This is most likely the case. It was either not built, or maintained to specification by contractors. This is an issue most of the time something fails like this. Remember, in construction, the engineers who designed it, aren't the ones who actually build it, it is contractors. Yes, there are a lot of compliance things like construction oversight and even using a 3rd party company to access the risk during the design and build itself.

This sounds like a case where the maintenance was not carried out properly. Or the procedure the contractors were doing was wrong. Then a storm came and it exceeded its limits.

Source: I'm not a civil engineer, but I've lived with one for some time and know a bit from conversation.

Edit: I don' mean to just say, "it's the contractors" fault. It could have been higher up with budget cuts and telling the contractors, don't do this because we don't want to spend the money. This is the exact reason of having a 3rd party firm monitoring it as far as risk assessment and compliance goes.

Another Edit: The civil engineer I live with said the rain or lighting should have had no effect, UNLESS it was a foundation issue. Which another commentator mentioned the foundation was undergoing maintenance at the time? Seems to be the most likely scenario.

This happened when the municipal archive in Cologne, Germany collapsed. There was a subway construction site under the ground. Apart from problems with groundwater, iron reinforcement material for the tunnels had been stolen. The whole archive with many documents from the middle ages was reduced to rubble, and two lifes were lost. Had that happened a few days earlier, hundreds of people could have died.