Ageing Infrastructure

What do you think is the most likely reason for a water grid shutdown?  It isn’t terrorism and it isn’t pollution. The answer is, the age of the infrastructure used to deliver the water or collect the sewage. Think about the city you live in. Chances are it has existed for hundreds of years, if not longer. Most cities water systems grow in phases. They keep adding to the network every year as the population grows. The end result is most cities have infrastructure that range from less than a year to hundreds of years and with many different materials. I have seen water mains made of wood in service as late as 2011. Like any piece of equipment it all has a useful lifespan, beyond that lifespan failures become increasingly more likely to be catastrophic. The result is a large volume and dollar amount of material and equipment that needs repairs or to be replaced.

Wooden Water Main circa 1909 source www.nytimes.com

Wooden Water Main circa 1909 source http://www.nytimes.com

Normally the stress on water systems comes from population growth.  A water main that was ok in the 1980’s may not be large enough for today’s population.  As cities infill and build higher density buildings they frequently overburden the water systems.  Either causing contamination or total failure of the system.

Older equipment is also more susceptible to natural disasters, terrorism and human accidents. These three things can break a new system too, however they don`t have to try as hard with the older systems.

Climate change is having an affect too.  As severe weather events are on the rise, storm sewers might be found lacking, as was the case in Calgary, Alberta and Toronto, Ontario recently.  The system was grossly undersized for the amount of rain that fell.  They said things like “it was a month’s worth of rain in one day” on the news.  When the fact is, it once was a months worth of rain, and is now something more frequent, lets say a weeks worth of rain.    I’m not suggesting we build our systems to meet a 1000 year storm, but I am suggesting that our current idea of a 100 year storm may be an underestimation and that the error is getting worse.  To bring it back to infrastructure, if we are built to the current 100 year storm levels, what happens if the 100 year storms are getting worse?  We will find out in the not too distant future.

Calgary, Flood, Floods, Water

Flooding In Calgary AB 2013 source: http://www.newinfills.ca

What are the options for people to take? The first and most important thing to do is to plan ahead and replace older parts of the system before they fail.  A $50,000 job to replace an old section of pipe at a time you choose is a lot cheaper than waiting for it to fail at the time you are least prepared.  If you are connected to a public utility, ask them about their equipment replacement plan.  If they are not looking 25 years into the future or longer then ask them why not? If you have private systems, you need to ask the same questions.  Can you afford to replace the septic system when it fails? Or can you afford to dig/drill a new well when the casing cracks?

As you can probably surmise the addition of more people + more rain + more water and more sewage means system failures will become more frequent and probably for longer periods of time.  What does this mean to the average person?  Plan for system failure.  Have a backup system ready to go when it does.  Know the age of your equipment and it`s expected lifetime. That way you wont be caught off guard.

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Septic Tank Problems

Septic systems range from the very simple to the extremely complex. Even on the simplest septic systems there are still many things that can go wrong. If you believe that septic systems are something you bury and forget about, then I guarantee that you will come across many of these problems. There are simple things anyone can do to keep their septic system running properly for decades.

First a general description of a septic system. The system starts where the common drain leaves the house. This drain can go to a municipal sewer or to an individual septic system. The water flows by gravity into the septic system. The inlet to the septic tank is protected by a T shaped baffle. It is open on the top and bottom. It is designed to contain floating debris in a small area and to direct solids to settle down towards the bottom. The water is contained here where solids settle out to form a sludge layer and floating objects form a scum layer. In between there is a clear zone where the water has very few solids. The water in the tank is treated by anaerobic bacteria. The bacteria break down organic compounds in the water until there is almost nothing left.
The water leaves the tank through another T shaped baffle on the other side of the tank. This one goes down to the clear zone and allows clear zone water to exit the tank without coming into contact with the scum layer. Some tanks have a septic pump, the pump is installed on the opposite side of the inlet and at the expected height of the clear zone. Larger tanks might have a dividing wall to keep sludge and scum on one side and clear water on the other side.

