The City of Evansville, situated in the southernmost tip of Indiana, was
founded in the early 1800’s and is home to nearly 120,000 people. Like
many municipalities across the US, the city has its share of aging infrastructure, with much of the sanitary sewer system dating back nearly 100
years. As part of an effort to proactively upgrade the system, the Evansville Water and Sewer Utility needed to replace a 60-inch by 48-inch brick
combined sewer and storm water line with two new separate lines: a 12-
inch sanitary sewer line and a 60-inch storm sewer.
The major trunk line, with its proximity to the Evansville East Wastewater
Treatment Plant, was at the confluence of multiple smaller feeder lines. As
a result, any water event in the area tended to increase flow, sometimes exponentially depending on its severity. Average daily flow rates in the eight
city block junction ran at levels of roughly one million gallons per day
(MGD), whereas the system would rapidly rise within minutes to upwards
of 20-25 MGD during significant rain events.
AN AMBITIOUS PROJECT REQUIRING EXPERT PARTNERS
This was a high-profile project for the City due to the significant size of
the new lines versus the narrow right-of-way, the challenges with the rapid
increases in flow, and the proximity to an assisted living facility, high-rise
apartments, and the brand new Ford Center entertainment complex. The
City was looking for a skilled construction company for the project and
Blankenberger Brothers, Inc., a local firm with extensive experience in
municipal infrastructure, won the bid for the upgrade. With the high-profile
nature of the project, Blankenberger needed to focus on the upgrade work,
and needed a partner that could handle the bypass effort.
“The City was very concerned about getting the project right,” said Brian
Fox, Project Manager for Blankenberger Brothers, Inc. “So we knew we
had to choose a partner that could take care of the bypass, allowing our
team to focus on the system upgrades.”
The rapid flow increases of the trunk line had to be addressed with the
bypass, and Blankenberger assumed they would need to have 24/7 pump
watch duty as part of the bypass solution. It was an expense they felt they
would need to bear, to manually manipulate pump activity due to rapid
fluctuations in system flow. As they went through the vetting process for
potential bypass partners, they were provided a proposal from the bypass
experts at the local Xylem branch that made them think otherwise.
Xylem’s proposal included Godwin Field Smart Technology (FST) - a
remote control and monitoring system that would monitor crucial pump
operating data including system levels and flow, anticipate increases, turn
pumps on and off as needed, and even provide remote access to monitor
system activities through a website, accessible via smart phone or via any
device with internet access. It was a solution that made sense to Blankenberger, providing peace of mind and reducing the need for on-site personnel, and so they hired Xylem and contracted them to deliver a turnkey
solution for the bypass, from design through installation and ongoing
system monitoring and pump maintenance. The reliable Xylem solution
allowed the Blankenberger team to focus solely on the upgrades.
A customized bypass pumping solution to handle the toughest challenges
Xylem engineers developed a bypass solution that employed a tiered
pump approach. The plan called for the daily “dry-flow” requirements of
one MGD to be handled by a Godwin 6” CD150M Dri-Prime pump. To
handle the initial onrush of increased flow, the team installed two Godwin
8” CD225M Dri-Prime pumps to kick on sequentially. As a severe weather
event continued to bring on additional water, two Godwin 18” CD400M
Dri-Prime pumps and an additional Godwin CD400M as a lag standby
pump were set up as the primary workhorses of the bypass. These pumps
could move upwards of 10 MGD each and as much as 30 MGD when all
three are online, but they typically take eight to ten minutes to prime.
With the extremely rapid influx of water into the system during rain events,
the team did not have the luxury of time, so Xylem devised a solution
whereby the Godwin CD400M pumps would turn on when the smaller
CD225M pumps kicked on, ensuring the system could handle a sudden
increase in flow rate. The engineered bypass pumping solution provided
a buffer of time for the larger pumps to cycle through and get primed to
Suction points for the pumps were out of the new 26-foot-deep drop structure that Blankenberger installed as part of the upgrade, and the discharge
point was approximately 400 feet down the line.
CUTTING-EDGE DIAGNOSTICS, MONITORING AND CONTROL
The Xylem team set up each of the pumps with Godwin FST, which
provided an advanced, automated monitoring and control solution for
Blankenberger. Fed by data from MJK flow meters in the discharge line
and level transducers in the 26 feet deep drop structure, the FST automatically stopped and started the pumps as necessary based on pre-set levels in
the structure and pre-set flow rates.
The FST provided Blankenberger with real-time diagnostic and reporting
information about each of the pumps, such as engine RPM and temperature, and also provided monitoring data about the system, including pump
on/off status, flow rates, and levels in the drop structure. This enabled
Blankenberger to prepare for upcoming storm events with smart contingency planning measures, such as pumping down the system to the lowest
possible levels in advance of the event, to provide maximum storage
space and reduce the likelihood of a sanitary sewer overflow (SSO). The
FST data could be accessed remotely by the Blankenberger team, which
ultimately eliminated the need for onsite 24/7 pump watch duty, saving
the firm – and ultimately the City – over $100,000 in man hours over the
course of the project.
Auto-dialers were also set up to alert Brian Fox via text message when the
Godwin pumps were started, giving him remote visibility to pump activity
and reassurance that the system was working as designed.
“Having the FST in place provided us all with an extra level of confidence
that the system was going to handle whatever flow rates we might experience. That peace of mind to us and to the City was great to have, given
the high-profile nature of the project. The fact that the FST also ended up
saving us over 2,000-man hours of 24/7 pump watch duty was an added
benefit we didn’t expect going in, and that was terrific,” concluded Fox.
Circle 126 on Card or http://pen.hotims.com/69825-126