Colstrip Water
PPL Montana pumps water from
the Yellowstone River six miles west of Forsyth to Castle Rock Lake. Our system
draws water from Castle Rock Lake and is treated at The Colstrip Water Treatment Plant.
The waterplant is a variable declining rate direct filtration facility. It
is designed for raw water to gravity flow from Castle Rock Lake through an
in-line mechanical mixer. It mixes aluminum chlorhydrate, (a
coagulant), activated carbon and/or potassium permanganate (removes taste and
odor), and fluoride with the raw water flow stream, then through a static mixer
where a nonionic polymer is applied as a filter aid, and into an open distribution
channel at the head of four filter bays. Media in these filters is a dual
media of anthracite coal and sand.
Filtered water leaving the filter bays enters a
weir trough where chlorine is added for disinfection. Water cresting the clearwell
weir trough falls into the clearwell and becomes available for pumping into the
Colstrip distribution system through the high service pumps. Colstrip has over 26
miles of distribution system. The high service pumping system is designed to serve
three separate pressure zones in the Town of Colstrip.
Zone 1 is the oldest and
the lowest part of the town. It is served by two 500,000 gallon reservoirs. Many
of the old mains in this part of town have been replaced in the last few years.
Zone 2 is the second highest portion of the distribution system and it is
served by a 2,000,000 gallon reservoir in the northern portion of Colstrip.
Because of a declining population in this area, this reservoir is maintained at
1,200,000 to achieve better turnover.
Zone 3 is served by a 650,000 gallon
reservoir in the southwestern part of the town. Six high service pumps serve
these three pressure zones. Water from the clearwell is also used for backwashing
the filters. The backwash is sequenced and controlled by a SCADA system located in
the control room. The SCADA (supervisory control and data acquisition) system
also monitors and records the function of all treatment processes, reservoir
levels, the wastewater treatment plant and sewage lift stations. There are
turbidity meters on all filters and the clearwell that are recording
continuously the clarity of the water. We have online chlorine and fluoride
analyzers which monitor and record residuals leaving our treatment plant on a
daily basis. We test chlorine residuals daily in our distribution system. We also
test for total coliform bacteria (i.e. e-coli) monthly from 3different sites in
our distribution. We are sampling quarterly from the distribution to comply with
the Disinfection By-Products Rule. We also sample yearly to comply with Phase
II and Phase IV of the Surface Water Drinking Act. All of our outside testing is
done by Energy Laboratories of Billings except the total coliforms, which are
done by Aquatec Laboratories of Lewistown. Both labs are certified.)