Radon mitigation & sump

This one has me puzzled.

The radon system is installed in a pump crock. I can only figure that when they tested that they may have had high levels of radon in the water.

Why would you install a radon system into a crock for a sump pump?

The basement floor had excessive cracking that appears to be from hydrostatic pressure & there is evidence of moisture. The cracks appear to be worse due to the caulk that was used by the radon mitigator.

The lid to the crock was sealed for the radon system. The lid doesnt flip open and is sealed for the radon system. How are you supposed to test the sump pump.

If the pump fails then there is a problem with water intrusion.

I feel that the radon & sump should be independent of each other.

I recommended that the radon company and a plumber be contacted to evaluate the pump and to see why we installed the radon system in the crock.

What do you think?

There where also numerous hairline vertical cracks in the foundation walls.


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How old is the radon system? Maybe it was installed before ongoing maintenance issues were thought of and they just did it the easiest way they could.


The house is 10 years old.

Not sure when they where installed. No date on system tag for radon.


Well, that is too new for someone other than Uncle Fred to make a mistake. In my opinion the system looks bad, but we do not deal with Radon around here much, so I’ll defer to someone with more experience.

I’m no Radon expert but according to my brother-in-law who is a Radon mitigater this is not an uncommon way to do Radon mitigation. The idea is to depressurize the area below the slab. That’s why it important to seal any cracks in the floor and monitor the slab for any deterioration of the caulk and look for any new cracks. Post mitigation Radon testing should have been done to determine the effectiveness of the system. It would also be a good idea to do periodic testing to determine the continued effectiveness of the system.

From the photo’s I would not be able to tell that, that was a Radon system. But you say that it is tagged saying Radon System?

I would have thought that it could have been a sewage grinding pump sump. But then again there isn’t enough information to make that guess as to what I see in the photo’s.


That is how they do it in Columbus.

Looks OK but remember I am not there you are.

I think it is the cheap way for the radon specialist to install.

When I see a floor with excessive cracking & water intrusion. I want to see the pump & the foundation drainage. How can the pump be accesable if it is in a sealed radon mitigation system. Seems like a cheaper way for the radon system to be installed.

I see to many crocks filled with water & a defective pump that is why the floor gets cracked and water intrusion from hydrostatic pressure.

I sure dont want to be the guy that gets the blame when the basement floods or gets a puddle.



If it was in my house and the sump ran frequetnly, I would want a backup sump or at least a sensor/alarm to tell me when the sump pump failed to run.

When the owner had the mitigation system installed he may have been given more than one option. I suspect he chose the most inexpensive one.:shock:

Using a sump crock is a preferred way to mitigate, it makes for better suction than a hole in the slab and some dirt removed. The idea here is that the foundation drain system makes for better depressurizing since it covers a large area and not one small suction point.

I have seen installers use clear plexi covers so you can see into the crock, those covers also get sealed.

You can go to the website for Radon Away for a look at the items sold for mitigation that we come across. ASHI also has a one page checklist for inspecting mitigation systems.

This is the most cost effective way to mitigate radon and often all you need is a passive system to get the levels down. I routinely tell my clients that the open sump crock is probably the first and highest source of radon. I regularly recommend adding a sealed cover and vent to reduce radon levels. Just putting a sealed cover on it can get the levels down below 4 pCi/L. Then if you need to get it lower add the inline fan.

You mentioned there are numerous hairline cracks in hollow block basement wall(s).

so while these pump n pipe systems can certainly help lessen Radon gas that is under a basement floor, they cannot help lessen any radon gas that can certainly enter through cracksn other openings in basement walls, especially block. With…Poured, ya better watch out for them rod holes that are often only plugged with a cork that will disolve in a lil time. And some will leak/allow radon to enter pretty quick…careful.

back to block walls, whether there is a visble crack on the inside or not, what matters most is whether there are cracks etc on the Outside of the hollow block wall(s). Block walls often have hairline to 1-2++ Inch wide cracks on the outside and one may not see any or one hairline crack on the Inside of basement.

Again, this is where water first-enters INTO the hollow blocks and, because of gravity this water will drop/travel down within the cells of blocks and most often enter at/near/along the cold-joint,cove and onto floor.

