From:
Re:
G. Motion:
Attachments:
Discussion:
City of Nashua, Public Works Division
Board of Public Works Meeting Date: February 8, 2018
David L. Boucher, Superintendent
Wastewater Department
Primary Clarifier Upgrades — Final Design Phase
To approve Amendment | to the contract to Wright Pierce for professional
services for the final design and bidding phase services for upgrades to the
NWTF primary clarifier in an amount not to exceed $221,875. Funding will
be through: Department: 169 - Wastewater; Fund: SRF Loan; Activity:
Primary Tank Upgrades.
Wright Pierce Sample Contract, Work Scope and Cost Proposal
There are 5 primary clarifiers at the wastewater treatment facility that were last
upgraded in 2006. Wright Pierce was originally hired to evaluate the condition
of the tanks in February of 2017. They performed an extensive evaluation of
all components of the primary tank operations and submitted to the Wastewater
Department a Draft Preliminary Design Report (PDR) in January 2018. The
PDR is being reviewed by the Wastewater Department but it has provided a
defined scope from which Wright Pierce can proceed into the final design and
bidding phase.
Wright Pierce has proposed extensive upgrades to the existing primary tanks to
make the operation more reliable and less labor extensive. The proposed
upgrades include new chain and flights to improve the collection of the settled
primary sludge, creation of sludge hoppers where collected sludge will
concentrate, additional opening in the grease channel to allow for improved
grease flow thru the tanks to the collector near the outfall of each tank,
electrical, structural, odor control and other upgrades as well.
Wright Pierce has estimated it will take 5 months to complete the preliminary
design. Following completion of the final plans, the project will go for bid
which can typically take 2 months before selecting a qualified low bid
contactor.
The cost proposal has been reviewed and negotiated upon with Wright Pierce.
Their costs are reasonable and are approximately 8.8% of the estimated
construction cost of $3.6 million. Design costs in the range of 8 to 9% of
construction costs are considered reasonable for a project of this size.
