The Explosive Effects of Severe Thunderstorms on Underground Utility Vaults / Networks

Everyone is familiar with the old adage “April showers bring May flowers,” but here’s one you probably haven’t heard: “April Showers brings lack of power.” Confused? We’ll explain.

In Louisville, KY, where our corporate office is located, we’ve had record rainfall totals during the month of April. On Friday, April 3, 5.57 inches of rain and stormwater was reported at Louisville International Airport, destroying the old all-time April daily rainfall record of 4.08 inches, recorded nearly 45 years ago on April 1, 1970. The slow-moving storm system delivered a two-day rainfall total of nearly 7 inches of stormwater.

As water continued to pile up on roadways around Louisville, many drivers disregarded barriers and drove into the water on April 3, 2015. (Photo credit: WDRB)
As water continued to pile up on roadways around Louisville, many drivers disregarded barriers and drove into the water on April 3, 2015. (Photo credit: WDRB)

As to be expected, such a massive amount of rain and stormwater in such a short period of time caused a number of flash flooding incidents, which led to road closures, detours and accidents, school closures and delays, mudslides, and millions of dollars of damage. At least one flood-related death was reported.

To make matters worse for Kentuckiana, another severe storm system worked its way into the area the following week and caused additional flooding and damage. Though the second system didn’t “bring the thunder” as fiercely as the Good Friday downpour, its long-term effects may have a greater impact, especially if it steals the Thunder … as in Thunder Over Louisville, scheduled for Saturday, April 16, 2015.


A Spectacular Fireworks Extravaganza

Thunder Over Louisville 2014 (Photo credit: Jacob Zimmer, Courier-Journal)
Thunder Over Louisville 2014 (Photo credit: Jacob Zimmer, Courier-Journal)

For those who may not be familiar, Thunder Over Louisville is an annual fireworks show over the Ohio River in downtown Louisville that serves as the official kick-off to the Kentucky Derby Festival. Over the last 26 years, it has wowed and impressed as one of North America’s largest pyrotechnic celebrations, coordinated by Zambelli Fireworks Internationale, who launch the fireworks from eight 400-foot barges as well as off of the Clark Memorial Bridge. Producing the single day event costs more than a million dollars, and requires months of preparation as well as more than 2,000 people working the day of the event. An Air Show featuring popular military aircraft always occurs during the afternoon.

The economic impact of Thunder in the Louisville area cannot be understated. A 2011 study initiated by the Derby Festival concluded the event generated more than $56 million for the local economy! That may sound like a huge amount of revenue for one day, but the sheer volume of people in attendance each year support the claim. Since 1997, an average of 625,000 people annually have attended, many lining the banks of the Ohio River in Louisville, and in Jeffersonville and Clarksville, Indiana.

Half of the Great Lawn will be under water for Thunder Over Louisville. (Source: Katie Bauer, WAVE 3 New
Half of the Great Lawn will be under water for Thunder Over Louisville. (Source: Katie Bauer, WAVE 3 News

For the 2015 show, this may be a problem due to the enormous amount of stormwater. The swelling Ohio River is creeping onto the Great Lawn, the show’s most popular viewing area. At least half of the Great Lawn will be underwater, and the NWS river forecast for downtown Louisville on Saturday is 23.9, nearly a foot over flood stage!

Thunder Down Under…more specifically, Utility Vaults

Though annoying, stormwater intrusion following large-scale flooding is often inevitable, no matter what activity it is disrupting. Whether its Thunder Over Louisville attendees forced to watch the show from a new location, or underground utility workers forced to perform unscheduled maintenance on a malfunctioning or clogged vault pump, the effects of the storm are felt long after the clouds have dissipated. That’s the way extreme weather situations play out. But while it’s difficult to prepare for the immediate devastation of a flash flood, hurricane or tornado, there are tools available to help prepare for the aftermath, at least when it comes to mitigating the damage that water intrusion can inflict upon underground electrical equipment.

Dan Koons, one of our experienced field agents, has spent some time over the last few years in the murky bellies of utility vaults. “Most below-grade utility vaults house some sort of energized equipment,” he says, “and where there is energized equipment, there will most definitely be pumps.” It’s vital to protect these transformers and cables to avoid outages or even explosions, especially during the winter months or in coastal cities. Not only are they thunderous enough to rattle windows of office buildings and set up car alarms for blocks, the explosions are also very dangerous, and burn at extremely hot temperatures while emitting thick black or brown smoke.

