Radon gas mitigation system

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  #1  
Old 10-16-18, 03:40 PM
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Radon gas mitigation system

Hello all,

have recently found out I have high radon levels in my home. My plan is to install a mitigation system.

I am not totally convinced of the science behind the suction beneath the "foundation method" and was wondering if anyone can clear up any ambiguity.

I just have a hard time believing that placing suction at one corner of your basement floor will provide enough to satisfy the requirements to reduce the value of radon.

Thanks in advance!
 
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Old 10-16-18, 05:18 PM
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Not sure why it doesn't make sense but here goes: The pressure under your slab is lowered due to a fan pulling air out of the space. This causes air in your home to be pushed into the space under the slab. Hence, the air with the radon in it was exhausted outside your home instead of rising through the slab into it.
 
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Old 10-16-18, 06:44 PM
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Hello Stickshift,

Yep...i get all that. I am just wondering how a small suction fan can mitigate that much area. For example if the fan assembly is placed in one corner of the floor, then essentially it would have to draw air from quite a large area underneath the slab specifically the entire square footage of the basement, which in my case is around 2000 sq. ft.

I am just curious is this type of mitigation system will do the trick.
 
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Old 10-17-18, 04:42 AM
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Where I live in Pennsylvania, radon mitigation systems usually provide an inlet pipe located in a far corner of the basement plus the discharge pipe with the fan located on the other end of the basement that allows outside air to purge through the underside of the concrete slab, venting that area and discharging the radon ladened air to the outside. Some systems are installed as you stated but they are usually for minimal levels of radon.
 
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Old 10-17-18, 07:01 AM
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sometimes more than one fan is needed. Its going to take the path of least resistance so it will always go towards the fan. Might not even need a fan. The chimney effect might be enough pressure difference.
 
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Old 10-17-18, 08:45 AM
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Your system may depend upon what is under that slab. With a new installation there would/should be a layer of gravel and some pipes extending to farther areas. When an existing basement has no gravel to allow air movement results may be poor.

Providing an inlet in the far corner may help, but if that slab was poured over a clay surface it might do no good. But your slab can be tested and the company doing so should know how.

You just said "high" but didn't give that a number or say where the test was done?. Some people consider 10 to be high where others would be concerned at 200?

Bud
 
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Old 10-17-18, 10:19 AM
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Hello

@Bud, I think that you use picocuries in the USA where we measure in Bq per cubic meter. Mine came in quite high at 701. The guideline prior to 2007 in Canada was 800, now they changed it to 200...so yes...I am quite high.

This reading was taken from the basement level using a short term 48 test using a electronic radon device....the safety siren PS3RD model.

I have come to understand that short term tests can give false positives and false negatives, so I am now conducting a 7 day test using the same machine.

In my research I have found that this particular model, the "safety siren PS3RD model gives you consistently higher than normal readings as compared to government sponsored tests.

I ran a 48 hour test upstairs and it came in at under 200 Bq/m3.

I did a number of days of research on Radon gas, and understand that these values are not "concentrations" but rather "event" per second. A number of factors can influence these tests as well, like cell phones, plasma tv's etc etc...and my house is full of these items.

Regardless, I think it wise to reduce any value with respect to radon...so if the test still comes in under the EPA guidelines, I will still install a system.

No doubt the company tomorrow will run there own test......

Also, my slab is over crushed rock, so there is no immediate soil base to deal with.
 
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Old 10-17-18, 10:48 AM
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It sounds like you have an understanding of the pros/cons of radon testing... there are a lot of opinions out there about it. So I'll focus on your technical question.

The radon fan/pipe method does work well. There's likely some loose fill (gravel or even loose dirt) under the slab, so the fan will suck all that air out, including most radon along with it. But it all does have to do with how large the space is, and if there are any foundation breaks. My basement has 3 separate rooms/foundations, so it needed 3 separate holes drilled, pipes, all into one fan.

It sounds like you're in the lower end of commonly seen levels, so the fan/pipe solution is a good, cost-effective solution.
 
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Old 10-17-18, 11:09 AM
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I had to do some conversion to relate to your standards. This article provided this quote:
"The U.S. Environmental Protection Agency has maintained a radon action level of four picocuries/litre (pCi/L) since the 1980s. This is equivalent to approximately 150 Bq/m

The EPA notes that concentrations of radon below this level still pose a risk and recommends Americans
consider mitigation if radon levels are above two pCi/L."

A little math and that says by our scale your reading of 700 was about a 14 here. You also mentions a 48 hour test upstairs but not where the 700 reading was found. Canada's guidelines specify frequently occupied spaces thus if you measured a basement that number would be of less concern

But back to your question. With your slab and low initial readings a single vent location should be fine.

