HOUSTON/NEW ORLEANS Technical issues on Monday muddled the timing of BP's planned final kill of its blown-out Gulf of Mexico oil well as concerns lingered over the environmental and health fallout from the world's worst offshore oil spill.
A relief well seen as the permanent solution for the crippled deepwater Macondo shaft was on hold while engineers studied the potential impact of pumping mud and cement into the bottom of the now sealed well, the long-awaited "bottom kill."
Worries that this move could damage the cement seal already injected in from the top and force out residual crude trapped in the well have obliged BP and the government to carry out more tests and discuss different technical options.
The studies have delayed the likely timeline for the well being permanently killed until late August, although no oil has leaked into Gulf waters since July 15, when BP placed a tight provisional cap over the mile-down wellhead.
The top U.S. spill response official insisted a definitive kill operation was still the goal. BP and government scientists should decide in the next day or two how to go about it.
"We need to have a stake in the heart of this well," retired Coast Guard Admiral Thad Allen told reporters.
Allen said he was keen to give the go ahead for the "bottom kill", but did not want to incur any risks in the operation, such as damaging the cement seal or driving out into the ocean 1,000 barrels of oil thought to be trapped in the well.
He said he could issue a directive for BP to proceed with its relief well later this week, and the final "kill" could come about 7 days after it was restarted.
The U.S. government's science team was meeting to discuss technical options for the planned kill operation.
The first option would have BP place a mechanism over the top of the existing wellhead capping stack that would help relieve possible pressure. The second would have the company replace the existing blowout preventer -- a giant stack of valves -- with a new one with higher capabilities.
FOCUS ON FOOD SAFETY, ENVIRONMENT
U.S. President Barack Obama's administration, which has been criticized for its handling of the catastrophic spill, is seeking to reassure skeptical Gulf Coast residents and the wider public that the worst of the emergency is over.
For 87 days following the April 20 Deepwater Horizon rig explosion that triggered the crude release, an estimated 4.9 million barrels of oil spewed into the Gulf, contaminating wetlands, fishing grounds and beaches from Louisiana -- the worst-impacted state -- to the Florida Panhandle.
Obama says the biggest environmental cleanup in U.S. history will not end until the last of the oil is gone.
He has eaten Gulf Coast seafood and took his family to Florida's Panhandle Coast at the weekend to demonstrate that the region's beaches were clean and "open for business".
Louisiana's white shrimp season opened on Monday, but although boats put out to trawl for the prized seafood delicacy, fishermen were worried about the oil spill impact on their catch and the prices they could get.
More than a fifth of federal waters in the Gulf remain closed due to fear of oil contaminating the seafood.
As part of the official campaign to allay safety fears, Commerce Secretary Gary Locke toured a seafood processing plant in Lafitte, La., about 25 miles south of New Orleans.
"We need to let the American people know that the seafood being harvested from the Gulf is safe to eat," Locke told reporters. "A lot of testing is done before we open state and federal waters to fishing," he added.
The U.S. Interior Department said it would limit the practice of allowing environmental waivers for deepwater oil drilling projects and instead subject such drilling to close analysis as it evaluates its review process.
Allowing companies to skip the environmental review process for specific drilling projects has come under intense scrutiny because BP was granted waivers for its ill-fated Macondo well.
The massive Gulf of Mexico oil spill has also triggered human health concerns. Prior spills have shown that contact with oil and chemicals can affect the lungs, kidneys, and liver, and the mental strain can boost rates of anxiety, depression and post traumatic stress for years afterwards.
U.S. health experts said doctors in the Gulf region needed to be alert to these effects.
BP announced in Houston it was providing $52 million to federal and state health organizations to fund behavioral health support programs across the Gulf Coast. "We appreciate that there is a great deal of stress and anxiety across the region," said Lamar McKay, president of BP America.
The BP ships and teams working on the final well kill operation may also need to keep an eye on the remnants of a tropical depression which has looped back into Gulf waters.
The U.S. National Hurricane Center was giving the system a 60 percent chance of redeveloping into a depression and computer weather models project it will return inland over Louisiana after passing by the Deepwater Horizon oil spill site again, following a previous brush last week.
(Additional reporting by Chris Baltimore in Houston, Julie Steenhuysen in Chicago, Ayesha Rascoe in Washington, Scott DiSavino in New York and Pascal Fletcher in Miami; writing by Pascal Fletcher; editing by Anthony Boadle)