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Lift Stations: A Key to Sanitary Sewer Overflow Prevention curred in the past, to keep thing flowing smoothly.
Mike Darrow
Lift Station Basics
President, FWPCOA
hese days a sanitary sewer overflow (SSO) or wastewater spill of any size can be a major issue, involving repairs, cleaning, and/or replacement to correct the problem. For operators, this is the easy part; because of media attention, public notification, and regulatory fines, we’re in the unenviable spotlight when these events occur. We all are in a profession that is not used to being in the public glare. Traditionally, we are behind-the-scenes professionals doing our best to keep things flowing and operating properly. At times, it can be challenging to keep everything running smoothly, all day and every day, without incident. Anytime a utility has a SSO spill that hits the waters of the state or is over 1000 gallons, we are required to notify the state watch office and put the incident on the public notification website through the Florida Department of Environmental Protection (FDEP). With this step, we must be more focused on preventive measures. It’s best to look at each and every lift station in your collection system to be sure of proper operation and continued service. Another good practice or measure is line cleaning, jetting, or checking manholes of known hot spots in your system, where blockages have oc-
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In my humble opinion, the key to preventing a majority of spills is proper lift station maintenance and operational setting or controls. As you all know, the lift station moves wastewater from a low point in the collection system and pumps it to a higher point to restart the gravity flow and direct it to the wastewater treatment plant through a force main. For reference, look up Chapter 62-604, Florida Administrative Code (FAC), which lists the requirements for design, operation, and maintenance for proper lift stations. These stations and collection systems must be designed and operated to protect public health, ensure proper flow, remove waste streams, and be energy-efficient in their operation. Chapter 62-604, requires that the following basic measures be in place: S Two same-kind pumps installed in the station. With either of them out of service, the other pump will have the capacity to handle the flow at peak hourly flow. S Visual alarms and audible emergency alarms that function in the event of a high level in the wet well. S Access control to prevent the public from entry in the lift station area. S Control panel that has surge protection. S Periodic inspection of the lift station and its mechanical equipment.
October 2018 • Florida Water Resources Journal
Pumps In your system, look at the pumps in each station. Some questions that come to mind include: S Are all pumps running? S Is there a backup option? S Are they keeping up with the flow? S Are the pumpdown and run times equal for each pump? S Does this pump keep having issues? You should try to have all the pumps running in a duplex or triplex station; if not, is there a backup pump? It‘s common practice of good systems to have backup pumps available to cover the times when a station pump is down for maintenance. Make sure that each station has a quick-connect fitting available on the discharge to hook up the backup pump when needed. Use the floats of the backup pump as a secondary control. Try to have multiple portable backup pumps to be moved around to cover downtimes, depending on the size of your utility. Another form of backup is standby power generation. Many large lift stations will have a stationary generator available for use in power outages. Here too, portable generators are an option to move around to cover trouble spots. After several recent storm events in the state, most of the lift station issues and spills were power-related, with spills occurring from power lost from the electrical utility going down and no power to run the lift station. In very large-scale events, the number of lift stations you have on hand may need to be increased; therefore, your utility’s capital improvement plan may need additional funding to purchase more necessary equipment.