(CNN) -- One hundred days after an oil well operated by BP ruptured in the Gulf of Mexico, and 13 days after crews finished capping the well to contain the gushing crude, the man who is overseeing the federal response is optimistic that steps planned for the coming days will finally, permanently seal the well.
"The relief well, while it is deep, is something that has been done before," said retired Coast Guard Adm. Thad Allen. "The technologies involved here are not novel, but obviously, the depth is a challenge here. But we are optimistic we will get this done."
Allen offered that assessment as preparations proceeded for two efforts to kill the well about a mile below the surface -- first, sealing it from above by pouring down mud and cement in an operation known as "static kill," and then closing it off from below by an intersecting relief well.
The static kill could begin Sunday, while the relief well may be ready for the "bottom kill" effort five to seven days afterward.
Allen said no anomalies or breaches have been detected at the formerly leaking well, and pressure is rising slowly, with the latest readings show pressure of 6,942 pounds per square inch -- all signs that it is structurally sound. The static kill would not work if there's a leak.
At this point, crews working on the ruptured but capped oil well have once again connected through the relief well to existing underwater equipment. They are cleaning out and conditioning the relief well, getting it ready before laying casing pipe to reinforce it.
The Q4000, the ship that would pour the mud and cement for the static kill, is on the scene and ready to go.
Workers had been forced to disconnect their equipment and retreat from the well site late last week, when Tropical Storm Bonnie loomed as a potential threat. But when Bonnie lost power, workers returned to the site over the weekend.
Meanwhile, with no more oil flowing from the well, it's getting harder and harder to find oil on the surface, according to Coasdt Guard Rear Adm. Paul Zukunft, the federal on-scene coordinator.
He says crews flying over the Gulf have only been finding "light bands of oil," compared to the huge swaths when the well was still spewing.
At the height of the spill, skimming vessels were collecting 25,000 barrels of oil a day.
But authorities are not quite ready to dismiss the 811 skimmers that have been used to collect surface oil. Allen says that's won't happen at least until after the well has been sealed.
"We're not out of the woods yet. We still need a permanent kill," Allen said.
Boom used to try to stop oil from reaching shore is another matter. Zukunft said 11 million feet of boom have been arrayed throughout the Gulf.
He said that in coming days, authorities will consider removing some of the boom, in some cases by the fishing vessels that were employed to help lay it out. Zukunft said there are concerns that if storms develop this summer, the boom could be pushed into fragile marshland, damaging it.
But collecting the boom could take time. Zukunft said that if 60 miles of boom are recovered each day, the process could take through Labor Day. The recovered boom has to be decontaminated before it can be used again.
Allen said he'll be meeting with parish presidents Thursday to outline the steps ahead.
Then there's the question of oil that may be lurking under the surface. Allen noted it took weeks after the Deepwater Horizon explosion for oil to reach shore, and oil in the form of tar balls could continue to wash up on beaches for some time.
"When you put somewhere between 3 million and 5.2 million barrels of oil into the Gulf of Mexico, I don't think anybody can understate the impact and the gravity of that situation," he said.
Meanwhile, BP's incoming Chief Executive Officer Bob Dudley says that resolving the crisis is "the single highest priority for BP going forward."
Dudley, whom BP named Tuesday to replace CEO Tony Hayward on October 1, said on CNN's "American Morning" on Wednesday"The only way you can build a reputation is not just by words but by action."
"I picked up that people think that, well, once we cap this well, we're somehow going to pack up and disappear," he said. "That is certainly not the case. We're -- we've got a lot of clean-up to do. We've got claims facilities. We've got 35 of those around the Gulf coast. As of this morning, we wrote a quarter of a billion dollars in checks, for claims. There's still more to go. We know that. We haven't been perfect at this. But it's a deep, deep personal commitment from me for BP and the many people in the Gulf coast to make this right in America."
BP estimates that in August, it will pay at least $60 million in advance to Gulf coast claimants who have lost income or net profit because of the oil spill in the Gulf of Mexico, the company said in a statement Wednesday.
Responding to criticism from the nonprofit consumer advocacy group Public Citizen, Dudley added, "I don't think BP is reckless. Nor do I think we do things to cut corners, nor have we designed wells that are somehow different than many of the other wells in the Gulf of Mexico. But, having said that, we've had a tragic accident, and there is no question that we will make some changes going forward, significant changes. And from between now and October, there will be a lot of planning and looking in what we need to do to focus on safety and reliable operations. We're going to learn, not only BP, but the entire industry is going to learn from these investigations."
The toll to the region has been crushing as millions of barrels of oil spewed from a mile below the surface for almost three months.
By Wednesday, 100 days on, thousands of workers had lost their jobs, sensitive wetlands had been damaged, and tourism was at a near-standstill.
Oil gushed from the ruptured well after the Deepwater Horizon rig exploded April 20, leaving 11 workers dead. Officials have said the relief well is the only permanent solution to the disaster.
CNN's Ed Payne, Aaron Cooper, Lesa Jansen, Allan Chernoff, Vivian Kuo, David Mattingly, Rich Phillips and Matt Smith contributed to this report.