Anyone do retaining wall work? My back yard is flat for about 15’ then a 5’ retaining wall (drops down). It is flat again for about 12’ then it transitions to a downward slope (8’ out 4’ down) to a 3’ city retaining wall, then to the sidewalk. I want to put a wall where the 12’ flat part transitions to the slope. I'm ready to sign with a contractor that I feel good about but I just want more opinions. The retaining wall that is about 5' 6" out of the ground, 65 feet wide with two "wings" that come back about 12' to level ground. The bid is about $15,000 for two soil samples (1 at the beginning for the engineer, and 1 compaction test at the end for the city), an engineer to design the wall (required by the city), backfill, all permits, geogrid and the keystone blocks. What do you think? I live in San Diego if that makes any difference. Thanks guys!

 

The price will change depending on location. Get 3 or 4 bids with refernces ( many contractors I know have job books w/ pix of previous jobs) andspeak w/ former customers to gauge their satisfaction w/ the job. Make sure they are legit and insured! Remember...cheapest isn't always best. Good, Fast, Cheap...pick any two

 

I've done retaining walls for the last 4 years. I work with another guy that has built them for almost 15 years now. What is the square footage of the new wall? It sounds like your new wall is going to be 8' behind your 3' wall, which is good. Depending on the soil, a good rule of thumb is to start a second tier at distance twice the height of the lower wall. So, 3X2 equals 6' and I think you are going to be at 8'. It sounds like the engineer should have an easy job. I'm glad to hear that geogrid will be used. It's kinda expensive, but well worth it. It there a "cap" going on the new wall? Is the wall straight or curved? If the wall is going to be 4' exposed, then there should be about another 8-12" of block burried for the base. Below that should be 6-12" of compaced "base" material. Usually crushed road rock with the "fines" in it. The backfill should be a class 5 material 8-12" behind the wall. A drain tile behind the wall at the grade level in front of the wall should be used and either exit through the wall or around the wall. Water is a retaining walls biggest enemy. If the wall block is 6" thick then geogrid should be used aproximately every 3rd course. (this can vary with the soil type) $15,000 sounds kinda cheap if your new wall is going to be 4'exposed height by 65 ft long.
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Here are some pictures of last years projects.










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That's some real nice work there!

 

Thanks for the replies guys.
aaa3 – I’ve checked his contractor license and he is part of the BBB in good standing. The problem with getting more bids is getting the contractors themselves. I’ve called 10 contractors and 7 never showed up/called back (I’m NOT going to chase down someone to take my money), Of the 3 that showed up the 1st guy spent like 2 hours with us talking about wall types, backfill options, taking measurements and such. He said he would call in a couple of days with an estimate but I never heard from him again. The 2nd guy showed up and I could tell right away, he didn’t want the job; after 10 minutes he left and said he would call back and never did. The 3rd guy is the only one who showed up at EXACTLY the time he said he would and gave us a bid EXACTLY when he said he would and even itemized the bid. He seems like a stand-up guy.
Brian – Kudos on the work, do you live near San Diego? J I don’t know how far the wall will penetrate the soil (engineers call) or if the wall will have a cap, the wall will be straight with approximately 90 degree wings. I don’t quite follow "A drain tile behind the wall at the grade level in front of the wall should be used and either exit through the wall or around the wall.". So you think he gave me a good price?
Thanks again guys.

 

Sorry, I live in Minnesota. Here is a picture of what I am talking about with the drain tile. If you can't run water around the wall or out one of the ends...then you have to route it through the wall like the picture shows. The price seems pretty good. I've done a 2 tiered wall about 60-70 feet long and each wall about 3.5 feet tall and it was around $18-20k. There was some other landscaping involved, but that was peanuts compared to the rest of the job. It sounds like there will be easy access to where your new wall is. That should knock a little off your price compared to someone who tries to do the same thing, but say in the back yard. If you are leveling off the area between the two existing walls, there will be a lot of excavation that needs to be done. This adds to the contractors "base price". I am glad I don't have to get involved with landscape engineers. I know I am lucky in that way. I do how ever deal with landscape architechs. They SUCK. Their drawings and the real world never match up. Yet, they demand that you do the work EXACTLY as they show on the plan.[:@] They won't compromise. What do I know, I just make their drawing become reality.

I wish you the best of luck with your project. Sounds like the contractor you picked should treat you well.