H. Motion:
Attachments:
Discussion:
City of Nashua, Public Works Division
Board of Public Works Meeting Date: February 8, 2018
David L. Boucher, Superintendent
Wastewater Department
Digester Cleaning Project
To approve change order 2 to the Digester Cleaning project with Denali Water
Solutions in the amount not to exceed $100,000. Funding will be through:
Department: 169 Wastewater; Fund: Wastewater;.Account Category: 81 Building
Improvements.
Denali Water Solutions Estimated Quantities to Complete Cleaning
The cleaning of the primary and secondary digesters at the Nashua Wastewater
_ Treatment Facility was sent out to bid in July 2017 with Denali Water Solutions
the low bidder at a cost of $237,310. Change order 1, for $48,400, was approved
by the BPW on October 26™ for the contractor to provide odor control of
undigested sludge by adding chemicals. The new contract total is currently
$285,710.
During initial meetings with Denali, they estimated to complete the digester
cleaning in a period of six weeks. However, there were delays encountered in
equipment and lines freezing as a result of the extreme cold weather encountered
from December 20th to January 12". The dewatering took much longer to
complete due to the cold weather and holiday shutdowns. The estimated
completion date for cleaning both digesters is now February 3". In addition, their
services will be needed to keep dewatering the incoming sludge before filling the
primary digester in order to inspect the inside of the digester and change valves at
the base of it that are not properly sealing.
This change order will be for an additional $100,000 which will include
dewatering sludge before startup for vessel inspection and valve replacement.
The new contract amount will be $385,710. The contractor will be paid as normal
for what they actually dewater on a dry ton basis. Although costs have increased
the overall cost is still below the original estimate of $750,000 as a result of the
contractor setting up at single location to dewater both the incoming sludge and
sludge in the digesters.
