An independent contractor is performing warranty work on fire hydrants throughout the city for the next few weeks.

The work involves replacing the old grease, which has a component that was damaging the threads in the hydrant, said Dean Hylland, the city’s Water and Sewer superintendent.

Waterous, which manufactured the hydrants, is paying for the work, Hylland said.The police department has received a couple of calls about suspicious activity regarding the work, according to Chaska Police Chief Scott Knight.

People shouldn’t be discouraged from calling the police department when they see something out of place, he said. However, “In this case, we don’t want people worried if they see people out and about working around fire hydrants,” he said.

“It should be underlined that people have no business, or would not be in anyone’s home or doing any work that requires them to enter anyone’s home,” he said. “Activities should be confined to the immediate area of the fire hydrant.”