To the left, an area one spit deep, and about 4x2.5ft. To the right, the amount of heavy rubble I got from it. To the right-hand edge, the end of the big riddle. This took me 2 hours, which if that continues to be my work rate will mean... I'll finish it in 125 days of work, (an allotment working "day" being 2-3 hours).
To get that figure, I'm estimating the area I've dug as 1M², and each bed as 7.5x3.5M² - say 25M² each, and there are 5 beds. So (VERY roughly), 125M² of beds to riddle. When the worst of the glass is gone (that is, everywhere adjoining the old greenhouse has been riddled), it will be safe for dogs. So I can incorporate dog-walking into allotmenting, and be there every day
Longer than 125 days, really, because this in the photo took 2 hours or so just for the big riddle, and it wants medium riddling, too. Now, I did some work with medium riddle this week: a shovelful of earth (which has already been through the big riddle), onto the grid over the barrow, and then push it around by hand or with the trowel, until the good earth has fallen through, and you're left with pebbles and bits of glass. I did 8 barrows full of that in 2 hours.
But this area near the old greenhouse, part of no.1 bed, is the nastiest, least gardened, and most glass infested area of the plot. The other beds should be easier, maybe I won't need the big riddle as the ground dries out somewhat in the summer, and I can go straight to medium riddling. I will spend more time as the days get longer and warmer.
All of which means I'm kind-of on course to get the beds done by autumn, and the shed and poly-tunnel erected by the end of 2017. It's appropriate that the allotment - which has been there since 1917 - should spend its centenary having what amounts to a nearly complete dis- and reassembly. It's going to be a better allotment than it's ever been before.