http://theadvocate.com/news/3703961-123/sinkhole-drillers-halt-to-insert
Sinkhole drillers halt to insert pipe casing
Group asks residents to keep odor, health log
Texas Brine Co. drillers reached an expected stopping point at a depth of 600 feet Wednesday in their around-the-clock push to peer inside an underground cavern that may have failed and caused a sinkhole to surface in Assumption Parish swamps, company officials said.
Halted about two-thirds of the way into the solid, 325-foot-thick caprock overlying the salt dome deposit that contains the cavern, workers with Riceland Drilling Co., of Lafayette, prepared the bore Wednesday to receive metal casing to support the well, the officials said.
“It may be tomorrow some time or later before they insert the casing,” said Sonny Cranch, spokesman for Texas Brine, of Houston, on Wednesday.
The well stopped about 100 feet from the top of the Napoleonville Dome, from which Texas Brine had hollowed out the underground cavern that is the focus of attention from regulators as well as the residents evacuated since Aug. 3.
The sinkhole swallowed up swamp between the Bayou Corne and Grand Bayou areas south of La. 70 South. It was found early Aug. 3.
The Louisiana Department of Natural Resources has ordered Texas Brine to drill the observational well to see what is happening inside the cavern.
DNR scientists think the cavern failed, released its brine contents and caused the sinkhole.
Cranch said that once the hollow, 16-inch-diameter casing pipe is set into the hole, it will be cemented in place, then workers will wait on the cement to cure before they push farther underground.
The drillers plan to drill to a point 400 feet above the cavern roof, which is 3,400 feet below the surface of the Earth, stop, then drive into the cavern.
Once the well is finished, diagnostic equipment will be inserted into the bore and used to inspect and investigate the interior of the cavern.
Updated dimensions of the sinkhole were not available Wednesday.
Estimates from Aug. 15, before parts of the sinkhole’s rim collapsed last week, had the hole 640 feet at its widest and 295 feet at its narrowest, parish officials have said.
In other developments, the Louisiana Environmental Action Network, a Baton Rouge environmental group, has asked Bayou Corne-area residents to log odors and any health symptoms that they feel as a result of the odors.
In two statements released Tuesday, LEAN noted air monitoring by the Louisiana Department of Environmental Quality since Aug. 4 over the sinkhole and in the neighborhoods near the sinkhole had picked up, depending on the location, benzene, toluene, ethylbenzene, other volatile organic compounds and components of natural gas.
Benzene is a known carcinogen.
LEAN also said the levels of those chemicals are below Louisiana ambient air standards, which mark a threshold for health risks.
Officials with DEQ and the state Department of Health and Hospitals have repeatedly said the samples of air from the area show there is not a health risk. DHH officials have been monitoring DEQ samples.
“To date, for the chemical analyses reviewed, the results are not at levels for possible health effects or no completed chemical exposure pathway to the general public has been identified,” said J.T. Lane, DHH Office of Public Health assistant secretary, in an emailed statement Wednesday.
Lane did say the agency encourages residents to follow evacuation orders, avoid restricted areas and discuss health concerns with their doctors.
LEAN group is concerned about the cumulative impact of all the chemicals in air together over time and developed the odor and symptom log as a way to track it, according to Wilma Subra, an environmental chemist who provides technical assistance to LEAN.
She said residents have already reported headaches and respiratory problems.
Copies of the log form are available at http://leanweb.org/odor-and-symptom-log. They can be mailed to LEAN, P.O. Box 66323, Baton Rouge, LA 70896.
Air standards have been set conservatively and factor in the cumulative impact of multiple chemicals in the air, said Tim Knight, DEQ Assessment Division administrator.
“They take that into account when they set the number,” Knight said.
He said air has been sampled from in front of more than 95 private homes.
In addition, DEQ’s Mobile Air Monitoring Lab has been at the Bayou Corne command post. The lab monitors the air.
It had tested 26 separate samples from in front of area homes through Aug. 20, DEQ officials said in a statement.
Maximum concentrations from the 26 samples are far below ambient standards and comparable with statewide monitoring, officials said.
The lab itself picked up slightly higher levels of methane and non-methane organic compounds but they are not toxic.
Texas Brine also announced it would start its own voluntary air monitoring of homes within five miles of the sinkhole site.
Texas Brine has hired Sage Environmental Services. Monitoring will be conducted twice a week with hand-held devices on public roads in front of each residence, Texas Brine officials said.
The Napoleonville Salt Dome, one of many large underground salt formations along the Gulf Coast, was pushed up vertically from ancient sea beds and, for decades, industry has used the dome for brine production. The perimeter also has been the focus of intensive oil and gas exploration.
Hollowed from the solid salt formation, caverns left by brine production are often used for storage of natural gas, butane and other hydrocarbons. Brine is used for several industrial processes.
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