Horses and vehicles over the drainfield?

[4horses]

Our drain field needs replacing. The workers want to run it directly from the house towards the barn. This puts it right in the middle of the path that we drive vehicles over and horses will be walking or running over on a daily basis. I would like it put closer to the house. Any thoughts as to doing this? They are saying it will be fine once grass grows over it. They said if we put it closer to the house, we would need to add gutters to the roof to prevent water runoff from the roof ending up on the drain field.

Just wondering how safe it is to do what they suggest? As I have always heard to not drive over or have horses walk over the drainfield. Suggestions?

[Janet]

There have been several previous discussions on this subject.

The consensus seems to be that it is highly dependent on the soil type.

My personal anecdote. I lived for 10 years with the drainfield under the main pasture. It had been there for at least the previous 10 years with the original owner, who also had horses on it. (But we had no reason to drive vehicles over it.) There were no problems. The subsequent owners do not have horses. I drive past it every day and, for the subsequent 20 years, I have not seen any evidence of any work needed on the drainfield.

This is in northern Virginia, in an area with a lot of shale, and very low lying (sodden ground in the spring).

[4horses]

The soil is sand/clay based (Florida).

[Simkie]

I’ve always been instructed to not drive anything heavier than a small riding lawnmower over the drain field, and to keep horses off it.

Trashing the field is such a costly expense. I’d put it away from traffic.

[Bluey]

Every location may have different needs, better check what yours require.
In our area, they recommend not to have drain fields where you drive over.
We have two, one for the barn bathroom.
They told us we could park light vehicles and trailers over it, but not drive on it, so we fenced it and mow the grass in it like a lawn.
The house one is deeper and right by the house and is in a horse paddock.
We never have more than 4 horses there and they have a 100+ acre trap to wander on, don’t just stand there all day.
The installer put a load of sand over part of it and is where horses love to take naps.
Has been there now almost 20 years without any problem:

[Jarpur]

The only thing we drive on either of our drainfields (we have two that we can switch between) is a lawn tractor when we mow. However, the fields are in a horse pasture, and we allow the horses to graze that area. We have so many, many deer – we can’t control where they travel, which is frequently across the drainfields – that I’m not worried about a couple horses occasionally grazing the drainfields (we rotate pastures, so it’s not regular, heavy use).

We would never park vehicles on the drainfields. I’d be very wary of placing a field where there is regular (daily?) vehicular traffic, or even an often used horse path.

I just consulted a booklet on taking care of a septic tank system that I received from our local environmental department, and it emphasized that the field should not be used for vehicular traffic or parking. On the rare times we’ve entertained enough guests that we had to allow pasture parking to accommodate cars, we put up temporary electric fencing, along with orange cones and signs, to keep people from driving on the drainfields.

[StormyDay]

I’m in Virginia. Lots of clay for our soil. My drainfield is in the pasture. I moved in a year ago, and the drainfield is 30+ years old. It’s been under the pasture that whole time. The previous owners had cows in the 90’s, so there was at one time a herd of cows living on it. Since the early 00’s the property had been farmed, and the farmer used a absolutely massive tractor, probably a 10,000lb tractor, which drove over it many times a year.

And, amazingly, it’s still just fine.

I think it must have a lot to do with soil and how deep they bury it. Because we can get long, cold weather here, the drainfields are deeper than other locations.

[TheJenners]

I have an alternative system so I can’t really weigh in on personal experience, but I’d not be driving over a drain field regularly… They are entirely too expensive to risk compacting or damaging it by driving vehicles on it.

As for grazing over it, I don’t see an issue as it should all be deep enough that horses won’t punch thru, assuming your soil isn’t sodden and muddy. But even then, I wouldn’t risk. I got into a huge fight with the County over my alternative drain field (mound) because they wanted it right behind my BARN. Yes, you read that correctly. As in, in the way of traffic coming in and out of the doors to access future paddocks and etcs, which would have been obviously if they had asked. Instead I had to send many emails explaining that what they see as a “shop” on a sat map is actually a livestock barn and what they saw as the back side of said “shop” was not, actually, the blank back side of a “shop.” The amount of small words and short sentences I had to use was unreal…

My mound is already fenced off and will be in a paddock once I get the field hayed again and put up the rest of the fence.

