Well Development Techniques Part (4)

Well Development Techniques Part (4)

Well Jetting

Development by high velocity jetting may be done with either water or air. A jetting tool is attached to the lower end of the drill string and lowered to the bottom of the well screen. Rotation is controlled by the rotary rig. The jetting tool activated by either air or water forces high-pressure fluid out the nozzles of the tool very effectively, developing the formation. Because of the high pressures used damages to the well screens may result through improper use of jetting tools. However, jetting is seen as possibly the most highly effective development technique in terms of well yield after completion. The essential point to be made is that yield depends to a great extent on the development method used. Particles loosened by jetting tools may be later removed by pumping or bailing.

Well Development Techniques Part (3)

Well Development Techniques Part (3)

Air Development (air surging and pumping)

Several techniques for the air development of wells exist. However, all inject air into the borehole such that aerated slugs of water are lifted irregularly out the top of the well casing. Air pressure may be cycled on and off to create a surging action desirable in well development. Sufficient air pressure will result in a continuous flow of aerated water out the top of the well, removing sediment and fine particles from the borehole.

For small wells, air may be injected down the drill stem into the formation. For larger diameter wells a separate airline and eductor pipe are inserted into the borehole. The size of the eductor pipe and airline depend on air pressures and volume available as well as the casing diameter. Numerous sources caution drillers that under some conditions the use of air development approach can create aquifer air locks, in such cases a development with water is a wiser choice. Even so air as a development is probably the most popular and widely used method of well development today.

The type of discharge produced from a well during air development depends on the air volume available, total lift, submergence, and annular area. In practice, two different flow conditions can be recognized when air is used when air is used for water well development although other flow regimes may exist at much lower or higher velocities in smaller diameter pipes. The picture above provides an illustration of how multiphase flow (water and air) occurs in the casing during air development. The percent submergence, total lift, and capacity of the compressor will control the relative proportion of air and water for a particular well.

A. Introduction of a small volume or air under high head causes little change in the water level in the well. In this case, the air pressure available is just sufficient to overcome the head exerted by the water column.

B. As air volume increases, the column becomes partly aerated. Displacement of the water by the air causes the water column to rise in the casing. Drawdown does not change because no pumping is occurring.

C. Further increases in air volume cause aerated slugs of water to be lifted irregularly out the top of the casing. Between surges, the water level in the casing falls to the near the static level.

D. If enough air is available, the aerated water will continually flow out the top of the well. With average submergence and total lift, the volume of air versus water is about 10 to 1. Higher air volumes may increase the pumping rate somewhat, but still higher rates may actually reduce the flow rate because flow into the well is impeded by the excessive air volume.

Well Development Techniques Part (2)

Well Development Techniques Part (2)

Washing and Backwashing

Drillers working in different regions have, through experience, come to rely on those well development techniques producing the best results in their areas. However, new techniques should always be considered and tried with the goal of obtaining the cleanest well with the best possible yield.

Overpumping is the simplest method of removing fine particles from formations. The theory is that if a sand free yield can be achieved by overpumping then a sand free flow will be the result when pumping at the normally expected lower rate. However, overpumping by itself is not considered the best well development approach. Overpumping is considered a limited approach to well development because water flows in a single direction only.

Backwashing reverses water flow and helps in the dilution, agitation and removal of sediment, fine particles and drilling fluids. Backwashing requires the introduction of water back into the well. If water taken from the well is to be reintroduced for backwashing, care must be taken to allow the settling out of particles from the removed water before reintroduction. Even so backwashing should not be the final step in the well development process; rather it may be an effective beginning or intermediate step. Washing and backwashing reverses the flow in the borehole during development. This reversal causes the collapsing of bridges in the particles of the near well area. This is desirable because collapsing these bridges further removes fines from the near well creating a cleaner flowing well.

Mechanical Surging

The forcing of water into or out of a well screen by use of a plunger type action is called surging. Surging tools can be used by both cable drillers and rotary drillers and can be used in combination with other development methods. Surging promotes a repeated change of direction in the flow of water in the well screen area. This repeated change of direction can produce good porosity in the near-well zone.

