Slipline Saves Time

New Castle County, DE
Installation Date:

Delaware DOT

Delaware DOT
A crumbling culvert under four-lane State Road 48, called Lancaster Pike, in New Castle County needed to be replaced. The 72" RCP was corroding and the reinforced steel had been exposed.


Instead of replacing the pipe, a 100’ run of 60”  N-12 pipe was used to slipline the corroding RCP. By sliplining the pipe, the Delaware DOT saved more than $850,000 and months of construction on the road, which averages nearly 16,000 vehicles a day. The sliplining of the pipe only took two days to complete and came without interruption to traffic.

Installation was easy as five 20’ (6 m) lengths were joined and slipped into place by a four-man crew and backhoe. A slurry of fly ash, cement and water was pumped in to fill the void between the worn-out 72” (1800 mm) RCP and the new N-12. The slurry filled voids between the two pipes in case the RCP did eventually crumble and would maintain the structure’s integrity.

N-12 was selected because of the smooth interior, which improves hydraulics, the watertight joint, corrosion and abrasion resistance and exceptional strength.


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