What to do with a shallow buried concrete pipe?
What to do with a shallow buried concrete pipe?
(OP)
What would be the best way to handle this? We are realigning an existing 36" RCP sewer line that currently has about 2' of cover. The new sewer will need to be installed beneath an access road that frequently has loading trucks.
Would it be better to just use a reinforced concrete jacket around the pipe or use a higher class of concrete pipe? How much more strength does a jacket provide?
Would it be better to just use a reinforced concrete jacket around the pipe or use a higher class of concrete pipe? How much more strength does a jacket provide?





RE: What to do with a shallow buried concrete pipe?
RE: What to do with a shallow buried concrete pipe?
RE: What to do with a shallow buried concrete pipe?
I would follow gbam's suggestion of determining loads, maybe an H-20 loading situation or more. Second, the pipe manufacturers tend to be very helpful with this. They will have real world tests of pipe load capacity. You can use a higher class RCP (make it poly lined too, if it is wastewater application, hydrogen sulfides in ww are known to erode concrete)
My guess is you can find a new pipe that can handle the loads without going to special jacket. Probably be less expensive to install too, rather than re-use of old pipe (which may be old and deteriorated) with some form of jacket around it.
RE: What to do with a shallow buried concrete pipe?
RE: What to do with a shallow buried concrete pipe?
My initial discussions with the manufacturers is that we can get by with 1' of minimum cover over standard class 3 RCP. I'm hesitant mainly because the acceptable standard is to provide at least 4' of cover. So if we install it at a shallower depth and run into any problems, we're at risk for deviating from the standard.
Thanks again for the options... definitely food for thought.
RE: What to do with a shallow buried concrete pipe?
You also have not said anything about the underground soil conditions.
Another alternative that has not been proposed so far is that you can probably use two smaller pipes instead of the single larger one. For example, 2- 24" pipes instead of the 36". That may be your best option.
RE: What to do with a shallow buried concrete pipe?
I'm going to assume you have access to information on the existing soil types at the site. Now the pipe is crossed by access road so you need to determine the loading. HS-20 is a standard load and should be fine unless you have evidence of larger trucks using the road. Next select a type of bedding based on the soil information and determine the D-load on the pipe. Then select a class of pipe that meets that load.
There are some excelent examples in the design manual. As gbam said it will likely be cheaper and easier to install a higher class of pipe rather than constuct a concrete cap. I've seen loaded twin axle dump trucks drive over class 5 rcp with 6-inches of cover with no ill effects on the pipe and Class 3 RCP will likely be sufficient but as stated before just run through the design calcs to make sure.
One thing to remember is if you specifiy a higher class of bedding you can use a lower strength pipe, but you'll have to have tighter controls on installation to make sure it is constructed correctly. Its usually better to assume a lower bedding class for design purposes as it will result in a more conservative design and account for any installation errors.
RE: What to do with a shallow buried concrete pipe?
RE: What to do with a shallow buried concrete pipe?
http://ma