It sounds like either you have a blockage in one of the pipes to or from the septic tank which is preventing water from freely flowing. The ponding next to the tank would seem to indicate the the problem is in these pipes rather that a severely clogged drainfield. I would suggest that you have your tank pumped first and then the lines leading to tank and from the tank to the distribution box cleaned before looking at more drastic measures. If these line are not clogged, then the problem is probably in the drainfield and Septic-Scrub may help. If you call me, we can discuss further.