Nalco Plant, W.A. Parish Generating Station Both Report Air Pollution Incidents

Two Fort Bend County industrial plants reported unusual discharges of air pollution last week, according to the Texas Commission on Environmental Quality.

Nalco Holding Co.’s Sugar Land plant, on U.S. 90A near State Highway 6, reported that the liner inside a storage tank caught fire on Thursday during a “welding project” on the “man way” of the tank.

The resulting fire created a “smoke cloud” for no longer than five minutes, the company reported to TCEQ.

Nalco officials told the state agency the company’s emergency response team immediately put fire water monitors on the tank to initiate cooling. The water kept smoke from escaping out the top of the tank, and limited the length of the event.

Nalco said the site doesn’t have a “certified opacity reader,” so it was unable to determine “opacity percent” during the emissions discharge.

Industrial plants such as Nalco’s must obtain permits to discharge air contaminants. If more contaminants are discharged into the air than allowed under the permits, such discharges must be reported to the state, and are known as emmission events.

Nalco told TCEQ that while the “actual opacity percent” of the event isn’t known, “Nalco did not violate the 6-minute time duration for opacity event because the fire water monitors suppressed the smoke that was coming from inside the tank, and also the fire was contained to the inside of the vessel.

Meanwhile, the 610-megawatt Unit 6 at the W.A. Parish Electric Generating Station near Thompsons discharged opacity emissions for 18 minutes on May 25, at up to 93% opacity. The unit’s permit allows for 10% opacity.

The company said the event occurred “due to differential pressure increased above the set point that inadvertently bypass the opacity emission control system baghouse. The baghouse was manually put back in service.

The incident marks the fifth emission event reported by the generating station since April 11.

One of those events, on April 19, occurred at the plant’s Unit 8. The other three – on April 11, 22 and 26, occurred at the station’s 649-megawatt coal-fired Unit 5.

The 3,565,000-kilowatt generating station, which operates four natural gas-fired electricity generating units and four coal units, is one of the largest power plants in the U.S.

In Oct. 2005, NRG Energy bought out the plant’s owner, Texas Genco LLC, in a $5.8 billion transaction that gave it ownership of W.A. Parish, among other plants.