DANBURY — Police officers typically work long and physically draining hours, but many of those in Danbury have had it a little worse this summer. “A lot our officers are being ordered to work doubles,” said Sgt. David Cooney, president of the police union. And sometimes, “they’ll be working 16 hours straight and then they have to come back after eight hours.” This is because the city’s police department is facing a critical staff shortage following a combination of factors, including a higher-than-usual turnover, seven retirements, several officers on vacation and a slow training process. “We have the perfect storm,” Cooney said.