This may work and get the job done. Just make sure that you slope the trench properly so that the water runs around the house and doesn't put pressure on the foundation and basement wall.

B dry works and it's much cheaper than what use to be done to waterproof basements. It's also less messy that digging a trench inside the basement. I use to be one of the guys that used a jack hammer to break up the concrete along the inside perimeter of the basement. I also had to help dig the trench, and haul all the dirt out of the house in buckets by hand. It's a hard job and takes about a week to get down the old way. The B-Dry system put my old company out of the waterproofing business as it was much easier to do and worked just a well from what I understand.

I worked for a company that did basement water proofing back in 1997. B-dry came into business here about that same time.

I'd ask for references and then follow up with the references to see how the job was done and how it's working.