Ned_ie,
You're having alot of the problems that I had with my old system...
I've posted here about them before! I replaced a system I bought from a crowd in Cork that went belly-up with a biocycle.
I agree with beefy2003. The system you describe doesn't sound like a biocycle! It's probably just your average wastewater treatment system - alot of people call treatment systems "biocycles", just like we call vacuum cleaners "hoovers". If it's a biocycle it'll be a 3m diameter concrete tank with a green lid with "biocycle" written on it, it'll have a green box for the air-blower and, most importantly, it will have a pump built into it as standard. (When I bought my system off biocycle I asked them if I really needed a pump? They told me they couldn't supply the system without a pump, because the system would be no better than a septic tank! The pump ensures that the effluent gets distributed out to the percolation area.) Also, you mention "the last tank", which I presume means you have a system with more than one tank...the biocycle only has one tank! It sounds like you got conned! I believe some companies selling treatment systems claim to be selling "biocycles". It makes it really difficult for Joe Soaps like us to know what we're buying.
I disagree with your solicitor that there's bugger all you can do. Sounds like he's covering his own @rse! He probably was involved in the signing-off, along with your engineer, so THEY'RE responsible! The engineer was paid to sign-off on the property, including the treatment system. You should do a bit of homework first!
1. Go to the County Council offices and look up the planning application - see what planning was granted for, and what was actually installed - the fact that you bought the place second-hand could see some interesting info turn up here!
2. See who did the design for the system and the percolation area, and then who installed it. They obviously didn't do it properly, so they could be NEGLIGENT!! See who certified the work, because they might also be NEGLIGENT! All engineers should have professional negligence indemnity insurance to cover when they make f**k-ups like this, and it's them that should be footing the bill for it, not you!
3. You should hire a PROPER consultant engineer and a PROPER solicitor!
Apologies for going off on a bit of a rant, but I feel strongly about this because I got screwed before by cowboys and hate to hear about other sob-stories.
I don't think your house insurance will cover this, because insurance companies are smart enough to know how crap the majority of treatment systems out there are!
J.