Year in and year out — from coast to coast — we are reminded how dependent we have become on the underlying infrastructure that delivers the clean water, electricity, and communications we have come to take for granted. It's typically only when a hurricane, tornado, flood, ice storm, or earthquake suddenly knocks out our community’s utility services that we truly realize the implications of losing access to these fundamental services. Emergency backup power generation must be at the heart of emergency planning as a key to safeguarding quality of life, including quick post-emergency recovery. This is true regardless of whether a community’s electric utility services are damaged or completely lost due to a natural disaster or accident. In August of 2005, Hurricane Katrina delivered a brutal reminder to the City of Gretna, La., of just how critical it is to have a robust emergency backup power solution in place.
When Katrina hit the New Orleans region, Gretna experienced wind speeds in excess of 120 mph. As a result of the hurricane, the city saw its potable water plant, wastewater treatment plant, and network of 14 sewer lift stations go completely without electrical power, bringing down the entire system that operates and controls the potable water supply and sewer system serving more than 17,700 residents.
Due to area flooding, wind damage, and generator failures, 75% to 100% of the city’s water and sewer system was down for more than four days. Working 16- to 20-hr days, the Public Utilities Division team managed to restore service after a very trying week and half. “The wastewater plant went down, and the master lift station generator failed — but we didn’t find out about these failures until the storm had passed,” recalled Mike Baudoin, director of public utilities for the City of Gretna.
“I know what it’s like to experience a true catastrophe,” noted Baudoin, whose own home was destroyed by the hurricane. “People can’t come back to their homes unless we have city infrastructure up and running. In the hurricane’s aftermath, both our wastewater plant generator and the 250kW generator for the master lift station were found to be under-sized and aged, requiring upgraded solutions.”
Using a $1.8-million Mitigation Funding Block Grant that was approved by the State of Louisiana and FEMA, the City of Gretna contracted engineering firm Burk-Kleinpeter, Inc. (BKI) to upgrade and modernize the pump stations. This included designing a cost-effective emergency backup electrical power solution that could be easily managed by the four-person Public Utilities sewer collection department.
According to Bart Mullis, associate-electrical engineer for BKI, the fact that the City of Gretna is a small municipality with a modest budget necessitated design of an emergency backup power solution that could be easily connected without reliance on electricians.
“For wastewater facilities, backup generators serve the purpose of maintaining a safe flow of wastewater (sewage) not associated with flood control,” explained Mullis. “In this case, because of the City of Gretna’s limited resources and very small staff, we decided it would be best for our client to rely on quick-connect portable generators that eliminates the cost of permanently installed generators."
BKI's scope of deliverables for the City of Gretna encompassed significant improvements and upgrades to the electrical infrastructure for the wastewater treatment plant. An important part of the project included replacing one failed permanent generator and installing a second for redundant power at the two primary lift station facilities. A critical design choice was adding ESL Power Systems’ StormSwitch Manual Transfer Switch to 11 sewer lift station pump sites and to the raw water intake location.
According to Mullis, the ESL product provided an ideal off-the-shelf solution while eliminating the added costs for a custom-engineered system. “The StormSwitch unit allows City of Gretna workers to easily add emergency generator backup power to numerous pumping system locations needing different amperages, while at the same time meeting the UL1008 standard with a robust NEMA-3R-rated enclosure and complying with National Electrical Code Art. 702 requirements for optional standby systems,” he said.
Baudoin’s post-Katrina advice after rebuilding the City of Gretna’s wastewater facilities is simple, “You can never have enough backup systems,” he emphasized.