Washington (CNN)There was a plant and a cover-up Tuesday at the White House.
The sinkhole steps from the briefing room on the North Lawn was filled in with concrete, the surrounding area covered with dirt and a fresh layer of sod.
The sinkhole, which was first spotted a week ago Saturday following days of heavy rainfall, became a social media sensation, but the first family, staff, reporters and visitors to White House grounds were never in any immediate danger.
"On Friday, May 25, crews excavated an area around the small sinkhole on the north White House grounds. We found an underground void about six to eight inches in diameter, which was likely caused by recent heavy rains that eroded the soil," park service spokeswoman Jenny Anzelmo-Sarles said in a statement Friday evening. "In the coming days, we will plug the void with concrete, fill in the excavated area with gravel and soil, and resod. The excavation confirmed that the sinkhole, which did not grow larger since it was first noticed on May 20, does not pose a risk to the White House."
Workers dug a nearly waist-deep hole Friday afternoon. The perimeter around the sinkhole, two traffic cones with some caution tape, was expanded to a larger enclosure with orange safety fencing over the weekend. But after more work in the area on Tuesday, the only evidence of the sinkhole was four short wooden posts and a rectangle of slightly greener grass.
"Sinkholes are common occurrences following heavy rain," the park service noted.
The geology of the White House doesn't naturally lend itself to sinkholes, said expert Terry West, a professor of earth, atmospheric and planetary sciences and civil engineering at Purdue University.
Most sinkholes, West told CNN, form from cavities in underground limestone, but "the geology at the White House is really not that type at all. It's more of a sandy clay material that is remnant from when the oceans were at a higher elevation."
West suspects the sinkhole resulted from previous construction on the lawn. This particular stretch of grass has had its share of disruption over the years; during the Obama administration, the lawn was excavated and under construction for months.
"It would seem to be a sinkhole that would come about by an underground collapse of some sort, would be my best guess. It could be some construction debris that was not very highly compacted and has now begun to settle and fill in with soil around it, but it looks like it'd be more related to man-made activities than to natural causes," West said.
It could also be the result of a leaky water pipe that caused erosion, West said. There is an in-ground irrigation system on the lawn to keep the grass green.