In article ,
Lee Nowell writes:
Hi All,

A friend has an old indoor swimming pool which he got converted into a
playroom. They removed the inner lining and constructed a deck over
the pool enabling him to use the old pool below as a good storage
area. This worked a treat until the winter rains came and it
transpired that the water table is very high and the pool was not
tanked on the outside. Net result water is seeping into the storage
area and stinks!!

Ordinarily, he would fill it all in then finish with a DPM and
concrete slab but this is going to cost a fortune - mainly because of
access/ distance issues to transport the gear to the pool. As a
cheaper option, a builder has suggested dropping the timber deck 100mm
adding some DPM/ sealant on top of it and pouring a 100mm slab of
reinforced concrete. I guess he would have to dig some of the edging
away to ensure the slab sits on the pool side walls. Would this
approach work?

For a few years, until the timber went rotten and it all caved in
one day when the kids were playing on it.

The other thing is that the walls were probably not built to
withstand the static pressure of the soil long term without static
pressure of the water in the pool to compensate. They might start
collapsing in, and that movement might affect the building's
foundations. You really need a structural engineer to advise, but
if this is the case, you either have to turn it back into a pool,
or backfill with rubble. Structural engineer might advise if you
could use permanent horizontal props between opposing walls
instead, as is temporarily done when trenching. If the walls are
string enough to hold the static soil pressure, then you can
probably get them tanked, or lined and use a sump pump as is
done in cellars below the water table.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]