Acid Sulfate Soil?

Hey all,

I did a property search through the council for a property I'm looking at and it says that it is in a zoning/overlay for "Acid Sulfate Soil".

House has been there for over 40 years and entire area is developed with a new housing estate (within the last 5 years) across the road. Is this something to be worried about?

When I rang Terri Scheer, insurance seemed pretty normal. Is this more of a development issue if you wanted to knockdown rebuild later on down the track?

 

Yes it is common on east coast oz especially near the ocean not to be worried. It just means if you put metal underground (pipes, improperly treated foundation materials) they are likely to corrode. All plumbing I see with new builds is PVC anyway. Plenty other scary-er things out there in my view. https://en.wikipedia.org/wiki/Acid_sulfate_soil

 

Thanks! I got worried when I looked at the Wiki and it said it could cause problems for the water supply. Thanks mate

 

Yep. Most of Wyong for example is ASS (best planning acronym around) but lots of development still happens.

What level are you?

 

I'm unsure. All it says on the council website is "Acid Sulphate Soil"

 

Check out asris.csiro.au

 

As the others have said ASS is fairly common close to the coast and in areas of low elevation (typically less than 10mAHD). It is present in undisturbed waterlogged environments, but if it is left undisturbed then it will pose no (or little) risk. If the ASS is disturbed and exposed to the atmosphere (via excavation or drawing down of the groundwater table) then iron sulphides in the soil react with oxygen and produce sulphuric acid, which can lead to the problems you probably saw on wiki (metal corrosion, concrete cancer, groundwater acidification, fish kills etc).

In short, if the house has been there for 40 years and you are not planning on doing any other significant excavation works, then there will be no additional problems (any reactions produced from the soils during the original development would have already been released into the environment). If however you are wanting to develop the site, there may be some potential issues, although they are easy to manage (minimise the area and depth of the disturbance, addition of lime to any stockpiles etc) and Council will likely want these management measures documented in an ASS Management Plan to be submitted with the DA.

Also, just because the area is listed as being within an ASS area on the Council website (or ASRIS), does not mean that the soil beneath the site is actually ASS, those plans are very generic and only indicate that there is a potential for ASS to be present. If you grab a couple of soil samples and send them to a lab they can conduct some cheap pH analysis (you want to request: pH(f) and pH(fOx) analysis), which can be used to work out if ASS are present, I think the lab charges about $10/sample and a $30 batch fee.

 

I have this overlay on one of my houses.
It is not an issue.
There are different variants of the overlay depending on the depth of the acid sulphate soil, deeper the better I recall from memory..
I think it only has implications when you wish to build very deep foundations as the soil can react with metal and corrode it.