Septic Tank, Septage, scum, sludge, clear, zone

Basic Septic Tank Design (source: biozoneseptoc.com)

The sludge layer if not removed every three to five years can cause a major failure of the entire system. Not everything can be broken down completely.  There are always things that either never breakdown or breakdown too slowly and they accumulate.  The sludge layer will eventually reduce the capacity of the tank and the solids will block the inlet or the outlet of the tank.  The sludge layer will be a rapid problem if the people using the system treat the toilet as a garbage can.

The scum layer is all the floating solids the get flushed into the system. Grease and oils cause a large part of the scum problem. But they are far from the only culprits. Cooking oils and grease coat the walls of the pipes and tanks and slowly reduce the size of the of the inlet and outlet eventually blocking them, and you can see how that is a problem.

The drain field is where the treated effluent gets released back to the environment. It may be called something else like a tile bed or weeping tile. They are usually subterranean but can sometimes be on the surface. Regardless there are still buried pipes and they are easy to collapse if you drive a vehicle over them. Lawn tractors are OK but even compact cars are too heavy for the shallow plastic piping. If the piping becomes cracked or even a section collapses then pipe will become blocked with dirt and your waste water will have nowhere to go except back into the house.

Hydraulic overloading is the technical name for putting too much sewage into your septic tank.  This can happen if you have a party and there are more people using the system or if the sludge layer reduces the capacity of the tank.  The end result of overloading is that poorly or untreated sewage leaves the system negatively impacting the surrounding area.

Leaks are bound to occur with age.  You can also create leaks by driving over the tank and excavating too close to the tank.  Leaks are a huge problem once they occur.  The groundwater and soil contamination is extremely expensive to clean up.  You may also be liable for damage to the neighbor’s water supply depending on the riparian laws where you live.  A leaking tank needs to be replaced immediately.

Proper maintenance will prevent most problems.  The worst thing anyone can do is to bury the septic system and forget about it.

Why is my water that color?

As someone who works in water treatment I fequently receive questions about red, black, pink or cloudy appearances in drinking water. Contrary to what might be expected none of these colors are inherently dangerous to human health. They do however make the water look unappetizing. They are called asethetic water quality indicators. Well the colors themselves isn’t the indicator, what causes the water is. I will outline the causes below.

Red water is usually caused by the oxydation of iron and iron bacteria. To be a little more accurate the color is a reddish brown, if you see a red that belongs in a paint can then I highly recommend NOT drinking it. Iron oxydation (rust) is not dangerous at all. Many water sources contain iron naturally. Iron is prevalent in groundwater. The red color comes from iron particles rusting when they come into contact with oxygen in the water. The rusting is accelerated when the iron is introduced to chlorine. As you know chlorine is very commonly used as a disinfectant. When there is a lot of iron and a lot of chlorine then there can be a visible particles of rusted iron in the water. This looks really bad when you turn on the faucet but iron is something they add to mineralized bottled water and iron is a necessary element in proper nutrition.
Iron bacteria can enter the water at the source or if the water is stored in a metal container or watermain. Wells can become contaminated with iron bacteria. When they do, read this to know what to do about it.

Black colored water is not to be confused with black water which is a term used for sewage. Sewage is often a yellowish brown, unless it has gone septic and then it is very black and very smelly. An odorless black tint to water is usually due to manganese. Manganese behaves a lot like iron does except it oxidizes a lot slower. Water stored for a couple days or more will turn black if there are high levels of manganese in the water. Manganese is more often found in groundwater than in surface water. Sometimes it wont be noticeable in the water. It will however be noticable as a black stain on appliances and reservoir walls.

Pink water comes from potassium permanganate (KMnO4). Permanganate is a treatment chemical used to help oxidize iron and manganese. When too much is added the water turns pink. When a lot is added then the water turns purple. The pink isn’t dangerous to human health. It is hower alarming to see pink coming out of a faucet. To read how to use potassium permanganate as a disinfectant read this.

