From your description, I believe that you have a drop box system. This system is used when there is a slope to the ground. I do not understand how the term raised bed corrleates to your description. A raised bed generally has a pump to pump the water up to the bed. A drop box system uses a series of distribution boxes down the side of a hill. The top box has three exits, one to each side and one down the slope of the hill. Somewhere down the hill, there should be another box with the entering pipe coming from the up-hill side, and again generally three exits. This continues down the hill until it gets to the bottom. The basic problem with this type of system is that the upper trench gets all of the water until it overflows or clogs. Then the second trench gets water until the same thing happens and so on. The best way to try to treat this system is to treat the trenches one at a time. Treat the upper trench to restore flow and then go down the hill. The upper trench is pumped to remove water to at least several inches below the laterals and then the 1-2 bottles of Septic-Scrub added to the trench. Sometimes the water can be removed by blocking the side exits and forcing all of the water down the hill. This allows the trench to rest and the water to be absorbed. when the level has dropped, then the Septic-Scrub can be added. The same thing can be done for each trench. I do not know where you live or what the weather is like now. If the weather is bad, then this can probably wait until it warms some. The upper drop box can be blocked now and rested until the treatment. I would think that 3-4 weeks rest should allow the water to drop enough for a treatment. If I have not explained myself sufficiently, please do not hesitate to call.