A problem at the Allentown wastewater treatment plant is causing a “rotten egg” smell.

• Allentown’s wastewater treatment plant is having problems
• The accumulation of solid waste caused the unpleasant odor to spread to the city
• The repair may take two weeks

ALLENTOWN, Pa. — An “operational issue” at the city’s wastewater treatment plant has caused a foul odor.
“The (Lehigh County Authority) apologizes for the unpleasant sewer odors that some residents in Allentown may notice over the next two weeks while this work is completed,” according to a news release from the agency on Friday.

“The smell of sewage can be described as an ‘earthy’ or ‘rotten egg’ smell but it is not harmful to human health.”

Over the past few weeks, there has been a buildup of excess solids at the Klein Island Wastewater Treatment Plant on Union Street, according to the release. The odor emanating from the plant, which processes more than 30 million gallons of wastewater daily from city customers and more than a dozen other surrounding communities, could get worse.

“Solids are a natural byproduct of the wastewater treatment process, where solids and organic matter are separated from the water,” officials said. “The solids are typically ‘digested’ through biological processes in the plant, and the remaining materials are used as fertilizer in agricultural fields or disposed of in a landfill.”

However, over the past few weeks, plant employees have noticed “accumulation of solids in the plant that has disrupted the normal curing process, resulting in some odor complaints from customers in the vicinity of the plant,” according to the release.

While a buildup of solids can be normal, a mechanical problem last month at the LCA industrial processing plant in Vogelsville sent a higher-than-normal load of solids to Allentown, officials said. In general, solids will be removed at the plant in Vogelsville and will not affect the plant in Allentown.

At Kleins Island, staff will “manually remove excess solids and optimize treatment performance.” The mechanical issue is also being addressed at the Vogelsville plant.

“This work is expected to begin on Saturday and continue for approximately two weeks,” officials said. “During the cleanup process, LCA expects sewer odors to be more noticeable in some locations close to the plant.

“Extremely hot and humid weather can exacerbate odor problems.”

More information can be found on the Authority’s website.