In article ,
dutchman writes:
|
| I would use the pointed angle iron fencing posts, backed by good chain link
| fencing, then back filled with rocks. ...
|
| Wooden stakes and boarding will as you realise rot and then the backfill
| would be exposed and again washed away
|
| I have noticed on another river the 'council' have used coir rolls ( a
| bit like long sausages) resting upon willow faggot rolls. All with
| wood posts at intervals, to hold it all back.
|
| I would have thought that that would have only lasted 2 or 3 years,
| and washed away.

Well, the faggots that Ely cathedral were built on have lasted for a
good few centuries!

What people don't understand nowadays is that most heartwood won't rot
if it is EITHER waterlogged OR dry. It is attacked primarily by fungi
that need gaseous oxygen to reproduce. Sapwood is another matter,
as it contains enough sugars to allow anaeobic decomposition. And
some vegetable products (like coir) have lignin but no sugars. That
is why posts rot fast at the soil boundary, and much less below and
above it.

If you wander around the country, you can often see wooden spiling
that is largely intact and over a century old. But you have to do
it right, which means using appropriate materials for the conditions.

| Whereas I am being told if you use vaccum tanalised timber they could
| last over 10 year.

They will.

| How long would steel last in water ??? unless it was heavily painted
| or stainless, in which case it would proably get knicked round here.
| And what size crosssection for the steel

It has similar properties to wood, in that it will rust fastest at the
water boundary. It depends a lot on the type of water (i.e. mineral
content) - in most fresh waters, it will last quite a long time - in
some others (e.g. sea water), next to no time.


Regards,
Nick Maclaren.