Sanitary Sewer Point Repairs & Pipe Lining Brentwood Borough Municipal Engineering & Inspection Team Fall 2005 The Borough of Brentwood, along with all ALCOSAN communities, is under a Consent Order (COA) from the Allegheny County Health Department. The COA requires the Borough televise their sewers to locate and repair all significant structural defects. The order requires that 1/6 of the Borough be televised each year for a period of six years. All defects located via CCTV inspections must then be repaired. Brentwood Borough is an older, urban community that has generally small residential lots with limited space to maneuver construction equipment. Gateway Engineers determined the most economical way to make the required repairs was to use a combination of open cut excavation and trenchless rehabilitation such as cured-in-place pipe lining. Trenchless methods are only viable if the condition of the pipe is suitable for this type of repair. For instance, lining could not be used to repair a total collapse. (Above) A short section of pipe is replaced via traditional open cut excavation. After excavating to physically locate the broken pipe, a trench box is used to brace/shore the trench walls. A short segment of pipe is removed and replaced with a new PVC pipe. The trench is then backfilled with aggregate to the bottom of the pavement section. In the adjacent photo, a liner is being cured with steam. The inverted liner containing resin is usually inserted through a manhole and inverted through the host pipe by a column of water. The resin that is contained in the lining prior to inversion is then forced against the host pipe. As heat is applied to the liner, the resin hardens and takes the shape of the host pipe. The new liner bonds to the host pipe leaving no annular space for any inflow or infiltration. Brentwood has saved thousands of dollars by using trenchless methods in locations where surface features such as sheds, decks, pools and other structures would be cost prohibitive for traditional open cut excavation. After making repairs, the next important step in this sequence is restoration. In the photo to the right, the crew replaces a wooden retaining wall near an apartment building off of Brownsville Road.