To remove iron, manganese and permanganate is accompolished with greensand filtration. Don’t let the name fool you, greensand is black in color. Greensand is chemically activated to remove oxidized minerals from water.

A yellowish tint (sometimes brown) to the water IS potentially dangerous. Yellow tea colored water is indicative of organic material in the water. Organic material is mostly non living particles but it also includes bacteria, viruses, and other pathogens. Sewage is also this color. So beware of yellowish water.

Not many different things can cause a truely cloudy appearance to water. Turbidity is sometime said to be “cloudy” but it is caused by suspended particles blocking light from passing through. Usually turbidity is also colored at the same time. Unless the particles are white in color, then turbidity isn’t cloudy, it is dirty.
Cloudy water is caused from dissolved gasses (usually oxygen) in the water getting released. This happens when the temperature in the water is significantly different than the temperature of surrounding environment. Since large bodies of water are slower to heat up and slower to cool down, this difference happens every spring and fall. It is called reservoir turnover. The way to test if it is just dissolved gasses in the water is to let a glass sit for five minutes. All bubbles of gasses will disappear and the water will look and taste normal. If the water is still cloudy after five minutes, then the problem is caused by turbidity and it must be removed by filtration.

Not everything that can happen to drinking water is dangerous. Reddish tints from iron and blackish tints from manganese are natural and harmless. This article should help you determine when visual changes to the water are cause for alarm and when they can be ignored safely.

Cleaning Up Contamination with Super Chlorination

Super chlorination is a technique used to clean and disinfect water holding vessels that cannot be washed in the traditional sense. This is different from your standard disinfection, which is for cleaning the water, not the container. Super chlorination is used when reservoirs become contininated with microorganisms or have been emptied for any reason (indicating possible esposure to contamination).

Super chlorinating is simple. On a very basic level, it is just adding a large amount of chlorine to a reservoir either as a wash applied directly to the wall or as a very strong chlorine/water solution which fills the entire reservoir.
On a more specific level, it is dependant on the strength of the hypochlorite and the amount of time the chlorine is left in direct contact with the container. The stronger the chlorine the less time required. For example, if you decide to spray the walls with straight 10% sodium hypochlorite then there is almost no time required. Whereas the normal chlorine levels in most municipal drinking water systems is not enough to ever disinfect the vessel it is in. Those low levels of chlorine will only protect the water from contamination in a reservoir that is already free of contamination.

Now you might be asking how to figure out how much chlorine to add to make super chlorinated water. If you think all you need is to dump a large amount of chlorine in then I will point out that releasing large amounts of super chlorinated water into the environment is illegal in most jurisdictions. So it is necessary to calculate how much dechlorinating agent is needed. The easiest way to know the dechlorinating needs is to measure the amount of chlorine added. In order to save money or time it is best to calculate the ammount of chlorine necessary.

50 mg/L (50 ppm) of available chlorine is a great place to start. 50 mg/L left for 24 hours will meet the best pratices and standarized procedures for most jurisdictions in North America. Below is a table outlining how much chlorine you need to add for various volumes of water.

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Super Chlorination Volumes at 50 mg/L (from the City of London Port Health Authority)

From this chart you can see exactly how much chlorine to add. Add the hypochlorite solution when the system is haIf full. Then fill the tank or reservoir the rest of the way with clean water. If you are disinfecting something with plumbing, like a building or a boat, then make sure the super chlorinated water makes it to each cold water faucet by flushing until you can smell chlorine (or can measure it). Do not flush the hot water faucet. all you will do is waste chlorine and hot water.

This procedure will disinfect any reservoir. Regardless of the levels of bacterial contamination, because if it doesn’t work the first time repeat the process until it does. The most likely culprit if super chlorination doesn’t work the first time is that a pipe connected to the tank wasn’t flushed completely.

Whether you have a large tank of reserve water or your rain barrels start growing dangerous microorganisms, you may need to super chlorinate one day.

