Washington, May 11 (DPA) Energy company BP grappled with containing a massive oil leak on the floor of the Gulf of Mexico as officials prepared to open investigations Tuesday into the cause and long-term political affects of the spill.

BP chief operating officer Doug Suttles said Monday his company hopes a smaller dome to contain and capture the crude oil spurting from the well will work better than a large one that failed over the weekend.

BP hoped to have the smaller dome – about the size of an oil barrel, 1.3 by 1.3 metres and nearly 2 metres high – in place over the main leak before the end of the week.

A larger four-storey-high container hit a glitch over the weekend when gas mixed with water formed hydrate crystals, blocking the exit from the upside-down funnel that was intended to siphon leaking oil through a pipe to a tanker ship above.

Tuesday, the official investigation of the April 20 explosion of the Deepwater Horizon drilling rig was to open in Kenner, Louisiana, outside New Orleans, with public hearings conducted by the US Coast Guard and the Minerals Management Service.

The probe aims to identify what led to the loss of 11 lives, the sinking of the rig and the subsequent oil spill that is threatening the livelihood and fragile ecology of the Gulf Coast.

The well rupture, now sending 5,000 barrels of oil a day into the Gulf of Mexico, could have severe consequences for new offshore drilling efforts in the US, which US President Barack Obama backed just months ago.

The energy committee of the US Senate will also tackle the issue Tuesday in Washington, when it hears testimony from Lamar McKay, head of BP America, and officials from two other companies: Transocean, which leased Deepwater Horizon to BP, and Halliburton company, which provided some services such as cementing in the drilled well.

The smaller dome will be placed at the very top of the blowout-preventer (BOP), the valve which failed to automatically seal off the well on the day of the explosion.

Eventually, BP hopes to seal off the gusher through a relief well, which could take another two months to finish. In the meantime, if the smaller dome fails to capture the crude oil outflow, BP said it could try forcing “junk” – bits of old tires and rubber – into the failed BOP opening to stop the flow.

The manoeuvre however could widen the leak and increase the outflow, Suttles said on the weekend, a risk that needed serious consideration. BP may try that option within 10 to 14 days.

On shore, wildlife and US Interior agencies were monitoring the coastline from Louisiana to western Florida for the arrival of the oil slick that could wash over more than 300 km of floating booms off the shore.

Some balls of tar had washed up along the coast, including on Dauphin Island off of Alabama, and workers had removed 30 pounds of it, a US Interior Department official said.

Interior officials said that a total of 15 oiled birds were being cleaned, including a northern gannet and a brown pelican which were to have been released Monday.

Suttles indicated that the size of the slick was “significantly smaller than seven to 10 days ago”, reduced by skimming, controlled burn-offs and dispersants applied to surface oil.

But marine biologists worried about what was going on beneath the surface, especially now that the Environmental Protection Agency had given the go-ahead for injecting chemical dispersants at the leak source, 1.5 kilometres below the Gulf surface.

“It’s sort of the devil you know versus the devil you don’t,” Linda Greer, a senior scientist at the Natural Resources Defense Council, was quoted by the Washington Post as saying. “It’s really shocking to me how little research has been done into these basic

questions.”

Under US law, BP is responsible for the clean-up and damages. The company said Monday it has already spent $350 million on the efforts.

BP’s Chief Executive Officer Tony Hayward has acknowledged that the future of offshore drilling in the US – now on hold due to the disaster – depends on how well BP does in preventing a major environmental disaster.