Lawmakers meet on sinkhole; edge collapses

Photo provided by the Assumption Parish Police Jury -- The slough-in, or edge collapse, is shown in this image marked in red. The red line in the photo attached depicts the area is swampland that sloughed in when the "burp" in the sinkhole happened early Sunday morning.

Louisiana lawmakers are meeting with state Department of Natural Resources officials, Texas Brine officials and others Monday, a day after another burp and edge collapse at the gradually growing sinkhole in northern Assumption Parish.

The burp and slough-in followed a period of increased seismic activity last week, parish officials said in a blog post.

The slough-in, or edge collapse, happened in swamps just west of a pipeline corridor that at one time formed part of the once-smaller sinkhole’s far western edge.

The sinkhole is believed to have been caused by the failure of a Texas Brine Co. LLC cavern in the Napoleonville Dome. Residents of the Bayou Corne and Grand Bayou communities near the sinkhole have been evacuated more than seven months.

The joint meeting of the state House and Senate Natural Resources and Environment committees was announced last week.

The burp was recorded shortly after 3 a.m. Sunday, surfacing oily hydrocarbons and debris from the 140-foot-deep sinkhole, which has had widely varying depths since it first emerged, parish officials said.

Parish officials noted that a similar period of an increased number of tremors preceded a belch on Jan. 19. The tremors and belch led to the closure of the failed cavern’s surface well pad after it began cracking and part of it sank about six inches.

Parish officials reported that DNR’s Office of Conservation’s contracted experts noted the deep tremors around the sinkhole and the failed cavern have subsided considerably since last week.

But shallow tremors remain, these experts said, probably indicating the sides of the sinkhole falling in and water movement in the sinkhole and below it.

Parish officials reported that the sinkhole continues to be monitored.

“And (the Office of) Conservation will advise the public of significant changes in subsurface conditions,” parish officials reported on the blog post.

State Office of Conservation officials, Texas Brine officials and experts have said the sinkhole is gradually finding a stable size and shape as the failed salt dome cavern, which had a sidewall collapse deep underground, fills with rock flowing in from outside the cavern.

Comments

1) Comment by zealer99 - 18/03/2013

I do not know much about the local soil conditions but I believe if I were a evacuated resident, living withing a few hundred feet of the sinkhole, and considering moving back home, I would wonder if the sinkhole was draining the shallow ground water. Subsidence and unstable soil conditions could be created if the sinkhole drains the shallow groundwater. The geology is over my head but I believe one of the major problems with coastal wetland loss is subsidence of the land as it squeezes out water and loses the buoyancy that the water gave the soil particles. Ground water drains slowly, so it might be quite some time before the subsidence is apparent, if it were to be a problem. It is also possible that this problem may not occur until there is a serious drought.

2) Comment by Mygulfbleedsforu - 18/03/2013

There was another article about the sinkhole on this site earlier today. I think your comment was on that article. You might still be able to see it if you take the "News" link above.

3) Comment by morellok2 - 18/03/2013

Funny how comments get deleted on this website. My previous post was asking if the "commission" finds that it is safe for residents to return will that bring their property values back up to presinkhole values???? Not likely. Also, will Texas Brine still have to go through with the buyout if it is deemed safe for them to return? Some of the folks may prefer to return but those wishing to be bought out should still have that option and Texas Brine should pay the presinkhole value.