I have problems when it rains in the garden as its on a slope on 3 levels , the water gathers at the bottom , i have dug a trench along the front where a retaining wall is to be built and dug it along and down the side of garage as the water was seepingin there aswell. B ut the problem i have is whats the best thing to put into the trench as we had soakaways which seemed to fill with clay/mud so i need something to catch the water and run it into the drain at end of garage not sure what to use. can you help.
I too had this problem as my bungalow is part buried in a hill.
I dug down through the clay and formed a trench. Then I part filled the trench with small clean stones creating a downhill slope on top of which I laid dpc in the shape of a "U" This I filled to almost ground level then I laid another dpc and filled to ground level. Then I lose laid concrete slabs over. The water runs gently through the stones remaining clean. The top layer of dpc collects all the dirt out of the air and keeps the lower layers clean.
By the way, this system called a French drain was res erected by an American farmer who took the idea from the Romans some of who's drains remain working until this day (apparently)