Title
Resolution to Approve Change Order No. 1 to a Construction Contract with Liquiforce Services (USA), Inc. in the Amount of $314,700.42 for the Nichols Arboretum Sewer and Siphon Rehabilitation
Memorandum
Attached for your review and approval, please find a resolution that will approve Change Order No. 1 for the Nichols Arboretum Sewer and Siphon Rehabilitation Project in the amount of $314,700.42. The change order was necessitated by several differing site conditions that were discovered during the course of construction of this project.
The Southside Interceptor Sewer is a 36" trunk line sanitary sewer that services a large portion of downtown Ann Arbor, the University of Michigan's Medical Campus, and other areas further downstream such as Geddes Avenue and E. Huron River Drive on its way to the Waste Water Treatment Plant. A portion of this sewer contains a 624 foot long, double-barrel, 24" diameter inverted siphon with cast-in-place concrete junction chambers at each end. One of the barrels of the inverted siphon was plugged and inoperable for some time. The cast-in-place junction chamber walls also had a moderate to severe level of hydrogen sulfide damage due to the turbulence within the inverted siphon. Sanitary sewer overflows have occurred within the section of the sewer within the Arboretum intermittently over the last many years.
The Nichols Arboretum Sewer and Siphon Rehabilitation Project is part of a multi-phase project that has been systematically rehabilitating the Southside Interceptor over the course of the last five years. Subsequent phases of the project are planned into the future to complete the rehabilitation of this sewer.
As the project name indicates, this project is rehabilitating the portion of the Southside Interceptor that is under the wooded portion of the Nichols Arboretum from the entrance gate on Nichols Drive to a point approximately 600 feet east of the prairie in the Arboretum. Due to the extremely difficult loc...
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