Once again, 525 Union Avenue was a busy place yesterday. The regularity of the Sunday work (so predictable that you can set your watch by it) and the total lack of attention to it by the Department of Buildings is starting to seriously bore us. It also makes us think the Bloomberg Administration should simply legalize Sunday construction work, because its Buildings Department conducts itself as though the work is legal, anyway. It is the only fathomable explanation we can find for the Department’s staggering non-feasance, or worse, at 525 Union and other Brooklyn buildings which buzz which construction activity on Sunday mornings.