To:
From:
H. Motion:
Attachments:
Discussion:
City of Nashua, Public Works Division
Board of Public Works Meeting Date: June 23, 2016
David A. Simmons, Superintendent
Wastewater Department
NWTE Capacity Analysis Update
To approve a contract to Hazen & Sawyer for professional services for an
update to the plant capacity analysis in an amount of $19,898, Funding will be
through: Department: 169 Wastewater; Account Classification: 53
Professional & Technical Services.
Hazen Sawyer Scope of Work and Fee.
The Wastewater Treatment Facility (WWTF) has been using the services of
Hazen & Sawyer (Hazen) for analyzing the WWITF capacity to determine
constraints and limitations of all treatment processes that specifically impact
secondary treatment capacity based on current and future predicted wastewater
flow rates. Hazen completed a WWTF capacity analysis in 2014 and prepared
a final report in March 2015. The capacity analysis was based on plant data
collected from July 2013 to January 2014. However, during this time period,
the plant was not always working at optimal capacity due to on-going repairs
and equipment upgrades. Since completion of the March 2015 Capacity
Analysis Report (Report), these repairs and upgrades have been completed and
recent plant data indicates improved solids settling characteristics which may
impact the findings presented in the Report.
One of the findings from the Report was that the wastewater plant is limited in
capacity due to lower than optimal capacity of the anaerobic digester as a result
of lower solids concentration that existed at the time of the study. Recent plant
data suggests that the plant is operating with a higher solids concentration. A
re-evaluation of the data is necessary to confirm if the plant capacity is greater
than previously thought.
The update of the March 2015 Capacity Analysis Report is also tied into the
WWTF’s NPDES discharge permit. The permit requires the permittee to
submit to the permitting authorities a projection of loadings, and a program for
maintaining satisfactory treatment levels if the effluent discharged over 3
consecutive months exceeds 80 percent of the facility's 16 million gallons per
day (MGD) design flow, so it is critical to have updated capacity report.
Hazen is ready to begin this update to the March 2015 Capacity Analysis
Report right away. Any updates to Report will be conveyed to the EPA prior
to the WWTF engaging in any project needed as stated in the original report.
