COLIFORM “PRESENT” - How to Fix it - Coliform bacteria do not occur naturally in most aquifers. Fractured or creviced bedrock aquifers that are close to the surface are the exception. Be aware that there are three different groups of coliform bacteria; total coliform, fecal coliform and Escherichia coli (E. coli) each has a different level of risk. Keep in mind that coliform bacteria do not always show up in every sample. They can be sporadic and sometimes seasonal when they occur in a water supply. If your water is contaminated with coliform but not fecal coliform or E. coli, don't panic. You have a nuisance bacteria problem and the source may be infiltration from the surface from rain or snow melt. Typical causes are improperly sealed well cap, well repairs performed without disinfecting the well, failed grouting or surface drainage to the well. If your well had coliform bacteria present you should shock chlorinate the well, repack the soil around the well pipe to flow away from the well and replace the well cap. Then after at least two weeks and the next big rainstorm retest the well for coliform. If coliform bacteria is still present then a long-term treatment should be implemented: using UV light, ozonation, or chlorine for continuous disinfection. Coliform bacteria are commonly found in soil, on vegetation, and in surface water. Some coliform bacteria strains can survive in soil and water for long periods of time. Coliform bacteria will not likely cause illness.

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Coliform “PRESENT”

How to Fix it

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Coliform bacteria do not occur naturally in most aquifers. Fractured or creviced bedrock aquifers that are close to the surface are the exception. Be aware that there are three different groups of coliform bacteria; total coliform, fecal coliform and Escherichia coli (E. coli) each has a different level of risk. Keep in mind that coliform bacteria do not always show up in every sample. They can be sporadic and sometimes seasonal when they occur in a water supply.

Elizabeth Ward

 

This spring in the well water clinic we run each year we found 25 wells out of 114 that had coliform "PRESENT."

On a state level, the occurrence of coliform is higher.

Of the approximately 7,000 households that participated in the Virginia Household Water Quality Program clinics from 2007 to 2015 they found that 41% of the wells had coliform bacteria, and 9% had E. coli bacteria.

Though the 7,000 households may not be representative of all private drinking water wells in Virginia, it is the largest database on private drinking water wells available.

It is safe to say that coliform contamination is widespread. 

If your water is contaminated with coliform but not fecal coliform or E. coli, don't panic.

You have a nuisance bacteria problem and the source may be infiltration from the surface from rain or snow melt.

Typical causes are improperly sealed well cap, well repairs performed without disinfecting the well, failed grouting or surface drainage to the well.

If your well had coliform bacteria present you should shock chlorinate the well, repack the soil around the well pipe to flow away from the well and replace the well cap.

Then after at least two weeks and the next big rainstorm retest the well for coliform.

If coliform bacteria is still present then a long-term treatment should be implemented: using UV light, ozonation, or chlorine for continuous disinfection.

These systems can cost up to $2,000 installed.

If your well test PRESENT for coliform standard protocol is:

1.    Carefully check the well and water system for points of contamination. Make sure you have a sound and secured sanitary well cap and that the soil around the well is packed to drain water away from the well. 

2.    Then treat the well and plumbing system with chlorine for 12-24 hours to disinfect system (the 12-24 hours is essential). Then flush the chlorine from the system- not to your septic system. Make sure that this is done correctly. 

3.    Retest the water after the chlorine has left the system in about 10 days to two weeks. If coliform bacteria is “ABSENT” you’re done. If not, then it is time to install a long term disinfection system. (UV light or continuous chlorination)

In an existing well system that formerly was bacteria free look for these defects:

·          A missing or defective well cap and check seals around wires, pipes, and where the cap meets the casing may be cracked, letting in contaminants. 

·         Contaminant seepage through the well casing - cracks or holes in the well casing allow water that has not been filtered through the soil to enter the well. This seepage is common in the wells made of concrete, clay tile, or brick. This can also happen to a steel pipe well that was hit by a piece of equipment such as a car, snow blower, lawn tractor or mower or that has rusted. 

·         Contaminant seeping along the outside of the well casing - many older wells were not sealed with grout when they were constructed or the grouting has failed. Check the grouting carefully especially if water seems different after severe rains. 

·         Well flooding - a common problem for wellheads located below the ground in frost pits that frequently flood during wet weather. 

Coliform bacteria are commonly found in soil, on vegetation, and in surface water.

Some coliform bacteria strains can survive in soil and water for long periods of time. Coliform bacteria will not likely cause illness.

Coliform bacteria do not occur naturally in most aquifers. Fractured or creviced bedrock aquifers that are close to the surface are the exception.

