Question about levels

[Wild Dingo]

Okay... so on this block there are no datum pegs left the last datum survey was done in 1987 so the pegs are long gone but we do have a "site drawing" which gives basic then acurate site measurements of the fenceline

So in doing the new house... the ONLY requirements the shire has stated they require are
1) That the house MUST be 800mm - 1mtr ABOVE the flood level
2) That it have adequate bracing

Number 2s a given the mob over east wont sign off on the plans until the information is in and will have to be braced its a given and why were taking so long getting the damned plans done dipstick! duhhhh

Number 1 I questioned the shire on as to what exactly was the flood level "use the mud line on the existing house and go 800mm - 1mtr above that" HUH?? thats gonna be acurate well for the mud it will but the flood waters were at least 6in above that.

So given theres NO other drawings plans or survey information available ANYWHERE and definantly no contour plans anywhere (Ive spent near on a week scouring every known dept and office to find some but there simply are none)... we are left with what? the basic "site drawing" of the whole block... thats okay for a drawing to locate the house which we also need to do so no probs... BUT!

We need to get the heights above the flood level... so we are thinking as the house is standing the mudline is clearly visible on the sidings all round the house... Ive gone around and marked the mud line measured up 6in marked there then measured up 1mtr above that

So if we get a dumpy theolodite whateveryercallit thingy and place that level with and adjacent to the flood level +6in mark and measure out to the first corner put the measureing stick up on that mark that height is the first corner flood level height put a star picket in marked at that height (write and mark it on the mudmap) then go to the lower corner (deeper in the water mark) do the same there that would give us the second "datum" spot and the second height above flood level right? mark and stake that point... we can then mark the height at 1mtr above that mark as the subfloor joist level of the house and that would be pretty much it right?

Then using those pegs as "datum" points we can simply measure and peg the whole house site including the stump hole locations (if were feelin energetic that is)... this should give us the exact a) location b) area size and most importantly c) the exact heights above the KNOWN flood level (and the ONLY notated marks of it) as per the shires request

Im having the bloke thats erecting it come down and take some measurements next weekend to mark it all out but I wanted some clear idea of what heights and such we need to be sure of... pity I dont have a surveyor mate eh?

Anyways cheers

[joe greiner]

Don't know what kind of floods you have in Oz, but all I've seen the water was quite muddy, and the mud line was the flood level. Even so, they've given you a tolerance of 200mm (= 1000 - 800), which is more than 6in. Whatever; unless there's a signifiant cost difference, more clearance is good if the next flood is higher.

I don't get the need for two datums, though, if I'm reading you correctly. With an ordinary builder's level (cheap version of a theodylite), you should be able to transfer a level plane all over the place, staking intermediate reference heights as you go. You could also hire one of those whirly laser things and spray a red line everywhere it can see, and measure up or down a constant height. Even simpler if you set the instrument height (either builder's level or the whirly laser) at your 1m + 6" above the mudline as you propose.

Joe

[ausdesign]

Shane (i think it's shane) normally the council would give a miniumum floor level height - i.e. "finished floor level to be a minimum 7.6 meters above AHD." or wharever.
Normally this requires a surveyor to come on site & set up a point for you.
We're currently doing a design & the owners got a surveyor to put a spike in the front fence post at the required datum - cost $500 for that & a site survey & site feature survey.
A lot of towns that are around a 'flood prone area' have spikes scattered around the district - usually in telegraph poles. (don't know how they get on now with the concrete ones)
I reckon you need to make sure you're at the right height council wise in case you get one of those 1 in 100 year floods & your insurance co. gets narky if you're below the level.

[Wild Dingo]

Cheers fellas!

Peter the problem is that NO ONE has a flood level for the east side of the Brunswick River except for the mud line on the house thats it.

