I'm used to 3-gallon batches, so I'm having a hard time wrapping my head around those numbers. The grain weight and strike water volume are a bit more than triple what I do, so that much looks on target for a 10-gallon batch. Looks like 1.33 quarts/lb which is a nice ratio.
Typically I drain the mash, and see what the volume in the pot is. My sparge volume is the difference between my desired start volume, and the collected first runnings. The grain is already saturated, so no more absorption to account for.
Just guessing here, but I expect you collected on the order of 6-7 gallons of first runnings. If you wanted to start with 12-gallons in the kettle for a 10-gallon batch, that would put your sparge volume in the 5-6 gallon ballpark.
I'm really confused about what you ended up with, so more info is definitely in order.