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 move water.
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.