Sewer Lift Station System Vulnerability Analysis

The 2004 Atlantic hurricane season was one of the worst in history with fifteen named storms, and six hurricanes. Four of these hurricanes — Charley, Frances, Ivan and Jeanne — made landfall in Florida causing over 40 billion in damages. That, many Floridians thought, was a once-in-a-lifetime experience. As it turned out, 2004 was second in severe weather activity only to the year 2005. The 2005 hurricane season over-shadowed the previous year as the most active on record to date. A record twenty-eight named storms developed, a record fifteen of which became hurricanes. Of these, seven strengthened into major category 4 and 5 hurricanes, including Hurricanes Katrina and Wilma. Hurricane Wilma stands as the most intense hurricane ever recorded in the Atlantic.Hurricane Katrina made landfall in South Florida on August 25, 2005, causing widespread power outages, resulting in countless sewer overflow incidents throughout the region. At the time, the City of Miramar operated over one hundred sanitary sewer lift stations. Immediately after Katrina's passage, over 60% of the city's lift station facilities had no electrical power to operate the pumps that convey sewage safely to the receiving wastewater treatment facilities. Fortunately, the City sustained only a few minor spills during that critical period when electrical power was not available in the affected areas.As a result of Hurricane Katrina, the city realized that a formal response plan needed to be developed in order to safeguard residents' health, safety and property during times of widespread power losses. This paper describes the methodology used to conduct a sanitary sewer overflow risk assessment, and proposes suggested refinements based on the outcome of a subsequent severe weather event.