There is a lot of speculation and panic about the road failure on 30A between CR283 and CR83. I have seen a lot of photos and have seen the site in person. As a civil engineer I have dealt with similar situations over the years. Similar in the sense of slope failures, road failures, drainage failures and the need for designed solutions. Similar too in that there is the public outcry, rush to armchair solutions that were "common sense" and the attempts at pressuring the powers that be for politically imposed remedies to problems that really require engineered solutions.
While I am an engineer, I am not the engineer on this particular project, so I do not want to add another solution to the pile. I live in SoWal and I drive this section of road, but do not have a business on 30A. I am writing tonight because I feel for both the engineer and the business folks that have to deal with this situation. In this small community if I do not know them personally, I most likely know someone who does. I have concern that people do not understand the nature of road failures like this. I have concern that pushing for a quick patch will cause more harm down the road. Harm such as another washout during, or just prior to, tourist season as opposed to the one we have, which fortunately came just prior to the end of the summer tourist season. (Just think if it had come just prior to spring break).
As to the problem, the failure of this section of road is really more of a failure of a dam than a roadbed. The water had piled up and pushed on the north side of the embankment. The small culvert under the road was both too small and too clogged to handle the water. The water over topped the road and eroded the down stream side of the embankment undercutting the asphalt road. Roughly half of the road width washed away. The whole time that this was happening, the dam is being pushed on by the water on the north side of the road. There is a very good chance that what soil is left in place under the north side lane has been compromised.
The culvert that was there and has been there for 40 plus years, is undersized and being undersized was a good portion of the problem. Once it becomes clogged or blocked it is too dangerous to clear mechanically or by hand. The idea of just filling in the hole in the road and paving over the top neglects the fact that this section of road is really functioning as a dam and has been pushed out of place. If there were just a flat area with a drainage ditch on one side, that might be possible, however there is a fairly large lake on the upstream side of the road and the road is really a dam.
To repair it back to the way it was (undersize culvert and all) would require pulling most if not all of the fill material back out and re-compacting it. With that amount of effort you would want to replace the pipe at a bare minimum. I would hate to have the road out for any amount of time and leave a too small, 40+ year old pipe in the ground. So, you would want to replace the pipe and maybe up size it. Even if leaving a 40+ year old pipe in the ground doesn't bother you and you just want to fill the hole, you are probably talking in the neighborhood of 2 months to 3 months to do the work. What is accomplished if you shorten it to 2 or 3 months (i.e. roughly half the time to fix it properly btw)? What you would have accomplished is putting the failed road design back exactly as it was. Ready for more debris to clog the pipe and ready for the rain to over top again.
Installing a bridge on one side or the other of the existing road way? Quite frankly there is not enough room. You need about 28 ft of width minimum for the structure. Part of the equation is that you have to have a properly aligned road leading to and from the bridge, or culvert, in to provide for a safe and drivable road. There are many design standards that have to be met to provide the required level of safety.
Another thing is that as narrow as that section of road is, any temporary fix has to be within the footprint of the new bridge. So to construct the bridge would require taking the time to remove the temporary fix.
So, lets think about the time line for a bit. Temporary patch, figure at least 2 to 3 months to remove and repack the material. Then a week or so to repave at a cost of roughly $200,000 to $300,000. Then to perform the permanent fix would require a month or more to remove the patch, at an additional cost of $100,000 +/-. The permanent fix then cost $500,000 and takes about 2 months after all the permits are in place. So, using very rough numbers we are looking at about $300,000 in temporary fixes Those temp fixes would be complete about the same time the permits are complete. So, how much of a window of usable road? One, two, maybe 3 weeks of usable time before closing it off for the real fix (and who has been complaining about wasted tax dollars?). That is time could probably be better spent getting the site cleaned up and prepped for the real fix, thus possibly shorting the construction time on the permanent fix.
I have been critical of county government on many things. What I have seen so far on this incident has been pretty good. Granted the signage is a bit of a disaster currently, but a little rethought on the county's part and some positive suggestions on the local's part could go a long way to solving the detour marking problem. I am sure too that the preventive maintenance might not have been what it should, but who knew that we were going to have record rain falls the whole summer. Plus, quite literally it is water under the bridge.
In many ways we lucked out, it is the off season, so traffic is low. The snowbirds will be arriving soon and just might actually discover some new places when they go to rubber neck the giant hole in 30A.
I know it may be uncomfortable for many business owners. The rain this summer i am sure skewed the business counts one way or the other for all. But really what is the alternative. A quick short lived fix which will still take several months and leave that section of road at risk? A patch that will take up most, if not all, of the permitting time so that when the patched up road is ready to use, it will be time to tear it back out to do the real fix? Or to stay the course that the county is on currently, which is to fix it right as quickly as possible and to use their extra effort to try and expedite the planning, design and permitting process.
I feel sorry for all those impacted. I feel sorry to the point that I am really concerned they may be hoping for solutions that are not there, rather than planning for the reality that is. As my earth structures professor loved to say, "hope is not a plan".
Good luck to all involved. I am not sure that I have helped, but maybe I have provided a little insight into the engineer though process.
p.s. I plan not to spend much time on the remaining portion of asphalt especially the undercut portion and especially when it is raining or the water is up. Better safe than sorry and there is no telling how unstable that area may be.
