grizz and everyone else,

My situation: 50 year old septic system with seepage pit/dry well. The pit is no longer draining well causing a backup into the septic tank and into the house. Pumping the tank gave me temporary relief, but there was substantial backflow of water from the pit. (The tank has been typically pumped every 2-3 years.)

I've read through grizz's "Septic Leach Field Rejuvenation" article and many of the posts on this forum. Here's my questions:

1. Does the sodium percarbonate/hydrogen peroxide treatment work in the long-term? Seen lots of posts showing short-term rejuvenation, but not much long-term success. Did I get this right? (Also, finding the service hole to do this treatment may be quite a challenge as the pit is quite deep and I don't know what I will find once I get there. I suspect I will find a concrete cover.)
2. This system is 50 years old and this is the first "failure"--I got my money's worth. Is there any chance of rejuvenating this old of a system? Should I put my money into fixing it for the long run (e.g., new trenches) or try this rejuvenation?

The rules on septic systems in my area are now quite strict. I'm not really sure what they will permit now and how much it will cost me, but I do know that new seepage pits are no longer permitted.