Disinfection with Potassium Permanganate

Potassium Permanganate is a very versatile chemical. It can be used for disinfection, removing hardness, removing iron and manganese. It has another health related use, it can be mixed into a paste and used as a topical salve for athlete’s foot (or similar problems). As a result potassium permanganate is a great addition to any emergency preparedness supplies.

Potassium Permaganate has the chemical formula of KMnO4, and it comes as a deep purple dry powder. This chemical is a very powerful oxidizer and it should not be stored anywhere near acids or fuel sources or it could result in fires, explosions and/or toxic gases being formed. Explosives is another use of this chemical (one which I will not be explaining here). This chemical can be stored for over a year if it is kept clean and dry and in a sealed container.

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Before touching the dry powder, make sure you wear a particle mask (ideally a N95 or better). This chemical will irritate the airways if inhaled directly. Also the powder once mixed with water becomes a powerful dye. It will stain clothes permanently, stain skin temporarily and cause corrosion on any metal or masonry it touches. Anything that becomes exposed to a potassium permanganate solution becomes brown, a similar shade of brown to a henna tattoo.

To make a topical treatment with KMnO4 mix the dry powder with water until it has the consistency of playdoh. Apply the mixture on the affected area and repeat as necessary. Remember that I am not a doctor and I am not giving medical advice. I am only outlining that this chemical CAN be used for medical purposes. Whether or not you SHOULD use KMnO4 for medical applications is not something I can tell you.
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Potassium permanganate is very similar to sodium hypochlorite in the sense that they both disinfect water through oxidation. Disinfection of drinking water can be achieved by adding it to the water until the water turns pink. The pink in the water is the residual potassium permanganate. Meaning that there is nothing left to use up the chemical and any bacteria has been used. Think of the pink water as being similar to the point where you can smell bleach when using sodium hypochlorite for disinfection. Just like with the smell point of bleach has surpassed the disinfection point, you do not need to keep adding KMnO4 until you see pink. Disinfection has occurred well before you can see a lasting pink tint to the water. Using the color change is a simple and easy to remember method for disinfection of drinking water. And if the pink tint disappears at any time then you know you need to add more of the chemical to redisinfect the water.
If you want to avoid pink water and spend less money on chemicals you can buy a testing kit for manganese. Most kits can measure the residual levels of KMnO4 at levels well below the pink water threshold and well above the disinfection requirements.

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For better results with disinfection it is best to filter the water through a greensand filter. Now this is not an indication of the color of the sand (it is actually black in color). Greensand is an activated filter media designed for removing iron and manganese through a process called ion exchange. The good news with a greensand KMnO4 combination is that the potassium permanganate will reactivate the filter media.

One thing to note is that potassium permanganate once added to water will make the water more corrosive. If the water is very pink it can also stain any container it is stored in. The pink water is perfectly safe to drink. I mean the water is not dangerous because of the pink coloring. It may however be dangerous for another reason or contaminant.

Another thing to note about KMnO4, is that if you add it to chlorinated water it will form a percipitate (solid). This is manganese dioxide, it is harmless except it will consume all the available chlorine in your water leaving you open to contamination from microorganisms.

With a few simple precautions KMnO4 is an excellent chemical to have on hand. It can be stored longer than sodium hypochlorite (bleach) and it can be added directly to the water unlike calcium hypochlorite. It also is very easy to see when enough of the chemical has been added. If there is a lasting pink tint that doesn’t disappear with time then the water has been disinfected.

When it comes to disinfecting your own drinking water, always be careful with the quality of chemical you use. They are not all created equal. The north american standard for chemicals used in drinking water is NSF/ANSI 60. Choose chemicals that meet this standard above ones that don’t. The will be significantly safer for your health and well being.

As with all my disinfection articles, I will remind you to always drink the safest water you can and combining treatment techniques is the best way to achieve safe drinking water

Can I use a storm-water pond as a back-up source of water?