Mechanical surging is the first of two methods of well development that removes particles and clogging materials by the force of water impinging on them. A development method such as mechanical surging is a vigorous development method not suited to all aquifer types. However, mechanical surging has less potential for aquifer damage if a continuous flow of water into the well from the aquifer is maintained. Mechanical plungers may be fitted with one-way valves allowing them to lift water and fine sand out of the hole. Solid plungers do exist but have more potential to damage the aquifer. The results of mechanical surging should be measured by checking the well yield periodically, every hour after the process begins. Surge plunger should be a good fit in the casing. The plunger may be attached directly to the drill stem or operated by hand depending on well depth

Mechanical surging does have potential to damage the aquifer and should be done with aquifer. The force exerted during mechanical surging depends on the length of the stroke and the vertical velocity of the surge block. Swabbing is another variation of surging. Swabbing does not depend on reversing flow into the well. Rather the swab is slowly lowered to the desired depth and then drawn upward. Swabbing creates a pressure differential below and above the swab during the up stroke. This differential creates a powerful action which draws fines from the near well area into the bore hole for removal.

Well Development Techniques Part (1)

Well Development Techniques Part (1)

Well development is the process of cleaning out the clay and silt introduced during the drilling process as well as the finer part of the aquifer directly around the well screen prior to putting the well into service:-

1. Increase the rate of water flow from the aquifer into the well.
2. Stabilize the aquifer to prevent sand pumping to produce better quality water
3. Increase service life of the water pump
4. Remove organic and inorganic materials.

Types of well development techniques:

1. Chemical
2. Washing and Backwashing
3. Mechanical Surging
4. Air Development
5. Jetting

Chemical

Chemical agents are introduced into the development zone as solvents. Their action is intended to dissolve or loosen any clogging or blocking materials to make them easier to remove. The action of chemicals may also enlarge aquifer pores and improve permeability. Chemical based well development techniques can be gentle or violent in their action.

All chemical agents introduced into potable wells should be approved for such use by local authorities. Chemical methods are often used in conjunction with other well development techniques. This is particularly true when additional action is needed to break up mud cakes or flush out gelled muds. The chemical solution is allowed to stand in contact with the aquifer for the recommended soak period. After the soak period the solution is pumped or bailed from the hole. While well drilling fluids will break down naturally, the breakdown process may be enhanced by the use of chemical agents. Once degraded, the drilling fluids are much more easily pumped from the aquifer. Other chemicals may be used to break down clay smears and gelled bentonite. Chlorine breaks down polymers.

A tremie pipe can be used in conjunction with packing devices to isolate the areas of the borehole to be subjected to chemical treatment. Chemical treatment can be used to break down drilling fluids, clays and polymers. Acids are often used for improving the yield in limestone, dolomite and other calcium carbonate formations

Controlling and Managing Saltwater Intrusion

Controlling and Managing Saltwater Intrusion

One key to controlling saltwater intrusion is to maintain the proper balance between water being pumped from an aquifer and the amount of water recharging it.  Constant monitoring of the salt-water interface is necessary in determining the proper management technique.  In the past, many communities who came across a saltwater intrusion problem simply set up new production wells further inland.  This only complicated the issue.

Since then, various methods have been employed to help alleviate the concerns of saltwater intrusion.  Efforts towards the promotion of water conservation, and restricting withdrawals from coastal aquifers have been the focus in many areas.  Using alternative freshwater sources has also been encouraged.  Ocean water desalination plants are showing up in coastal regions around the world.

Where there are no other options for fresh water, efforts to maintain groundwater levels by ponding surface water and stormwater runoff, or using river water to recharge the groundwater table have been successfully implemented.  Aquifer Storage and Recovery (ASR) systems can help restore aquifers that have experienced long-term declines in water levels due to over-pumping.

Deep recharge well creates groundwater ridge.

Other methods to control saltwater intrusion, such as using deep recharge wells, have also been successful.   These wells create a high potentiometric surface, which allows for the pumping of groundwater below sea level landward of a groundwater ridge created. In some instances, barrier wells have been set up near the shore to pump out salt water and recharge a fresh water gradient toward the sea.

