Underfloor drainage problem

i think i might have put this in wrong section so have duplicated it here - sorry to the admin lot if i have transgressed

------------------

i've got a 7 year old 2 storey townhouse, double brick foundations with single brick from then on up, sloping block, front to back drops about 1 meter over depth of house, the vents were all blocked by the bearers, irregular shape, we got termites which have chewed through some flooring mainly because of damp problems

we back on to a railway which i believe is the worst place to expect termites to be active, the railway runs through a cutting which is 8 - 10 meters lower than us, sloping soil sides with trees and undergrowth

some of the soil base under house is lower that the outside paving at back of house which has allowed water to gather at back of house in the subfloor and at times pool - this area is about 1.2 metres below floor area

we have a basement which takes up a small area of under the house and is about 1 1/2 meters high with a concrete floor and lip up to level of the outside paving level, this area has an automatic pump in a sump with a drain running around the outside, in the corner is a cutaway through the concrete lip for water to drain from rest of sub floor which is all higher, but i don't think is adequate

what we have done so far:

have had a 12 volt fan installed through a vent in the most difficult corner to vent
vents installed all over, maybe 12 in total, mainly double size

we are about to have chemical termite barriers put in but want to make sure we have no more drainage or damp problems and intend to get any work done before hand, by yours truly - ta wife!

so i'm digging an ag-drain right from the cutaway throught the basement's concrete lip the whole width of the house (hell of a job - but hey someone's got do it - down about 800mm max), across the gradient at the bottom of the gradient to catch any water running down this slope, to drain any water that may still come in and stop the problem long term - it will have adequate drop off and be as low as i can get the outlet to the concrete basement area to be, this ag drain will be about 1 meter lower than the outside of the house

at the same time i am lifting level of soil at back of sub floor to the level of the outside paving to stop water pooling there, which it has done in the past

----------------------

ok, what i need to know is, am i following thr right course?

with the ag drain, does the pipe just sit on the soil base of trench and then agregate on top, and how much agregate, full depth or partial and then backfilled with soil?

anything else i should consider?

---------------------

hard to describe so i have put a pic up

http://djdesign.customer.netspace.ne...oosethesod.jpg

i think i have to add if anyone wants to tell me that self regulation of the building industry works, or that council knows about construction may i say at this juncture that you have sh*t for brains, when is this state - victoria - going to have a 10 year waranty is what i wanna know?