culvert heaved

[bellweather]

Last fall I installed a 12" plastic culvert pipe accross my driveway, and after the spring thaw it was evident that the pipe heaved up somewhat. I thought I did a pretty good job on the installation...I even set the pipe in a 3" bed of gravel (see pics), though it wasn't quite 24" deep to the top of the pipe. What I think may have gone wrong was my excavation on the oulet side was such that a small pool remained, which I suspect may have lead to water migrating under the pipe. Is this a reasonable assumption? I also noticed that this year a lot of rocks and branches have appeared on the road surface, again due to frost heaving. Maybe it was just due to the harsh wet winter? Or maybe this is normal for the first year, and the pipe will settle in? Any thoughts will be appreciated.

 

[bellweather]

one more pic...

 

[SteveV]

Hmmm... I just planted a 4 inch culvert 50 feet long across a driveway and front yard in gravel. buried 12-18" deep following a ledge downhill. My biggest concern is pipe flex; the corragated plastic is cheap enough but does it flex and walk around as vehicles drive over it? We'll know next year. Don't have access to the pictures right now but will post later. Have you checked the State of Maine's camproads to see if they have anything to say about culvert depth vs diameter? SteveV

 

[Henro]

Hers's my guess...

Is there any slope so that water that finds its way into the stone under the culvert can drain out one side or the other?

Things heave because water as it freezes expands. If you do not have a way for the water to get out from under the pipe, you may have ice form, more water get in during warm periods, then freeze again...more upward push...sort of like a hydraulic jack under the pipe.

In a place where the pipe is flat and drainage is not easily accomplished, it may be better to just lay the pipe in dirt and skip the stone. That is what I have done in the past and have had no problems with heaving or any kind. My pipes are not that deep for the most part. I have 40', 12', and 80' of 18" pipe in dirt, and another 50' of 8" pipe all set in dirt without any stone at all and without any problems. We do get our share of freeze/thaw cycles here in Western PA too.

My pipes do have slope to them...so I guess IF I had stone around them water would drain out from under them anyway. Just want to mention though that laying my pipe in dirt has not been an issue for me, and could be the answer to your problem. The key is to do whateaver it takes to keep the water from laying under the pipe, where it can freeze and push up. At least in my mind... /forums/images/graemlins/smile.gif

 

[SteveV]

Here's some interesting reading posted by Hazmat back in 2002.
Maine_Camproads
Basically, they're saying to bury the culvert to a depth of at least 1/2 the diameter of the culvert. SteveV

 

[trlong]

Have you looked at the condition of town highway and state roads in your area this Spring? Are they in good condition or, did they take a beating as the ground froze and thawed? I don't know how bad the winter was in your area of Mass.. As for North Central VT, we got beat pretty hard. Culverts that never stay plugged after the first good warming trend were solid ice and causing major drainage problems, and heaving.

It looks as though you did a good job of installing the culvert. I have not looked at the Maine website yet but, you may need to chalk this one up to an excessively bad winter.

Henro has a good point on pitch/drainage. Ofcourse, he lives in the banana belt! /forums/images/graemlins/grin.gif (Kidding Henro!)

 

[bellweather]

Actually, the paved street I live on took a beating...so much so that the town posted a "Frost Heaves" sign to alert drivers to slow down due to the dips and bumps. Now that it's spring, the street has settled down quite a bit. My plan is to go through another winter and then decide if action is required. Hopefully I will not need to dig up and reset that pipe. Took me a whole weekend the first time. Thanks for the input.

 

[Larry_T]

what you will have to do if it dose not stay down, is to put 2 inches pink or blue styrofoam board 2 feet whide over top of pipe level ground off even top of pipe. cover with ground. works in WI

 

[TOMDUALLY]

Took me a whole weekend the first time<font color="red"> </font>

I know what you mean about taking the whole weekend to do the job, Looks like you have the same model of backhoe(2nd picture) that I have. Get's the the job done, takes longer and when your finished you know why it's called a 'BACK'hoe. /forums/images/graemlins/tongue.gif /forums/images/graemlins/tongue.gif

 

[LBrown59]

I just started adding 80 feet of culvert to the 40 feet I already have under my driveway.

I'm using 15 inch diameter corrugated double wall smooth bore plastic.

Is the 12" stuff you used double or single wall ?