Driveway culvert

Dave41A · Jan 5, 2020

Good afternoon. This is somewhat tractor-related so I'll post here. If not, then please suggest an appropriate forum. Anyway, this past summer I replaced a culvert under my gravel driveway. The old culvert was an 8 inch steel pipe that the previous owner had installed. Through frost heave it had worked its way to the surface and was about 1/4 to 1/3 exposed. I would hit it when clearing snow. It also was not nearly deep enough to adequately drain water, which would wash over the driveway in heavy rains and melts. It also made a good "bump" when driving in or out.
So I dug it out and replaced it with an 18-inch driveway-rated polyethylene corrigated culvert. I set this one at about 3 foot depth. I backfilled with the material I had removed, which here in WNY is a high clay content soil. There is a lot of driveway aggregate mixed in.

Anyway, now that it is winter--and a mild one at that--the driveway above the culvert is "sagging" and I have a pronounced dip there. I suspect this area thaws faster when everything else is frozen as warmth can get under it from the black culvert pipe. I will fill this with more gravel as a wintertime fix--but this is just a band-aid. What had been a "bump" is now a growing sag or pothole.

My question: What are best options for fixing this? Should I dig back out and backfill entirely with crushed stone? The culvert sits back from the road 100' feet or so, so I am entirely responsible for maintenance (not the town).

Any insight is appreciated. Thanks in advance. Dave

David G · Jan 5, 2020

clay settles, should back fill with clean rock.

Richard G. · Jan 5, 2020

We have clay here.
I would just keep adding gravel until it has quit settling.
Richard in NW SC

Scott 730 · Jan 5, 2020

Not unusual for the road surface over culverts to have a dip in them in the winter. They all go away in the spring.

Janicholson · Jan 5, 2020

ABC road base, which includes 3/4" and down crushed stone. The fines bind the larger material, and consolidate the fill. Don't disturb what you have done, it is expected to subside. Jim

MKinON · Jan 5, 2020

Just keep adding granular on top as it settles, or in spring dig it out and backfill and pack it as you go up. I wouldn't use clear stone, but granular that contains fines. You could also pack the sides of the pipe with native fill and pack it well and then continue with granular over the top that will pack easier. You don't want anything under, or around the sides that will let water flow into it easily, especially where frost is an issue.

Mike M · Jan 5, 2020

If you get a heavy rain those plastic ones can and will float up and out. County had this issue up the road from me.

dpendzic · Jan 5, 2020

more likely is that the culvert is warmer than the driveway material on the sides of it. Thus you are experiencing a frost heave on the sides but the culvert is staying level. I have this every winter on my culverts and it goes back to grade in the spring
just add gravel as you need it over the culvert in the winter

jaoneill · Jan 5, 2020

I would tend to agree with those above that say to just keep filling the dip. That is a decent sized excavation and it is likely that the excavated material that you backfilled with is just "settling-in". Unless you filled it in "lifts" of 6" or so, and used a mechanical tamper on each lift, it can be expected to settle substantially the first year. As someone above noted, the clay that it contains will help prevent water from finding its way around the pipe so it should be left as is. Fill the dip, or the top 12" or so with processed gravel or stone, and continue to do so as it continues to settle, and by this time next year you won't know you ever disturbed it.

Jim

paul · Jan 5, 2020

Keep filling it.

Clay dirt will slump and compact for 3 years or so, you dug it to 3 feet and then dumped the dirt back in. The professionals compact and press down every 8 inch lift as they put dirt back in, and their patches still settle more often then not.

Digging it out will only start the process over. Unless you go pro and really compact each thin layer you put down.

Just keep adding on top and it will mello out in 2-3 years. The clay absorbs water, then as the water slowly leaves it compacts naturally a bit. Over and over until it settles itself.

Paul

kcm.MN · Jan 5, 2020

I have no idea how the road base there compares with the base here. We live in a wetlands area, and have 20+ miles of gravel going to town. Nearer to our place, it's usual for the culverts crossing under the road to have those dips. Sometimes they are so bad that the county has to put flags in hopes people will slow down. I've heard some folks hit one in front of us and it sounded like their rear end got ripped out from under the truck.

All the county does is re-grades the road as they can. Don't know if that is something that has a permanent fix available. And the only thing I can attribute it to is the very high water table most of the year. The parts of the 20 miles that are not as wet don't seem to have the dips. Worst time for them is Spring thaw, but have seen them form at any point in the year, to some degree.

showcrop · Jan 5, 2020

As jaoneill said it needs to be compacted. An excavation contractor would have back filled with compact-able gravel, which means crusher run or crushed gravel depending on the part of the country, and place it in lifts of 6-8 inches at a time and run the plate compactor over it. Clay doesn't compact well and it is also not stable for a heavy vehicle going over it when there is any water in it. I would dig most of it out and replace with 1.5 inch crusher run. If you don't have access to a plate compactor beating on it with a hoe will work pretty well.

