Subsequent to Sewer Collections maintenance staff pipe inspections, severe deterioration of several existing gravity mains were identified in the West Grand neighborhood, the Cypress Knolls neighborhood, several areas north of the City’s downtown area, and along Louisiana Avenue west of Frances Avenue Park. All of the gravity mains lined contained extensive cracking, infiltration of water, sand, and root intrusion.
As Council is aware, this type of project has been included annually in the Public Works Capital Improvement Program as a continual proactive approach to rehabilitate an aging infrastructure. This type of rehabilitation method has a considerable reduction in cost from traditional pipe laying construction because it eliminates the cost of restoration and allows the existing facilities to remain in place with no disruptions to the general public. In addition, sewer lift station pump run times are reduced which result in lower operating and maintenance cost for equipment repair and treatment of the effluent. For this project 2,351 linear feet (LF) of eight inch cured-in-place-pipe (CIPP), 685 LF of 10” CIPP, 324 LF of 12” CIPP was installed, and 57 sewer lateral reconnections were performed.
The change order is related to the Wastewater Treatment Plant’s 24” pipe replacement and valve installation project. During the draining of aeration tank/basin No. 1 and No. 2, City Construction Services staff inspected the internal piping from the bottom exterior of the tanks inward to the top of the tanks. Visual inspections determined extensive corrosion of the existing pipe interiors. It was determined at that time that pipe lining was an appropriate method to prevent a possible pipe failure due to the pipes existing conditions. In addition, the City’s existing lining contractor was performing these activities for the City at that time and could be utilized for the time sensitive remediation work.