Archive for December, 2009

Plants as indoor air cleaners

December 9, 2009

Here we go again.  WebMD reported this week that HortScience had an article in August about research on using house plants to remove indoor air pollution.  Interestingly, the article did not report anything about been there, done that.  Well, not me personally.  But, a few years ago, NASA was doing similar research.  At that time, a bunch of people were proposing that plants could be used to clean indoor air.

The research seems to be clear.  Yes, some plants appear to be able to remove some indoor pollutants.  The truth is in the practicality.  Usually, these studies are designed using injection of an initial concentration of a chemical inside an airtight container that contains the plant.  The chemical’s concentrations are then monitored over time to determine how well the plant removes the compound.  The first possible problem with this kind of research is that some of the compound could be lost to surfaces inside the container.  If this research is like most of this kind of research, such losses are not included in the study details.  Another problem is that, over time, chemicals can also break down, depending on the environment and the chemical.  Again, study details don’t usually describe how this loss is accounted for.  And a final detail about the study methodology is sometimes overlooked, and that is loss of chemical to the study.  Each time a sample is removed, the chemical concentration inside the container decreases.

Those facts were about the practicality of the study design.  Reality is probably the least practical aspect of the study results.  We don’t usually have only one chemical floating around in the air.  Does that mean if a whole bunch of plants would be needed if they each have their own chemical they like to dine on?   Realistically, chemicals are not put into the environment in one squirt and then left to decline over time.  Some chemicals are emitted into the air over time, such as those from building materials.  Even more complicating is the fact that chemical concentrations can vary over time because the emissions from materials vary over time, depending on a range of environmental factors.  I have collected this kind of sample data myself, as have many other researchers.  The changes in chemicals floating around a building are pretty amazing to study, actually.

In our buildings, air is constantly being exchanged–moving in and out.  No building is airtight like the containers used for most plant studies.  Air coming in also can carry chemicals into a space and air leaving can taken them out, which is also another reason why chemicals and their concentrations can vary dramatically over time.  Changes in the rate that air enters and leaves a space can be controlled by factors inside and outside the building.  Wind direction and speed, house design, sun and many other factors can influence air movement inside a home.  Operation of the air handler, people movement, heat sources, interior design and many other factors can influence air movement inside a home.  As vapors, chemicals are also influenced by the Ideal Gas Laws, in particular the part about partial pressures which says that vapor pressure of any one chemical in one area will equilibriate with vapor pressure of the same chemical in an adjoining space if the chemical can move between them.  So, chemicals at a higher concentration inside compared to outside a building will eventually equilibriate with concentrations in the outside air.

Materials inside a building also absorb and re-emit chemicals.  Ever smell cigarette odor on non-smoker who has been in a smokey bar?  The fixed things in buildings, the things of which the building is constructed, as well as the solid materials floating around in the air and the other things moving through the building, such as people, pets and their related materials, all absorb and re-emit chemicals.  The researchers call things that absorb sinks and the things that emit sources.  A dynamic exchange is going on between these things all the time.  Further, something that is a sink at this time can become a source when a chemicals concentration changes.  So, what is a plant to do?  Then again, how many plants should a person have when the emission rates could be constantly changing?

But, let’s dig into that question a little more.  How many plants would be needed.  Past research has shown that plants absorb a definable, but minute amount.  Such research predicted that a small forest would be needed to make a significant dent in the chemical concentrations.  Again, we are talking about static chemical concentrations, whereas most buildings have dynamic concentrations.  That brings me to another subject that seems to often overlooked.

Past “Plants Eat Chemical Compounds” researchers also took a lot of criticism for one major overlooked factor.  Plants grow in soil.  Soil contains–dare I say that M word–yes, mold!  In fact, many plants have a symbiotic relationship with certain molds to help them absorb nutrients.  But, many molds themselves emit chemicals into the air.  So, a person has to ask, is it practical to use plants to absorb one chemical when the soil in which they grow could be emitting a whole bunch of other ones?  Probably not.

NASA had a good reason to research whether plants absorbed chemicals or not.  NASA was interested in using plants on spaceships making long journeys where plants might be used for food and to help control the air quality inside the ship.  Currently, NASA uses chemical filters to control chemicals emitted into their ships.  On a long journey, those filters could become saturated, and in some cases then start re-emitting chemicals back into the air.  Having something that absorbs and holds the chemicals would be nice.  Having something that absorbs those chemicals and then turns them into a product that the spaceship residents can use would be great.  Now, given we are kind of like astronauts flying along on this great ship Mother Earth, we still have enough air to take care of plants, chemicals and us.  The amount of air around us is currently adequate to support a recycling system that maintains a reasonably (although I admit debatably) healthy air quality.  Other systems inside out buildings do a better job than plants.