Geo-TH,In · Jan 5, 2020

Dave,
Rain, freezing, thawing is mother nature way of compacting. I would filled it in with rock, gravel and add a little dirt to fill in between the rock.

A friend has driveway issues. He's on stick to your shoes clay.

I can add gravel to holes in his gravel drive and water fills holes. Car drives over hole . Water and rock splashes out.
I add clay and rock to hole. Once clay dries out the rock stays in hole.

I'm working on pole barn floor.
Before I put down concrete I'm building the floor to grade I want. I'm using white rock and a little damp top soil. The tractor is packing it in so hard. I'm having trouble removing places where I added too much.

So blend a little dirt with rock.
Drive over it to compact it. Then add more.

jaoneill · Jan 5, 2020

Showcrop's answer would be a surefire instant fix, although it will still settle some the first year. Save some work and cash; or do as Paul & I suggest, your choice.

Jim

jaoneill · Jan 5, 2020

Sorry my last sentence didn't make sense, wife was hassling me to mash the spuds. Here is corrected version: Showcrop's answer would be a surefire instant fix, although it will still settle some the first year. Save some work and cash, do as Paul & I suggest, your choice. Smile

David G · Jan 5, 2020

agreed.

Dave41A · Jan 5, 2020

Rollie: Thanks for the helpful link. I agree crushed stone would be better than gravel. By the way, and if you don't mind me asking--do you live near "North East" PA? If so, we're neighbors--I'm in Chautauqua cty, NY.

Rollie NE PA · Jan 5, 2020

I am northwest of Wilkes-Barre

Rollie NE PA · Jan 5, 2020

Near Dallas.

Dave41A · Jan 5, 2020

Got it. You're actually in "NE PA," as opposed to "North East PA," which is in the NW corner of the state...
I once looked at a IH 244 that was for sale in North East PA--being sold by a gentleman named "Rollie" of all things. Not the most common name, so I thought maybe you were the same individual. Thank you for your assistance.

ztrmowers · Jan 5, 2020

just fill the dip in with crushed rock or what ever you have that's normal on any dig up job takes things time to settle back in. you dig it up and start over you will have same issue again

K Effective · Jan 5, 2020

I'm quite certain you should just move away and leave it for the next guy.

sms · Jan 6, 2020

My better half lived on a dairy farm near Sherman for a couple years and loved it there.

showcrop · Jan 6, 2020

(quoted from post at 20:31:54 01/05/20) just fill the dip in with crushed rock or what ever you have that's normal on any dig up job takes things time to settle back in. you dig it up and start over you will have same issue again

ZTR, tens of thousands of excavation contractors are out there everyday digging holes and refilling properly, in lifts that they compact properly. On many projects tests using very sophisticated equipment are performed to check compaction. Gravel is also tested for proper percentages of content of sizes of materials. There are various different names for almost identical gravel products in different geographical areas. You can't go by your local name only. Rollie's link shows that what he says can't be used must be used. It is just different names. I am not as I said earlier recommending that the OP do it this way, just telling the proper wsay of doing it.

jaoneill · Jan 6, 2020

You and I certainly agree on the proper way to fill the ditch but, in this instance, given the OP's lack of expertise and, I would guess, equipment, simply filling the sag as it develops will eventually do the trick at a lot less cost and effort.
After all, that is the way it would have been done prior to the development of the more modern methods in the last 20-30 years. And actually, except for the more costly, "professionally" performed projects, it is way most folks continue to do it. :wink:

showcrop · Jan 6, 2020

(quoted from post at 20:31:54 01/05/20) just fill the dip in with crushed rock or what ever you have that's normal on any dig up job takes things time to settle back in. you dig it up and start over you will have same issue again

ZTR, tens of thousands of excavation contractors are out there everyday digging holes and refilling properly, in lifts that they compact properly. On many projects tests using very sophisticated equipment are performed to check compaction. Gravel is also tested for proper percentages of content of sizes of materials. There are various different names for almost identical gravel products in different geographical areas. You can't go by your local name only. Rollie's link shows that what he says can't be used must be used. It is just different names. I am not as I said earlier recommending that the OP do it this way, just telling the proper wsay of doing it.

Billy NY · Jan 6, 2020

Some confusion here, clean crushed stone will not compact, no range of different aggregate sizes within it. Gravel without too much really large aggregate, crushed stone, crusher run, whatever they call it where you are with the array of aggregate sieve sizes from fines to say 3/4" at optimum moisture content will compact sufficiently.

What showcrop is talking about is filling the depth of the hole in increments, say 12" lifts, compacting and an inspector would test each lift with a device such as a Troxler nuclear density meter.

If you have decent gravel or crushed stone material, and there is no other issue, placing and compacting with various means should make the difference. What retains the cover over the pipe one the ends, is it stable or not retained, sloped at correct angle of repose is the only thing I can think of unless the subgrade under the pipe is unstable, and I have seen that happen with sanitary sewer lines. Some variables to consider, but nothing complicated with the right material and say a plate compactor or even running over with the tires of a tractor, just do so in smaller lifts if need be.

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