PITTSBURG, Calif. – Authorities in this San Francisco suburb are investigating manhole-cover thefts. More than a dozen of the city’s estimated 1,600 manhole covers have disappeared from streets and parking lots, said Pittsburg Police Inspector John Conaty. The iron discs – which weigh nearly 200 pounds each – are usually removed at night in places with little foot or vehicle traffic. They’re so heavy and awkward that police believe two or more people are involved. City officials are trying to replace the stolen ones as quickly as possible, but they remain flummoxed at the crime and the possible motive. Many scrap yards refuse to take the covers. 160Want local news?Sign up for the Localist and stay informed Something went wrong. Please try again.subscribeCongratulations! You’re all set!