I've read so many websites with info regarding this problem. We found out finally that the smell is coming from the crawlspace and that we have a high water table. The water from the crawlspace isn't making it to the sump pit in the basement area and is just setting in there under the 20 mil cover. When it rained hard some would puddle up on top of the cover as well. That is the problem!
So I put in another sump pit in the crawlspace. I pulled back the liner and dug a nice deep hole and wouldn't you know it was filled with water instantly. Fun Stuff! I put the pit in - dropped in a new pump and ran PVC pipe out and just connected it to the other sump exit pipe by putting in a Y connector. Turned it on after about a hour to let the joints dry and there goes the water out from under my house and away from the house.
Next I filled in the area around the pit basin with gravel all the way to the top. No need to concrete since its a dirt floor. I then pulled back the 20 mil liner and made a few cuts to wrap it nice around the new pit top. Installed the lid and all done.
This was done 2 weeks ago and all musty smells have disappeared ! I continue to run the dehumidifier in the crawlspace and now I can just let it drain into the sump pit - no more emptying the bucket every other day!
If you have this kind of problem and are trying to make up your mind if you want to DIY - just be search to do your research - watch some videos and feel confident that you can handle it before starting.
