Annual Wastewater Manhole Rehabilitation Program

Project Number 01-476-009


 

Project Updates

01/22/2012

 

The City has awarded this project to Quest Civil Constructors Inc

Project is complete.





Project Schedule

 

Construction on this project began at the end of April 2012 and is expected to be completed by March 2013.

Project Details

 

The City of Mesa maintains approximately 31,700 manholes in its wastewater collection system.  The majority of these manholes are constructed of concrete or brick.  Due to the corrosive environment of wastewater, these materials can deteriorate over time.  This deterioration occurs more rapidly in lines that are larger in diameter (15-inch and larger).  These larger lines are typically the main collection lines in the system, where wastewater is in the lines longer for conveyance to treatment plants and where more turbulence occurs due to other lines joining the system.

Currently, new manholes for these size lines are installed with state-of-the-art coating systems that may extend their service lives over 20 years.  However, the City has older manholes that were not installed with the new coatings.  The deterioration of the concrete or brick can affect the structural integrity of the manhole and, ultimately, the street above the manhole.  City Staff inspects the existing manholes on wastewater main lines periodically to identify manholes that are deteriorated to the point where they must be rehabilitated with repairs and coatings, or replaced.  550 manholes have been rehabbed since 1996 with 233 being completed in the last 5 years.

This project will rehabilitate an additional eighty (80) deteriorated manholes.  The existing concrete is cleaned, and any structurally deficient concrete is removed.  New concrete is then bonded to the existing concrete, restoring the manhole to its original dimensions.  Other areas of the manhole in need of repair are also rehabilitated (bench, adjusting rings, frame and cover, etc.).  The manhole is then coated with a corrosion resistant epoxy coating that protects the manhole from the corrosive action of wastewater.

Project Funding

The recommended total award of this project is $777,378.80 which consists of the lowest bid of $706,708.00 plus an additional $70,670.80 (10% allowance for change orders).