You can read about Fort McMurray’s situation in the CBC article.
This is the second recent account this year of a multi-million-dollar flood mitigation project in the Province of Alberta that has gone awry and resulted in disastrous unintended consequences. The first was in the community of Exshaw in the spring/summer of this year.
CBC reports “The inconsistent and porous berm allowed water to gush through the system of berms from multiple angles, the report said.”
“Water passed over parts of the berm that were too low to withstand a once-in-100-year flood, entering the sewer system, causing backups into people’s basements, it said.”