Bangkok Flooding: Officials Hope Floodwalls Will Protect Thai Capital

VIDEO: Residents scramble to protect Thailands capital city.
WATCH Massive Flooding Headed Toward Bangkok

Thai government officials are bracing for the possible onslaught of flood waters today as the capital city of Bangkok secures its floodwalls.

The Thai military has been working around the clock to firm up floodwalls just outside of Bangkok, as the government rushes to stay ahead of floodwaters and save the commercial heart of Thailand.

Today, Prime Minister Yingluck Sinawatra said 10 provinces in Thailand were still at "critical risk" from flooding, but that Bangkok's 9 million residents would likely be spared.

Monsoon rains have swamped more than half of Thailand since July, killing nearly 300 people, and displacing millions more.

Soldiers have widened canals, and built floodwalls to keep the water from spilling south, into the capital.

The worst flood to hit Thailand in decades, has now become the country's most expensive disaster, with damages topping $3 billion.

In central Bangkok, the waiting game continues. Paesita Dussaewlnwa, who works at a jewelry store, put up a concrete flood wall last week, and stacked sandbags behind it.

She moved all her products to higher ground, after watching rain pound the capital for days.

"Yes we are concerned. We worry about the water because In Ayutthaya, it is 100 percent flooded, and all of that will come here," Dussaewlnwa told ABC News.

Much of Bangkok lies behind a sturdy system of flood walls, dams and dikes that have been reinforced recently, according to officials.

"I insist that the floods will only affect outer Bangkok and will not be widespread in other areas," Prime Minister Yingluck Shinawatra said Friday while touring the city's defenses.

Today, U.S. marines joined the fight by bringing sandbags and relief supplies.

"They'll be working of course with the Thai military. This is an important step for us to see how we can help Thailand best at a very, very difficult time," said Kristie Kenney, US Ambassador to Thailand.

While the plan to divert water away from Thailand's economic center is working so far, it is little relief for those living outside of it.

In the old capital of Ayutthaya, residents walk through waist-deep water, as they try to save what's left of their homes and businesses.

Volunteers float supplies in, filling boats with water bottles. More than 200 major highways and roads are now under water.

"The worst is not over," Army Col. Wirat Nakjoo told The Associated Press. "The dams are at near full capacity and there's still a lot of water that needs to be released."

The Associated Press contributed to this report.