04-10-2024 Council Packet - Laserfiche WebLink

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STAFF REPORT TO: Mayor Fischer and Members of the City Council FROM: Eric Seaburg, P.E., City Engineer Bill Dircks, Public Works Director DATE: April 3, 2024 RE: Little Canada – 2024 Sanitary Sewer Rehabilitation Project ACTION TO BE CONSIDERED: Motion to award the Little Canada 2024 Sanitary Sewer Rehabilitation Project to Insituform Technologies USA, LLC in the amount of $310,505.13 BACKGROUND: In 2020 the City adopted a program to start rehabilitating its public sanitary sewer system by utilizing cured-in-place-pipe (CIPP) liners as a means to restore the structural integrity of the existing clay sewer pipe system as well as to reduce inflow and infiltration of groundwater into the public sewer system. The first two projects of this kind were completed in 2020 and 2022 by Hydro-Klean, LLC, with the third project in the program planned for 2024. This 2024 project includes manhole rehabilitation as an additional work scope to further reduce infiltration into the sanitary system. Due to some quality issues found in the post inspection liner during the 2022 project (that were caused by the excessive heat used during the “steam curing” process), this project will only utilize water curing methods to help reduce the risk of improper curing of the CIPP liner. Removing steam curing as an option will provide better quality control of the liner installation. This requirement also limits the number of contractors that are now able to perform this type of work. Steam curing, the most common liner cure method, involves heating water vapor until it reaches temperature and using that to cure the liner. Steam cure is the quickest cure method and tends to present the lowest cost per foot to install. However, this method is difficult to control the temperature within the liner, which can overheat the liner material and cause blistering, which was experienced in 2022. These defects required additional inspection time to resolve and cost the city additional time and money needed to complete the project in 2022. It also results in a potential weakness in the liner system as time passes as there is a seam from the repair. Traditional curing (or water curing) fills the liner with water and uses that as the medium to heat up and cure the liner. This method is a little slower than the steam cure as it takes additional time to heat the water. The benefit of utilizing this curing method is that we can better control the curing temperatures of the water and provide a better end product to the City. For this reason, water installation and curing is being required for the project in 2024. In order to facilitate these improvements, a $350,000 budget has been allocated in the Capital Improvement Plan (CIP) to complete these repairs in 2024. Of the $350,000 budget, $250,000 of it has been allocated for the CIPP improvements and $100,000 has been allocated for the manhole rehabilitation type improvements.