Blocked Drains

If you drive into Belfast's Clarence Street West (Oh, hold on, you can't) the construction of a new hotel means the street is blocked off daily from around 7.30am until around 5 ish Monday to Friday. The cement lorry's etc arrive and through the day the roadway becomes covered in an over spill of cement. This has been going on for a lot of months.
The road gets hosed down and guess where it goes .... yes, down the drain. Now, is it just me or am I right in thinking if you hose enough cement down the drains eventually it will harden and block the drains? I cant wait until the hotel is up and running to see how many times the street gets dug up to fix the blocked drains. I took this photo this evening hours after the rain had stopped .... looks like the building inspectors should have gone to Specsavers.......