Building herb spirals for my FYP

Me and my Feinds have opted to build 4 herb spiral at the north south east and west points of our plot plus some keyholes in between. we have  put an underground tank which collects the excess water from the pond so it can be recycled in the next irrigation cycle. I have also used hugelkulture in the spirals: I have put huge logs , then branches, then straw, then straw, glass clipping, a mixture of topsoil and compost. i am facing 2 problems now: lots of debris are being collected in the pond and are entering the water tank. i don't know what irrigation system to use because one sprinkler on the top can't irrigate all the areas of the spiral because of a fault of the design. could someone help