Go ahead and get estimates for both, first, BUT, plan A has fewer ways it could go wrong. (No bridges, no bedrock)

We have a very steep 1/4 mile well established driveway that was in fairly good shape when we purchased our property 2 years ago. Once we put in the septic system on top of the hill, the drive began washing out. We tried moving enough earth to stop the process but ended up paying for a professional fix. They moved some large stones to divert the water, dug several ditches and laid 2 truck loads of rip rap on the driveway. The rock is still sinking and it looks like we'll need more in about a year. If your ground is wet and there is no base, rip rap sinks at an incredible rate. Just our limited experience.

Personally, I think the high ground is the best investment for the future. Water is relentless.

Having said that, I would first find a way to assess the bedrock along the planned high ground route. There are companies that do this, but there might also be diy ways of accomplishing the same thing. When you know exactly what you would be dealing with, then you can make a more informed decision.

Good luck!

I WOULD DEFINITELY OPT FOR PLAN B AND WOULD WITHOUT QUESTION - WHILE I AM ALREADY ON THIS PATH MAKE IT WIDE ENOUGH FOR A TRUCK TO TRAVEL . . . NO SENSE GOING BACK LATER AND PAYING FOR SAME THING. WHILE I KNOW YOU PROJECT YOUR FUTURE PLANS EXTENSIVELY THE COST TO DO THIS NOW WHILE YOU ARE DOING IT FAR OUTWEIGHS THE COST OF OF DOING IT TWICE.

An idea for a bridge - old mobile home or school bus frame (don't know how long the span is) anchored on both ends makes a sturdy bridge. The bulldozer could drag it up there, then bolt planks down across it. Should be wide/sturdy enough to drive passenger vehicles across, I would dry dump trucks or cement mixers though.

How big would the bride have to be? My father-in-law lives in a Detroit suburb with a tiny stream in his backyard (that is in a large gully - 8 ft banks, 30ft span, roughly) and he built about a 40 ft bridge out of 2 trailer I-beams that he welded. Something like that could work if you're just planning to take an ATV across and not a really heavy vehicle.

About a year after we bought our Shenandoah Mountain property, we decided we needed to improve and move a road to where we intend to build our forever home. The knoll was about 2,000 feet higher than than the lowest spot on our property and would require about 800 feet of new road to be built along the shallowest slope of a very steep hill.

We were blessed with having a steel bridge already in place to ford the stream at the entrance to the land, so getting an earth-moving machine where it needed to be wasn't as much an issue for us as it would be for you, but we did learn a few things that may be relevant to your decision:

1. While Hubby and I carefully laid out the path we wanted the new driveway to be, following the slope at a gentle incline, the man and bulldozer had different ideas once he got started. He took the driveway up slightly higher grades and put in the bend not where we indicated. While we were annoyed at the divergence from the plan, we had to finally trust that he knew better about the capabilities of his machine and where the road would be better laid. Our terrain is identical to yours and bedrock was an issue. He adjusted the road to deal with the jutting rock and crumbling soil on the fly. Perhaps your excavator will also be as confident and problem-solving.

2. Charlie (our contractor) charged us about $2,200 for what ended up being only a few hours work. Once the big machines move in, they make quick work of what would be months of hand labor. We found it to be a good value for what we got. He was an independent operator and grateful for the extra work. A lot of country folks are. I believe we paid a fair price and helped a neighbor at the same time.

3. Earth moving and tree-felling with a big machine is not for the faint of heart. It did look like complete devestation for the first year afterwards - broken trees, bare exposed roots, bare rocky soil - but after a year, the landscape has mellowed and Mother Nature is reclaiming her own. We have harvested much of the downed wood to use in our Hugel beds, and it has created a lot more edge space - the younger trees and mountain laurel are sucking up the new light coming through the canopy with abandon. We have also used the margins along the new driveway to plant flowering trees to soften the harshness of the gash.

4. While our new driveway is now (approximately) where we originally envisioned it, if I had to do it all over again, I would ask that Charlie make it wider than the width of his bulldozer blade. Our small Subaru can manage the narrow track, but when we start building the house, I doubt the Big Machines will be able to do so. I would recommend that you over engineer your road now, rather than have to do so again later in case you ever need a vehicle larger than an ATV to traverse your property.

