The high-tech plant blends into the wooded backdrop.
Providing high quality drinking
water for a city of 59,000 people
is a challenge in itself.
Retrofitting the controls and
instrumentation for six water treatment
plants and 13 remote stations, and
tying them all together is an even
greater challenge. When the City of
Meriden, Connecticut, Water Division,
was facing this task in April 2001 they
called on USFilter for help.
The water plants and remote stations
had limited monitoring and control
capabilities. The newer treatment
facilities used motor control centers or
analog controls, while the older treatment
plants, remote pump stations,
storage tanks, and metering facilities
were manually controlled. Operators
had to drive to each facility to solve
problems. Effluent water quality data
from the filters and water usage data
had to be collected at each individual
plant. Record keeping and daily, weekly,
monthly and yearly reports were
also prepared manually, which was
very labour intensive. After-hours and
unmanned plant alarms were sent as
general alarms to a security service
and then to an on-call operator.
Operational benefits of implementing
a SCADA system are continual
monitoring and alarming of process
variables, automatic generation of
reports, built-in security, streamlined
record keeping and archiving, and
potential operational and energy savings.
A team from USFilter met with
consulting engineer Metcalf & Eddy,
the City’s Water Division personnel,
and the City’s Management of
Information Technology (MIS) staff to
discuss the best solution for automating
each water treatment plant and
connecting it to the remote facilities
using state-of-the-art controls technology.
While the City knew they had to
install a SCADA system to automate
and upgrade current controls, they also
knew they needed someone to do the
design/build and act as general contractor
of this phased installation. With
its extensive experience in systems
integration and project management,
USFilter recommended a Microsoft Windows-based Honeywell distributed
control system integrated with
USFilter D620i remote telemetry units
(RTUs), and Cisco networking equipment.
USFilter provided design engineering,
installation, training, commissioning
and service.
The Honeywell control system integrates
continuous, batch and discrete
control capability into a single, costeffective,
scaleable control solution.
The key element of the process is the
seamless integration of the C200 controller
with the Honeywell process
server for optimum performance.
Additionally, the Honeywell control
software offered an option called
Distributed System Architecture. This
feature allows multiple plants to share
point data, alarms, messages, and history
without the need for duplicate
configuration on any server. This
means that, with proper security credentials,
an operator or engineer can
log in to the system from anywhere on
the network and ‘see’ all six plants and
remote RTUs at the same time.
USFilter documented the “as-is”
wiring of the equipment at all the facilities,
and then met with City operations
personnel to work out a description of operation for each facility.
These descriptions served as the basis
for how the operators would interact
with and use their new system, and
also served as a guide for USFilter in
engineering the controls. The City also
added several new instruments and
controls in areas that previously had
none.
While the company was building
the panels, the project team met with
the consulting engineer and the City to
agree on standards and conventions for
the control system screens with which
the operators would interact. When
this phase was completed, the City’s
water division personnel and MIS
department visited USFilter for a week
of training, then returned later for a
week of hardware and software
Factory Acceptance Testing.
After testing was complete, the
hardware was shipped to the site.
Installation began in June 2003.
During a seven-month installation
period, each plant was individually
taken off-line while the instrumentation
and controls were installed and
tested, and then placed back online.
Control system servers are located
at each of the six treatment facilies: Broad Brook Water Treatment Plant,
Merimere Filter Plant, Elmere Filter
Plant, Bradley Hubbard Water
Treatment Plant, Evansville Avenue
Water Treatment Plant, and the Platt
and Lincoln Water Treatment Plant.
Each of these facilities’ servers is dedicated
to supporting local plant process
control and monitoring. The servers
also connect to, and communicate
with, all the plant’s remote locations,
such as pump stations, wells and tanks.
Each location uses a standard
switched Ethernet network topology
communicating over ISDN lines. This
allows the City’s MIS personnel to easily
dial in to the network over a standard
telephone line to troubleshoot/upgrade
each piece of equipment in the system,
including controllers, routers, device
servers and all PCs. The ISDN network
serves as a private isolated network for
control system use only. It was chosen
to use Cisco ISDN networking equipment
because of its widely accepted
use, and because the City was already
using Cisco.
The control system servers at each
water treatment facility collect and
store continuous process data, and
securely display the data, locally and
remotely, in any user-desired format.
The data is transferred automatically
from each of the treatment facilities to
the central redundant server located at
the Broad Brook water treatment plant.
Supervisory staff has access to the
entire control system from any computer
in the system, including secure
dial-up access.
The control system reduced labour
costs, improved operating efficiency
and allowed more accurate reporting of
water usage, water quality and realtime
operation.
The phased start-up of each plant
was completed according to schedule
in February 2004. The networked operation
of all six water treatment plants
using the control system has proven to
be a great success. Says Dave Lohman,
Assistant Director of Water Operations
at Meriden: “We’ve seen labour cost
savings now that our operators can
handle issues that arise at a plant without
having to drive to that site. Being
able to monitor operations of all the
plants at once reduces the reaction
time, and ultimately improves operating
efficiency. It also increases security,
and has allowed us to more accurately
report water usage and effluent water quality.” Dave adds: “Another
plus is the fact that we can automatically
manage filter run times, producing
more product at less cost.”
Additionally, all plant and RTU
alarms now dial out automatically
using control system software. This
eliminates the need for a security company
to contact the on-call operator.
Instead, the control system calls the
operator’s home, cell phone or pager,
and if there is no answer, the system
will call the next person on the list. The specific plant alarm is enunciated
(such as “Broad Brook clearwell level
high alarm”), so the operator knows
the specifics and can either dial in to
fix the problem or drive to the site.
