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  Discussion on Arena Boundary drainage
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Member:
nikky19

Posted on Wednesday, Oct 14, 2009 - 1:07 pm:

I have had my outdoor arena for 20 years now and gone through just about every surface, hogfuel, sand, sand and rubber etc. Also have had railroad tie boundaries and 4x6 posts. The problem having been that they retained the masses of water that falls from our Oregon skies and it took so long for arena to be able to percolate out all that rain.
So, removed old 12 year old sand/rubber mix this year and replaced with new just straight sand. I decided not to put back the boundary to see if that would help with draining the arena. WELL... had the biggest deluge of rain last night and there has been an enormous runoff from the arena, lots of little chasms near the edge and lots of sand in the ditch. Now that experiment is over, I'm thinking I need to put back the boundary that I saved, which I'm afraid means I'm going to have a return to the old lake problem unless someone knows of a way to allow drainage from the arena with the boundary in place - I tried an idea of stockings in the past but it didn't help for too long, like weeks!.
Anyone have any ideas, experiences? Thanks
Member:
lucyc1

Posted on Wednesday, Oct 14, 2009 - 3:24 pm:

We have had good results with installing french drains along the edges.

We have 2 100X300 dressage arenas. Footing is a combination of a fairly course sand and a very fine, silty sand. We have railroad ties holding the base and the footing in place. We had the same problem: almost any amount of rain was a problem. The arenas became lakes, and stayed that way because the rail road ties essentially made a dam.

I don't know how long our solution will last, but the last two years have been MUCH better. Essentially we made a french drain on the inside of the railroad ties. Unfortunately our arenas only drain in one direction instead of shedding from the center to the sides. If yours is graded to slope from the center toward each side, you should have even better results than we do, and I'm very happy with ours.

The biggest problem with ours is that the fine, silty sand has so much silt in it that we have to remove the silt that builds up on top of the gravel that covers the drains.

The drain runs the entire length of the arenas. We dug a very narrow trench very deep. We lined the bottom with big gravel (#4's as I remember), set the drain pipe, HOLES DOWN, on top of the gravel, then filled in the trench with course gravel in layers, down to a finer gravel at the top. As I remember we used pea gravel for the top layer. Initially we used a landscape fabric to screen the fines, but it clogged so quickly we had to remove it.

Clearly there are many ways to do this, and the kind of sand you are using will be one of the determining factors -- but our arenas drain so much better. We have not had to cancel a show due to wet footing since installing the drains.

One other point: if we know rain is coming, and we absolutely need the arena footing to be firm we make sure it is very well dragged -- no hoof prints to hold little lakes -- and, if there is going to be a great deal of rain we compact the footing. We would love to have a roller to do this. It's on our wish list -- we use a vehicle and drive back and forth until the entire arena is evenly compacted.

Didn't mean this to be so long -- but we are very happy with it. The only thing we would have done differently, if money were no object, is to have the drain be bigger. It could have been directly under the railroad ties as well as under 4 to 6 inches at the edge of the arena.

Hope this helps!
Member:
mrose

Posted on Wednesday, Oct 14, 2009 - 3:57 pm:

Lucy beat me to it; we also had French drains in our outdoor arena when we live in Truckee, CA. Loved them. Water drained really quickly, and even after heavy snow melt and rain, the arena was useable within a day or so. Normal amounts of rains just percolated through and ran off. We never had problems with washed out sand.There is a correct method to install them,so you should do a little reading.
Member:
dustee

Posted on Wednesday, Oct 14, 2009 - 5:29 pm:

We also used French drains - absolutely necessary and wonderful. We also had a bunch of boarders, and the rule was this - you could use the outside arena at any time, but, whenever there was a draining area, or puddles that had not yet finished draining, you were not to work your horse in them. You would end up ruining an area, making it deeper, ruining the underlayment within the structure of the arena, etc. Everyone was very good about this, and kept us from having to add arena surface to areas trashed by silly horsemen. I don't know what a good arena costs nowadays, but ours was around $15,000.00 and I hated to destroy it.
Member:
nikky19

Posted on Wednesday, Oct 14, 2009 - 8:42 pm:

Hmmmm......thanks everyone for your input. I definitely do need to do more reading on french drains - I really didn't think they worked that well because of the clogging factor, but,,, holes down??? Doesn't seem logical, but somehow must work as it is for all of you. My neighbor has put in a full court two years ago and has no Lake problem because she purposely put in the gravel loose so it could drain through - I know.. that's a future problem coming, but loose gravel seems to be the working factor of the french drain system. Presumably the horses don't travel over it, but doesn't your sand get pushed up and over the area causing compacting problems.

