Tremors increasing at massive 13-acre Louisiana
sinkhole
The
head of Louisiana’s Department of Natural Resources named 13
scientists and other experts Friday to serve on a blue-ribbon
commission tasked with determining the long-term stability of the
area around northern Assumption Parish’s sinkhole
.
The
13-acre sinkhole and consequences of its emergence and continued
growth, such as methane trapped under the Bayou Corne area, have
forced the evacuation of 350 residents for more than seven months.
The
sinkhole, found in swamps between Bayou Corne and Grand Bayou on Aug.
3, is believed to have been caused by a failed Texas Brine Co. LLC
cavern mined into the Napoleonville Dome.
Members
of the new panel are being asked to set up scientifically based
benchmarks in regard to the sinkhole and then determine when they
have been met in order to give assurances that the Bayou Corne area
is safe for the return of evacuated residents.
“The
work of this commission is crucial to the future of public safety in
the Bayou Corne area,” DNR Secretary Stephen Chustz said in a
prepared statement announcing the 13 appointments.
“We
must ensure we have done all that we can to get the right people to
provide the right answers in making recommendations for the future of
the people who want to return,” Chustz said.
The
secretary made the appointments in consultation with Jim Welsh, state
Commissioner of Conservation, and Kevin Davis, director of the
Governor’s Office of Homeland Security and Emergency Preparedness,
the statement says. The Office of Conservation is part of DNR.
Gov.
Bobby Jindal called for formation of the commission earlier this
month after meeting with Assumption Parish public officials and Texas
Brine executives about the sinkhole.
DNR
officials said in a statement that the blue-ribbon commission’s
first meeting will be held in early April. Patrick Courreges, DNR
spokesman, has said some of the group’s meetings would be public,
but it was not clear Friday if the panel’s inaugural session would
be open to the public or not.
Underscoring
the lingering concerns about the growing sinkhole and when it may
stabilize, yet another round of seismic activity forced parish
officials to halt work around the sinkhole Friday morning for the
second time in a little more than a week, officials said.
John
Boudreaux, Assumption Parish’s director of Homeland Security and
Emergency Preparedness, said the seismic activity was detected about
7 a.m. Friday under the sinkhole and the failed Texas Brine cavern.
Seismic
monitors detected an increase Friday in the “very long period”
tremors that scientists have said indicate fluid and gas movement
below the sinkhole, parish officials said in a blog post.
Parish
officials added that Friday’s seismic activity was limited to the
sinkhole and the Texas Brine cavern. The activity appears to have had
no effect on a second Texas Brine cavern nearby for which structural
concerns recently have been raised, parish officials said.
Water
movement in the sinkhole and increased bubbling along its western
edge were also detected Friday, the post says.
Boudreaux
said work was stopped within the 71-acre area surrounded by a berm
mandated to encircle the sinkhole. The shutdown area took in the
sinkhole’s lake-like surface.
He
said crews had been working on oil retardant boom on the sinkhole at
the time the work was stopped about 8:30 a.m. Friday.
But
he said work related to 3-D seismic surveying of the subsurface —
which involves the firing of small, buried explosive charges —
continued Friday because it is outside the berm area.
The
new blue-ribbon panel members include some of the experts who already
have been working on the sinkhole under contract to the state Office
of Conservation or on a scientific working group monitoring the
sinkhole.
Members
Gary Hecox, senior CB&I hydrogeologist, and Will Pettitt, an
Itasca Group rock mechanic expert, both have delivered presentations
to residents and the state Legislature about the sinkhole.
Working
group members include David Borns, Sandia National Laboratories
Geotechnology and Engineering Program manager, and Thomas Van
Biersel, DNR hydrogeologist and a former Louisiana Geological Survey
professor at LSU. Van Biersel is coordinating the sinkhole working
group, DNR officials said.
Sandia
researches salt domes for the federal Strategic Petroleum Reserve,
which stores the nation’s emergency supply of crude oil in
Louisiana and Texas salt domes.
Chustz
said in the statement Friday that while experts around the world were
sought, the panel includes scientists who already have been working
on the sinkhole as well as a Bayou Corne-area resident selected, “to
ensure that the members share our sense of urgency.”
Before
Friday’s work stoppage, a burst of early morning tremors on March
13 caused work to be halted for about a day inside the same berm
area.
That
halt was followed by one of the sinkhole’s periodic burps on Sunday
morning, when oil and debris surfaced, as well as the collapse of
0.95 of an acre of land on the sinkhole’s western edge.
The
sinkhole’s surface is believed to be about 13 acres in size with
the addition of that last slough-in and with a re-estimation of the
sinkhole’s remaining edge, which added a few acres of surface also.
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