The Sewer and Drainage Division Confined Space Entry team has been at the corner of Superior and Orange streets quite a bit this week to repair the leaky pipe seam it identified last week. They've been here at least three times, actually, because after each successive repair, a new part of the seam has split open. But that has given me an opportunity to see how the internal fiberglass-epoxy patching method works, since I wasn't around to observe when they did the first repair on Monday.
In the first picture, we see the crew applying two-part epoxy to the sheet of fiberglass and making sure it's nice and smooth. The sheet will be folded over several times to make a thick patch over the failing seam inside the pipe.
Once that's done, the team wraps the sheet around a cylinder the size of a carpet roll that is actually an inflatable bladder with a pipe inside it. The internal pipe allows whatever water is flowing through the sewer pipe to pass through rather than back up behind the whole thing.
When it's all ready to go, a team member drops down into the manhole using a windlass and then the "carpet roll" is lowered down behind him with an air hose attached to it. When everything is in place inside the defective sewer, the air is turned on and the bladder inflates, pressing the epoxied fiberglass sheet against the inside of the pipe.
It takes a couple of hours for the epoxy to cure, during which it gets quite hot. Once it has set, the bladder is deflated and brought back up out of the manhole.
After each repair, the crew pumped dyed water into a nearby sinkhole on Orange that had developed once enough earth had been washed into the sewer by water seeping through the street's pavement and through the faulty seam. This afternoon, it appeared that the third patch was the charm, as fresh asphalt was put into the sinkhole before the crew left. The street repair is only temporary, as the city has a bigger rehab project in the works for Orange Street in the area.