On Thursday, March 12, ALDOT held a meeting at Arab High School to discuss the length of time and what was going to be done about the section of Highway 231 that was destroyed in a landslide on February 13.
Highway 231 is an important link between Marshall County and Huntsville. Thousands of people from Marshall County drive it daily going to work in Huntsville.
The meeting started with an interesting beginning. The number of people in attendance were not as many as they assumed would be there, but Mayor Bob Joslin said it may be good thing with people being afraid of the coronavirus. There were a lot of space between people and the auditorium was much larger than having it at Arab City Hall, where it was originally planned.
Another interesting beginning was two bats made an appearance. One person joked about the bats being named Corona and the second named Virus.
Joslin spoke about the importance of doing this update. He was grateful that ALDOT wanted to speak about the landslide and get the information out to the public.
There are all kinds of rumors posted on social media about the problems with the roads and Joslin was glad to be able to get the truth out there.
ALDOT Director John Cooper - who is from Marshall County - started the briefing by discussing what happened on the Highway 231 slide. He said while observing social media comments, there are two big questions that he wanted to address first. The first question is what happened and the second question is when will the road be opened.
What happened is that Highway 231 had a significant slide on the side of a mountain. There is about 50 feet of overburden of mixed sandstone, clay, sand, soil and large boulders on top of a layer of clay, which in turn is on a bed of limestone. What is happening is that this is trying to slide off the side of a mountain. The limestone is on an incline which makes that easier to happen.
As more and more water seeped into the clay on top of the sandstone, it made it easier for that mass to move. Many motorists who travel this road know that there was slight movement about a year ago on the southbound side (the side going up the mountain) and they have been monitoring the area ever since.
Cooper said there had not been any significant movement until February. When there was significant movement, they addressed the reasoning for the movement. They found that they have this 50 feet of overburden and it is not an easy thing to deal with.
On the second question of when will the road be opened, Cooper said ALDOT is working on an estimate. They are very early in the process and they are not yet at the stage of taking bids. They have not had the opportunity to speak to contractors and get their input at this point. They can design from an engineering standpoint, but the construction will be more geared towards timelines and having a product that will work for a long time.
He said once they know more on the bid package, he will present it to contractors and develop a much more precise bid package including a timeline. There is a working estimate of one year and they are working with contractors to see if the time can be cut down into a period of months.
"I wish I could tell you we are working with a shorter period of time, but like I told you, it is a massive slide and it is not going to be an easy thing to deal with. It is going to be a significant contract and so we are working with that estimate of a year and we will try to narrow that as we move forward," Cooper said.
North Region Engineer Curtis Vincent said his area includes all state routes and bridges within the 13 northern counties in Alabama. Vincent is a Marshall County resident and lives in Guntersville. His office is in Huntsville. His commute is from Guntersville to Huntsville everyday and he varies his routes so he can see what is taking place in his territory.
He travels from Guntersville to Highway 69 to Union Grove Road and from Union Grove to Highway 231. He wanted to acknowledge the inconvenience of the travelers that use that route. He feels their pain because he makes that commute himself and he knows what has happened. He sees it.
His job is to make this inconvenience as short as possible. He said ALDOT did not make the slide occur, Mother Nature had a lot to do with that. They are responsible for the roadway though. His goal is to have the road safe and opened as quickly as possible.
He said he was sure that everyone was aware that we had one of the wettest Februarys in the state's history. The excess water that infiltrates the soil can cause the soil to lose the strength required to maintain the slope in a stable condition to support the road.
The weakening of the columbium soil appears to be the cause of this slide. He discussed it in easier terms by saying we have this mixture of about 50 feet of rock, soil, clay and fragments and then you have all of this water coming off the mountain side. Water has its way of finding the path of least resistance. There is no doubt that it was going into cracks and crevasse in the ground and going underneath the road way. This allowed for the fine particles to settle to the bottom and sitt on the limestone or moving out in the voids. That allows the material to move and drop.
In 2019, we had significant rainfall in February and March which caused a crack. The crack was identified in the right hand lane of the south bound roadway as you go up the mountain.
At the time they noticed the crack, they began to monitor the crack. They began to regularly go out and check it to make sure it did not have more issues. Over periods of times, they would do some work to the area. The whole time they were there, they were monitoring. They would not allow the roadway to be unsafe.
Over a long period of time, they decided to get some other people to come in and do some technical work. They had some instrumentation installed to better understand the movement of the mountain. The device measures the movement in the earth's surface. These devices were driven down about 70 feet into the solid bedrock.
He added that the cracks in the pavement are not uncommon for roadways alongside mountains in this particular part of the state. Asphalt cracks as the earth moves. He gave an example of an old house. The house's foundation can crack because of the settling of the earth. This is similar to what happens in the roadways too.
He pointed out Tennessee has also experienced a lot of these same type situations. He believes there are about 40 similar type situations up there that he has heard about.
He said they had been monitoring the roadway and sent out a press release that they were about to close that roadway to do some work on the outside lane for repairs. This information was sent out on February 12 with work to begin on February 13.
Intense rainfall occurred on February 12 and February 13. At 3 a.m. on Feb. 13, it was reported that significant movement had occurred. This was not only in the southbound roadway but the northbound roadway as well. It was more than cracking, it was shifting of the earth under the roadway.