We have had a surveyor come out and do the contours based on the mud line as the base height and thus can get the 800 above that mud line along with the contours... that was easy actually and not too painful $$ wise

What got us in the end was the soil tests... the first one went well and easy a spike rammed in and pressure readings taken... results sent to the mob in Victoria... trouble was that wasnt what they wanted they wanted core samples taken... so at a fair bit more pain $$ wise they went ahead and did those tests

The high end where the FFL would be 1.8mtrs above ground level was fine as in they didnt hit the water table until they had reached the 1.7mtr depth... but then on the creek side where the house needs to be above 2mtrs above ground level they hit the water table at 1mtr.

He called me out to tell me what he was finding... first a layer 200mm of yellow sand then a layer of 500mm black clay then a layer of sandy gravel 200mm and then gradually nothing but water (100mm - 1mtr) the scooper thing he was using was coming up spotless and dripping water.

So that blows that to hell and gone

We are waiting on the final soil tests to be done on Monday and then we will go get the results and have a yarn with him, but preliminary results are that we cant do the build.

Soooo after a weekend and a couple of days of bein phissed of upset consoling the missus who had her heart set on this new place and working out the budgets again and reassessing what the hell were going to do... present thinking is that we sort this house out do a mad run around with a bobcat to sort the block throw a few trees shrubs in and put it on the market cut our losses and buy over near the coast in Australind... move on you know

Anyway just thought Id update
Cheers!

Yep your right Peter ...Shane it is!

[les88]

Shane
It seems to me that in the end it would be easier to build on a block without flood issues or go to the extreme and build a queenslander on 9 foot poles.
les

[ausdesign]

That's a real shyte Shane.
Times like that I'd go out & hang onto the electric fence for a while to take my mind off it.

Maybe a raft slab will be the go ! . . sorry you're probably not up to any jokes.

[Wild Dingo]

That's a real shyte Shane.
Times like that I'd go out & hang onto the electric fence for a while to take my mind off it.

Maybe a raft slab will be the go ! . . sorry you're probably not up to any jokes.

Sorta like the one everyones sayin... "buggar building a sail boat Shane buid a bloody great houseboat mate moor her to the front gate by a long line and enjoy the next flood" Does make sence actually

Les her decision goes like this... okay that was not a fun filled 2 years so for our next trick we SHALL do the following... YOU (meaning me) will prowl the estate agents for a DECENT rental for 6 months... YOU (meaning me) will move every one out then YOU (meaning me) will stick everything into the seatainer and YOU (meaning me) go ballistic fixing it... so I get a month to sort this place and 5 to sell it... ooh why me? cause Im the dopey buggar that thought we might just be able to make this place a goer after all the issues of the last 2 years... so of course its MY fault never mind the fact that SHE found the place never mind the fact that SHE signed for the place never mind the fact that the first I knew about it was when SHE faxed the paper work out to work for me to sign never mind the fact that it was a done deed by the time I saw it... never mind the fact that I wanted to sell the bloody place a month after we moved in (Like the morning after the damned flood)... but no its my fault sigh

But no shes now set her mind at ease an is now in good form... so its all good Im just glad shes finally come around to my way of thinking

As for the Queenslander on 9ft poles... well trouble is thats pretty much what we were aiming at due to the shires need to be 800 to a meter above the flood level and thus over 2mtrs above ground where we hit a snag is that the stumps that is the 9ft poles have to go in the ground... unfortunately there was only a meter of ground for them to go into then water... this was an unknown as to how deep the water was just that there was water and no obstruction (ala no soil) soooo unless we wanted to spend a shyteload on pouring concrete down the hole until it stopped going in and hope that works... it isnt going to happen... actually the ONLY two alternatives to the place right behind the house we could go to is either RIGHT smack on top of the present house... or 80mtrs up the back paddock to higher ground sorta RIGHT NEXT to the railway from Worsley (meaning caustic loaded trains passing within a phart of the back of the house ever 2 hours day and night) no thank you!!... so as the build would take a minimum of 12 months all things going well we will upstakes fix and sell and buy elsewhere... maybe then things will get onto a good even keel eh!!

THANK YOU MR SOILY!!! Yer a bloody bottler! oh an thanks to the Victorian engineers who wouldnt sign of on it without the tests we here in West Aussie dont do