srmofo wrote:
I agree. We're over $7,000 into that solution already and I'm not spending another dime on it for this portion of the yard. We have a full gravel field under about 75% of the yard, complete with piping. All roof surfaces are piped directly into the system, and we have a surface drains strategically around the yard. Even with all of that, we have a swamp in certain portions of the yard for March and April each year, and then are dry (on the surface, wet 6 inches down still)) for the rest of the year.
We just finished filling in a gulley and bringing our elevation up over 8 feet on a 1/3 of an acre on our property. That portion is dry as a bone (4 triax of drainage stone, pipe, pourous fill, and then top soil) and can be fenced normally. But, this one problem portion is right on the property line and not worth more expense in trying to tame mother nature for sake of fencing - I think the metal spikes method is the way to go there.
As for setting the metal spikes... Seems to me like pouring mixed concrete into a post hole, and then pushing the spike into that would make for a rock solid solution. Overkill? Or worth the effort? (most of my holes are already dug)
Pressure treated posts that were rated/treated for ground contact or below-grade use should not have rotted out that fast. The 'old' CCA rating was 0.40 for ground/below-ground usage. Don't know what level or chemical mix your posts were. But I -have- seen so-called 'pressure treated' wood on the stacks that on checking the FinePrint of the product label (and it was in actual fine, small font, print Grrrr ) that said 'pressure treated wood' was NOT rated for ground contact or below-grade use.
Then again, I have also seen (and experienced, first hand) carpenter ants happily (or at least repeatedly and continuously) gnawing and tunneling and nesting right through some 0.40 CCA-treated rated-for-below-grade-use 2x lumber. Grrrrr again.
Except for exempted industrial/commercial use, CCA-treated wood is unavailable for residential use in the US since Jan 1, 2004. The 'main' replacement treatments since then are mostly ACQ or CA-B and CA-C. Note that because of the increased levels of copper in the 'new' treated wood, they are ~3-5x more corrosive to steel than the old CCA treated wood and thus require the use of hot-dipped galvanized or double/triple zinc coated or stainless or other 'approved' coatings on fasteners/hardware that is used with the 'new' treated lumber. (also note, NO use of aluminum, such as flashing or hardware or fasteners, with the 'new' treated lumber.)
http://www.strongtie.com/productuse/corrosion.html
Regarding concrete and water, concrete is porous and holds water. Putting a wooden fence post or a metal (steel) post or spike into concrete that is sitting in wet water-laden ground WILL rot or rust that post or spike. Unless the post or spike is very rot/rust resistant to begin with.
Cedar (eastern or western red) or black locust are naturally "rot resistant", but that only really applies to the heartwood. The sapwood of those species is NOT rot resistant.
Sloping a concrete post footing only would have any benficial effect if the ground/soil can actually drain. Since you state that your soil is pretty much wet year-round (combination of clay and high local water table), sloping the top of a concrete post footing will do NOTHING for the existing ground water.
Those Ox-Post pieces are made to drive into the ground without having to dig a post hole and then the 4x4 goes into the socket on top. Used something similar years ago for a mailbox post. It was tough to drive dead plumb (always had a bit of a twist and was off plumb, Grrr) and although it was painted/coated (but no HD galvanized) from the factory, it rusted out in a few short years. And that was in ground that actually drains! Also, if you have rocks in the ground (or big rockes, or boulders), you CAN-NOT drive those things into the ground or drive them straight or drive them plumb.
Your call as to how much time, effort, and money to spend. Both up-front and in maintenance/repair/replacement.
If the ground is that wet and PT posts aren't lasting, I'd say to check into doing plastic posts filled with concrete (plastic posts by themselves have to generally be reinforced internally with wood or steel or concrete, and wood and steel sound like they are not good choices for your wet ground).
http://www.hooverfence.com/vinyl_fence/concrete-post.htm
Strength of concrete (no rot or rust issues, barring any rebar or such) and a plastic-wrapped outside for appearance (may or may not fit in with your 'look'). Also possible issue of chalking, cracking, or other weathering (UV) issues long-term with plastic exposure to weather and especially sunlight.
Again, your call.
Thanks!