In all of these cases, hydrologic studies and water quality monitoring are essential to help better understand the movement and interaction of fresh water and salt water in the subsurface, and determine the best method to manage saltwater intrusion.  Potentiometric surface mapping of an aquifer can provide important information determining the direction of groundwater flow within a confined aquifer.  Plotting water level elevations on a map and contouring the results determines this.  The contoured surface is known as the potentiometric surface, which is actually a map of the hydraulic head in the aquifer.

Monitoring well networks allow continuous observation of the saltwater interface, after management strategies have been put in place.  This provides early warnings of saltwater intrusion and tracks the effectiveness of the strategy.  Overall, proper groundwater monitoring techniques and groundwater management, combined with groundwater conservation are needed to keep saltwater intrusion under control, and ensure fresh water supplies are sustained for future generations.

Methods and Instrumentation used for Investigation of Saltwater Intrusion

Methods and Instrumentation used for Investigation of Saltwater Intrusion

Late in the 1960's, efforts rose toward drilling for chemical analysis of groundwater samples and the determination of flow patterns based on piezometric levels.  Geophysical methods of investigation were introduced later, and were found to provide more information faster than the drilling techniques.  Subsequently, geophysical methods became more important for saltwater intrusion monitoring.

Today, there are numerous methods available including: well logging, chemical analysis of groundwater samples, research into the interaction between aquifer matrix and groundwater, and most common, chloride concentration profiling, and vertical conductivity and temperature profiling.   

Conductivity and Temperature used to Estimate Salinity

An aqueous solution's ability to carry an electrical current by means of ionic motion is measured through conductivity.  Salinity is the measured mass of dissolved salts (ions) in a solution. As such, conductivity readings provide a good indication of salinity.  In general, as salinity increases, the total dissolved solids (TDS) of a solution increases, and so too does conductivity.

As defined by the USGS, salt water has a total dissolved concentration of 35,000 mg/L, of which, 19,000 mg/L is chloride (Barlow, 2003).  Being the major constitute of salt water, chloride concentration profiling is a very common method for saltwater intrusion investigations.  As the concentration of chloride increases in salt water, so does conductivity.   As such, conductivity is a very good indicator of chloride content and salinity.

Conductivity is interdependent with temperature; therefore profiling both of these variables becomes an important factor when determining the behavior of the transition zone and the salt-water interface. 

Through using devices such as the Solinst Model 107 TLC Meter(Temperature, Level, Conductivity), salinity can be estimated through conductivity and temperature readings, both taken at a discrete depth.  The TLC Meter features a 'smart' probe that provides accurate temperature and conductivity measurements, and is attached to high quality flat tape for depth readings.  The probe and tape are mounted on a sturdy reel making operation easy.  Instruments such as this make vertical temperature and conductivity profiling simple.

For example, using standard methods, a conductivity reading of 25,000 µS/cm and a temperature reading of 20˚C yield a salinity estimation of 17ppt (APHA et al, 2005).  Through this method of investigation, borehole profiles of salinity can be used to track the fluctuation of the salt-water interface.  This, in turn increases the potential to control saltwater intrusion problems.

For continuous monitoring of the salt-water interface, an instrument such as the LTC Levelogger Edge allows accurate datalogging of conductivity along with temperature and water levels as often as every 5 seconds.  The LTC Levelogger Edge is ideal for long-term saltwater intrusion monitoring applications due to its compact, low maintenance, waterproof design.

The LTC Levelogger Edge combines a datalogger, 5-year battery, memory for 16,000 sets of readings, pressure transducer, and temperature and conductivity sensors in a small 22 mm x 190 mm housing.  It is simple to deploy, calibrate, and program.

To easily create a network of monitoring wells, the LTC Levelogger Edge can be integrated into a Solinst STS Gold Telemetry System, which allows convenient access to remote, real-time data.  The STS system also sets alarms to trigger when a specific conductivity level is reached, notifying personnel of potential saltwater intrusion conditions.  The LTC Levelogger Edge is also SDI-12 compatible and can be integrated into an SDI-12 or SCADA network.

By using an instrument like the LTC Levelogger Edge, the salt-water interface can be tracked over time, and provide real-time warnings when intrusion conditions occur or worsen.

