Special Board of Aldermen 10-14-2021 Page 15
homes and industries to the wastewater facility. Within the city, we have 13 pump stations. These pump stations are the
buildings or structures on the ground that houses pumps and controls these pumps take any sewage from a low
elevation, brings it up to a higher elevation so that it can be carried by gravity through these pipes to the wastewater
facility. We just finished an upgrade of six pump stations. We're getting ready to start Phase II, which is the remaining
pump stations. We upgrade all the pumps, buildings, underground structures and all the controls to the pump stations.
We also have nine combined sewer overflow structures. These are kind of relief points throughout the city. They're
designed - they're important that if we have like a flash flood, any swarming gets hydraulically overloaded. These are
relief points where highly diluted water would discharge into the river preventing water from coming up into streets or
backing into homes. So we have nine of those through the system. We also maintain eight siphon chambers. This is
anywhere the sewer system travels under a body of water. We maintain the pipe that goes under the body of water, also
the structures on either side for maintenance purposes.
These are some of the numbers we see at the wastewater facility. So the facility has a design flow of 16 million gallons
per day. We can receive a peak flow of 110 million gallons per day during major storms. Our average dry weather flow
is roughly 12 million gallons per day and we have an annual flow of 4,611 million gallons. We also received septage
from Hudson and Nashua. That's roughly about 800,000 gallons per year. So I'll turn over these next couple of slides to
the Operations Supervisor Noelle Osborne.
Noelle Osborne, Operations Supervisor
Thank you. Noelle Osborne, Operations Supervisor. As Mayor Donchess was mentioning, we are highly regulated at
the wastewater facility. Here's a list of the permits that we have. The first one being the NPDES permit and PDES.
That's the National Pollutant Discharge Elimination System. This one's issued by the US EPA but it includes State
standards. So New Hampshire has limitations that are even stricter than the EPA has and we have to follow those as
well. This is our all-encompassing permit. It reflects site specific conditions so it's specific to Nashua and allows us to
discharge into the Merrimack River. It regulates the process through the facility what we've discharged from the facility
as well as the biosolids processed, the management of the collection system, and the discharges from our combined
sewer overflows.
The next one is the New Hampshire SQC - Sludge Quality Certification. So while the NPDES permit does regulate the
basics of our biosolids process, we applied for and were granted additional qualifications for our biosolids giving us what
is called a “Class B Status”. This just means we have additional process and testing requirements but in the end, it
grants us the ability to beneficially reuse the product with the land application. That allows us to reclaim some of the
non-renewable resources in the biosolids such as phosphorus and it's a benefit to farm owners. The Massachusetts
AOS is the same as the SQC - the sludge certification, but in Massachusetts so like the SQC, it allows us to land apply in
Massachusetts.
The air permit is to the New Hampshire DES. We have on site three large emergency generators as the facility has to
continue to run even when there's no electricity from the main grid. We also have two energy recovery generators which
are still offline, but we hope to have operational soon. We have multiple odor control units that help to remove pollutants
called mercaptans from the air, which is basically just sulphur containing compounds that are air pollutants and have that
egg odor. All of the discharges from these units are regulated through this air permit and require monthly and annual
inspections, testing reports, and lots of upkeep and maintenance.
The AST and UST are the above and underground storage tanks. Each of the three emergency generators require large
quantities of fuel to be on hand at all times and these are stored in those above and underground storage tanks which
require regular inspections and maintenance. The multisector general permit “MSGP’” - the wastewater facility due to the
nature of the equipment and the large footprint is considered an industrial site. It has its own stormwater collection
system with catch basins and outfalls. So these are regulated under that MSGP and require testing, inspections, and
reporting. The MS4 permit NPDES Phase II Municipal Separate Storm Sewer System, this permit regulates the storm
water collection system throughout the entire City of Nashua and includes things like reducing inflow and infiltration, as
well as storm water treatment, testing, and reporting.
Hazardous waste SQG and RCRA - that's a Small Quantity Generator and Resource Conservation and Recovery Act.
So the facility does produce a small amount of hazardous waste in the laboratory as a byproduct of our testing. So this
certification lets the State know what we produce and that we have the training to manage it and we report that to them.
So governing documents. Within the permits are requirements to create governing documents and these documents are
written for the City of Nashua either internally or through the use of a consultant. They're specific to our needs and
abilities to accomplish specific tasks. So the collection system O and M is through the CMOM portion of the NPDES
