Not sure if this is something the community here has interest in.
A section of the creek bank has fallen away, revealing that all of the soil has been recently deposited (~ last few decades). The garbage inclusion likely spreads for dozens or maybe hundreds of cubic meters of earth. We don't want to disturb the soil to clean this out so we're limited to surface level cleaning.
On the flipside: it's lots of deep fertile topsoil. The fast growing weeds, like lantana, absolutely love it.
The waterways & stormwater outlets are more complex in terms of ownership than it just all being national parks, the local councils (third tier of Australian government, below federal & state) and Sydney water are also involved. I believe the creek water is managed by one authority and the creek bed a different authority, just to make things more fun.
What do you mean by clean? Mostly insoluble and chemical stable solids, little in the way of soluble pollutants and insoluble liquid pollutants?
Upstream of this at the outlet there was big rockwork installed years ago, much of which is bigger than 60cm, but a lot of it has still washed around and collapsed. I'll see if I can grab some pictures next time I'm there.
We only focus on some very small patches of a very large regional park. More than half of it (by my estimates) is taken over by vine weeds (mostly balloon vine, morning glory & madeira) that smother the native trees -- if you blur your vision then it looks like verdant green rolling hills. Small native plants only survive in some sections, others are completely overtaken by tradescantia (wandering jew) and lantana.
Occasionally some commercial bushcare contractors come through to work sections, but again only small (and more accessible) areas. The national park is also a rail corridor and no-one is allowed near that without lots of prep + supervision (+ money to pay for supervision), so those bits are generally bad.
Glad you've found some power over the chaos. Hope it's not too heart wrenching.
Yay. A bureaucratic nightmare!
As in likely below environmental guidelines for contaminants of concern (metals, hydrocarbons, organic compounds). And by relatively they are probably circum-threshold values. If I were to go to sample it I would expect a lot of variability.
I can't imagine the invasive plants issues you guys have down there.