For solid materials floating around in our building air, particle filters do a very good job–as long as air is moving from the building through the filter.  For gaseous materials, chemical absorption filters can work well; but in most cases, they are impractical for many buildings.  More effective, though, is dilution where outside air is brought indoors to reduce chemical concentrations.  And that is where I am going to leave things for right now.  I promise to cover more about control of gaseous chemicals in a future blog.  Suffice to end this blog this way:  use plants to make you feel good mentally; but use dilution or filters to make you breathe well.

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Paving options–permeable pavements

December 5, 2009

While I was at the Lexington National Home Association center this week for training, I was able to see two of the newer options that might be the future replacement for asphalt pavement and alternative drainage.  In these systems, the water is allowed to penetrate the pavement into a deep gravel bed equipped with drainage lines.  This system replaces gutters to channel water to a retention pond.  I have included photos of the systems.  The photos of the gray material shows a gravel/epoxy pavement system and the photos of a patterned material shows an open paver/gravel paving system.

Using either of these paving options can have a great advantage depending on the options used.  For example, retention basins might be eliminated because the water reservoir can be in the gravel bed below the pavement.  The possibility exists that the water can be further used for watering purposes if a membrane is installed below the gravel to capture the water.  Eliminating the retention basin, which is the lake you see in most communominiums, can potentially reduce maintenance costs and headaches for a community, such as needing to constantly treat the water for algae, replacing fountains and eventually dredging to remove accumulated sediment.    Catch basins might also be eliminated because the water runs down through the pavement rather to gutters and then to catch basins.  Another advantage is minimal icing in winter because the water does not sit on the pavement where it can refreeze.  Of course, the greatest advantage is not having the upkeep costs associated with asphalt, which is directly tied to oil prices.  One of the disadvantages, at least for the open paver/gravel system is that the community might have to mow the streets.

NHA is still experimenting with the pavements.  We will have to see where these go.

A sobering reminder

December 2, 2009

The following news item was released on December 1, 2009:

3-Year-Old Ind. Girl Drowns In Basement

FORT WAYNE, Ind. (AP) — Authorities say a 3-year-old Fort Wayne girl drowned after she fell into a sump pit pump pit in her family’s basement.

The Allen County coroner says Alexis Stark-Bork was pronounced dead at a hospital soon after she was found in the pit about 2 a.m. Saturday.

Police say Alexis was last seen watching television in the home’s living room. About 20 minutes later, the girl’s parents noticed she was missing and she was found face down in the pit.

An officer reported finding the pit’s cover about 6 feet away underneath a futon.

(Copyright 2009 by The Associated Press. All Rights Reserved.)

What a sobering reminder.  I have heard of drownings where a toddler has fallen head first into a regular 5-gallon bucket.  I never thought about a sump pit system, even though a sump pit is a bucket of sorts.  In fact, I have seen cases where a regular 5-gallon bucket was used for one.  A sump pit holds water like a bucket; but, unlike a bucket, when enough water builds up in the sump pit, a float switch is supposed to activate a pump that empties the water.  Even though the lid not being on the sump pit appears to have been the reason this child drowned, other issues could be involved.  For example, even though the toddler would have raised the water level in the sump pit, why didn’t the float switch activate the pump and lower the water to a safe level.  Likewise, I have also experienced many other cases of problematic sump pit systems, which before I would have only considered as potential moisture problems. Now, I see them as potential safety problems too.

First and foremost, sump pits are supposed to have lids.  That point is pretty obvious in this toddler’s case where the lid was not used.  The obvious lesson is to make sure that if the sump pit has a lid, USE IT.  Sump pits can be deceiving.  When water is not flowing into the pit, seeing the water in the pit can be difficult for an adult–and probably impossible for a toddler.  In fact, in my own sump pit, I have to check the position of the float switch sometimes to determine whether water is in it.  One particular time stands out in my mind when the float switch failed to activate the pump.  The sump was filled to the brim and I could not notice it until the area around the put got wet.

Furthermore, I know of at least three sump pit designs and I would be very safe in assuming many others exist.  The various sump pits do not have interchangeable lids.  Therefore, make sure to use the right lid for the sump pit.

That is not the end of the discussion, however.  Manufactured sump pits have a rim specifically made for a lid.  Homemade sump pit systems, such as 5-gallon buckets or plastic barrels, don’t.  Someone will likely argue that the latter have lids.  However, when their lids are cut to allow access for the plumbing, they are likely not structurally able to bear the same weight as the manufactured lid.  I have seen a variety of lids that were well constructed and possibly could work as well as the lid manufactured for the sump pit.  More often, I have seen lids that are not well constructed.

