Dewatering a city the size of New Orleans was a Herculean task, but the bigger question was: How many buildings, such as the one pictured, could be restored?
Hurricane Katrina was one of the most destructive storms to hit the Gulf Coast in decades. Once the storm passed and the levees were patched, dewatering and cleanup began immediately. Areas of Louisiana, Mississippi, and southern Alabama were so devastated that it resulted in one of the largest disaster response mobilizations in the United States. Then, of course, came Hurricane Rita, which flooded parts of New Orleans all over again.

Dewatering a city the size of New Orleans was a Herculean task, but the bigger question was: How many buildings could be restored? In the hot and sticky climate of the Southeastern United States, mold is always an issue.

As was discovered, buildings that were submerged under water for two or more weeks not only had mold issues, but they also were potentially contaminated from all the pollutants that were in the water.

Even buildings that weren't flooded may still have problems, as many were without power for days or weeks, giving mold and mildew an ample opportunity to flourish in the non-air conditioned environment.

In truth, the cleanup still continues. In the end, portable air conditioning units, as well as portable desiccant dehumidifiers and fans, helped - and continue to help - the hardest-hit areas along the Gulf Coast to recover.

The catch to the Hurricane Katrina recovery was starting the cleanup and restoration process immediately after the water was pumped out of a home, because a submerged building deteriorates much less quickly than a previously submerged building. The home above, unfortunately, was unable to be saved.


It can be said that many of the commercial buildings in the New Orleans and surrounding areas sustained relatively minor damage compared to the residential areas.

John Bevington, president of ChillCo Inc. (Mandeville, La.), rode out Katrina in his home, noting ironically that it did get "a little breezy." His company, which services and rents chillers, is located 24 miles across Lake Pontchartrain from New Orleans. Once the storm abated, Bevington leaped into action, moving his rental equipment around the city in order to start drying out the buildings.

"The high-rise office buildings and hotels really only got two feet of water or less in their lobbies," recalled Bevington, referring to downtown New Orleans. "Some of them didn't even get that."

Unfortunately, many of the houses, though, sat in eight feet of water for almost three weeks, and they were destroyed.

"Proportionately speaking, the commercial buildings did pretty well," said Bevington.

There are three reasons why commercial buildings fared better than residential structures during the hurricane and subsequent floods, according to Dr. Michael Pinto, CEO of Wonder Makers Environmental (Kalamazoo, Mich.), and a member of the Association of Specialists in Cleaning and Restoration.

"First, they are usually built more substantially, so they lose windows and drywall, but they're built out of concrete and steel, so they're sturdier. Second, because they're commercial buildings, people put more importance on them in terms of trying to get them back up and running."

The third reason is that commercial buildings usually have more resources available to them, in terms of insurance and awareness. For example, many have contingency plans drawn up and contracts already in place, so they are ready for most emergencies that could come their way.

Nick Sickmen, marketing manager for Carrier Rental Systems (Houston), agreed, noting that his company had rental equipment in place at many locations two to three days before the storm.

"The companies that have plans in place beforehand know that generators, air conditioners, and drying equipment go fast. There's only so much of this equipment in the rental market," said Sickmen.


According to Pinto, if buildings aren't completely dried out before being restored, then long-term safety may be sacrificed for short-term gain.

"If they don't dehumidify and restore the buildings properly, and by that I mean dehumidify, physically remove all the porous material that has been impacted by the water including drywall, carpets, ceiling tiles, and then open up the wall cavities so they can properly clean and sanitize, then it's going to smell like a flooded building for decades."

Dehumidifying quickly - usually with portable desiccant dehumidifiers - was very important in these situations as mold grows in no time at all. In moldy areas, desiccant equipment was preferred, because it is designed to dry out a building in a more precision-controlled manner than other types of dehumidifiers.

"Typically a refrigerant-based dehumidification system can only get to about 45 percent relative humidity. With desiccant equipment, you can go much lower than that," said Oliver Stulz, vice president of sales, Stulz Air Technology Systems Inc. "Once you get below that point, that's where the desiccant starts to shine."

The damage that results from water is progressive, so the longer the wet conditions existed, the more that was absorbed and the greater the recovery problem. The first step was to get power to the building, and in New Orleans, this usually required generators, said Pat Rucker, president of Entech (Dallas). He said the standing water had to be pumped out. Drying equipment, air conditioning units, and fans then worked together to help the drying process.

It was tough knowing when a building was dry enough before beginning a restoration process. According to John Bergman, sales and marketing consultant for Des Champs Technologies, if mold had started, it could go into remission when the relative humidity was reduced below about 60 percent. However, it could regrow and give off spores if the humidity was allowed to rise again.

"It's the spores of mold that cause the respiratory problems and bring on the lawsuits," said Bergman.

According to Mickey Lee, vice president, Global Technology, Munters - MCS Division (Glendale Heights, Ill.), the drying contractor had to first decide which building materials to remove and replace, and which could be dried. For example, highly porous materials that absorbed contaminated water were normally removed and replaced, rather than dried.

After the restorative drying effort started, the contractor had to demonstrate a familiarity with moisture-measuring instruments, which were used to test the affected materials for moisture content.

Lee added that the contractor had to monitor how dry the building was by determining the pre-loss moisture contents of the gypsum board, wood floors, and other building materials; by frequently monitoring the moisture in the building materials to track their drying progress; and by monitoring daily the conditions of the air inside the water-damaged areas, as well as the status of the building's HVAC system.

According to Lee, drying was usually considered to be sufficient when the interior ambient conditions were at or better than normal room conditions (e.g., the building's HVAC was able to maintain the proper ambient conditions), and the moisture on and in the building materials themselves did not support active microbial growth.

The catch was starting the cleanup and restoration process immediately after the water was pumped out, because a submerged building deteriorates much less quickly than a previously submerged building. That's why many of the restoration companies responded so rapidly after Hurricane Katrina passed. "There's a window of opportunity, and if they can get in there during the window, they can fix a lot of problems before they actually happen," said Sickmen.

Publication date: 07/10/2006