6" of Rain - Gravel Driveway Catastrophe

[deezler]

Last Friday night delivered a surprisingly intense, narrow band of rainfall to the Southeast Michigan area. After already receiving a 2+" burst during the daytime, a thin band set up on radar and just trained along for ~3 hours during the late evening, bringing another 4-6".

I went to bed nervous, but generally confident that my sandy soil would soak most of it up. What I did not count upon, was my neighbors front yard ponding up and spilling over into my driveway, turning it into a raging river that evidently served as primary drainage for at least an acre of already fully waterlogged soil. We have a ditch and culverts up at the road for drainage, but I will have to investigate why they didn't take the majority of the water flow.

Snapped a screen shot of the radar after it had been going for a while: The band was just moving in a dead straight line right over us.



It went on to even grow a bit in intensity and several freeways around Detroit are still flooded some 50+ hours later. Lots of ruined basements (thankfully I don't have one, lol).



Anyway once I dragged my butt out of bed on Saturday I went for a walk to survey the damage. Was pretty shocked to see my driveway torn apart and the majority of my gravel blown off.



My shallow ditches on the drive edges have always handled even heavy downpours without any appreciable erosion. But this was clearly an order of magnitude more water flow.



Well, not much to be done except get to work on repairing things. Gave the Cub a quick tune up and then got started.

 

[deezler]

First I had to switch from my box blade (my go-to summer time attachment) for the rear scraper blade. Clearly I would have a lot of grading to do to get things back into shape.

I started by filling up the eroded ditches. Thankfully I had a pile of reclaimed 2-3" crushed concrete right nearby to draw from. A bit mixed with dirt now, but hopefully will act more like rip-rap if this kind of disaster ever strikes again.



Got the ditches filled and drove over them a few times for compaction. Then it was time to reclaim and carry the gravel back up hill. Next, several passes back and forth with the rear grader blade, angled to pull from the edges towards the middle of the drive. Finally, flipping the blade around backwards to feather everything back out. I don't have energy or time to care for my areas of grass that got blasted with gravel deposits, so we'll just see how it recovers on it's own... sigh.



Above is the final product of a rushed 2.5 hour repair job. I have a quote coming from my excavation guy for a possible top-coat of more natural gravel - he's the best tailgate spreader I've ever seen and makes each yard go a long, long way.

Going forward, I'll need to find the time to make more major topographical changes to prevent this. I simply should not have to deal with roadway and road-frontage flooding using my driveway as a relief valve.

 

[zzvyb6]

The condition of yours before the fix is better than most of the folks on my road !

 

[JJT]

Around here, 6"+ in one day would be a once in 20-50 year event. The repairs look good. If that's your first wash out, I would not spent a lot of time adding more ditches. If it's a repeat event, contact the town to see what they can do for you, if the water is coming from their right of way. Good ditches are a requirement for good roads.

 

[duffer]

Nice job on the repair. But it looks like from your pics that even the drainage swale you installed won't handle that kind of water. I fought the same thing you are for years, until I put in some culverts under the driveway to relieve the pressure from the "high side". Makes a world of difference. If you decide to install culverts, don't use 12" ones. They can't handle the volume. Go at least 18". I put in 2 - 24" ones, and they even get tested once in a while.

Don't waste money on new gravel until you get the drainage fixed.

 

[/pine]

Actually what you got was a trip to school...
One of the first factors when designing any lane. road etc...is determining storm water runoff...you start with a storm intensity factor...i.e., 25 year, 50 year, 100 year storm etc., etc...

You had the perfect opportunity to correct the problems that caused the majority of the issues during what was likely a big number year storm for your region...

There will always be exceptional storms but if you design a lane for a 100 year storm correctly...you wont have big issues wilt lessor storms...

Every time it rains enough to create runoff...you lose fines...the pitch and or crown usually determines how much...

 

[deezler]

Yeah /pine, it was a lesson. My driveway handles it's own rainfall run off just fine. But it is not supposed to be the exit path for the main drainage ditch of my 50mph road frontage. I need to clear the weeds and look through my culvert.

But one smoking gun here is that my sweet old retired neighbor just raised the dirt level in the ditch on his side of my culvert so that it would be easier for him to mow the grass in it. I think he raised it just enough to pond his front yard during deluges, which can then head down my driveway instead. I wish my whole driveway was 2' up in the air on a giant berm, but that would be a major effort.

My short term fixes are likely 1) add a bit more gravel and crown up my drive a little taller, 2) a small berm to keep the ponded water stuck in his yard instead, and 3) make sure my culvert is functional. And maybe 4) add more escape routes for water to come off my drive into the woods sooner, so it cant pick up speed and volume, and wash off my gravel.

 

[Jchonline]

Perhaps show the damage to the neighbor and see if he might be willing to make some modifications?

 

[deezler]

^ he came down and saw me doing the repairs. I think he felt my frustration that my driveway was now draining the road frontage in a way it never has before. I told him I might have to add berms and cut the front ditch lower again, and he just said "well, you might have to mow it then", which, I would be glad to do. Right now he mows a fair chunk of my property (everything on his side of my driveway) because it is contiguous with and functions more like his yard.

 

[/pine]

Yeah /pine, it was a lesson. My driveway handles it's own rainfall run off just fine. But it is not supposed to be the exit path for the main drainage ditch of my 50mph road frontage. I need to clear the weeds and look through my culvert.

But one smoking gun here is that my sweet old retired neighbor just raised the dirt level in the ditch on his side of my culvert so that it would be easier for him to mow the grass in it. I think he raised it just enough to pond his front yard during deluges, which can then head down my driveway instead. I wish my whole driveway was 2' up in the air on a giant berm, but that would be a major effort.

My short term fixes are likely 1) add a bit more gravel and crown up my drive a little taller, 2) a small berm to keep the ponded water stuck in his yard instead, and 3) make sure my culvert is functional. And maybe 4) add more escape routes for water to come off my drive into the woods sooner, so it cant pick up speed and volume, and wash off my gravel.

I hear you...anyone that maintains an unpaved lane in anything but flat ground has their work cut out for them...the steeper it is the more of a endless job it is...usually for me it is places along the road where leaves accumulate and end up blocking ditches and the water overflows back onto the road...

Good Luck...