I'm not sure our experience is giving more weight to either of your options, but anytime we can share our experience with folks who are pondering similar situations, we all benefit.

Have a great day, y'all.

Have you thought of asking VDOT or Ag Extension about how to raise the floodplain road? Is there any feasible way to combine the two roads, say to start on rd A, then head over, past the gully, to rd B? Last--IF you do opt for rd B, VDOT still might help, somehow. I seem to remember that they do build swinging bridges, or used to. I also think you can drill core samples, along rd B, to test for bedrock. Instead of having an old trailer, or whatever, to bridge the gap, you prob. should use steel girders, but these wd be hard to bring in?

To check for bedrock: Drive a length of rebar every 10-20 feet along the proposed route on the uphill side. Chart how deep it goes before stopping at each point. Calculate if it will level out with a 12 foot wide road. Find where an old culvert has been removed and the hwy dept will give it for free. Start with truck able bridge across main creek. I had two 30 ft bridge timbers in the barn at my old farm. Bet they're still there. Re check possibility of entering from up creek side of property--cost of buying right-of-way.

Check for bedrock with rebar or a posthole digger. Then make the road big enough for your truck.

I've been reading this blog for seven years, hearing about your creek and mud track issues. The only downside I can see is a future lack of posts about being stuck on the homestead because of a flood LOL. Plus, you are not getting any younger, and things get more difficult as you age. Dry, year round access might even save your life someday.

Plan C. Here in Japan, farms sometimes build a monorail to their mountainside terraces, or even to isolated hamlets that have no road access. A lawnmower sized engine pulls a driver's seat and a flatbed car with 4-500lbs of stuff up slopes up to 45 degrees. Very low impact, sturdy, but slow (40m/min).

Mark and I don't like the idea of a bridge rotting out under us after a few years

This is probably expensive and/or time-consuming, but I think stone bridges are very cool. Could you build (or have someone build) one?

Based entirely on my freshmen level psychoanalysis skills, I think you should pick plan B because I think that is the one you are currently most hopeful for.

That or a small hubbercraft?

How much trouble you'll be having building a road in the marsh depends on how deep it is. The thing with trying to build on marshy soil is that you have to connect whatever you're building to a solid layer below, otherwise it'll just sink. This is the reason that e.g. in Amsterdam houses are built on piles driven into the marshy ground until they reach the underlaying hard sand layers. If you put a layer of riprap on top of your marsh, it will just sink over time. You'll have to keep adding riprap until your layer of riprap is thick enough to fill the whole swamp. And then you might still have issues with high water.

W.r.t plan B, others have already mentioned how you can probe for rocks. A well-constructed wooden bridge will not rot away in a couple of years, provided it it high enough above the water to stay dray, and the abutment is well-constructed. The problem with bridges is generally building the abutments. It must be sturdy enough not to move or wash away. And when using a wooden bridge, it must keep the ends of the beams dry.

For a relatively small span like this, a beam bridge would suffice. The question is how much load does it need to carry, and how much deflection (bending) will you accept under maximum load? I can guarantee you that a bridge that is just strong enough will deflect way more under load than you'll be comfortable with.

If you'd build a beam bridge with e.g. abutments built from cinderblocks and cement, the weight of the components that need to be transported will be limited. And if you don't want to haul around long beams, you could even go for laminated beams built on-site out of relatively short and light planks.

http://www.motherearthnews.com/diy/how-to-build-a-log-bridge-zmaz84mjzloeck.aspx

Says a tree beam bridge lasts 20 years

In Minnesota when i lived there they were tearing out an old road through a swamp and found tamarack logs laid the length of the swampy place. they placed dirt and gravel fill on top of that and had used it for 40+ years. Once a lot of semis started using the road it soon was not good enough, but that will not be your case. If you do put fill down putting down a fabric road base will go a long way to keep your fill from leaving.

I still think you should consider a ferry raft.

the raft http://www.bradleyit.com/1/post/2013/05/new-post.html

In use as a ferry https://www.colourbox.com/image/ferry-raft-floats-on-the-water-image-11502686.

A lot easier to set up and doesn't fight nature.

I had a driveway put in an used an old oil tank. I got it 4 free, had both ends cut out. Rolled it off the trailer right end to the creek bed and put fill over it. It was 10' high and has held up for 8 years.