[candyappy]

Under the pasture " maybe" depending on soil, wet, number of animals etc…

Driving over with vehicles or machinery. Never!

That was just the advice given to us by a company that did septic systems.

[ThreeWishes]

Horses yes. Driving over it a big fat no.

[cayuse]

If a drain field is the same as a leach field, when I had mine done 18 months ago I was told absolutely no vehicles and they had to put some sort of special geo-textile surface over it and under the top soil so the horses (we are talking minis and medium pony) could walk on it. The engineer said the repeated weight of the hooves on the soil would compact it enough so the leach field would become inefficient without the special textile stuff.

[Mango20]

I think there is a big difference between driving over it occasionally, and driving over it regularly. Same goes for it being in a part of the pasture the horses graze from time to time, or being in a dry lot where horses are standing around on it all day. Also, depth and soil type would make a huge difference. I’d tend to believe your local experts, and get a second opinion if you’re unsure.

Mine is in my front yard, which slopes a bit. My soil has a lot of shale in it, along with clay. My horses get to graze the front yard as a treat once in a while when the ground is dry. I also drive the truck over the drain fields maybe twice a year when I need to bring it around to the basement door or have decided a landscape bush needs to be pulled out. I think any compacting from those isolated instances would spring back if left alone a while. My neighbor’s drain fields are in a pasture.

[BrendaJane]

well, you want gutters on the house anyhow.
I think the workers have no concept of the frequency of traffic. I would not want the leech lines in a high traffic area like that.
and in sandy soil I would not want horses on it either.

Something to ask @clanter ?

[clanter]

@BrendaJane

Something to ask @clanter ?

we are on city sewer system so have no real world experience, I would defer to the people actually install the system.

A typical septic drain field trench is 18 to 30 inches in depth, with a maximum soil cover over the disposal field of 36"; or per the USDA, 2 feet to 5 feet in depth.

18 inches sure is not much and a general rule is for soil that has been disturbed and not compacted back It Usually, it takes around 7 years without intervention for this soil to settle.… so I would expect the soil over the leach field would settle thus reducing that depth

[sparkygrace]

When we built an addition to our house, we had to run a new drain field into the pasture. Our property is small and it was the only choice. I only have one horse that grazes in that area, so it has been fenced off for a year. He can’t be on pasture now, but I will turn him out there later this summer. The septic people had to follow code and sunk four lines of pipe even though we will only need one. I was not pleased!

The photo shows the new drain field. We won’t drive on that area, but will mow with a riding mower.

[Calvincrowe]

We just spent $25K to replace our 50 year old septic system. We had to sacrifice a small paddock next to our barn in order for a new drain field to be installed. No livestock, no vehicles, nothing bigger than a small riding lawn mower on it, ever, was what the engineers and installation company, and the county inspectors all told us. Ours is just 20” below the surface—we have rock hard clay below that depth. Is it where I wanted it? No, but it was the only safe, logical spot to put it on our small acreage. Do not drive on it!

[sparkygrace]

Our former drain fields were in our yard. Lots of vehicles drove over them, tree trimmers, construction people. They weren’t damaged. I think when “livestock” was mentioned to us, it was referring to lots of animals. Like cows.

[Calvincrowe]

Well, ours was in the yard, too. And the septic engineer and county inspector both pointed out why it failed: compression from years of cars, tractors and feet. We limped it along for ten years but it was scary. When raw sewage came up our shower drain all over DH’s feet we knew our time was up.

If possible, not driving, or having heavy foot traffic, or heavy animals on your leach or drain field is preferred for long life and proper functioning. Your experience may be different.

[sparkygrace]

Ours did not fail, but we found the pipe leading from the tank to the drain field had broken. That was repaired when we put in the new drain field. I’m not worried about one horse turned out on the area with the drain field. He’s not big and the areas that were excavated are compacted and reseeded. My property is tiny, so fencing off that entire portion leaves me with little pasture.

[happilyretired]

At my farm in Central Florida (south of Ocala – mainly sandy) we built a small fence around our drainfield so that no one can hand graze their horse in that area (its right outside the barn).