Storm-water ponds are the closest alternative source of water for many people living in urban areas. In an emergency this source of water may be all that is available to you.  Eventually any water you have stored will be consumed and the water in a storm-water pond may be the difference between life and death.  With the proper treatment your local storm-water pond can be a great backup source of drinking water.

Industrial storm-water pond (source: info.evergreen.ca)

Storm-water presents a unique set of challenges during treatment. Because storm-water ponds collect surface water, the water is exposed to all the contaminants on the ground in the catchment area. This includes but is not limited to pesticides and fertilizers applied to lawns, motor oil and gasoline leaking from vehicles and litter like cigarette buts. It all ends up is the storm-water pond. Those chemicals are already in storm-water ponds on a normal day. During an emergency there may be additional contamination from sewage runoff from an overloaded or broken sewage system. The water in the pond will also contain all the microorganisms like ecoli, giardia and cryptosporidium normally in surface water. Any one of these will make you very sick if you get infected with them.
Finally, there will be high levels of nitrates in storm-water ponds. Too much nitrates consumed by young children can cause blue baby syndrome.

The first step in treating water from a storm-water pond is straining. Straining the water through a cloth or loose sand filter will remove large particles (ones you could pick up with your fingers). Remove as much of the suspended particles from the water as you can. Straining the water first will extend the life of your proper water filter.

If you have a clarifying agent like aluminum sulfate, this is the best time to add it to the water.  It will make contaminants too small to be filtered become attracted to each other and become significantly larger.  Larger particles are easier to remove from the water. Let the water sit still for at least 30 minutes without disturbing it.  All the newly formed large particles (called floc) will sink to the bottom.  When you take the water from this container, make sure you leave the majority of the settled material at the bottom of the container.

Urban Storm-water pond (source: greenbmp.blogspot.com)

The next step is to filter the water. Filter the water even if it looks clear, the human eye is five times too weak to detect dangerous levels of particles. Filter the water at least once through an activated carbon filter. Activated carbon is known to remove many different chemicals from water including pesticides, chlorine and fluoride. Activated carbon is not the same as charcoal. Charcoal is similar, it can remove toxins from water but it is nowhere near the efficiency of activated carbon.

The third step is oxidation. Oxidation will help with disinfection as most disinfectant chemicals are also oxidizers. Chemicals like sodium hypochlorite and potassium permanganate are both oxidizers and disinfectants. Oxidation will break down many of the remaining contaminants and inactivate many of the remaining bacteria. Keep adding the oxidizer/disinfectant till you can detect a residual after 20 minutes. The 20 minutes is the minimum you should wait for a gallon of water. Wait longer for larger volumes. This is because oxidation is a chemical reaction that isn’t instant. It needs time to complete the reaction.

The fourth step is to filter the water again. Filtering again is necessary because the disinfection/oxidation step will create some potentially carcinogenic byproducts. We filter before oxidation to minimize the amount of chlorine (or other chemical) and to limit the possibility of forming dangerous byproducts. We filter the second time to remove any byproducts that have been formed.

The final step is to boil the water.  This will help with disinfection, but the main goal of boiling at this point is to remove any volatile chemicals.  Any chemical with a boiling point lower than water will be removed after boiling.

A note about disinfection.  If all of these steps are followed there is no need for a step dedicated for disinfection.  Between the oxidation and the boiling of the water any microorganisms will be inactivated.  If you are storing the water for a long time then add some sodium hypochlorite for a residual disinfectant.  The residual disinfectant will prevent the water from becoming recontaminated before you drink it.

One additional possible step is to aerate the water.  Ponds are frequently stagnant.  Stagnant water is green with algae, it smells bad and tastes worse. After the water is made potable, transfer the water back and forth between two glasses. This adds oxygen to the water and will make the water taste better.

This may seem like a lot of work for something as small as a storm-water pond.  What I have described are the basic steps to turn the potentially toxic water in the pond into clean and safe drinking water.

