More than 100 people were evacuated from a northwest Harris County office building right after the start of business Tuesday morning.
Workers on the third floor of the Harris County Appraisal District's office in the 13000 block of the Northwest Freeway complained about a foul odor around 9 a.m.
An email was sent out to workers shortly thereafter, explaining that the smell was coming from fire standpipes.
"The water's in there a long time, and when you go to drain it, it smells bad -- kind of like a sewer," building engineer Tony David said.
Engineers were working on draining the pipes as part of regular building maintenance.
Mainly workers on the building's third floor were affected, the building has seven floors. Authorities said they were not sure why the stench was so heavy on that particular floor.
"It started to smell almost like gas, almost like a chemical smell at first," said third-floor worker Kaleena Patrick, who was among the evacuees.
In all, nine employees left because they were sickened by the odor. One of those nine was taken to a nearby hospital with non-life-threatening injuries and the other eight were sent home for the day.
"The city's ordinance requires these standpipes be drained and inspected at least once a year, so this was a routine operation," said Jim Robinson, chief appraiser.
Robinson said maintenance like this will now take place on Saturdays, when the building is empty.