Cement Bag Retaining Wall

[WoodChuckDad]

I have searched the old forums and only been able to find one thread on a retaining wall made from stacked cement bags. It isn't anything revolutionary, but it is something that I have not done before. I am creating a bridge crossing over the dam overflow of my pond. I hired an engineer to speck out the pipe needed and he gave plans for the bridge as far as the pipe needed and the grade but the retaining wall is up to me. The plans call for two 48 inch pipes, 60 feet long put in at a slope that takes the exit end10 feet below the entry end. At first I was going to use a precast headwall but the cost delivered will top $10,000. Also it would weigh around 6,000 lbs so maneuvering it into place would also be a challenge. Instead, I am going to use stacked 80 lb backs of quicker, pinned together with Rebar. I will come up 2feet above the pipe so total height will be 6 1/2 feet. I have ordered 400 bags of concrete to be delivered on the same day the pipes are to be delivered. I have seen a few threads about building retaining walls so I assume following the same principles would make sense. Should I put 1 inch gravel between the wall and and back fill? and if so, how much and how high?

 

[countrybumpkin]

Google " bag Crete retaining wall" you'll have plenty of reading and ideas. They also make special bags for building walls.

 

[WoodChuckDad]

I contacted sakrete about the project. The guy I spoke to said they have to hat production and do a special run for those bags and I wouldn't be able to order less than a trailer. He also said it would be 9-11 dollars per bag. He advised me to just get it at lowes and use the regular 4,000 psi bags. So, I'm pushing forward.

 

[EddieWalker]

How are you going to stop water from flowing along the outside of your pipes?

Once your trench is dug for the pipes, it will be 100% impossible to get good compaction all the way around it, which means the soil used to back fill will be softer then the compacted soil already there. This will give water a path to travel.

The sacks should work OK as rip rap to cut down erosion from the waves of the lake, but it will not stop water from flowing through it and down the sides of your pipe. You will have to build forms and pour concrete, and after you remove the forms, seal the concrete and where it contacts the pipe with some sort of water proofing. This will be a thousand times easier to do now compared to later when you discover the leaks you will have.

 

[WoodChuckDad]

Eddie Waker, Where's the love, man? Don't tell me that. There is a spillway tube in the pond. I've never seen a wave on that pond at all. Currently the overflow creek is dry. When we have been having lots of rain it gets about 2-3 inches in it and about two feet wide. These pipes are sized for the 100 year storm. My plan is to start by diggings own a foot and building a faoundation that rises up 6 inches above the creek Then do the stacking on top of that at a slight angle toward the bridge. I figured this would give the water some direction toward the pipes openings and give time for soil compaction. There will be a 50 foot wide trapezoid of earth on top going from end to end over the pipes. I can't imagine I need to go higher. The engineers original plans just had me doing earth with rip rap on it at a 1 to 3 angle. (1 up and 3 over).

 

[WoodChuckDad]

So now you have me thinking and worrying. I may build up the base line to a foot above the inlet line. Like you said, better now than later. I'll take lots of pictures.
This is what I am going to be crossing....gently building up from where I am standing to the crest on the left. The area of the downed trees over to the right is about where I will have the retainer wall.

 

[davrow]

Check out this youtube video of a guy using lunch bags (instead of full concrete bags) to build the wall around a culvert. It is an existing culvert instead of a new one.
It is two parts, building it, then how it works in a good rain. (this is just part one, need to search youtube for part two if interested)

 

[Ed of all trades]

Davrow thanks for the video, might use that idea. Ed

 

[WoodChuckDad]

I've come across that one. Like the way it turned out. Our soil compacts really well here I think that I should have pretty good luck with this. Materials will be delivered this week. And I will start work on it next weekend. I'll post pictures when I get them.

 

[Rustyiron]

I've dry stacked several "headwalls" for pipes over the years. No problems at all and the paper just go's away in a year or so. No special backfill, I just try to make a tight fit at the pipe and between the bags and don't be stingy with the rebar.

 

[EddieWalker]

Maybe I miss understood. Is this for the overflow of a pond or a culvert in a creek/ditch? If it is in a pond, the water will work it's way down the side of the pipe unless you specifically seal it. If it's a culvert, like in the pictures posted, go for it. I have done this with several culverts, both at the entrance into it and where the water exits the pipe. I prefer 50 or 60 pound sacks over 80. It's a lot cheaper, lighter and nearly the same coverage. Just not as deep, but that's not gonna matter. After stacking them, I pound the rebar through them. Dry sacks are real easy to get rebar through with a hammer.