Saltwater Intrusion Basics

Saltwater Intrusion Basics

Groundwater Monitoring, Management and Conservation Keep

Saltwater Intrusion Under Control

Almost two thirds of the world's population lives within 400 km of the ocean shoreline; just over half live within 200 km, an area only taking up 10% of the earth's surface (Hinrichsen, 2007).  Most of these coastal regions rely on groundwater as their main source of fresh water for domestic, industrial and agricultural purposes.  As the world's population continues to grow at an alarming rate, fresh water supplies are constantly being depleted, bringing with it issues such as saltwater intrusion and increasing the importance of groundwater monitoring, management, and conservation.

Freshwater-Saltwater Interactions

Saltwater intrusion is a major concern commonly found in coastal aquifers around the world.  Saltwater intrusion is the induced flow of seawater into freshwater aquifers primarily caused by groundwater development near the coast.  Where groundwater is being pumped from aquifers that are in hydraulic connection with the sea, induced gradients may cause the migration of salt water from the sea toward a well, making the freshwater well unusable.

Because fresh water is less dense than salt water it floats on top.  The boundary between salt water and fresh water is not distinct; the zone of dispersion, transition zone, or salt-water interface is brackish with salt water and fresh water mixing.

Under normal conditions fresh water flows from inland aquifers and recharge areas to coastal discharge areas to the sea.  In general, groundwater flows from areas with higher groundwater levels (hydraulic head) to areas with lower groundwater levels.  This natural movement of fresh water towards the sea prevents salt water from entering freshwater coastal aquifers (Barlow, 2003).

Groundwater pumping/development can decrease the amount of fresh water flowing towards the coastal discharge areas, allowing salt water to be drawn into the fresh water zones of coastal aquifers.  Therefore, the amount of fresh water stored in the aquifers is decreased (Barlow, 2003).

The Ghyben-Herzberg Relation assumes, under hydrostatic conditions, the weight of a unit column of freshwater extending from the water table to the salt-water interface is balanced by a unit column of salt water extending from sea level to that same point on the interface.  Also, for every unit of groundwater above sea level there are 40 units of fresh water below sea level.

X  Groundwater Level        Y  Sea Water Level

Salt-water interface in an unconfined coastal aquifer according to the Ghyben-Herzberg relation.

This analysis assumes hydrostatic conditions in a homogeneous, unconfined coastal aquifer.  According to this relation, if the water table in an unconfined coastal aquifer is lowered by 1 m, the salt-water interface will rise 40 m.

Generally, saltwater intrusion into coastal aquifers is caused by two mechanisms:

· Lateral encroachment from the ocean due to excessive water withdrawals from coastal aquifers, or

· Upward movement from deeper saline zones due to upconing near coastal discharge/pumping wells.

Saltwater intrusion into freshwater aquifers is also influenced by factors such as tidal fluctuations, long-term climate and sea level changes, fractures in coastal rock formations and seasonal changes in evaporation and recharge rates.  Recharge rates can also be lowered in areas with increased urbanization and thus impervious surfaces.  Intrusion has also occurred in areas because of water levels being lowered by the construction of drainage canals .

Most incidents of saltwater intrusion occur in coastal regions, as has been the focus of discussion thus far, but inland areas can also be affected.  Salinity issues in some regions surrounding the Rio Grande in New Mexico and Texas have been attributed to upwelling of deep-circulating groundwater, which is more saline due to natural underlying geologic formations (Doremus, 2008).  The more saline groundwater is brought to the surface through pumping for irrigation and other uses.  Similar occurrences have been noted in the Mississippi River Valley Alluvial Aquifer in Arkansas, where in response to pumping, there is also upward movement of saline water from deeper formations

Intrusion Occurrence

Incidents of saltwater intrusion have been detected as early as 1845 on Long Island, New York.  Intrusion occurs in coastal aquifers worldwide, and is a growing issue in areas including North Africa, the Middle East, the Mediterranean, China, Mexico, and most notably, the Atlantic and Gulf Coasts of the United States, and Southern California. The increased use of groundwater has caused the salt-water interface to move inland and closer to the ground surface along much of the U.S. Atlantic Coast, as well as Southern California.

