We are going to be doing an outdoor this year. The area is unfortunately in a low lying spot, so I was thinking to not disturb the topsoil and just build up the base on top of the existing ground. What are your thoughts? Excavate first or just develop the base on top of what's there now?
And favorite recipe for a good base? (We're in Pittsburgh so good drainage is key)
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Generally when building an arena you want to use the existing soil to build a crown or a pad a little larger than the actual arena, think of it as the foundation for the arena foundation.
You usually want to compact the crown and add some slope to it to allow water to sheet, not run off of it.
The sub-base of the arena is probably most important part, it is the true foundation of the arena, and if it is weak the whole arena will be weak. Be careful not to use sub-base material that is too large, it tends to float and can turn your arena in to a stone-bruise festival.
Because your arena is in a low lying area you may need to consider tiling/draining, However this is the kind of decision that someone experienced in site preparation may need to help you with, and it is worth it, you do not want to go through all the effort, money, and time and end up with a ring that holds water 50% of the outdoor season.
Consider the location and access etc. My brother builds golf courses for a living and he cites these type of things, that are not given as much consideration that drive the costs up through time and frequently subsequent work to repair etc.
I'm hoping PNWJumper will chime in here. I sent her a PM when I was putting in mine and her advice was absolutely perfect!
Lol, thanks showidaho! Glad it worked out for you
Nothing more to add than what showidaho said. It's a tad bit wet year round up here in the PNW, so we opted to do "full drainage" rather than french drains, which is why we did the 4" of 1 1/4" rock for the sub base. It keeps the arena rideable year round as long as I drag it before a deluge (if there are hoofprints they tend to hold the water and make the footing a bit soupy...though still not unrideable). So like showidaho's, my arena is 4" of inch and a quarter rock, 4" of quarter inch minus, and then 2 1/2" of coarse washed sand.
We had a contractor do the whole thing and he was extremely exacting about how he leveled the whole thing. We have a 1% grade side to side (across the 100' width) and end to end (across the 180' length). We had to do excavation anyways (we cut 4' into one side of the pasture and built up 4' on the other end), but even if it had looked relatively flat, there was no way I was going to risk the future performance of the arena because of something I might miss. If you are thinking of doing it yourself I would pay close attention to JB's advice on your Around the Farm thread.
The area we built our arena in was not a particularly dry spot, but I don't know that I would have wanted to build the ring in the lowest spot on the property, seems like you'd be fighting drainage every time it rains, even if you build the arena up off of the existing ground. But if that's the only spot you've got I would work with someone who specializes in arenas or excavation-type work (we used a guy who had only done one other arena and whose speciality was road contruction) to give you the best advice for the spot you've got.
Do not try to do this over the Internet. Ask around at barns which are happy with their footing and I bet the same name comes up pretty often.
Yes, using a "footing expert" may cost you more at the beginning, but I guarantee that it will save you $$ in the long run.
I spent $35,000 on a ring that I later hated because I tried to do it this way (on the Internet). Everyone's situation is different - you need a hands on approach.
And -- here's a biggie: Once the finest ring in the world is installed, you can still ruin it by not using the right drags to maintain it properly. Do not skimp on this piece of equipment.
I used a harrow that had tines that were too long and I broke through the top layer and churned rocks in with the footing. The ring was never right again. And all because I did not want to spend $800 on a roller.
I now have a grass jump ring; mowing it in the summer is much easier than maintaining a dirt ring.