Damndrugtest
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Sep-12-2003
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Message #174715 posted by Damndrugtest (Info) May 08, 2008 16:27:28 ET
But a very interesting one. I'd heard of sinkholes before but had never actually seen one. This one happened yesterday and hasn't stopped growing. Geologist have been brought in and are saying it's the biggest they've ever seen.
http://www.chron.com/disp/story.mpl/front/5761654.html
DAISETTA — The nervous vigil at a huge sinkhole that mysteriously opened in this Liberty County town on Wednesday -- and grew rapidly throughout the day -- is continuing early today as county officials hand off oversight of the emergency to the Texas Railroad Commission.
The sinkhole, which appeared near the center of Daisetta on Wednesday morning and grew to four football fields in diameter and 200 feet deep by nightfall, did not grow severely during the night and no evacuations have yet been ordered, a Liberty County sheriff's official said today.
Still, authorities are preparing to act quickly if the sinkhole should resume its stunning expansion from Wednesday, when it swallowed trees, telephone poles, storage tanks, oil field equipment, a tractor and the cab of an 18-wheeler.
With the arrival of daylight, said sheriff's Cpl. Hugh Bishop, authorities can tell the sinkhole grew somewhat during the night, but at a slower rate. No injuries have been reported.
Bishop estimated the sinkhole's size now at 600 yards wide and 200 feet deep.
"There are signs it's slowing down, but it's a nature thing. We don't know what to expect," he said.
Bishop also said officials with the Railroad Commission and a geologist are on site to determine the cause of the sinkhole. One possibility is that it resulted from the collapse of one of the many salt domes in this region.
The good news, Bishop said, is that the crater is not growing eastward toward FM 770, the main road through Daisetta. It seems to be expanding toward the southwest and north, he said.
The sinkhole is near the intersection of FM 770 and FM 834 on the north side of town.
The next likely victim if it continues growing appears to be a maintenance shed on the Deloach Vacuum Disposal Co. property.
"The building is on the edge," Bishop said.
The sinkhole announced itself about 10 a.m. Wednesday as ground that had been "flat as a pancake" began to collapse, said Tom Branch, the county's emergency management coordinator.
Sometimes as much as 20 feet an hour would vanish into the growing pit.
Lester Edwards, Liberty County's hazardous materials coordinator, said nobody knows how big the hole may get or when it will stop growing. He said all authorities can do is monitor the pit and keep people from danger.
By nightfall, the hole was located on the property belonging to the Deloach Vacuum Disposal Co., but only a block from the town's fire station and Hull-Daisetta High School.
Officials for Deloach, a saltwater disposal company, could not be reached for comment.
In 1981 a smaller sinkhole developed on the opposite side of town. That one appeared overnight and grew to 250 feet wide and 30 feet deep. It expanded from a much smaller sinkhole that appeared in 1969 and was on Gulf Oil Corp. property near a salt water disposal well.
The new sinkhole formed near another salt water disposal well owned by Deloach.
Daisetta sits above a salt dome. Salt water separated from crude oil taken from production wells is often disposed of in wells in the dome.
Mary McCann, whose husband, Harold, was the town's mayor when the last sinkhole formed, lives near the new one.
She said Deloach workers were injecting salt water into the well "when the ground started separating and everybody ran like devils." She said the workers ran to FM 770 and stood watching the phenomenon.
As to what's causing it, "I wish the heck I knew," McCann said, but she said she suspects the salt water well was at fault.
"I think we're in jeopardy. This property is our life's savings. We're old people," said McCann, who is 80.
Power precautions
Entergy, the power company, was called to the scene early Wednesday to cut electric lines to Deloach as the hole sucked down utility poles. The move was made to prevent power from being cut off in the town of 1,200.
Sunoco, a leading manufacturer and marketer of petroleum and petrochemical products, secured two 6-inch crude oil pipelines near the sinkhole that were starting to leak, Edwards said.
Ramona Nye, spokeswoman for the Texas Railroad Commission, said the owners of two crude-oil gathering pipe systems and one natural-gas gathering system in the area were warned to keep close watch for potential damage. She said none had experienced any damage so far.
Railroad Commission investigators were monitoring the site and checking pipelines in the vicinity while Texas Natural Resources and Conservation officials were monitoring air and water quality. No pollutants had been detected.
A mile south of the site, an old abandoned oil well began gushing massive amounts of salt water Wednesday. Nye said, "So far we don't think it's related."
May take weeks to stabilize
When spectators stood on the edge of the sinkhole they didn't have to wait long to see something happen. The hole was surrounded by giant growing cracks that extended several hundred yards in concentric circles.
Without warning, dark, oily water in the bottom of the hole began to churn and whirl and then chunks of earth fell from the walls. Equipment, tanks and sheds slid with the dirt and disappeared into the hole.
Sometimes water poured from a nearby lake into the growing hole.
Geoffrey Paine, a geologist and geophysicist with the University of Texas, said sinkholes are rare and generally form in areas where underground salt or limestone formations are dissolved by water and allow the surface to collapse.
"It's not something easily predicted, but we do know where the salt domes are," he said. He said water can leak into the formation through drill holes, disposal wells, oil production wells or water wells.
"Sometimes areas that have been drilled over the years can allow water to dissolve the salt to create voids that collapse from the materials above it," he said.
It often takes up to two weeks for the hole to stabilize, Paine said.
Oil has been produced in the area since 1918, according to the Handbook of Texas. Although most of the old wells have long since been abandoned, some oil and gas is still produced.
The 1981 sinkhole became a lake, McCann said. "It sealed itself," she said.
The current mayor, Lynn Wells, filled most of the earlier hole with dirt and built a house on it. He said he's not seen any problems on his property since the new sinkhole began forming about 500 yards away.
Investigators will continue to monitor the situation and try to determine whether any regulations have been violated, Nye said.
"We don't know what's going to happen," Wells said. "We just have to monitor things and make sure everybody is safe."
DDT
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