Confronted with a deteriorated sanitary sewer routed deeply beneath several major roadways and a well- established residential area, the Baltimore County Department of Public Works opted for a relining program rather than replacement. A sizeable portion of the Long Quarter Outfall Rehabilitation Project involved placing 24-inch diameter liner inside a deteriorated reinforced concrete main via sliplining.
As the relining process began, the contractor determined that the unusually close working conditions were best suited to segmental sliplining pipes. Contech A2 Liner Pipe with gasketed joints was selected for the installation.
A2 Liner is a light weight, profile-wall, PVC segmental sliplining pipe available in 10- or 20-ft. lengths. The StabJoint coupling permits fast joining and provides a positive seal, while fitting flush with the interior and exterior linear pipe surfaces for optimum internal flow and to prevent hang-ups on the host pipe during placement.
Although A2 Liner can be installed without interrupting flow in the line, sliplining on this project was performed during short-duration pump station shutdowns.
“This was our first installation experience with A2 Liner Pipe, and it’s all the things we need: fast, easy and simple” said the contractor’s project superintendent. “We achieved sliplining rates approaching 200 feet per hour, which is remarkable performance”
Segmental sliplining pipe, especially in 10-ft. lengths, also permitted smaller insertion pits. Crews found that 14-ft. pits were adequate, which meant less excavation and restoration times. The light weight liner pipe also eliminated concerns about construction loads on the existing sewer.
“We were able to complete the original relining project in approximately one-half of the 100-working-day
time limit,” said the installer’s project manager. “One of the contributing factors was
the switch to segmental sliplining pipes. We installed approximately 1,400-LF of the 24-in. A2 Liner product
in the existing 27-in. RCP lines. In addition to better-than-expected installation rates, the A2 Liner passed the
required air test on the first try.”