ok. i haven't ever done anything like this per say, but i feel confident that i am capable. here's the scenario: i have a customer who has a small (18") drainage ditch in her yard. it holds water almost all of the time and is in a really poorly drained area. french drains are out of the question due to conditions. what i want to do is give the ditch a makeover. i'm thinking of hand excavation the run of the ditch down another 12" or so, backfilling the excavation with small pebbles, building up a short wall on either side using riverstone, and laying field stone along the run over the pebbles. my biggest question is what should i do to provide a firm foundation for the river stone? i was thinking of pouring about 4-6" of concrete for the river stone to sit on. i'm very open to any suggestions anyone has, but am not looking to sublet it, as i'm starting to bank winter work and she is agreeable to waiting. btw - the run of the ditch is about 25'