Municipal sewer rehabilitation without open cut

The problem municipalities are solving

Collection systems in most American cities were built in two or three waves, and the oldest wave is now past its design life. Clay and brick mains leak groundwater in and sewage out. Joints have opened; crowns have cracked; roots occupy whole segments. The symptom at the treatment plant is inflow and infiltration: on a wet day the plant treats rainwater that entered through broken pipe, at the same cost per gallon as sewage, and when the system surcharges it overflows. Replacing those mains by open cut means a trench down the middle of every affected street.

Cured-in-place lining of mains

A main is lined from manhole to manhole. The segment is bypass-pumped, cleaned and televised, and a resin-impregnated liner matched to the host diameter goes in by inversion or winch and is cured by hot water, steam or UV. A robotic cutter reinstates the lateral connections from inside. What results is a structurally independent new pipe that stops infiltration, carries the full design flow thanks to its smooth wall, and is rated for fifty years. Traffic control at two manholes replaces a street closure.

Pipe bursting for undersized or collapsed mains

Where a main must be upsized to meet new flow, or has collapsed so that a liner cannot pass, bursting replaces it on the same alignment with fused HDPE or restrained-joint PVC, often one size larger than the original. The launch and receiving pits are at the manholes, and the service connections are reconnected from small excavations at each lateral.

Laterals and manholes

Much of the infiltration in a system enters through private laterals and through manholes. Lateral lining programs, including lining the connection to the main, are now common and are often paired with homeowner cost-share programs. Manholes are rehabilitated with cementitious and epoxy spray linings or cured-in-place manhole liners that stop groundwater at the structure.

What municipalities specify

• Pre- and post-rehabilitation CCTV in a standard coding format, with defect ratings that justify the method.
• Liner design per ASTM F1216 or the equivalent, with the wall thickness calculated for the host pipe condition, depth and groundwater.
• Bypass pumping plans, traffic control and resident notification as part of the bid.
• Contractor qualifications: certified installers for the liner system, resin and cure method named in the specification.

Contractors listed on this site who perform municipal work note it on their city pages. Public works departments evaluating a lining or bursting program can reach the network through the contact page.