Yeah, when Many see this water at the bottom of wall and floor coming in, they very often think/assume its because there is a problem with the drain tile or problem under the floor, some even bs `n say its due to hydrostatic pressure under the floor and this is NOT true!!! 90% of the time they are mistaken!

Anyways, through these openings on the outside radon gas can enter into the hollow blocks and if the top of walls are uncapped or, have open JOINTS Between the solid blocks then, Radon can easily travel up `n into first floor, it sure can. No sump system can do anything about this,sorry.

And radon `n water/moisture can also enter through tiny little openings/pores on the outside of block walls or when the parging that was done becomes loose,cracked.

To stop mold, they say…we must stop/eliminate the water/moisture so, when this water enters basement walls it increases the chance of mold, sure does:mrgreen: …90% of basement leaks/seepage is due to OUTSIDE openings. Gotta go outside to stop/prevent the water from entering cracks etc, to help stop radon gas,efflorescence,termites and quite a few other of our lil buddys.

Heres another place radon,water,insects can enter :-k ....a brick ledge that is Often poorly sealed and often, underground a bit. Yep, keep raising that grade and NOT sealing the brick ledge and any bricksn mortar joints that`ll be underground is a… Mistake, Not a good recommendation.

Radon can enter from the soil Through these un-sealed underground ledges, doesn`t matter what kind of basement wall there is. If/when it enters high at that point its…Inside the house. So ya may want to, much more frequently, recommend to Your clients to, seal/tuckpoint,caulk,waterproof ANY openings instead of raising & sloping the grade or longer downspout extensions etc.

These Surface water diverting techniques do Not seal openings that allow all this shtt to enter peoples homes, Got Milk? :mrgreen:

Oh, i been hearing pretty often lately that, diverting some surface water 5-10’ away from a house can/will lessen hydrostatic soil pressure, lolol.

Not exactly folks, sorry. Ya think by diverting SOME-Surface water/rain away will somehow keep the same water from going into the rest of the soil several feet away from/around a founadtion? hahaha!

Eh, this amount of surface water that ya diverted several feet away is still going to percolate into n through the surrounding soil and, expandn create hydrostatic pressure for pete sake. Geez, rainwater will still go into the soil that is 10’,20’ 30’ away from the basement walls! And, its going to expand! lolol If you were lucky enough to divert ALL water several feet away from the entire DEPTH of a basement wall, ya really think the adjoing 10-20’+ isnt going to expandn create pressure? Cmon ya good HIs. Think. ](*,)

And what about tree roots that grow along & against basement walls? :-k

GC…the last time i played a Blank-tape at Full blast the mime next door went nutzzzzz

Good for you for checking out the safety of your basement! We just moved house and conducted a similar test. Our level was 212 Bq/m3 using the 3 month test over the winter.

The first thing I did was buy this digital radon mitigation detector I did some sealing mitigation with caulking around areas suggested in the pdf manual you probably received with your test? Over the past 2 months the levels in my basement using the radon meter are around 190. I find they fluctuate quite widely from day to day (we’ve had 50 - over 400).

As such, we decided that we definitely want to mitigate this situation.

I’m quite confident that mitigation is something a homeowner can do on their own, and I will be going ahead with it this summer. My understanding from some research is that you are looking at over $2,000 to have someone do the job. I feel that the job can be done DIY-style for around $600 including the radon meter.

So far, I purchased a $60 manometer and did a field test under my basement slab to make sure there is air flow (there is) and determine based on these measurements (and square footage of slab) what size of fan I would require. Turns out this fan will work
which is great because it is a low power consumption unit (15-21 W). My understanding is that you can hardly hear this even in the same room. I will be installing in the utility room.

I will probably use 3" PVC and a couple of 4" to 3" reducers from fan-pipe connections as well as a couple of angled pieces to provide the venting from slab to outdoors. This can be purchased at home depot for maybe $100. I will likely rent a 3" concrete drill for getting through the slab. I already have an unused 4" fresh air dump for the old furnace. I will repurpose this hole for my radon vent.

Also, if you have any moisture/humidity issues in your basement - this will (apparently) deal with that, since the air under the slab is basically being vacated, which creates a negative pressure which prevents the radon/moisture laden sub slab air from getting into the basement.

If you have a sump pump etc, connected soil crawlspace etc…you may require more steps than those outlined above. The pdf manual you received will outline what to do in that event.

I figure this whole job should be a day.