But, let’s assume that the lid is well-constructed, the most common material I have seen used is plywood.  So, let’s see, a wood product being used over a sump pit that contains water or is in a moist environment.  Over time, the wood can rot (and I have also witnessed that), rendering the lid useless as a safety device.

The bottom line is that homemade sump pit lids do not meet safety codes—so, just don’t use them.  Likewise, manufactured sump pit lids are not made to be used on homemade sump pits.  So, don’t use homemade sump pits.

Someone will likely argue that if sump pit is not located in basement where a child can find it, why use a manufactured sump pit, right?  Any parent or other person who knows kids will tell you that kids don’t always go only where they should.  Again, just use the right sump pit and lid for the job.  If that argument is not reason enough for some people consider this point.  If a person does use a lid that is designed for the sump pit or uses a sump pit that was not designed for safety, although I am not a lawyer, I can see where that person probably has just surrendered pretty much any legal defense.

Assuming that the correct manufactured lid was used for the correct manufactured sump pit, another factor to consider is that manufactured lids have a locking mechanism on them.  The more expensive sump pits, particularly those used with radon mitigation systems, have lids that have fasteners, such as screws.  The most common, and generally least costly, types of sump systems have a lid that twist-locks on the sump pit.  With these types of sump systems, the lid and sump pit rim have tabs.  The lid is inserted into the rim of the sump pit with the lid’s tabs misaligned with the sump pit’s tabs.  The lid is then twisted so that its tabs slide under the sump pit’s tabs, locking the lid in place. If the sump pit does not have a locking lid, get another system that does have one.

Even with sump pits that have locking lids, many times I have found the sump pit lid only sitting inside the rim and not locked.  In some cases, twisting the lid to lock it is not possible because the concrete around the sump pit lid had pushed the rim inward; making the lid/pit fit so tight the lid cannot be turned.  The lid should be set in the sump pit rim when the concrete is put around the sump pit during the pit installation.  Further, before the concrete sets, the lid should be twisted back and forth to assure that is will work properly.

Even if the lid fits and can be twisted, I have found many cases where the pipe from the sump pump prevents the lid from being fully locked.  For twist-lock sump systems, the pipe is usually supposed to be installed so that it is centered in the sump pit.  Manufactured lids have a slot that fits around the pipe, so that the lid can be set in place around the pipe.  When installed properly, the pipe is at the end of the slot in the lid, and the lid can be twisted and locked.  If the pipe is not centered in the sump pit, but is installed more toward the rim, the lid can only be twisted with difficulty or not at all.  Therefore, be sure to test the pipe installation to make sure the lid works before the pipe parts are glued or cemented together.  Check twice, glue once.

Speaking of plumbing, somewhere in the plumbing system, a check valve should be installed to prevent water in the pipe from re-entering the sump pit.  In most basement sump pump installations, the pipe runs vertically a number of feet before it turns horizontally to exit through the foundation wall to points thereon.  When the sump pump empties water from the pit and then turns off, all of the water in the vertical pipe can flow back into the sump pit due to gravity.  As the water in the vertical section flows back down the pipe, the water can also siphon water back from horizontal pipe sections.  A check valve allows the water to only flow in one direction–up the pipe.  With a check valve in the plumbing system, when the pump shuts off, water cannot flow back into the sump pit.

Without a check valve, a sump pit can partially, and in some cases fully, refilling after the pump shuts off.  Least case, the pump constantly cycles trying to empty the sump pit because the pit refills as soon as the pump shuts off.  The worst case is where a potential drowning situation could occur if the sump pit only refills so that several inches of water are in the pit, but not enough for the pump to be actuated.

Even if a check valve is installed, they sometimes fail, such as when grit in the water causes the valve to get stuck open.  So, first, make sure that a check valve is installed in the plumbing.  Usually, one is installed right at the pump or within a few feet of it.  In most cases, the check valve must be in a vertical position to work correctly.  For those who are not sure what a sump system check valve looks like, I recommend taking a trip to the ol’ Home Depot to see what one looks like.  Although they may vary in appearance, they normally have the same shape or markings.  If a check valve is installed, do not fully trust that it is or always will be working.  Periodically, operate the sump pump to the point where it shuts off.  When the pump stops, check to see if water is flowing back into the sump pit.  A little likely will back flow; but a lot indicates a check valve problem.

On the other hand, another problem I have found is where the float switch or pump is not working properly.  Float switches do fail, and one could fail so that the sump has adequate water in the sump to drown a child.  Usually, people do not discover that a float switch has failed until a basement floods or other moisture problems occur.  The lesson here is to periodically check the sump pump float switch by elevating it to the point where it activates the pump.  Check to make sure that the pump continues to operate until the sump pit is nearly empty.  By the way, be sure to use a non-conducting material, such as wood, to lift the switch, just in case an electrical “leak” has energized the water.

