research done by a company or institution that meets the requirements of the Law on geological research, which is audited by a company or institution that meets the requirements of the Law on geological research,
- Pre-study of economic justification for the exploration and exploitation of groundwater.

One has to submit a request for concession to research along with the mentioned documentation attached and three copies of graphic drawings of the concession field boundaries with a table display of elevation and coordinates of the concession field's fracture points. This request has to be submitted to the competent Ministry of Industry, Energy and Mining of the Republic of Srpska (for the wells which are on the territory of the RS). After declaring public interest for the subject concession, a concession agreement is made.

b) Once the well is completed, after the completion of field works it is necessary that a company that meets the requirements of the Law on geological research does a report on the performed well, which would give detailed information on the lithologic structure of the terrain, constructional characteristics of the well along with the results of measuring the capacity and water level during the test pumping and calculation of optimal capacity, and the results of physical-chemical analyses and microbiological examination of water.

c) For exploitation of wells used for water supply of facilities of companies and settlements, systems for agricultural irrigation of legal entities, mine drainage, exploitation of slightly mineralized, mineral and thermal waters (spas, aqua parks, swimming pools), for bottling, extraction of gas and mineral resources, it is necessary to submit a request for a concession to exploit groundwater. In the request attachment, one has to submit the following:

- elaborate on reserves,
- Study on economic justification for exploitation of groundwater.

After declaring public interest for the concession, a concession agreement is made unless it has been concluded before the stage of geological exploration works.