I am having an outdoor riding arena built and due to the lay of the land my best option is to grade the arena on a slope in one direction towards the woods (crowning not an option). It will be 100’x200’ and the slope would be along the length (the wood side) so that water would run across the width (100’). I have gotten many suggestions for a 1% grade on the 100’ side but I just need some clarification as I am uncertain if this means a 1% slope down 200’ or a 1% slope down 100’. Help! Thanks!
Mine is about 115 x 215 so almost exactly the same dimensions. It drains across the short side like yours will. I had a bit less than 1% slope graded. It drains fine. I don’t know why people want more slope than that. Water will go to the lowest point even if it’s a tiny difference.
The grade is 1% of the 115 short side. I did not crown mine either – I like the way it all drains evenly to one long side. I put in footboards, and water spills out of the arena evenly all along the long side over the footboards. If I were doing it all over again, I would have set the footboards (2 x 6’s) a little deeper so less water would collect before it spills over. If the edge of the long side is a bit wet after a rain, I just ride the quarter line that day. Easy peasy.
My outdoor – which is actually a natural field (nice grass now that I mow) – slopes about 1% towards a culvert. Slope starts along the long side and travels across the width of the short side down to the opposite long side. Drains pretty fast. Better I think than if the water had to drain from the short side all the way across the length to the opposite short side.
I have a 100 x 180’ arena. It’s sloped 1% across the 100’ side and sloped 1% across the 180’ length of the arena. That means the low point of my arena is one corner (rather than one whole side). But when we get hit with a major deluge the whole low side ends up collecting water, and like ToTheNines commented, I just stick to the quarter line when things are bad.
Mine is 80x160 (that feels so small compared to some here, but it works for me!). The slope is 0.5% across the short side and that works well – my arena builder did not want to go with more slope as that results in too much footing loss/movement. I still end up with a migration of footing that we have to deal with every so often, where the low side gets a bit deep and we have to move it around to even things out – maybe once or twice a year. I’m in a very wet area (60"+ annual rainfall).
I also have a 1% on both sides that drains to a corner. It’s enough slope to see from the second floor of my house but not really visible when you’re standing in it or riding.
The water goes to the edge of the long side and whatever doesn’t flow out the side heads to the corner.
