Line my sewer, please

If you go through the downtown on weekdays, you may notice the occasional steel plate embedded in the centre of the street.

If you go on the weekends, these plates are lifted and lanes are blocked to traffic through the core. Equipment and work crews are busy installing liners in the sewer pipes.

Cheaper than digging trenches and replacing the pipes, its sort of a like a inside job replacement.

I thought the large quantity of foam squeezed out of the sewer hole to be somewhat suggestive of … lubricant?