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Radon soil gas, water w/radon, & other household air quality mitigation plans

Radon soil gas, water w/radon, & other household air quality mitigation plans

Old 01-18-16, 02:35 PM
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Radon soil gas, water w/radon, & other household air quality mitigation plans

Howdy. I have two radon issues Iím trying to mitigate as effectively as possible for now, as soon as possible. Not necessarily permanently, but if that fits the fix thatís fine too. Reason why I donít care about permanent fix at present is because Iím planning a bigger addition and remodel in the next 2 years. I need time to plan and fund this but donít want to leave the radon as-is for 2 years either. Want to have it resolved.

I have radon in my household air that I think is being induced from my crawlspace area and also via my well water that is pumped to my walkout basement water cistern until household faucets call for it. So I have two radon sources: my crawlspace dirt and my water cistern off-gassing radon (confirmed to be 20,000 pCi/L by water labs). My electronic and charcoal testing has shown the radon is strongest at these two places, and weakens as the tester moves further from the areas. The strongest crawlspace reading is next to the corner concrete wall that has my cistern on the opposite side, located in the walkout basement slab addition. I may be getting some radon gas through the basement slab, but readings seem to stem from the cistern room and weaken as I move away from it.

My unfinished crawlspace is a 700 square feet rectangle that has a 4í tall interior ceiling in 90% of it; the other 10% is 3í tall. I have 4 passive vents from the crawlspace to the outside air that are 2Ē tall by 8Ē long. Iíve been leaving these open from May Ė October and closing them with foam panels during the remaining 6 months so pipes donít freeze. It is not tightly sealed with plastic, or encapsulated. Iím sure it isnít ďairtightĒ but thereís no visible air leaks I can see or feel either, or big cracks in my exterior walls, etc. I calculated the cubic feet of crawlspace air to be about 2,760 Cubic Feet. This crawlspace is adjacent and upwind/uphill to my concrete slab walkout basement addition. So my basement is downhill and downwind from the crawlspace.

My upstairs addition and area over the crawlspace is about 1,800 SF and the walkout basement below is about 900 SF. Total household square footage above the crawlspace and basement slab is 2,700.

I want to accomplish these objectives with immediate action:
1. reduce radon gas in household air to under 2 pci/l.
2. inject small amount of warmed household air into the crawlspace to keep it dryer and warmer in winter (pipe freeze and condensation prevention).
3. induce enough positive pressure into the crawlspace to help block radon gas from entering it, and push out what does enter by venting it to outside air by the crawlspace air leaks and/or vents that I could also uncover.
4. draw more fresh outside air into the household by the exhaust fan pushing household air into the crawlspace. My thoughts are the right balance of exhaust fan volume and crawlspace leaks/vents might allow my household to draw air indoors from windows and doors and other common energy leak points.

Proposed soil gas solution:
If I place a variable speed fan (up to 125 CFM) in the floor of my home that blows an undetermined amount of household air into the crawlspace, might I create a positive pressure that will help keep infiltrating radon gas and mold/allergens out of my crawlspace? I thought the pressure might make the gas rise elsewhere where itís easier to rise and escape. Or if gas does enter the crawlspace from the soil, it is pushed out leaks/vents by the incoming household air.

I have two different fixes that I think may remedy the radon-water problem I have.
1. First choice is to place a PVC pipe (maybe a 2Ē diameter) into the lid of the water cistern to suck the radon gas from the waterís surface area and blow it outside. Iíd either tie it into the existing radon evacuation pipe and use that fan or run a stand-alone 2Ē pipe with a small, dedicated fan and feed it outside like a mini-radon system.

2. Second choice, release radon gas in the well water before it enters the home.by pumping it into an outdoor cistern and spraying (a coarse spray, less likely to make snow when cold). Then transfer it to the indoor cistern after it has sat for a couple of days. The cistern would either be in a heated shed, next to my outdoor multi-fuel boiler/furnace, or Iíll put a tank heater in it during the winter.

Please keep in mind I have the usual household passive vents for 3 toilets, a 3Ē chimney for gas water heater, chimney and breather pipe for gas boiler (furnace not in use, broken), about 3 utility floor drains that drain to daylight, a septic field, as well as a 8Ē chimney pipe that removes woodstove smoke in the winter, 24/7. And two 75 CFM bathroom exhaust fans. Those are the other routes air can travel more freely from or into my house. I find it hard to believe with all of these avenues for air to stabilize that my household air doesnít stabilize pretty easily and quickly. But Iím not sure.

What do you think about my proposed fix ideas for my multiple source radon? Is my theory right, partly right, or crazy? Might it work? Its either my alternate plan or pay someone upwards of $2,500 to cover my crawlspace floor, poke a hole in my basement foundation for a radon siphon, and link the slab suction to the crawlspace soil and evacuate it to the outside as traditional radon mitigation goes. The two companies that gave me quotes arenít sure they can connect a PVC pipe from the water cistern to the main fan, because unless the tank is very tightly sealed it might lose a lot of pressure and not pull away the soil gases strongly enough from the slab and crawlspace. But maybe a booster fan could be installed on the cistern pipe?

Thanks much for any suggestions!
Old 02-05-16, 10:39 AM
Join Date: Feb 2016
Location: United States
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Watching with intense interest as I have a basement with 1/2 crawlspace, half concrete floor, and need to control our radon levels.

Old 02-05-16, 11:58 AM
Join Date: Oct 2008
Location: New England
Posts: 10,524
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Hi John, you might be better off starting your own (much shorter) thread as long posts often go unanswered. I could answer 5 posts in the time it takes to read just the start of this one.


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