Be aware that there are three different groups of coliform bacteria; total coliform, fecal coliform and Escherichia coli (E. coli) each has a different level of risk.

If your water is contaminated with coliform but not fecal coliform or E. coli, then you have a nuisance bacteria problem.

Bacteria washed into the ground by rainfall or snowmelt are usually filtered out as water seeps through the soil, so properly constructed water wells do not typically harbor Coliform bacteria.

However, coliform bacteria can persist within slime formed by naturally occurring ground water microorganisms.

The slime (or biofilm) clings to the well screen, casing, drop pipe, and pump and may even invade filter systems.

Disturbances during pumping or well maintenance can cause the slime to dislodge, releasing the coliform bacteria.

Keep in mind that coliform bacteria do not always show up in every sample. They can be sporadic and sometimes seasonal when they occur in a water supply.

You should not continue drinking water contaminated with coliform, either boil the water drink bottled water until you disinfect your well.

Bring the water to a rolling boil for one to five minutes (the higher the elevation the more time is necessary) to kill the bacteria.

You may also want to consider using bottled water as a temporary drinking and cooking water source.

You may have received a total coliform count. This gives you a general indication of the sanitary condition of a water supply and extent of the problem.

Bacteria can be introduced into a new well during construction and can remain if the water system is not thoroughly disinfected and flushed.

Well construction defects such as insufficient well casing depth, improper sealing of the space between the well casing and the borehole, corroded or cracked well casings, and poor well seals or caps can allow surface water or insects to carry coliform bacteria into the well.

These problems are common and the most likely source of the coliform bacteria contamination.

Unplugged abandoned wells can also carry coliform bacteria into deeper aquifers.

Since bacterial contamination cannot be detected by taste, smell, or sight, all drinking water wells should be tested at least annually for Coliform bacteria.

Elizabeth Ward was awarded an MBA from the University of Pittsburgh and an MS ChE from NYU Tandon School of Engineering, worked as a chemical engineer for both the US EPA in DC, and at DuPont before working in finance and then becoming consultant with Washington Advisors and is the author of "The Lenders Guide to Developing an Environmental Risk Management Program." Elizabeth retired from Washington Advisors and began her volunteer career and served 10 years as the Treasurer of the Prince William Soil and Water Conservation District.

https://greenrisks.blogspot.com/2018/05/coliform-present-steps-to-take.html

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E. Coli is Found in the Human Digestive Tract

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Drinking The Water Directly From A Private Well

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Did God Make Harmful Parasites in the Beginning?

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DISINFECTION OF GROUNDWATER AND WASTEWATER - Disinfection is an effective treatment process that can safely remove a variety of waterborne pathogens from a water supply. There are many types of pathogens that can get into a water supply. Each cause different problems, but there are several effective methods for their removal. Pathogens are anything that can cause disease. Water pathogens are usually either bacterial or viral. According to the Centers for Disease Control and Prevention (CDC), dangerous bacteria that are sometimes found in the water supply include E. coli, shigella and salmonella. Hepatitis A and the norovirus are two types of viruses that can contaminate municipal water systems. Most of the bacteria and viruses that are found in the water supply are not life-threatening for otherwise healthy individuals. Many can, however, cause temporary illnesses, as well as chronic health conditions. Short-term illness caused by bacteria and viruses is often characterized by nausea, diarrhea, vomiting and fever. A few gastrointestinal illnesses can be fatal, especially for very young children, the elderly and those with compromised immune systems. Neurological disorders and reproductive problems can also result from pathogens found in the water supply. There are several water treatment disinfection methods that can be used to remove pathogens from groundwater, wastewater and surface water.

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Disinfection of Groundwater and Wastewater

AOS Treatment Solutions

Disinfection is an effective treatment process that can safely remove a variety of waterborne pathogens from a water supply.

There are many types of pathogens that can get into a water supply. Each cause different problems, but there are several effective methods for their removal.

TYPES OF PATHOGENS

Pathogens are anything that can cause disease.

Water pathogens are usually either bacterial or viral.

According to the Centers for Disease Control and Prevention (CDC), dangerous bacteria that are sometimes found in the water supply include E. coli, shigella and salmonella.

Hepatitis A and the norovirus are two types of viruses that can contaminate municipal water systems.

PROBLEMS PATHOGENS CAUSE

Most of the bacteria and viruses that are found in the water supply are not life-threatening for otherwise healthy individuals.

Many can, however, cause temporary illnesses, as well as chronic health conditions.

Short-term illness caused by bacteria and viruses is often characterized by nausea, diarrhea, vomiting and fever.

A few gastrointestinal illnesses can be fatal, especially for very young children, the elderly and those with compromised immune systems.

