TJ - thanks for the info! I assumed it was a linear polymer but couldn't find much detail on the website. Based on the little external info I was able to find on the product, I had limited expectations.

Jambi - my neighbor thinks that my pond is leaking about 150-200ft laterally about 5-15ft below ground level and making his backyard wet. Now, my pond has been here since the 50's or 60's and his yard didnt dry up when I had the pond pumped dry. But he was willing to throw money at it and there was no downside in my view. (His neighbor, who also lives on a steep slop down to the river, has the same issue, with clear water coming out under their foundation. That one thinks it may be a natural spring, after doing some testing)

Kris