Bud
 
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Old 10-17-18, 12:34 PM
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@Bud and Zorftd,

Thanks for all the information guys.

@Bud...yes the 700 number was downstairs in the basement, and although it is finished we rarely occupy this space...The 200 level was upstairs.

@Zorfdt...you brought up an interesting point with regards to the basement slab....to be honest I am not sure if it was a single "pour" or there are multiple slabs. the reason I say this is that there are a number of rooms located downstairs each with a door...ie the furnace room, rec room, and bathroom.

I am assuming, (hoping) that the slab was poured then the partitions were built on top of the slab to accommodate the separate rooms....(i would not think a contractor would bury wood framing inside concrete to make a wall).

The "roughed" in construction that I have ever witnessed was 2 x 4 fastened to the slab to provide the framing for walls...I have included a rough drawing of my basement...the house area is a total of 3000 sq feet, so my assumption is the basement area is about half of that or less.

Regardless, there is one area of the downstairs where the mitigation system could be placed that is perfect. This location is the furnace room. This room occupies an oil burning furnace, and a roth oil tank, but it is also extremely large so it could accommodate the fan and piping.

I did some research on NS building code, and I need to be 6 feet away from an opening window, and 6 feet away from an air inlet. (EPA suggests 10 feet but NS code is 6). The other side of this wall provides both as there are no windows and the inlet for the furnace is at least 8 feet away and protected by the exteriour wall design, (see "RADON VENT PROPOSAL PIC).

Some codes demand that the vent pipe is routed up and through the roof. apparently up in Canada they don't do this due to the cold effecting the motor, and condensation freezing and interfering with the vent operation. Here in Nova Scotia, they vent them all out the side of the house.

I also checked on the oil tank vent pipe and apparently this is not an issue.
 
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Old 10-17-18, 12:37 PM
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i should also point out that the basement layout is not to scale...nor is it situated properly. if you look the external house pic, then look at the basement layout and turn it 90 degress to the left in your mind...it will conform to the actual structure.
 
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Old 10-18-18, 09:56 PM
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So....had the radon mitigation expert in today, We figure that the basement floor has support footing that basically runs from one end to the other end of the house. If you take a look at my last post, the footing would basically cut the living space down the middle with the furnace room, bathroom and rec room on one side, with the bulk of the living area on the other.

It seemed a perfect place to put the unit in the furnace room but I cannot see how it will be able to draw air past a footing (??)...he seems to think there will not be an issue...does anyone out there agree with this assessment...and if so...how would that work exactly?...in other words do footings go down 4 feet...or do they rest on top of the gravel fill?
 
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Old 10-19-18, 03:16 AM
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Interior footings should be just under the slab, no frost line down there, and typically just under the individual support columns. My basement is similar with 4 cement filled columns under a center support beam. So if you have center support columns you probably only have footings under them. I suspect he is correct, all will work out fine.

Bud
 
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Old 10-19-18, 07:05 AM
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@Bud9051,

Thanks for the information. I am also in the process of cleaning out my air exchanger, he says that without the exchanger levels can almost double! I am hoping rinsing the core and changing out the filters will have some effect on the levels.

On a side note, we let the radon detector run downstairs for about 4 days now...it still updates itself every hour (on the long term setting), but with the detector in the exact same location that I got the high 700 bq value, it is now reading 378.
 
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Old 10-24-18, 11:11 AM
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Ok Guys,

Just installed the mitigation system and they checked for flow on the far end of the house and according to them is was more than satisfactory.

The unit is nice and quiet but I am wondering when I will see a substantial decrease in Radon levels??

Before the install I was at 397 Bq/M3...following the installation the level has dropped exactly 2 points per hour, (the unit beeps every hour is above 200 Bq then displays the average for the hour).

So now I am at 358 after about 18 hours from when the fan was selected "on".

I was thinking I would see a dramatic decrease in levels after a couple of hours.....am I mistaken or does it take some time to "mitigate" the levels down to below an EPA standard?

Thanks
 
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Old 10-24-18, 11:34 AM
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I agree with you, although I'm not a pro in this field. I assume they installed a u-tube manometer. What is it reading?

Bud
 
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Old 10-24-18, 12:28 PM
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Its reading close to "1" on the suction scale. Apparently thats pretty normal.
 
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Old 10-24-18, 01:02 PM
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Between 0.5" and 1.75" is what I saw for normal so that sounds good.
Have you asked the company who installed the system?

I'm learning here. Where did you measure the 358 Bq/M3? I would try testing in other places to see what levels you get. I'm concerned that they have addressed the sub-slab issue but that may not be the only source or they aren't depressurizing the entire space below the slab.

