Hi, so i am currently building a deck. My plan was to have concrete footings below the frost line at each of the corners and then one in the centre at each side. I have just looked where i was going to dig one side of the posts and there is concrete already there that wont be removable because there is a pipe that goes through it. I have no clue what the pipe is for and if its still being used (i live in a house built in 1905) but i dont want to remove it. My issue now is because of all the work i have put into getting the garden ready for the decking and because of the layout of the garden, the decking cant be moved. I have seen videos of people building decks using above ground concrete piers just laid on the ground but im worried that in scotland the concrete might be ruined because its not below the frost line. It will have concrete footing below the frost line at the other side of the decking, just not where the pipe and concrete is. Would this work? Or does anyone have any other suggestions?