How Sinkholes Develop?... With Chemical Equation

How Sinkholes Develop?... With Chemical Equation

•Naturally occurring sinkholes are most commonly found in a type of terrain known as karst topography, which consists of bedrock (rock beneath the soil) filled with nooks and crannies. The underlying bedrock in karst landscapes is usually made of limestone. A great portion of the state of Florida is, in essence, sitting atop one continuous slab of limestone, making it vulnerable to sinkholes. Limestone is composed of calcium carbonate (CaCO3), which primarily comes from the remnants of corals and other types of marine organisms, whose shells are made of calcium carbonate.

•Sinkholes often form when acidic groundwater or acid rain dissolves limestone, a porous 9-rock present in the soil, creating voids and cavities. The soil resting on top of the limestone then sinks or collapses, causing a sinkhole.

•Limestone builds up slowly after these animals die and their shells are deposited and accumulate over time. Other substances composed of calcium carbonate include marble, chalk, Tums antacid tablets, and eggshells. To understand how limestone bedrock contributes to sinkholes, consider what happens when you place an egg in a glass of vinegar, which contains 5% acetic acid (CH3COOH). You will notice that little bubbles of carbon dioxide gas form almost immediately and, within a day or two, the eggshell will have completely disappeared, leaving you with the egg’s translucent membrane to protect the egg. The eggshell, which is composed of calcium carbonate, does not normally dissolve in water, but in the presence of acetic acid, calcium carbonate and acetic acid react with each other, causing the eggshell to dissolve according to the following chemical reaction:

•2 CH3COOH (aq) + CaCO3 (s) Acetic acid + Calcium carbonate
•➞ [Ca2+ (aq) + 2CH3COO– (aq)] + H2O (l)
•➞ Calcium acetate + Water + CO2 (g) + Carbon dioxide

•Any substance made of calcium carbonate will react with an acid. Limestone, being made of calcium carbonate, will react with an acid and will be slowly worn away. But are there acids underground?

•To answer this question, consider what happens to rainfall (which eventually 9-becomes groundwater) as it passes through the atmosphere. While falling through the air, the rain comes into contact with carbon dioxide. Although carbon dioxide comprises only about 0.04% of the atmosphere, that is enough to make rainfall acidic, lowering its Ph to about 5.6. So, by the time rainfall reaches the ground, it has turned into acid. The reaction is as follows:

•H2O (l) + CO2 (g) ➞ H2CO3 (aq)
•Water + Carbon dioxide ➞ Carbonic acid
•Carbonic acid then dissociates to give a hydrogen ion (H+) and a bicarbonate ion (HCO3 –):

•H2CO3 (aq) ➞ H+ (aq) + HCO3 – (aq)

•The ability of carbonic acid to dissociate by producing hydrogen ions is what makes this molecule an acid. Over time, acidic rainwater seeps into the ground and comes into contact with limestone bedrock. Water makes its way into cracks or pockets in the rock, reacting with the limestone and eventually making holes and fissures in the rock. Sinkholes occur when acidic rainwater has eaten away so much of the underlying limestone bedrock beneath the soil that the ground collapses.

•The more it rains, the greater the amount of carbonic acid leaching into the soil below.

•Humid areas have the most rainfall. High humidity in the air leads to cloud formation, which eventually produces rainfall. So it is no surprise that Florida leads the United States in the number of sinkholes because it has both limestone bedrock and high humidity.


•The acidity of rainwater is not the only reason water in the ground is acidic. Decaying organic materials and root respiration also produce carbon dioxide, which dissolves in soil water to form carbonic acid.

Land subsidence

Land subsidence

Land subsidence is a gradual settling or sudden sinking of the Earth's surface owing to subsurface movement of earth materials.

Causes of  Subsidence 

Subsidence is caused by a diverse set of human activities and natural processes, including :-
1.mining of coal , metallic ores,
2.Limestone , salt, and sulfur; withdrawal of groundwater, petroleum, and geothermal fluids;
3.dewatering of organic soils;
4.pumping of groundwater from limestone;
5.wetting of dry, low-density deposits, which is known as hydro compaction; natural sediment compaction;
6.melting of permafrost; liquefaction; and crustal deformation

Catastrophic Subsidence as Result For Water Level Decline (Sinkholes).

