Sparging problem?

[timb]

I attempted a barley wine from Wheelers' Brew classic european beers at home last week. The og should have been 1090 but somehow I ended up at 1068. Can anyone tell me where I've gone wrong.
The grain bill was 6Kg MO and 3.2Kg Lager Malt. Because of the size of my mash tun and as I batch sparge, I split this into two equal amounts of 4.6Kg.
I aimed to get 32 litres of wort, pre-boil.
I mashed with 11.5l of liquor. Mash tun loss is 3l, this, combined with grain loss comes to around 7.5l. So after 90 mins I added 4l, left to settle and drained off 8l of wort.Then added another 8l left to settle and drained again.
Then repeated this with the second batch of grain.
The volume of wort obtained was 32l, my normal, and I boiled as usual for an hour. Ended up with around 22l post boil but much weaker than expected.
Any ideas?

[MightyMouth]

I have been informed that batch sparging big batches is quite difficult and efficency can suffer as there is usually still a lot of sugar left behind. You can sparge for a 3rd time and try to boil longer to concentrate the wort.

[hoppingMad]

I'm a fly sparger so not much use here to you, but can I say, when I started and before I knew my brew system and efficiency well I would carry some dry malt powder for just such occasions.

[timb]

Thanks guys. MM, I think I had read that before but had forgotten. My process made sense in my head!Oh well, I guess it's time to try fly sparging or find a bigger mash tun
cheers!