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DEPARTMENT OF PUBLIC WORKS
WATER TREATMENT PLANT
71
Merrimack Drive, Tewksbury, MA 01876
Hours of Operation: Monday thru Sunday 24 hours a day
Lewis Zediana, Division
Supervisor/Chief Operator
Tel: 978-858-0345 Fax: 978-640-1212
lzediana@town.tewksbury.ma.us
Current Water Report, June 2006
CCR Report, 2003
The Tewksbury water
system began circa 1941, mainly to service the state hospital and
the surrounding homes near Long Pond. Remnants of the old pump house
can still be seen on Pond Street. As the Town grew and the demand
for water increased new wells were added to meet the demand for
water and to start the water system. The original wells were located
mainly in the Southern section of the Town with two wells located
just outside the center of Town near the Great Swamp. All of the
wells were high production overburden wells that drew water from the
sand and gravel strata from between 50 to 100 feet deep. Underground
water moving in a river like fashion travels in the Northeasterly
direction towards the Merrimack and Shawsheen Rivers. Eventually
this water finds its way into these rivers and finally out to the
Ocean. As the wells aged, reduced water output and ever increasing
Iron and Manganese levels forced the shutdown of many of the 15
wells that were built in Town. Eventually all of the wells were
phased out of use until 1992 when the last well house was closed and
the Town relied on producing its own water from the new water
treatment plant.
The first storage
tank stood on Ames Hill and its foundation can still be seen. This
old tank has since been replaced by two underground storage tanks
which were built circa 1951 and 1958. Both of these storage tanks
are still in use today. Each tank can hold up to 500,000 gallons of
water. The youngest and most visible water storage tank decorates
the horizon of the Tewksbury skies towards the Northwest. The Astle
Street tank (aka elevated tank) was constructed in 1971 and was just
recently refurbished and painted a respectable blue color. The Astle
Street tank can store up to 1,000,000 gallons of water. The
interesting shape used is called a torus and is designed to trap
sediment particles in the bottom round shape and add structural
stability. The top of the tank stands 135 feet above the ground
level and the overflow pipe is at the same altitude as the Ames Hill
storage tanks. Since Tewksbury is remarkably flat the elevated tank
design was needed to develop the ‘hydraulic head’ or water pressure
to run the water system. At the base of the tank the water pressure
can reach up to 58 pounds per square inch.
The Tewksbury water
system is a large maze of pipes measuring in diameter from as small
as 2” to as large as 36”. The water distribution system consist of
approximately 150 miles of pipe. To help keep this water system
clean annual flushing, usually scheduled for the fall, is performed
where crews from the water department open water hydrants around
Town. When flushing pipes, water from the hydrants can reach heights
well over 50 feet as the pressure removes sediment and scrubs the
pipelines clean. This process can consume over 10 million gallons
but is considered a basic maintenance procedure that all water
systems perform on an annual basis.
Since many lower
areas have water pressures over 80 pounds per square inch pressure
reducing valves are used to protect household devices such as water heaters from
experiencing too much water pressure. Please do not remove such
devices as they are designed to protect your internal water system.
The Tewksbury Water
Treatment Plant was built back in the late 1980’s and operates 24
hours a day, 7 days a week with a staff of nine DPW employees to
address the Town’s demand for water. The water plant draws water
from the Merrimack River which is considered one of the best raw
water sources in the area. The water drawn from the river undergoes
many treatment processes that removes particulate matter, disinfects
and polishes the water before transmission to the populace. Please
find below a brief description of the water plant capabilities.
· Plant Flow
– 7.0 Million Gallons Per Day (MGD)
· Primary Disinfection – Chlorine Dioxide, a powerful
disinfectant/oxidant. This chemical is generated onsite and is dosed
into the water at about 1 to 2 mg/L.
· Secondary
Disinfection
– Sodium Hypochlorite, bleach is used as a secondary disinfectant to help
remove ammonia and oxidize certain forms of manganese. Sodium
hypochlorite is used twice, once in the pretreatment and again in
the finished water just as it leaves the plant. The free chlorine
dose is controlled at about 0.7 mg/L and the success of this triple
disinfectant program is reflected in the zero bacterial detection
rate since 1988.
· Rapid
mixing/ coagulation - Two-stages, utilizing vertical shaft radial mixers. Coagulant chemical
is aluminum sulfate (alum).
· Flocculation - Two stages, having a total of 15 min. detention time and utilizing
vertical- shaft, axial-flow flocculators.
· Filtration – Four automatic backwash filters (ABF) having a design filtration rate
of 2.37 gpm/square foot. Filter media consists of 36 inches of
activated carbon over 12 inches of sand. ABF are able to stay in
operation while backwashing.
· Corrosion
control - pH adjustment using potassium hydroxide (KOH), followed by an
application of a blended zinc orthophosphate corrosion inhibitor.
· Final
Disinfection – Sodium Hypochlorite.
· Fluoride
source – Hydrofluosilicic acid. Controlled dosage at 1 mg/L (We call it Silly
acid).
· Treated water
storage - Two, 1-million-gallon storage tanks.
The water that is
pumped into the system is evaluated and tested
every four (4) hours. The facility runs 24/7 and is manned by
licensed certified operators. Strict rules enforced by DEP and
the EPA require notification of the public if any part of the
drinking water regulations are violated. Also we are on the web
through the EPA database for any violations for the last 10 years.
Please go to
www.EPA.gov, our water system number is 3295000. If you have any
questions please feel free to contact us.
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