•Water is stored in underlying carbonate rocks and moves through interconnected openings along bedding planes, joints, fractures, and faults, some of which are enlarged by solutioning.
•Recharge from precipitation, in response to gravity, moves downward into this system of openings or toward the stream channel, where it discharges and becomes streamflow

•Sinkholes can be separated into categories described as“induced” and “natural.” Induced sinkholes are those caused or accelerated by human activities, whereas natural ones occur in nature. Sinkholes resulting from water level declines

Induced sinkholes

•Induced sinkholes (catastrophic subsidence) are those caused, or accelerated, by human water development/management activities
•activities. These sinkholes commonly result from a water level decline due to pumpage.
•Are most predictable in a youthful karst area impacted by groundwater withdrawals.

Triggering mechanisms resulting from water level declines

(1)loss of buoyant support of the water
(2)increased gradient and water velocity
(3)water-level fluctuations

Effects of Groundwater Contamination

Effects of Groundwater Contamination

Understanding the common sources of groundwater pollution is always a good first step, but from there, you should realize what the effects on your health and the world around you can potentially be when this type of contamination is present. Now that you can recognize what are possible sources of groundwater contamination, read on to find out more about what this means for you and your community.

1-Health

Health effects are some of the greatest risks associated with groundwater pollution. Here are just a few you should be concerned with.

Hepatitis. In areas where septic systems have not been installed or kept up correctly, groundwater may become infected with hepatitis due to human waste present in the water supply. Hepatitis is a very serious condition that causes irreversible damage to the liver.

Dysentery. Much like hepatitis, dysentery can be caused by drinking water where waste is present—either human or animal in nature. Once again, when septic systems don’t operate correctly, the chance for dysentery is much higher, much like with hepatitis. Dysentery causes infection throughout the intestine and digestive system, and can also cause diarrhea so severe it can lead to dehydration and even death when not treated properly.

Poisoning. When wells are not dug or placed correctly, poisons from both nature and from human use of pesticides and solvents can leach into the well water and poison the water supply. When humans then drink this water, they can become very ill very fast from exposure to chemicals and other pollutants that are unsafe for ingestion. This can also make animals sick as well, including animals that might be watered from a well on a farm.

2-Economy

When groundwater becomes contaminated, the economy can also easily suffer. Check out this list of potential economic problems associated with groundwater pollution.

Depreciating value of land. When groundwater becomes more contaminated in a given area, that area becomes less capable of sustaining human, animal, and plant life. If the area is known for its natural beauty and that nature begins to suffer the effects of pollution, the chances of people wanting to live there decrease even more. Although it might not be an immediate result of groundwater pollution, the depreciation of land value is definitely a potential side effect.

Less stable industry. Many industries rely on groundwater to help produce their products and keep their factories running smoothly. Since the pH and quality of groundwater from a given area rarely changes, it becomes a vital part of many industries that rely on water they don’t have to constantly test. However, when groundwater becomes polluted, this convenience is stripped away, and the industries are less capable of stable production. This, in turn, can affect the economy in any given area as industries are forced to move.

3-Environment

Last but certainly not least, the environment can be seriously altered when groundwater is polluted. Here are just some of the ways in which this occurs.

Nutrient pollution. Groundwater pollution can cause certain types of nutrients that are necessary in small amounts to become far too abundant to sustain normal life in a given ecosystem. Fish might start dying off quickly because they are no longer able to process the water in their water supplies, and other animals might become sick from too much of certain types of nutrients in the water they drink. Plants might not be able to absorb water as easily, and the entire ecosystem will suffer

Toxic water in ecosystems. When groundwater that supplies lakes, rivers, streams, ponds, and swamps becomes contaminated, this slowly leads to more and more contamination of the surface water as well. When this happens, fish, birds, animals and plants that live in the area become sick and die off quickly. This is a huge factor in the destruction of the wetlands, which rely heavily on groundwater to recharge their lakes and ponds after drought periods. In turn, people who use this land for hunting, fishing, and even for their own sources of clean water are affected by this type of pollution.

Sources of Groundwater Contamination

Sources of Groundwater Contamination

It’s always a good idea to be able to recognize what causes groundwater pollution so you can help step up and make a difference when you see it in your area. When it comes to this type of pollution, every source can be grouped into one of four categories: direct, indirect, manmade, and natural. Although natural sources of pollution often can’t be changed much, there is always something you can do about other sources.

