that sucks, but...

i bet whoever did it didn't realize what they were doing. i mean, they knew they were breaking in to the velodrome to do some skids (haha, right? right...?), but they didn't realize the cost to the velodrome - either in repainting, in cleaning the skids off, or in the extent to which it would disrupt the racers.

does that make them any less accountable? no. but maybe there's a really good solution that does involve cleaning, repainting, and educating these bike gangs over there that it really sucks to lay down skid marks at the velodrome.

hope you find them. hope it doesn't turn felonious, and that you can show them the error of their ways, and that you can get to a workable solution.