"BP has asked the U.S. Coast Guard to allow it to abandon a containment dome on the bottom of the Gulf of Mexico that it capped and plugged this week after concluding it was the source of oil causing repeated sheens near the site of the company's failed Macondo well. The request was included in an exchange of e-mail messages on Sunday and Monday between James Grant, BP's Gulf regulatory compliance and environmental manager, and Coast Guard Federal On-Scene Coordinator Capt. Duke Walker. The email messages were obtained by The Times-Picayune.
The containment dome, which BP calls a cofferdam, was used in a failed attempt to capture oil spewing from the failed BP well after the explosion and sinking of the Deepwater Horizon drilling rig above it."
The cofferdam is a metal box! Not a well. Well's are plugged and abandoned. Because it is possible to plug a well and leave the seafloor close to it's original condition. The whole reason for the cofferdam's existence was to "hold oil". The fact that BP is asking to "plug and abandon" this think that is known to leak show that BP has learned NOTHING! This metal box will, over time, leak. . They might have to "abandon it" meaning not raise it to the surface today. But BP can not "abandon it" or the responsibilities associated with it and "walk away"! BP owns the monitoring on this "box" for the lifetime of the box or until they can suck the oil from it (not likely).
"A mixture of oil and slushy methane hydrate -- a frozen form of natural gas -- is believed to have plugged the exit leading to the stovepipe at the top of the dome during the oil collection attempt. Some of the oil and frozen methane are believed to remain in the structure.
" 'BP continues to believe that abandonment of the cofferdam in place is the best course of action and presents fewer environmental and safety risks than attempting to recover it,' Grant wrote in an email message to Walker on Sunday.
Grant attached a copy of the approval the Department of Interior's Bureau of Safety and Environmental Enforcement gave in Feb. 2011 to an earlier request to abandon the 40-foot-tall, 86-ton steel structure at its location about 1,500 feet from the Macondo well. He also included a copy of those plans, which included information about the risks involved in returning the structure to the surface, its condition at the time, and a third-party analysis of its stability on the ocean floor.
In a Thursday news release announcing approval of BP's cap-and-plug plan, the Coast Guard 'directed BP to submit a feasibility plan that considers the next steps toward either removing or remediating the threats of oil posed by the riser pipe and containment dome.'
In his Monday note to Grant, Walker's directions to the company included: 'Having temporarily mitigated this source of pollution, undertake the planning effort necessary to develop proposed courses of action to either remove or remediate the remaining sources of oil: riser pipe and the cofferdam/containment dome.' "