A case study delivered recently by ESL Power Systems recalls how one city responded to the devastation of the massive storm by putting in a system to provide back-up power in the event of future natural disasters or accidents. Below is an edited excerpt.
When Hurricane Katrina hit the New Orleans area with 120 mph winds in Aug. 2005, the City of Gretna, La., saw its potable water plant, wastewater treatment plant and network of 14 sewer lift stations lose all electrical power, bringing down the entire system which operates and controls the potable water supply and sewer system serving over 17,700 residents.
Due to 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-hour days the Public Utilities Division team managed to restore full 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.”
Utilizing 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 and quickly 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, which eliminates the cost of permanently installed generators. That's why we specified the StormSwitch manual power transfer switch system from ESL Power Systems, which is shipped pre-wired for very quick installation.”
Burk-Kleinpeter'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 generator for redundant power at the two primary lift station facilities. A critical design choice was adding ESL's StormSwitch Manual Transfer Switch to 11 sewer lift station pump sites and to the raw water intake location.
Mullis noted that BKI had previously worked with ESL Power Systems for seaport/shipyard electrical power projects. When he contacted ESL about the City of Gretna project, Mullis emphasized the need for a very cost-effective manual transfer switch system that delivered fool-proof operation without the need for a professional electrician or extensive employee training. Because very basic training is required to operate ESL's StormSwitch once the system has been installed by a certified electrician, the product provided an ideal solution.
“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 Article 702 requirements for optional standby systems,” said Mullis.
Baudoin's post-Katrina advice after rebuilding the City of Gretna's wastewater facilities is simple, “You can never have enough backup systems.”