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STORMWATER

Properly designed pumping systems protect against stormwater surge flooding By George Micevski

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ith flooding events seemingly on the rise, particularly in North America, local governments should be considering more modern, efficient and effective ways to manage major weather events that produce an inordinate amount of stormwater. This is especially true when working with aging infrastructure and combined-sewer systems that not only lack capacity to manage major storm events, but also threaten environmental damage when they overflow into nearby natural watercourses. There is not, unfortunately, a foolproof system for preventing floods. Nature will sometimes do what nature-

28  |  June 2019

wants to do. But that doesn’t mean people are helpless. There are preventive measures and mechanisms that can be put in place to help keep rising waters in check and protect those homes and businesses that would otherwise be in the path of the flood. A key flood mitigation tactic is to divert stormwater into reservoirs, or other holding areas, before it gets to areas where human populations have settled. But, doing so requires modern pumping and monitoring systems that can not only manage increased flows of water, but can do so with minimal human interaction or oversight. When a hurricane isn’t involved, flood-

ing often results because there is inadequate drainage, or the water coming into the city’s sewer system is simply too much for it to handle. In an older combined sewer system, this ultimately results in stormwater mixing with raw sewage, and possibly being discharged into a nearby river, stream or lake. Then, public beaches often get closed because of high E. coli counts. In cities that have updated their infrastructure and urban planning policies, stormwater is being diverted to holding or retention ponds. Or, maybe they have installed subterranean holding tanks, where storm and wastewater is stored until there is capacity at the treatment plant. The challenge is getting the water to these holding areas, particularly when fighting against gravity. For this, it is vital that municipalities, or owners of private property who have to manage large flows of storm or wastewater, have a pump system that can manage the massive flows of water that can be collected during a storm event. If the pump is insufficient for the flows coming in, it will be overwhelmed and the system will be compromised. This can result in sewage backup into homeowners’ basements, or water filling city streets because there is no capacity in the sewer. Flood waters are likely to containtrash and debris, which creates a risk of clogged pumps. Pumps of sufficient capacity are able to manage most solids without the threat of clogging. The 64 HD Series of ejector pumps by Zoeller Engineered Products, available from 25 horsepower to 60 horsepower, are specifically designed for better and more efficient management of large volumes of storm and wastewater. Pumps of this capacity are often used in municipal or commercial settings to pump sewage or stormwater from sewer

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Environmental Science & Engineering Magazine | June 2019