9:25 p.m. Advisory from the Office of Conservation

The Office of Conservation, in consultation with Assumption Parish Incident Command, is advising the public that Texas Brine is preparing to re-route the western wall of the sinkhole containment berm further west, and extend the northern and southern berm walls accordingly, due to ongoing surface subsidence in a portion of the existing western berm wall. While the sinkhole’s western boundary remains more than 100 feet away from the existing western berm wall, ongoing filling of the failed Texas Brine Oxy 3 cavern and compaction of the disturbed rock zone surrounding the sinkhole have created an area of surface subsidence outside the sinkhole boundary. The current western wall siting was chosen in order to make use of an already existing well access road to more quickly provide containment around the sinkhole, and Texas Brine will continue to use fill material to maintain the existing western wall until containment is established with the new route. In addition, the currently existing berm will be partially maintained following construction of the new containment route in order to provide access to the vent wells and monitoring wells installed along the original western berm. The Office of Conservation and Assumption Parish Incident Command are continuing to monitor developments in the area to ensure all necessary steps are taken to protect public safety and the environment.

6:50 p.m. 3D Seismic Data

The Office of Conservation, in consultation with Assumption Parish Incident Command, is advising the public that Texas Brine has submitted a report detailing its consultant’s interpretation of the results of the 3D seismic survey of the Oxy Geismar 3/Bayou Corne area. The Office of Conservation, in its Jan. 14, 2013 directive to Texas Brine, required the company to conduct the 3D seismic survey and provide the results to Conservation and Assumption Parish Incident Command. The Office of Conservation and its contracted experts have begun review of the report and interpretation initially provided. Conservation staff considers the report, and the assertions of Texas Brine and its consultant on that report, to be preliminary only at this point, pending independent verification and analysis by Conservation’s consultants. Though that analysis and review has not yet been conducted, the Office of Conservation, in the interest of keeping the public informed, is providing the report for viewing at http://dnr.louisiana.gov/index.cfm?md=pagebuilder&tmp=home&pid=939&pnid=0&nid=172.

Also Texas Brine Contractor has indicated that the shallow gas aquifer data has not been completed and were unsure when an interpretation would be available for review. We will make their interpretation available as soon as it has been presented.

1:50 p.m. Advisory from the Office of Conservation

The Office of Conservation, in consultation with Assumption Parish Incident Command, is advising the public that the Oxy 3/sinkhole monitoring alert status has been raised to Code 3 – requiring all work inside and around the sinkhole to cease until further notice. Per Dr. Stephen Horton with USGS, seismic monitoring detected several instances of subsurface activity in the area around the sinkhole and Oxy 3 area below the sinkhole, at an estimated rate of more than 10 VLPs (Very Long Profile seismic signals, often indicative of gas or fluid movement) in the early hours of Sunday morning, and personnel near the site have observed surface movement on the western side of the sinkhole area. The seismic activity is limited to the Oxy 3/sinkhole area, showing no indication of impact to the Oxy 1 area. Monitoring is constantly ongoing in the area and Conservation will advise the public of significant changes in subsurface conditions.

12:05 p.m. Advisory from the Office of Conservation

The Office of Conservation, in consultation with Assumption Parish Incident Command, is advising the public that the Oxy 3/sinkhole monitoring alert status has been lowered to Code 1 – allowing work in the sinkhole area within the containment berm. Per Dr. Stephen Horton with USGS, seismic monitoring has detected an decreasing trend of subsurface activity in the area around the sinkhole and Oxy 3 area below the sinkhole over the past few days. Seismic analysts are also advising members of the public following the seismic monitoring data online that the “LA 10” monitor has been picking up echoes of yesterday’s Pacific Ocean 7.2-magnitude earthquake that occurred off the coast of Japan, but these signals do not indicate any impact to subsurface stability in the Bayou Corne area. Monitoring is constantly ongoing in the area and Conservation will advise the public of significant changes in subsurface conditions.

8:30 a.m. Burp & Slough-In, 04/18/2013

There was a “burp” within the sinkhole this morning as well as a slough in on the east side (of which measurements are not yet available). Water in the sinkhole continues to move which is an indication that this event is not over.

The installation of the seismic equipment and implementation of the code system are essential in indicating that events like this will happen before they actually do. Over the last three days, the seismic equipment used in the monitoring process showed signs that prompted officials to heighten the code level in the sinkhole to Code 3 (explanation below). Dr. Horton and Dr. Hecox, both diligently observing the monitoring process, were able to raise the code level in prediction of such an event as this.

Code 1: Minimal to no seismic activity around/below sinkhole; 10 or fewer of the sharp seismic signals associated with rock movement, called mini-earthquakes (MEQs) or the longer signals associated with gas or liquid movement, called Very Long Periods (VLPs) within 24-hour period; allows work on sinkhole and inside berm area to continue

Code 2: Restricts work directly on the sinkhole, indicates some increased seismic activity around/below sinkhole but not at a level that indicates imminent threat of sloughing or movement below sinkhole (10 to 50 MEQs or VLPs in 24 hours)

Code 3: Restricts all work inside the containment berm, indicates seismic activity has elevated to a point similar to what has been seen in past monitoring prior to a sloughing on the shore or movement beneath sinkhole (More than 50 MEQs or VLPs in 24 hours)