REDMOND, Wash. - Construction has begun on Microsoft's massive parking garage, said to be the second-largest underground garage in the western hemisphere.

The massive structure is part of a $750 million project - the largest in Microsoft history. It will stretch across 10 acres of land on Microsoft's West Campus between NE 36th St. and NE 40th St.

Four, four-story buildings will stand above the four-story garage, which will hold nearly 5,000 cars.

Microsoft Development Manager, Terry Bendrick, said the outline of the parking garage will be four football fields long by 1.5 football fields wide.

"If you plunked it in downtown Seattle it would be two city blocks by three city blocks," he said.

The excavation alone is expected to take several months.

Tom Dean, Senior Project Engineer with GLY Construction, said about 864,000 cubic yards of soil need to be removed.

A steady stream of trucks moves in and out of the site, which is adjacent to SR 520 near Redmond.

"Between 60 and 80 trucks per day, 300 to 400 truck trips per day, with 7,000 to 10,000 yards of soil removed each day," said Dean.

Even though the site is in an area surrounded by businesses, there are concerns about the impact the project is having on people who live on 148th Ave. NE.

"We have to be quiet for them," said Dean. "We have sound monitoring equipment and certain hours we can haul. We can't start before 7 a.m.," he said.

Bendrick said Microsoft spent tens of millions of dollars to change the original plan to build an above-ground facility. Instead, the company decided to put it underground and create a green area above, with a rugby field and basketball court, as well as a commons building with food and retail areas for employees.

"To get people out and about and create a pedestrian campus instead of a concrete campus," said Bendrick.

Soil removal is expected to be completed by October.

As of March 1 of this year, Microsoft owned 78 sites in the Puget Sound region, totaling 8,499,162 square feet.  The company leases an additional 2,854,958 feet on 38 sites.