1-Direct

When learning about what causes groundwater contamination, you should first start with direct contaminants, as these are the ones you’re more likely to come into contact with.

Hazardous waste. When hazardous waste is disposed of or dumped incorrectly, the chances of it spilling and leaching into soil and water are great. It’s very likely for this type of spill to occur and go completely unnoticed. Unfortunately, this is also true of more widely recognized hazardous waste spills, but there’s very little that can be done about it. Once a spill occurs, it can almost never be removed from groundwater.

Landfills. Landfills are another direct cause of pollution in groundwater. The longer a landfill remains full of waste, the more the toxins from that waste seep into the soil below and around the landfill. This leads to groundwater contamination almost immediately. When landfills are very large, the amount of groundwater polluted by them is significant.

2-Indirect

But what are some sources of groundwater pollution that are less direct?

Atmospheric pollutants. Sometimes, when surface water in the area becomes polluted, this can lead to those pollutants evaporating into atmospheric air and water. In turn, polluted air can drift into areas where humans are more present, and polluted rain can fall as acid rain. This damages the environment and can also cause serious health risks for people in the area, too.

Petroleum fuels. Diesel and gasoline are well-known indirect causes of groundwater pollution. In some instances, these fuels, when kept in underground storage, can leak significantly and seep into the ground around them, leading to groundwater contamination. Most of the time, however, the use of these fuels pollutes the atmosphere and leads to indirect atmospheric pollution of groundwater through the rain.

3-Man-made

It’s no secret that human beings are a huge polluter of groundwater. These are just some of the manmade ways groundwater gets contaminated.

Septic systems. In much of the United States, city-based water and sewage are unavailable, especially in very rural areas. When this is true, septic systems are usually the go-to solution to provide running water and plumbing to people in these regions. Septic systems are very common in the U.S., and in most cases, they aren’t supposed to cause any groundwater contamination at all. Unfortunately, sometimes they are installed incorrectly or become damaged over time without regular maintenance. This causes human waste to leach into the surrounding soil, which in turn causes a lot of pollution very fast.

Chemicals. Road salts, solvents, and chemicals used on roads, in lawns, and around the home are some of the leading manmade causes of groundwater pollution. When these products are used on land surfaces or homes, they are easily washed away by natural rainfall. From there, since there’s nowhere else for them to go, they seep into the soil and reach the groundwater quickly. When humans and animals then drink this water, they are ingesting these chemicals, which can cause major health problems very fast. Also, when groundwater that has been affected by these chemicals is then used in agriculture or industry, it is unable to provide the proper nutrients and hydration required to get the job done.

Pesticide. Much like chemicals and other man-made solutions, pesticide is prone to washing into the soil after heavy rainfalls, especially when it is used frequently by farmers and other members of the agricultural industry. The chemicals involved in pesticides are very dangerous for both human and animal consumption, and when they reach groundwater, they can almost never be completely removed.

4-Natural

Learning about groundwater contamination involves finding out more about natural contaminants like animal waste, which is not a major source of groundwater pollution.

Animal waste. Although animal waste is usually more of a problem for surface water contamination and often stays out of groundwater, this isn’t always the case. In some situations, especially where animal life is very prevalent, urine and feces left behind by animals seep into the ground and cause some pollution to the groundwater there. When this happens, the type of pollution caused by these contaminants is usually easy to remove by water treatment facilities. However, it does make groundwater unsafe to drink without treatment.

Arsenic. Sometimes, arsenic is naturally present in rocks. When groundwater passes through or sits in these rocks for too long, it can cause arsenic to build up in the groundwater to levels that are capable of poisining animals or people who drink it. This is rare, but it does occur, especially in areas where mining has been present and might have exposed these types of rocks. Again, regular water treatment can usually remove arsenic from groundwater.

Radon. Radon gas is also another natural pollutant that can nevertheless cause serious problems. If a human being or an animal consumes water that has been polluted with radon gas, the results can be potentially fatal. Like the other types of natural pollution in groundwater, radon gas can sometimes be removed by treatment. However, it’s very important not to drink water that could have potentially been polluted with radon until it has been thoroughly tested by professionals.