I vote for plan B. Assuming that your load of rip rap covers the whole drive and gets you out of the muck (I'm doubtful it will) right now, it will still fail quickly in the floodplain. My first thought was that plan B gives you access in flood conditions. What would you do in an emergency (medical or otherwise) when the floodplain drive is impassible? Although you'll have a bridge to maintain and eventually replace, that can be planned and budgeted for unlike floods. Plan B sounds far more practical to me.

I like plan B. The flood plain will swallow everything you put on it over time. We're working on our own access road right now. It's amazing what even a smaller dozer can do. : )

Thanks to everyone for their thoughtful comments! Karen's firsthand data was especially helpful, as were the suggestions of using trailer beams to support a bridge and rebar to test for bedrock. Eric's rail solution has always felt intriguing, but like finding the parts would be too hard in our non-railroad-friendly neck of the woods. Keep those outside- and inside-the-box ideas coming!

I agree with the other sentiments about the road vs. the riprap. Are there any other options for the dozer route? i.e., if you get some rebar to test for the bedrock depth, could you potentially plot out a route that you know will work with the dozer, even if the one you described above doesn't pan out?

Also, I've seen culverts from time to time on craigslist, but I've never looked at the prices.

Hey, if the place had a nice driveway, it would have cost twice as much to buy and you would be over run with salespeople right?

I do want to ask, since it had an abandoned house and a tobacco barn when you bought it, obviously there was access for those residents. Did they have a road coming in, or cross the creek as you do? Or was there access from another direction, crossing other property that was divided off or sold, with no deeded access to your property?

Jake --- Unfortunately, no other options for the route. Which, I guess, makes testing for bedrock a bit less imperative --- either the dozer can do it, or it can't.

Eric --- I'd say the land would cost considerably more than twice what it cost if the driveway issue hadn't been part and parcel of the land. As for the previous residents, no one had lived here in at least 50 years when we moved in, and I got the impression that back then they traveled on foot and by horse. The path we follow was their original path, as best I can tell from the topo map, although there are some other possibilities that we don't have rights-of-way to. I think our current driveway would be much more feasible if you were just using a horse there every few weeks rather than trying to run a motor vehicle across it. Although, to be fair, we've had dry years where our driveway was pretty passable as-is. Our climate just seems to be running wetter and wetter lately, making that much less feasible.

Anna said: Jake --- Unfortunately, no other options for the route. Which, I guess, makes testing for bedrock a bit less imperative --- either the dozer can do it, or it can't.

Actually I think if there is only the one route that means that it is more important for you to test for bedrock. It would be painful if you had the neighbor come and start cutting a road when it could not be finished. That way you would be out of money and have a scar on the landscape.

Another idea for a bridge would be a used up semi-trailer, like the one the dozer would use for transport, a flatbed trailer, strong enough for almost any vehicle, although it would be quite narrow. A standard 53' box trailer could be a covered bridge. Dozer operator should be able to maneuver it into place with earthen abutments. Abutments could be reinforced when weather events erode them. An ideal find might be a junked car hauling trailer, but even with tracks for tires, still would be slippery when wet. But of course any surface, wood, metal or concrete would be slippery when wet, or worse if cold. Slide offs might be hazardous to the well being of travelers. Would be a good idea to add a gate at the beginning of the driveway to restrict access.

Plan B sounds good in the long term for some reasons but there are too many unknowns for my comfort level and will probably end up costing more than you plan.

If you have access to equipment that could dig ditches along your existing drive that would allow the water to drain away. Adding that dirt to the drive so it can be crowned would keep the road from holding water on the surface. I would recommend either making it wide enough that a dump truck could get in to dump gravel over geofabric or at least make it so the ditches are far enough apart that this could be done in the future if your needs change. This could be done in phases as money becomes available and wouldn't cause any unnecessary damage to steep hillsides that could erode.

If you have any access to used telephones from your local utility a couple of those can hold a lot of weight and probably span your creek.

I think a trail to get out on foot in all weather is important to have.

I'm interested to hear what direction you decide to take.

A good guide for wetland road building here. http://www.na.fs.fed.us/spfo/pubs/stewardship/accessroads/recommendations.htm I would definitely try to find the depth of the swamp along your road.