I live in the PNW. Well, in my country its the PSW, but I am only about 20 km from Washington State.
My arena is 16 years old and still useable all year round. I havenāt done anything to it except drag it witha chain link gate in 16 years. No footing added, no digging up and rebuilding. It drains within 3 hours when the heavy rains stop, and remains useable except when thereās a deluge. In the heaviest rains, like more than an inch an hour, whoād want to ride anyway?
We spent more money to do it right the first time. Friends and acquaintances who tried to save money have ended up replacing footing, digging up soft spots, installing drainage after the place was completed, etc. Cheaper to do it right.
First: PICK THE DRIEST SPOT ON YOUR PROPERTY. Donāt try and convert an old creek bed into your arena. The water will eventually win.
Second: remove all top soil, to the clay, rock or sand (lucky you if you have sand) base.
Third: crown or slope the land . Use a laser site and someone who knows how to site! Blast any existing rock to achieve this if you have to. Clay requires an experienced caterpillar operator- mine specialized in tennis courts and parking lots and had done a few riding rings. Sand-OMG you are lucky and can probably just ride on itā¦Mine was mostly clay base with one huge rock in the middle. We blasted the rock and used it to level out the low end of the land. It is built on a mild slope that originally dropped about 4 feet along the long side. Now it drops about 18 inches along the long side and about 10 inches along the short side.
Fourth: install good, big perimeter drains in ditches below the clay base, nestled in drain rock and test them to make sure they are properly sloped and working before you cover them up!!!
Fifth: lay down a good layer (6-12 inches) of large drain rock and have your caterpillar driver level it out.
Sixth: put down a good layer of ROAD BASE (4-6 inches deep- 1 inch minus angular gravel) and compact it with a vibrating compacter every 2 inches. You should be able to drive a machine or truck over it without shifting the base once its done.
Optional: If you like, put down geotextile at this point. However, geotextile makes it harder to spread the footing and if horses are allowed loose in the ring, they have been known to dig down to it and pull a whole length of it up, meaning all the footing has to be removed, the geotextile relaid and the footing replacedā¦Mine does not have geotextile and there is no problem- a few rocks float up after a decade or so, but my horses are barefoot and nothing bugs them.
Seven: put down your footing. Sharp sand or what is called gravel washings from the local granite deposits, is best, 3 inches deep is ample. Do not use river or ocean sand-cheaper by far, butround particles roll under the horseāsfeet and cause injury. If you use bark chips or hog fuel, you will be replacing it in 2-5 years and it will clog your base. If you use rubber mixed with sand or fiber mixed with sand, it will break down and create fine dust in about 5 years that is a hazard to your lungs. Sand is forever. Those other footings are softer and bouncier but sand is associated with fewer tendon injuries and less slippage.
Eight: Pay the bills and enjoy your ring, for decades to come
No slipping.