I second Cecils comments, I had a area on back side of my dam that stayed wet (approx. 4'wide by 10'long, no depth just wet) last summer when we had no rain for a couple months and everything real dry. Talked to my contractor several times and always got the (I'll stop by and take a look)it is now 9 months later and still no word from him. So after 3 months and several calls to him and no response, I bought the benonite from my well drilling supplier $11 a 50lb bag. I bought 5 bags 3 different times and used a feed scoop to just broad cast it in the area on water side of dam straight across the dam from where my damp spot was located. Made my bentonite about 2 to 3 inches thick and area stays real white for long time so you can see easily where benonite lands It is now 9 months later and my neighbor and I both think the problem is fixed because he would always mow up to my dam and he always would leave muddy trail where he would mow in this area, seems to have worked for me too. All seepages are different so like Cecil says no guaranties, but for couple hundred bucks it was worth the try to me. Hope this helps. PO