Terrorist Attack and Water Systems

Water systems are distributed networks of pipes, pumps and reservoirs. Like all distributed networks they can be very difficult to protect from vandalism and terrorist attack. There are two broad types of attacks that could hit a water system. The first type is an attack on the quantity of water available (physical supply) and the second is an attack on the quality of water. The end result of both types of attack is a lack of potable water entering your home.

The greatest defense for a water system is that most of it is underground. It is very difficult to access most parts of water distribution systems. Even for the operators of the system it is time consuming and disruptive to the wider community. If anyone unauthorized to dig in a road to access a watermain they will be reported to the authorities in the form of complaints about traffic or noise.
I think it goes without saying that depending on public complaints to defend against terrorism is nowhere near secure.

Water Treatment Plant (source: wikipedia.org)

The exposed parts of water systems are water treatment facilities, reservoirs and fire hydrants. These are the points where the system is at the surface and easily accessible. These different points also offer different security concerns.

Treatment facilities are as secure as any factory or industrial facility will be. The treatment facility I work at is always locked and there are a limited number keys. Then there is an electronic alarm system which brings a human on site if there is an intrusion alarm. There is also a human dispatched if the communication link is broken. A large city water treatment facility will most likely be manned twenty-four hours a day. The biggest weakness here is that properly armed people can force their way in and destroy the building if they so desire. Or they can contaminate the reservoir on site (if they know how).

Reservoirs of treated water are next most likely place for a terrorist attack. The biggest weakness here is that reservoirs are almost never manned during the day. They will be visited most days, but rarely will people be there all day. The good news is that water in reservoirs is monitored constantly(usually) with automatic analyzers. Reservoirs can be destroyed, and the water within wasted. Or the quality of the water can be destroyed this is where chemicals could be added easily.

The remaining pieces of the system are fire hydrants. Fire hydrants pose a unique risk to water security. It is very easy to add chemicals to a fire hydrant. It is however not easy to get that chemical into the water supply. This is because of the construction of the hydrant itself and the pressure in the system. There is a valve at the bottom of the hydrant which isolates the water. In order to add chemicals to a fire hydrant you also have to lower the system pressure which is rarely easy to do undetected. At this point I want you to remember the scene in Batman Begins where Sandman is dumping his psychotropic drug into a cracked watermain. I don’t expect realistic depictions from the movie, I do however want you to know this is nowhere near realistic. Watermains are pressurized, when they crack water shoots out at anywhere from 50 to 100psi. This is enough to erode foundations of buildings and the all soil around the break creating massive sinkholes. It is not something you can pour chemicals into. This is what it looks like when watermains break.

Just adding chemicals to water, is not as effective as it appears on the surface.  Most water supplies contain residual disinfectants, usually chlorine.  Disinfectants are highly reactive chemicals, they aren’t limited to just killing bacteria.  Highly reactive chemicals often react with other chemicals.  I am obviously oversimplifying the chemistry involved, but it is true that a large portion of any chemical added to water will be consumed by the chlorine in the water.

Adding Chemicals to Water (source: http://www.thejakartapost.com)

Cyber attack is another way water systems are vulnerable.  You may wonder why water treatment facilities are connected to the internet and the answer is for remote monitoring and control.  It may seem like an unwarranted risk having these facilities connected to the web.  It is not an unwarranted risk at all.  The likelihood of the automated system needing an intervention that cannot wait for someone to be onsite is greater than a targeted cyber attack. Keep in mind that even normal breakdowns of the watersystem can cause illness and even death.  These need to be responded to and are just as important as preventing cyber attack. I am not a technology expert so I will leave it to other people to suggest the best firewall setup.   Another thing to note about cyber attack on a water treatment facility is that even if the attacker is successful and shuts down the control computer, the facility can still be controlled manually.

Terrorism is something that needs to be addressed when it comes to water systems.  People inside and outside the system need to be aware of the risks and what can be done for protecting the security of out water.