To:
From:
Re:
B. Motion:
Attachments:
Discussion:
City of Nashua, Public Works Division
Board of Public Works Meeting Date: March 24, 2022
David L. Boucher, Superintendent
Wastewater Department
Digester Heat Exchanger and Stair Tower Exhaust Fan — Design Phase Services
To approve the contract with Wright Pierce to provide design plans and
specifications for a second digester heat exchanger and stair tower exhaust fan in
an amount not to exceed $40,900. Funding for this contract will be through
Department: 169 Wastewater; Fund: Wastewater; Activity: Heat Exchanger
Primary Digester.
Wright Pierce Scope of Work and Fee Schedule
The Primary Digester has a heat exchanger in the bottom level that heats sludge to
the proper temperature to keeps the digester running optimally. Currently there is
one heat exchanger in place. The wastewater facility has purchased a second heat
exchanger for redundancy, which will allow us to maintain the digestion process
should one exchanger become faulty or needs to be taken off-line for routine
maintenance. This project involves containment modifications, additional piping
and controls for the installation of the second heat exchanger.
There is an enclosed stair tower that provides access to the top of both the primary
and secondary digesters. At the very top of the stair tower is an exhaust fan that is
not working and difficult to access and repair as it is located on the roof of the
stair tower. A much safer approach is to abandon the existing fan and install a
new one at the top of the stair tower, below the roof level, so that it can safely be
reached by employees when servicing.
Both of these projects are in the same general location and it makes economical
sense to lump both projects into one. Wright Pierce has satisfactorily completed
many projects at the wastewater plant and we believe they will provide a well
thought out design for each component of this project.
