I got a call today about a patio that has some of the sand washing out there is a boulder wall in front of it about 2 feet high. There is a small section where the sand washed out from under patio about 2 feet by 2 feet. Any ideas on how to fix the problem after I repair it? I can see fabric behind some of the areas so if I dig behind the wall and refabric it will that work? Thanks.