Thanks Pete - well today's task - start unbolting the tank.
Originally, they have laid a slab, bolted 20 four foot square 1/4" thick pressed panels together, then laid concrete inside the tank and a flaunching round the outside, to make it water proof. Plan is to unbolt as many of the fixings as possible, then Darren the contractor will come in with his big digger and pecker, and break up the concrete and pull the panels out of the mess. Slight problem - some of the bolts are buried in the concrete so will probably have to be cut off with oxy-acetylene, but I want to unbolt as many as possible first to save the cost of the gas.
I have a humungous 1" drive air impact wrench made for the job. These are 5/8" Whitworth bolts that have been in situ outside since the 1960's, so the threads are pretty rusty. So having fed the pigs the important thing is to get the road compressor started, as it's minus 7 Deg C here
I'd expected to have to leave it on charge over breakfast, but amazingly it started off it's internal battery (which I'd rejected from my Discovery two years ago!)
So a bit of manoeuvring reversing it into position set up the hoses, connected the air impact wrench, stuck it on a nut, pulled the trigger - NOTHING - no rotation, just air passing straight through the tool
A few choice words and I dug out my baby 1/2" air impact wrench, but it just hasn't got the guts for the job.
OK take a break and investigate the 1" drive wrench.