Pipe Bursting and Manhole Rehab

Location: Gaston Oregon July 2009
Wastewater Agency: Clean Water Services
The Challenge: Pipe burst old 8” Concrete mains with HDPE DR17 pipe while utilizing existing poured in place concrete manholes.

The existing 8” concrete main was heavily corroded including the segment of the 8” main installed through the walls of the old manhole. They needed to remove the old 8” pipe and bring the new HDPE line into the manhole in a watertight manner. Their experience with breaking out an old pipe and then grouting in a replacement had not always resulted in a long term reliable connection. Likewise, elastomeric manhole sleeves can sag due to the weight of the pipe and the backfill causing leaks. Clean Water Services wanted a more permanent solution.

The OD of the old concrete was 10.5”, so they wanted to core drill out this old pipe and install the new 8” HDPE line. A 10” Inserta Tee requires a 10 7/8” hole, which was sufficient to remove all the old concrete. They brought this scenario to us to see if we had an answer. What we came up with was a specialty Inserta Tee. (Photo 2) We needed to still utilize the 10 7/8” hole so we needed our 10” rubber sleeve and the 10” PVC body to fill it. However, we then reduced to the gasketed outlet to 8” IPS repair coupling. A repair coupling style outlet allowed the 8” HDPE to slide unimpeded into the manhole. A normal Inserta Tee has a gasketed bell with a built in stop so the pipe can only slide to the back of the bell.