My arena has a high center is 66 x 170 in size, so the width doesn't leave me much leeway (dressage arena) for placing a french drain, but as I haven't put the boundary back in yet, I could do it beneath where they're going to be, and perhaps somewhat in front as Lucy suggests. Does the drainage work at each spot, or would I have to lay it so that it runs off at the length of the long side into the ditch at the side of the road outside my property? - My ditches around the arena are attached to it.

I did harrow it well and smooth before the rain, but just at the end of my ride after harrowing, down it started tipping with no let up predicted for a few days and I can't touch it once its so wet - One answer would be a roof of course, but that's not affordable - we get 50inches at least of rain here a year.

Lots of questions and thanks so much for your help.
Member:
lucyc1

Posted on Wednesday, Oct 14, 2009 - 10:14 pm:

The holes are down because that way, as the water fills the ditch that the drain pipe is in the water rises up into the drain. When the water drains off the arena it has lots of sediment in it. If the holes are on the top all the sediment ends up in the pipe and the pipe clogs more quickly. If the holes are on the bottom a good portion of the sediment settles into the gravel below the pipe, and the somewhat clarified water rises into the pipe. Water takes the path of least resistance so it flows out through the pipe even though there are holes on the bottom. Kind of ingenious actually.

The clogging factor is a big one. What size gravel, whether or not you use some kind of filter cloth etc will all depend on how silty your sand is. It would be great if you found someone local with experience in this area. I think ours will probably need to be redone in some number of years. And, as I said, we need to manually remove the build up of very fine silt directly over the drain.

The area the drain takes is pretty small -- about 6 inches of gravel or a little less.

Even though I am very happy with the VAST improvement, the system seems fragile to me, because of the silting up, and because of having gravel that can get dragged out too easily into the sand footing. Still, I would do it again, the same way, unless I learn of a better way.
Member:
nikky19

Posted on Wednesday, Oct 14, 2009 - 10:40 pm:

Thanks Lucy: It makes perfect sense about the french drains now that you describe it. The project makes me quake a bit because I've just finished having the arena resurfaced, compacted and new sand surface on top and the idea of digging into the edge... well, you can imagine. So this water enters the pipe and then travels down to the spot where it will dump so would need to be laser graded or something, no? I can't imagine doing that myself and I have very silty, silty sand - that's just about all we can get here, river sand, feels great for a while though and then turns to concrete. Plan is to keep it nicely harrowed and graded till that happens so its level for a new load of sand - that's what I've done in the past.
The fact that you would do this french drain again when needed gives me some hope about it.
Member:
lucyc1

Posted on Friday, Oct 16, 2009 - 8:54 am:

When we put our drains in we cut a very narrow trench. It didn't disrupt the arena much at all.

The issue of the silt is a problem. I've just put in a call the man who installed our drains. It was a first for him -- and my question to him is, in hindsight, is there anything he would do differently. If he has anything interesting to say I will pass it along.
Member:
nikky19

Posted on Friday, Oct 16, 2009 - 9:47 am:

Hmm... that will be interesting to hear what he says. Thanks for keeping me in touch with that.
I'm considering using the riprap concrete bag idea that allows surface water to drain through. Make a little wall about two/three bags thick and put the small trench with some pea gravel just in front and then put my white perimeter fencing in front of that (white buckets with 2"inch hole for the pvc pipe). I had kept the one whole length of landscape timbers (4x6) so will put those back on one side and had thought to do railroad ties on the other, but my husband's eyes glazed over at the thought of pounding in rebar again, so this concrete bag wall idea might be my saviour. Thank goodness for tractors!
Moderator:
DrO

Posted on Friday, Oct 16, 2009 - 4:07 pm:

The advice on installing french drains has been right on. Concerning Lucy's problem I think she nailed it when she said they cut a very narrow trench. This provides much less area to collect and filter silt. The more area you have around and under your pipes the longer the french drain works.
DrO
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