To:
From:
Re:
B. Motion:
Attachments:
Discussion:
City of Nashua, Public Works Division
Board of Public Works Meeting Date: September 28, 2017
Noelle Osborne, Plant Operations Supervisor
Wastewater Department
Digester Cleaning Project
To approve maintenance services for the Digester Cleaning to Denali Water
Solutions of Russellville, AR in the amount of $237,310. Funding will be
through: Department: 169 Wastewater; Fund: Wastewater; Account Category: 81
Building Improvements.
Denali Water Solutions Bid
The Primary Digester at the Nashua Wastewater Treatment Facility was last
cleaned out in 2006 and the secondary digester in 2013. Digesters need to be
cleaned to remove inorganic and grit material that can accumulate in the structures
over time. This material can decrease the capacity and the performance of the
digesters.
The primary digester contains a volume of 1,300,000 gallons and the secondary
digester contains a volume of 275,000 gallons. Cleaning of these structures
requires a specialized company with portable dewatering equipment to quickly
and efficiently process the large volumes, allowing us to get the digesters back
online as quickly as possible. It is estimated that it will take up to 30 days to
setup, dewater all the sludge and inspect the interior of each vessel. In the event
that the inspection shows repairs are needed, it would be necessary to hire a
separate contractor outside the scope of this work.
This project was sent out to bid on August 11, 2017 with bids due on September
5, 2017. The request for proposal was sent directly to the three firms located in the
New England area. One bid was received from Denali Water Solutions, which has
a local office in West Springfield, MA. Their bid was considered reasonable and
came in well below the engineer’s estimate.
This company has satisfactorily assisted the NWTF with dewatering of the sludge
storage tanks in the past. Other references were checked and found to be favorable
as well. Work is projected to start in mid to late October and should be completed
before the end of November.