An exploding transformer in New York City neighborhood of Chelsea
An exploding transformer in New York City neighborhood of Chelsea

What makes a transformer explode during a storm? The Slate Explainer tackled this question very well in the aftermath of Hurricane Sandy’s assault on Manhattan several years ago:

“By degrading the insulation. Electrical transformers are composed of a series of coiled electrical wires. The wires are sheathed in paper-based insulation, which prevents electricity from jumping across wires within the coil. Over the course of 20 to 60 years, depending on how hard the apparatus is made to work, the insulation in a well-maintained transformer degrades from 1,200 molecules thick to 200 molecules thick, at which point the coils should be replaced. Water accelerates that degradation process immensely. When the insulation fails, parts of the coil touch, causing a “turn-to-turn fault”—a form of short-circuit that creates a spark inside the transformer. The spark ignites the oil surrounding the coils, and the resulting explosion can be massive, as video from Monday night’s failure demonstrates.”

Unfortunately for the Big Apple, transformer fires or explosions aren’t limited to storm events. According to New York’s main utility ConEd, the city experiences more than 2,000 manhole/vault incidents per year, or nearly six a day.

In situations where there is flooding or heavy precipitation, the surface water is going to flow wherever it can, picking up leaves, trash, debris and muck along the way. Much of it will flow into the storm drain and eventually end up in the river. “What doesn’t go into the storm drains will go into any other opening it finds, like grates on sidewalks, which in most cities are substation vaults with transformers in them,” says Koons. “There are hundreds of thousands of volts of electricity in the substations. If water gets to the equipment, it can blow up.”

Just like a sump pump works overtime during heavy rains to prevent your basement from flooding, the vault pump should be able to evacuate the wastewater before it comes in contact with the transformer. But what about all the “gunk and junk” the flowing water picked up along its route? The unsolicited entourage of trash, leaves, mud, and other debris have the potential to crash the party by slowing, clogging or even stopping the pump flow.

Get Pumped About Utility Vault Protection

Here’s where we can help. Our innovative line of Utility Vault Sump Filters were designed to accommodate and PROTECT any pump from a number of common underground network challenges, including trash buildup, sediment, debris, oil and sheen. The Vault Sump Filter Systems are available in round and square panel configurations and can be custom-made to meet your site-specific needs. Standard square panels consist of four 1’ x 2’ panels. Complete Vault Sump Filter Systems include Vault Sump Filter Housing Plus Debris Filter and Agent-Q Oil and Sheen Filter.


In case you don’t need all levels of protection, filter components are also available separately. The Filter Housing is constructed of strong white perforated polypropylene, 0.125 gauge, with 3175 micron holes on 3/16” centers. It doesn’t absorb moisture and is resistant to chemicals and corrosion.


The Debris and Silt Filter would likely be most beneficial to have in use prior to a flood or water intrusion situation. Durable, washable and reusable, it is composed of a white Nylon Monofilament Mesh fabric that filters to 100 micron – about the thickness of one human hair.


If your goal is to keep contaminated water from draining into the storm sewer (or at least avoid unwanted EPA fines), check out the Agent-Q Oil and Sheen Filter. It consists of Agent-Q, a patented, state-of-the-art filtration media to protect pumps from oil and sheen (U.S. Patent No. 8,986,822). Agent-Q has one to four layers of fabric which contain, in sonic bonded quilted diamonds, at least 350 grams per m2 of C.I.Agent Solidifying Polymers.


Gotta see it to believe it? Watch this short animation to see how our filters can protect the pumps in all your underground utility pumps!

The effects of extreme weather may be able to disrupt our plans, but we’re doing our best to ensure it doesn’t disrupt the underground power networks in our own city across the country. Because in the end, flowers really are the only effect we want to experience from all those April showers. Well, that and explosions, but only in the form of fireworks bursting over the Ohio River during Thunder Over Louisville!


Want technical spec sheets on all of our Utility Vault and Manhole Maintenance Solutions?
Click here to download Vault Sump Filters Technical Data sheet
Click here to download Vault & Manhole Dewatering Technical Data sheet


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