 

[Threepoint]

Here's part two of the lunch bag video. Culvert Bricking With Cement Bags Part 2 - YouTube

Interesting idea.:thumbsup: I need to rebuild some wing walls for two large culverts that carry occasional but heavy runoff. I originally used 6" -8" gabion, hand-stacked dry. After 13 years, it needs either rework or replacement.

In the part-two video, it looks like the paper is still fully intact on the concrete bricks, and no vegetation has yet grown in the back-fill. So I'm wondering about long-term performance after repeated heavy run-off. Would be neat to see a follow-up video in a couple of years.

It also looks like they stacked the bags of concrete straight up. Wouldn't it strengthen the wall to corbel the bags into the slope with each successive lift? I seen that done a lot with both masonry and timber-tie retaining walls to create lateral counter pressure. Also wondering if backfilling part way up with 3/4" crushed stone (not river run or pea gravel) would help against failure from hydrostatic pressure.

 

[WoodChuckDad]

Maybe I miss understood. Is this for the overflow of a pond or a culvert in a creek/ditch? If it is in a pond, the water will work it's way down the side of the pipe unless you specifically seal it. If it's a culvert, like in the pictures posted, go for it. I have done this with several culverts, both at the entrance into it and where the water exits the pipe. I prefer 50 or 60 pound sacks over 80. It's a lot cheaper, lighter and nearly the same coverage. Just not as deep, but that's not gonna matter. After stacking them, I pound the rebar through them. Dry sacks are real easy to get rebar through with a hammer.

2.5 acre pond. has a spillway pipe of about 18 inches that is functioning fine. IF debris piles up around the pipe it lifts the water level an inch or so...I was surprised by that. There is an active stream that feeds the pond as well as a couple springs on the bottom of the pond. At the far end of the dam, there is a small spillway, overflow. Right now it is dry. in winter it seems to vacillate from damp to a 6 inch wide trickle with the occasional foot wide flow an inch or 2 deep. In the really big rains we had the last few months it was about two feet wide with 2-3 inches running across it. I am going to put two (2) 48inch diameter NP12 pipes in it and build up earth onto of them to create a bridge that takes me up that hill. My soil packed up very tightly, and I figured that with two 48 inch pipes water would take the path of least resistance and not mess with the soil next to the pipes. at the point of inlet I intend to dig down a foot to hit bedrock ( i know it's there because it is showing thru on the hill where they cut away the trees. ). I'm going to pour a footer reinforced with rebar and and rebar sticking out of it. so I can impale the first course of bags on top of that. Then stack the bags angled slightly toward the bridge to a height of about 6.5 feet and let that be my retaining wall for the bridge.

 

[WoodChuckDad]

I hope this makes sense

 

[WoodChuckDad]

 

[Rustyiron]

WoodChuck, you got any feelings why your engineer wants 60' of pipe rather than just enough to drive across like a single 20' legnth? 120' of 4' pipe will be costly. Engineers tend to cover their butt with the clients money.

 

[bigtiller]

View attachment 476309

That looks like a good place for a ford crossing. Your local concrete plant can prepare the correct mix that will cure under water if necessary.

 

[WoodChuckDad]

Ford crossing won't. work. It's way too steep. I need to make a bridge so I can drive up that hill.




The reason for the large diameter and long run of pipe is to achieve a deep enough drop from start to finish to make the water flow fast enough in the event of a large storm. I am the last semi flat piece of land before the mountain climbs another 2,000 feet. The terrain creates a funnel that drains 170 acres of land above me into the creek that feeds my pond. A significant storm event has the potential to really bring the water flowing thru there. I don't anticipate it happening any time soon but that is why it's so heavy built. And yes. The pipes are expensive.

 

[RedNeckRacin]

Two things. Eddie is correct about needing trench blocks. You are going to need them. Also, you are going to create a serious scour hole at the exit of those pipes. Your engineer buddy may have mentioned this or he atleast should have. Two 48" pipes at an almost 17% slope are going to be like huge water cannons.

 

[WoodChuckDad]

Two things. Eddie is correct about needing trench blocks. You are going to need them. Also, you are going to create a serious scour hole at the exit of those pipes. Your engineer buddy may have mentioned this or he atleast should have. Two 48" pipes at an almost 17% slope are going to be like huge water cannons.

I talked to him about that. As it stands? The overflow creek has been there for 20 years and has already dug down about ten feet to bedrock. I will be keeping my eye on it to make sure that I don't create an erosion problem.and I will probably arrange some large rock there just in case.