On Sat, 18 Jul 2009 22:12:08 -0700 (PDT), oldjag
wrote:

On Jul 17, 8:17 pm, (Rob) wrote:
Hi folks

I have 300 gallon tank formerly filled with gas oil / 35 sec heating oil /
medium diesel (not sure
of the U.S. terminology). The only way I can remove it is by first cutting it
up. Any suggestions / comments
so as to do this safely?

Regards
Rob

I did an old cylindrical 350 gallon tank under an enclosed porch.
Local companies wanted $1000+ 2$/gallon to dispose of the old oil.
The only opening in the block wall to the tank was much smaller than
the tank. The tank had ~ 250 gallons of 30+ year old fuel oil in it.
I pumped it into drums with a air driven diaphragm pump and gave it to
a local garage with a waste oil heater. He was glad to get it. I
purged the tank with Nitrogen, but was still nervous, so I broke up 5
lbs of dry ice and dropped it into the tank, the vent was still
connected and I was was getting a good flow of CO2 out of the vent
when I started cutting it up with the Sawzall. Took about an hour to
reduce the size to chunks small enough to remove through the small
doorway. The wall thickness on this old tank was pretty heavy, and I
was pleased to see after scraping the inch or so amount of sludge out
of the bottom none of the corrosion went through the bottom of the
tank which was resting on bare soil. Total weight at the scrap yard
was an amazing 800 lbs. which more than paid for the Sawsall blades.
My first involvement in conversion of navigational aids to solid state
in the mid '70s, we would pump out the underground diesel fuel tank
and fill it with sand. By 1990, the tank had to be removed and the
soil underneath hauled to a hazardous material handling facility until
all traces of contamination were removed.
At one point I did a survey of airports to list all underground fuel
tanks. One former military field had at least two tanks at each hangar
- some still in use after 40+ years and just inside the former Base
main gate, a storage tank for gasoline which was sold to civilian
employees (gas was rationed during WWII and civilian staff were
allowed to buy on base but couldn't drive on base unless they had car
insurance, which most did not). In this case, all evidence of the
fueling facility had been removed for grounds maintenance but the tank
was still there. I had stumbled on it's existence through review of
old base records.
Another case involved an abandoned fuel tank buried under an interior
courtyard with no access for excavation equipment.
Gerry :-)}
London, Canada