Background

Aging Sanitary Sewer System

The majority of the city’s sanitary sewer mains were constructed in the late 1950’s and early 1960’s, utilizing clay tile pipe. Over time, the joint materials have failed, allowing root intrusion. Clay pipe is also susceptible to cracking and construction damage. The conventional method of digging and replacing the pipe (“open-cut replacement”) is very expensive, and disruptive to property owners. 

Cured-in-Place Pipe Lining

The city’s Capital Improvement Plan includes annual funding for a sanitary sewer main lining program to extend the life of our sanitary sewers by 50 years or more. This technology, called cured-in-place pipe (CIPP) renewal, installs a new liner pipe inside the old clay tile sewer main without digging up city streets, which results in minimal disruption to residents during construction. 

The liner pipe is inserted into the main through existing manholes and cured in place with a heat or steam process. Any given segment is usually completed in one working day. Service line connections are reopened using a robotic cutter and remote cameras. During the process, existing flows are bypassed using pumps. 

This technology has been proven over the past 20 years, and has become more cost-effective than open cut replacement. This type of renovation is an annual project for the foreseeable future as our sewer infrastructure continues to age. 

The lining prevents infiltration of groundwater into the system through cracks in aged pipe, so this work is credited toward our inflow / infiltration program as required by Metropolitan Council Environmental Services.

Notifications

 Our contractor will give notice to affected residents at least 24 hours ahead of their work. In general, during the lining process, it is acceptable to use the toilet and wash hands, but we ask you not run a load of laundry or do dishes or showers which may cause your service to back-up into your home. This impact can be anywhere from a few hours to much of the day depending on the pipe size. All services will be restored by the end of the day, to prevent impacts overnight.

During the curing process, you may smell an odor from the resin used for the lining pipe. If you smell it, your sanitary traps could be dry. Please run water in seldom-used sinks and pour water into basement floor drains. This will refill the trap and help prevent smells entering your home from the sanitary main.

Schedule

Significant roadway crossings, such as Hwy 36 and Snelling Avenue, are proposed for lining in 2024.  To maintain service for our residents and businesses, the City is designing sewer bypass plans for our sanitary sewer pipes under these large roadways ahead of construction.

2023 – Bypass Design
2024 – Lining