You said they tested to far corners and they were fine, did they drill any holes?

Bud
 
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Old 10-24-18, 01:44 PM
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yes...the slab is definitley being evacuated..they drilled test holes and checked.
 
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Old 10-24-18, 02:18 PM
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Try taking radon measurements in other areas of the basement, changing other things as little as possible.

Bud
 
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Old 10-24-18, 02:32 PM
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well...its slowly going down...about 2 bq per hour...its at 351 now and I anticipate it being 349 in an hour and most likely lower than that tomorrow morning.

was just wondering if anyone knew the time frame for mitigation.
 
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Old 10-29-18, 08:08 AM
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Since my last post I have left the unit plugged in. We went on a short vacation and when we got home the readings from the unit indicated 241 bq/m3 on the long term setting and 141 on the short term setting.....which I consider still very high.

In conversation with the installer, he advised to give Pro Siren a call and speak to a tech to identify a problem with the way I am operating the unit.

The Tech suggested that the unit be "cleared" by holding the button down for 20 seconds and begin a new set of testing as these numbers that I am reading are also taking into account the high levels pre mitigation, and in order to get accurate levels I would need to start over.

I should see something in less than 48 hours, and will post accordingly.

Thanks
 
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Old 10-29-18, 08:19 AM
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Well, maybe, but one has to always wonder if the advice is real or intended to deflect the complaint. Time will tell. Make notes, date and time, for all conversations. Hopefully they will not be needed.

Bud
 
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Old 10-29-18, 09:08 AM
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@Bud9051,

I hear you...and will take notes.

However, by looking at the operating instructions for the unit it seems to coincide with the advise the tech gave me.

Here is an except from the manual with respect to the long term setting;

Long-Term Display
The display for the long-term reading is an average of the
levels of radon gas for the length of time that the detector has
been powered up or last reset.

So....(as you know from my previous posts), it was nitially 701 bq/m3 downstairs...I then reset it and it dropped to slightly over 400 bqs, therefore it was over 400 since the last reset. Once the installation was online it began dropping approx 2 bqs per hour...then seemed to stablilize at 241, which was the value when we got home yesterday morning...( it may have been lower if the weather was better....it seems that low pressure systems, wind and rain increase radon levels and thats the kind of week it has been up here).

Regardless, my initial assumption was that the meter would drop off rapidly post mitigation, but apparently these units take an "average" reading following the first sampling which takes 48 hours. Therefore...in my mind...the new "post" numbers were factoring in the old, (over 400), numbers. By resetting the system and clearing out the old memory, I should get a more accurate assessment of my new situation.

The installer is going to run his own test this week, as that was already the plan. But I always like to have a second opinion which I hope the Pro Siren 3 can deliver.

On another note, my manometer shows .8 to .9 suction, and the test hole when drilled on the other side of room showed, in there words not mine, a good negative pressure. Not sure what the values were graduated in, but the number that I saw once they ran the test was a value of .008 on the meter with a vacuum cleaner providing the draw, and a value of "2" with the vacuum cleaner removed.

Also note that I had concerns about the footing which basically ran the entire length of the house. This value was taken from the other side of the footing, so it would display, in my opinion, the worst case scenario.
 
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Old 10-30-18, 12:46 PM
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Hello all, As promised I would report my new radon levels following a reset of the Pro Siren3 device.

The new number is "12"...very happy with that.

Thanks to everyone for there advise.
 
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Old 10-30-18, 12:50 PM
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Thanks for the update.
That is what you were looking for.

Bud
 
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Old 05-21-19, 09:51 AM
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You are sorely mistaken. It is a concern but it has to do with the fact that the soil and rock type surrounding each house is different as well as different types of foundations will allow more of this gas to enter the residence. The soil permeability to radon is also a critical factor here. Every house can be a different situation.

Radon is responsible for the majority of ppl's exposure to background radiation and therefore it is everywhere. In nature radon is not much of a problem since it disperses and cannot form harmful concentrations. Allowed to accumulate in tight spaces it poses a health hazard.

So what if Radon is tasteless, odorless and invisible? Those are properties of the element and not a part of some scam. The test for it is also cheap. As far as the EPA limit, it is set low bc Radon is poisonous and has been linked with cancer. Radon is part of Uranium's decay chain...do you realty want that in your house? When radon decays, it produces all of the elements seen here:http://en.wikipedia.org/wiki/Decay_c...nium_series.29. Many of them are radioactive and can be dispersed throughout your house, getting into the food you eat, air your breathe and carried around with you on your clothes, all the while irradiating you.
 
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