At that time, ALDOT officials realized that they had a serious problem. The crews were out the first thing that morning determining the best detours to get people to south Huntsville.
Later on that day, an emergency letter was signed and they received three bids for an emergency project to remove the asphalt and concrete from the roadway. They were trying to remove some of the area around the slide area to see what was happening.
Reed Contracting was the low bidder. They awarded the bid of the emergency contract to Reed about 9 a.m. on Feb. 14.
Vincent pulled up on site at 10 a.m. There were 10 dump trucks, a track-hoe, a dozer and personnel working. He said he told the audience that because he wanted to show the immediate need of figuring out a solution.
He said they began with the detours. They added temporary signals at Highway 36 and Highway 67 and assigned Union Hill Road as a detour down to 36. There were temporary signals there as well.
Around Feb. 17, they had some testing done to determine where the solid bedrock was and on Feb. 18, Gov. Kay Ivey signed a proclamation of emergency. This will hopefully allow them to get some reimbursement back for the work that they are having to do now.
The testing coincided with the other information they had previously. The solid rock area was 50 feet below the ground.
On March 5, just two weeks later, they sat down with the director and gave a proposed solution. There was a lot of consideration including number crunching to determine the right way to fix the road. At that time, the decision was made to bridge the slide area with two bridges: a northbound bridge and a southbound bridge.
This roadway they are fixing was constructed in 1945. He said they have the original plans for the road. On the plan sheet, they found the area where the slide took place. It showed that there was a slide and loose soil area. It was known then and it lasted almost 75 years.
Reed is in another emergency contract. This contract called for them to remove 25 feet of the 50 feet of bad material. This had to be done regardless of the solution. It had to be done to release the pressure off the side of the mountain to keep it from moving.
Reed has been working on the site almost the entire time since the slide occurred. Vincent said we are lucky that there are local and close by. They had permits for the job that needed to be done and they have done an outstanding job. They are really moving some dirt. The dirt they are moving would have had to have been moved anyway.
The solution is to create two bridges. The concept is a northbound and a southbound bridge. The reason for two bridges is simple because they have a highef factor in safety. The way they will be constructed will connect them to the solid limestone. It will have the least impact to the mountain side and will allow for quicker construction. It is one of the lesser expensive alternatives.
The bridges will have columns and drilled shafts anchored in the solid limestone. The bridge will sit on solid supports anchored in the solid rock. It will not be impacted by water or anything that could cause damage to a flat roadway.
Victor said this has been a proven method of bridging over unsuitable areas in Alabama. Many of you may not realize, but on I-565 in Huntsville just to the west of State Route 255, there is a bridge there. It is bridging a cave. It is a proven solution and it works, Vincent said.
Some other options they looked at included replacing the entire section of bad material. It is approximately 850 feet in length and 50 feet of deep. That was a massive amount to remove. Once they put more material back in there, they have to consider that it is supported to the downside of the mountain.
The second option was to was to relocate the area to the east of the mountainside. The negative of that was that it require a lot of moving of the vertical sheer. If you were to shift the roadway up into the mountain, the road would not line back up. They would have to do some blasting and removal of rock to get it where it needs to be. They did not want to disturb the mountain more than it had already been disturbed.
Another concept was building a wall. That could be done by going into the solid limestone. It would require many shafts though and the steel would be so large that it would be a lot more expensive. The walls are also keeping the mountain sides from moving.
The last option was to build one bridge. The negative of that was that the roadways are at different elevations and those lanes have to be tied together. It would be more road and new drainage and a wall because of the elevation difference.
The plan is to move forward with the two bridges. It is the better and cheaper solution, Vincent said.
They are giving the design team 5 weeks to finish the drawing. He explained that is very quick.
The bridges will be about 1,000 feet in length and they are already removing 25 feet of dirt. It will not be sitting way up in the air, but closer to the ground. There will be enough height that water will be able to go underneath it. You do not have to build walls for these areas which is good.
They typically use about $200 per square foot of the bridge surface. That is a rough estimate. They are doing as much as they possibly can to get it open as soon as possible. They are planning on accepting bids on this work on May 10.
They are looking at somewhere around a year on construction, but Victor is optimistic about it being completed before then. He thinks they could incentive the contractor and get them in and out quickly. He thinks that it could be completed in less time than that.
Some people have asked why they do not build one bridge at a time so that traffic can be on it. He said the reason they do not do that is because he is hoping to get a contractor with multiple crews and begin working on each bridge. They do not have to worry about the normal traffic issues they typically deal with.
Vincent said he has learned while working on other big projects that incentivizing really gets the job done. You have to give that contractor a reason to get in there and bring in multiple crews, more equipment and get the job done.
There are still a lot of details that have to be worked out. The bidding will include the time and cost.
The cost for these two bridges is projected to be about $18 million.
The detours are being monitored and are watching the areas closely. He discussed that they added the signals and are setting timers to help with the various amount of traffic through the day and night hours. He asked for people to be patient and they will work on the issues.
He said he has heard a lot of rumors about how far it is to drive around the mountain. He drives this and has measured it. From Highway 231, down Union Hill Road and onto 36 back to 231 is 16 miles. If you were to take 231, you went 4 miles. The difference is only 12 miles.
He expressed that we are blessed to have a detour. We could take Highway 69 to 431 and go into Huntsville that way.
For more information, you can follow their special website at www.231fix.com