Neurological disorders and reproductive problems can also result from pathogens found in the water supply.

GROUNDWATER DISINFECTION SOLUTIONS

There are several water treatment disinfection methods that can be used to remove pathogens from groundwater, wastewater and surface water.

The following are a few of the groundwater disinfection solutions offered by AOS Treatment Solutions:

·      Chlorine Dioxide Control and Assistance — According to the Environmental Protection Agency (EPA), chlorine is the disinfectant most often used to inactivate waterborne pathogens. Chlorine dioxide is a specific type of gas that can also be used to treat municipal water supplies.

·      Sodium Hypochlorite (Bleach) — This is a disinfectant that has proven to be effective in purifying groundwater and eliminating odors. It is often used because microorganisms can’t build up a resistance to it.

·      Liquid Ammonium Sulfate (LAS) — Chem Trade states that liquid ammonium sulfate is a non-toxic, stable liquid that can be used effectively for the treatment of drinking water.

AOS offers several disinfection wastewater treatment solutions that can be used to purify and maintain water at high standards.

We offer a range of groundwater treatment services and solutions to municipalities, including independent water analysis, chemical program design, start-up and training, and system-wide or single-point performance tracking.

Contact AOS Treatment Solutions for any questions regarding groundwater disinfection solutions.

AOS TREATMENT SOLUTIONS

Since 1999, AOS Treatment Solutions has provided specialized treatment of water and wastewater to the industrial and municipal markets. Over the years, we have become a leading water/wastewater treatment company utilizing an analytical and scientific approach to developing optimum treatment programs. Through our meticulous testing methodology, we find cost effective solutions to meet the needs of all our customers.

At AOS, our goal is to provide clients with a single-point source for all their water and wastewater treatment needs. We use the latest testing equipment and analyzers to deliver practical solutions that enhance operational reliability.

All chemicals for municipal drinking water are NSF certified.

https://aosts.com/municipal-groundwater-treatment-solutions/disinfection/

DROWNING MACHINE - THE DANGERS OF LOW HEAD DAMS - A low head dam, sometimes simply called a weir, is a small structure that impounds a small amount of water and spans the width of river or stream. Usually made from concrete, the purpose of a low head dams is to raise the water level upstream on a river. This can assist with navigation of the channel by boats, create a drop for generating hydropower, and for water supply and irrigation. Low head dams almost always have subcritical flow upstream. The flow is deep, slow, and tranquil as it makes its way to the dam. But as the flow passes over the weir, it picks up speed and becomes supercritical. When this supercritical flow transitions back to subcritical flow in the slower moving water downstream, it creates a hydraulic jump. These could pose a threat to those using the waterway for recreation. Any location with fast moving water and high turbulence can be dangerous to swimmers or kayakers, but the location of this hydraulic jump can turn a manageable risk into an almost surefire way to drown.

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 Drowning Machine : 

The Dangers of Low Head Dams

Grady Hillhouse

Practical Engineering

Dams serve a wide variety of purposes from hydropower to flood control to storage of water for municipal and industrials uses.

But when a dam’s useful purpose fades away, the structure itself still remains.

Dams come in all shapes and sizes, but contrary to what you might think, the most dangerous dams are often the smallest.

A low head dam, sometimes simply called a weir, is a small structure that impounds a small amount of water and spans the width of river or stream.

Usually made from concrete, the purpose of a low head dams is to raise the water level upstream on a river.

This can assist with navigation of the channel by boats, create a drop for generating hydropower, and make water available at intakes for water supply and irrigation.

Thousands of these structures have been constructed over the years to take advantage of natural watercourses and rivers.

The heyday of low head dam construction was actually in the 1800s when mills and factories often relied on waterpower to drive grinding wheels and other equipment.

This was at a time when moving water was the most consistent source of power available in large quantities before widespread adoption of electricity.

Most of these old mills and factories are long gone, and the ones that still survive certainly don’t depend on water for power anymore.

That means many property owners are forced to maintain these old structures that no longer have any practical use.

Or more commonly and much worse, these dams are abandoned by their owner and gradually fall into disrepair.

In the U.S., dam safety regulations focus primarily on the possibility of a dam breaching and causing a flood wave downstream.

But, because low head dams are relatively short, a breach poses minimal danger, so most states don’t keep track of these small structures.

And, especially if they’ve been abandoned, it can be difficult to enforce maintenance requirements on the owners.

But, even though they pose little danger in the event of a breach, low head dams create a public safety issue that has caused more fatalities in the U.S. than all dam failures in the past 20 years.

To understand why, we first need to know a little bit about open channel hydraulics.

If you haven’t seen my video about hydraulic jumps, I’ll summarize it here. Go back and check out that video if you want to learn more.