When the float switch fails, a person has three alternatives to fix it.  The first one is to replace the pump and float switch as a unit, which is how they are usually sold.  The second alternative is to replace the switch, which is tricky for most home owners because the switch needs to be watertight to prevent an electrical short or worse an electrical leak that energizes the water.  If the home owner is not extremely handy, the pros should replace the switch.

The final alternative is to install a float switch parallel to the one that is not working.  The problem that occurs with this installation is that the float switch might not be adjusted properly.  Manufacturers of pump/switch assemblies preset the distance of travel for the switch relative to the pump.  When installing a replacement float switch in parallel with the old one, the installer needs to manually set this distance.  That setting can vary widely depending on how the switch is installed.  The problem is that if the switch has too much travel, the sump could have more than enough water to drown a toddler.

Just as likely as float switch failure, though, sump pumps also fail.  I had one case of a basement flooding where the sump pump was literally encased in minerals from the water.  In areas like southern Ohio, which has high mineral content in the water, concretions like this case can occur.

Grit carried into the sump pit with the water will also eventually doom most pumps.  The impellers on most pumps are normally plastic, and the grit can chew them up.  In some cases, the grit or even pieces of plastic from a degrading impeller can jamb the impeller, causing the pump to fail.  I recommend that the sump pit pump be set up off the floor of the sump pit a couple of inches to provide a grit settlement area.  A brick laid flat provides just about the right distance above the sump pit floor for this purpose.  The grit in the settlement area should be cleaned out ever year or so because this area can fill with grit where it can once again get into the pump.

Another electrical problem that can occur with sump pumps is that some codes require that they be installed on a ground fault circuit interrupter (GFCI) outlet or circuit.  Based on personal experience, a GFCI can kick out for some unknown reasons that have nothing to do with a short.  Most people do not discover that the pump is not working, again, until a basement floods or other moisture problems occur.  I recommend that most people install a battery-backup sump pump.  Until now, that recommendation was based merely on the threat of a basement flooding.  I now have another reason for that recommendation.

Even when a float switch or pump has failed, water can back up and pool below a basement slab, hiding for a time the fact that the sump system is not working.  Further, for most homes, periods can occur where the sump pump does not work frequently, leaving the sump pit with adequate water to drown a toddler.  In most cases, home owners treat sump systems as an out of sight, out of mind item.  They should not be.

The sad fact in the case of this toddler’s downing is that a thing as simple as the lid may have been the most important factor in saving her life.  Even if the float switch and sump pump were operating as intended, the toddler could have fallen into the sump on top of the float switch.  In which case, she could have submerged the switch, preventing it from actuating the pump.  If she had fallen in such a way that the sump’s water level was raised enough to allow the float switch to activate the pump, the water might have been lowered enough for her to survive.  No matter what, a lid would have prevented her falling into the sump.  And, I have seen my share of sumps that did not have a lid installed.

Even if the sump pit has a lid, if it is located in a room or closet away from the rest of the basement, make sure that room or closet has a door with hardware that a toddler cannot operate.  If the sump is located in a crawlspace, make sure the crawlspace is not accessible to any children.

Up to this point, I have covered all of the mechanical aspects of how problems with a sump pit system could have contributed this toddler losing her life.  Now, I will put on my other hat as a father (whose kids are now all grown) and a former volunteer EMT.  A toddler can drown in less than four minutes and in only a few inches of water.  If they fall head first into a bucket, or in this case, a sump pit filled with water, they do not have the upper body strength, or even know how, to get out of the situation.  A toddler’s weight distribution is different than an older child in that they have more weight distributed toward their upper bodies.  In effect, they are top-heavy.  Once head down in the water, they would have a very difficult time getting out of it and definitely not able to call for help.

This leads to the most important lessons of all.  A parent should constantly be evaluating the home for potential safety problems for kids.  I encourage all parents to take available kid safety classes when they are offered and freely exchange kid safety issues whenever they hear them.  While some aspects of homes remain fairly constant, designs, materials and systems are constantly changing.  My grandparents began their lives in homes that did not have electricity–now, it is all around us in our homes.  If you do not know about child safety in the home, here is a good place to start:  http://www.homesafetycouncil.org/index.asp.

I will close this final lesson, and it is one that most parents have heard before.  Always know where your kids are.  For toddlers, always have them within sight or hearing range.  Train yourself to listen for when they are not within site.  Most parents do; but the important skill is to make sure you keep attentive.  Drowning can occur in less time than a phone call.  If you don’t hear your child and you know they are not napping, then check up on them.  Always be in touch with them somehow.  Remember, less than four minutes can be the difference between you watching your child grow up or your having a lifetime of regret and guilt.


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