I've built my own anti-seep collars by digging above the pipe, to the sides and under the pipe. Then I poured in sackcrete mixed in wheelbarrow with a shovel and was good to go. This was however before I had any water working around the pipe. However I'd still give it a try instead of disturbing all the dirt. At least that's MHO.

If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.