Open channel flow - that’s flow not confined within a pipe - has a very important property related to its velocity that governs its behavior.

Slow, tranquil flowing water is called subcritical because waves propagate faster than the flow velocity.

Fast moving water is supercritical because waves move slower than the flow velocity.

Any time a supercritical flow encounters subcritical flow, an interesting phenomenon called a hydraulic jump is formed.

Low head dams almost always have subcritical flow upstream. The flow is deep, slow, and tranquil as it makes its way to the dam.

But as the flow passes over the weir, it picks up speed and becomes supercritical. When this supercritical flow transitions back to subcritical flow in the slower moving water downstream, it creates a hydraulic jump as you can see here in my model flume.

It’s easy to see why these types of structures could pose a threat to those using the waterway for recreation.

Any location with fast moving water and high turbulence can be dangerous to swimmers or kayakers, but the location of this hydraulic jump can turn a manageable risk into an almost surefire way to drown.

The depth of the flow downstream of a dam is called the tailwater, and it controls the location of the hydraulic jump.

In my model, I can adjust the elevation of the tailwater by adding or removing these stoplogs.

When tailwater is low, the hydraulic jump forms away from the dam. This is a fully developed jump that follows the traditional shape and flow patterns.

If I send down this piece of wood as a kayaker surrogate, it experiences some turbulence as it passes over the weir and through the jump but, it doesn’t have much trouble escaping downstream.

But, as the tailwater rises the jump moves closer and closer to the dam. Eventually if the tailwater is high enough, the hydraulic jump will reach the dam.

This condition is called a submerged or drowned jump. It may look fairly innocuous, but this is when things get dangerous.

Let’s send down our kayaker surrogate to see why. A submerged hydraulic jump creates an area of recirculation immediately downstream of the dam sometimes called a “keeper” for obvious reasons.

The jet of the hydraulic jump surfaces downstream causing a boil point. Sometimes this is easy to see and sometimes it’s not.

Either way, objects or people can will only be able to escape a submerged hydraulic jump if they are able to get beyond this boil point.

And, any rescuers who approach a submerged jump from downstream run the risk of being drawing into the hydraulic themselves.

The recirculating currents that trap recreators is dangerous enough on its own but there are other factors contributing to the danger at low head dams.

These currents also trap large debris between the strong hydraulic forces and the hard concrete surface of the dam which can batter someone trapped in the keeper.

The water is often cold, increasing the potential for hypothermia and further disorientation.

The turbulence of the hydraulic jump entrains a lot of air, reducing the buoyancy of a swimmer. And, low head dams often span the entire width of the river, meaning there is no still water nearby that can be used as a safe haven.

This is exactly why the low head dam is called the perfect drowning machine. All these factors added together create a situation that’s almost impossible to survive.

There are a lot of ways to mitigate this issue. The simplest option is just to keep people away from these structures.

Some states require that exclusion zones be established to make sure that kayakers safely portage dams instead of trying to run them.

Good signage and buoys as warnings can sometimes be enough to keep people safe. Another option is to modify the structure to reduce the potential for recirculating currents.

Researchers have proposed various retrofits to existing dams to improve flow conditions when tailwater is high. Of course, the most obvious (but also most expensive) way to address the issue is to remove these dams altogether.

In many cases they are no longer serving an important role, and removing dams can help restore ecosystems and improve connectivity for aquatic species in addition to removing a hazard.

If you’re swimming or paddling on a river with a low head dam, don’t underestimate the danger of these powerful hydraulic forces.

Different flow conditions on the river can dramatically change the behaviour of the hydraulic jump, as we saw, so be careful. Thank you for watching and let me know what you think!

https://youtu.be/GVDpqphHhAE

Hey, I’m Grady Hillhouse and this is Practical Engineering! I am a husband, a professional civil engineer, and educational video producer in San Antonio, Texas.

Randall Munroe said, "You can look at practically any part of anything manmade around you and think, 'Some engineer was frustrated while designing this.' It's a little human connection." My goal for Practical Engineering is simple: to increase exposure and interest in the field of engineering.

Of course, as a civil engineer, much of my content is geared towards infrastructure and the stories behind the humanmade world we live in. I like to help people make a connection between themselves and their constructed environment. In order for people to care about infrastructure, they need to be interested in the engineering behind it and see people who are passionate about finding innovative ways to meet humanity’s basic needs. I really believe this and it’s important to me. I hope that my videos are helpful to you and encourage you to take opportunities to be an advocate for civil engineering.

https://practical.engineering/blog/2019/3/16/drowning-machine-the-dangers-of-low-head-dams