Mammoth tanks have brought Shepton Mallet to a standstill.
Wessex Water is renovating Shepton Mallet Sewage Treatment Works but new tanks being transported on low-loaders caused something of a stink with motorists.
On Tuesday evening one became stuck on the roundabout outside Tesco at Townsend.
On Thursday another also became stuck at Glastonbury.
Spokeswoman Felicity Crump said: "The company we are using to transport new equipment to our site used trucks which were too large for the roads in the town. We apologise for the inconvenience and have been assured that this will not happen again."