AARST_Radon_Reporter_Q42025

8 | DECEMBER 2025 MITIGATION EXAMPLE 2 Another simple ranch house. The difference is, this one had a few more possible complicating factors. After the original system was installed, the radon concentrations went up. It was established that we had PFE under the basement slab and under the crawl space membrane over time. The fact that the radon concentrations went up did not seem too unexpected. It was the end of fall, and the weather was getting cooler. We knew that if we did not address the source, it would be more likely for more radon to enter the house, since the stack effect would be stronger. The standard pathways were addressed, so the mystery became, where is the unaddressed radon entry pathway? * We first put temporary systems on the 3 adjacent slabs (garage, front patio, back patio). Those systems did not fix the problem, so we knew there was a pathway that was somehow disconnected from the house. We sniffed the sewer system, freshwater system, and underground electrical line to see if they were hot spots around those pathways into the house. Nothing showed off, boring. I thought we were going to have to pull up all the carpet and scope all the exterior wall cavities to look for a well or pipe that was causing this disconnected pathway. The homeowners were not completely opposed to this idea, but I wanted to bounce ideas off some of the professionals I mentioned earlier, first. They all gave me great advice and suggested we were on the right path. One of them encouraged me to talk to the original homeowner. I had previously talked to the realtor that spoke with the original owner. I wanted to know if the original owners knew about a well or some other pipe that might convey soil gas into the house. At that time, I was told there was nothing like that. So, with encouragement from others, I bugged the realtor again for the contact information of the original owner. This time I got it. I called and the original owner of this early 1960s house answered. She was an amazing older lady. Super clear mind and what appeared to be (and was later confirmed to be) a great memory. She told me there was a well in the basement by the water softener. I asked if she was talking about the well in the back yard. She confirmed there was also one in the house…by the water softener. I had been in that corner of the basement 10’s of times and had even had a radon monitor setting on the brine tank. The radon concentrations on the brine tank were less than in the middle of the basement. I was skeptical. We ended up finding the open well head under the threshold of the door to the water softener closet. It was blowing 1700 pCi/l air into the house at approximately 10CFM. We capped the well head and put a suction point through the cap, and that solved the radon problem. My PFE data did not help me directly solve radon mystery in this house, but it did tell me where to stop looking, and that is the crux of fixing difficult houses. Get numbers and over time understanding how to interpret them becomes second nature. Believe the numbers and the numbers will set you free. *Story condensed to help prevent drowsiness