When my Siebel class visited the Monastery, we got several cases for the drive back to Munich. Good times on that bus... Orval is one of the true world classics to me, and I've never had a beer in its "style" that matched it. Pretty much got the whole recipe and process from Jean Marie Roc (sp?) when I was at the brewery so I'm going to attempt a clone sometime in the future. They definitely have some quirky processes that go into it. Definitely one of the most fascinating beers in the world. Maybe you could or would steer us down that quirky road to Oval nirvana.... I would enjoy trying to approximate the beer.
I'll try to get the vitals across.
Malt is 87% pils and 13% caramel 100EBC. Mash at 65C for an hour, then raise to 72C for 20 minutes. They use RO water with calcium chloride and gypsum added. Not sure on exact levels, but it's supposed to emulate the water from the original spring at the monastery.
Kettle hops are strisselspalt, hersbrucker, willamette, and tradition. Didn't get IBUs or addition times, which is the biggest hole in what I have. No whirlpool. The wort is centrifuged to separate break material.
Fermentation starts at 15C and rises to 23-24C. One week total and freshly propagated yeast is used every time. Single strain for primary ( belgian bastogne should be the right one).
Then the beer is transfered to lagering tanks and dry hopped for two weeks at 15C with 400g/hl of strisselspalt and hersbrucker. After that, the primary yeast is centrifuged out and 3 million cells/ml are added back for bottle conditioning, with a small percentage of that being brett, but the majority is the primary strain. They also add nitrogen at bottling. They then condition the beer warm for three weeks before shipping it out.
Wish I had more specifics about the hop schedule. I Think the IBUs are lower than you would expect, because the beer is so dry. Still a pretty hoppy beer when fresh though. Easily the hoppiest trappist beer.