It may not be the great plague, but a rat infestation wasn't what Tararua District Council staff expected, either.
The rats were discovered in a sewer main after a tomo, or sink hole, had formed in Dannevirke's Station St, near a fast-food outlet.
Because of the close proximity to fibre-optic cables, including the main east coast fibre cable, it was decided to use a hydro-excavation unit, district councillors were told.
However, during the initial investigations it became clear there was a lot of fat within this section of the sewer main, resulting in an exploding rat infestation, which contributed to the failure of the main.
Council staff say they are working with the regulatory team to reduce the amount of fat being discharged to the wastewater network and they have also begun a rat-baiting programme in the area.
News of the rat infestation caught Tararua District Mayor Tracey Collis off guard.
"I'm mortified," she said.
"I thought it was sea foam [in the photo], but it's fat."