(I can't find a forum on drainage issues so I'm trying this in several places)

We have a creek that comes down the hill and past the house, but in the heaviest cloudburst it has never left its banks. The problem is with underground seepage that goes under the house and makes our crawlspace damp. We will probably install a crawlspace liner/encapsulation system, but we still need to eliminate as much underground water flow as possible. Here's the crazy idea. It's similar to a french drain, but it's for groundwater, not surface runoff:

We want to dig a trench about 2 feet wide and three feet deep. We'll angle and place it at the best location to intercept the seepage, and give it a gentle downward grade to drain back into the creek. We'll place it so the creek doesn't back up into it during heavy rain and high water.

Here's the tricky part that I want to ask about:

I want to line the downhill side of the trench, and the bottom, with a waterproof barrier like heavy-duty vinyl or plastic.

We'll backfill the trench with gravel and put in a large perforated pipe as well. A layer of landscape fabric will go over the gravel, and over that will be ordinary soil and grass (remember this isn't for storm runoff, but underground creek seep). The main thing I want opinions about is the waterproof barrier. We really want to stop that seep, and this seems to make sense as long as we provide the drainage pipe. What do you think? And do you have a suggestion for what to use for a liner that won't rot/tear over time?

Thanks