Updated

Some 50 piles of gravel sit in the middle of what this spring will be the first makings of a grass field inside Levi's Stadium. In April, staff will conduct a "superflush," a mass simultaneous flushing of the toilets to simulate the potential overload on the sewage system with a large crowd.

The San Francisco 49ers' $1.2 billion home is 80 percent complete, with about half of the red seatbacks already installed in a lower bowl that will hold 45,000, or two-thirds of stadium capacity — the largest first level in the NFL. There will be roughly 18,000 seats in the upper deck.

"We're right at 80 percent and we increase that 2 to 3 percent per month," project executive Jack Hill said Wednesday while leading a media tour. "We're right where we wanted to be, right where we expected to be."

Team COO Al Guido hopes for a late July finish ahead of the San Jose Earthquakes' MLS match against the Seattle Sounders on Aug. 2 to open the venue.

The 49ers, who lost in the NFC title game to the Super Bowl champion Seattle Seahawks, are expected to play a Week 2 nighttime home opener based on the original stadium construction completion schedule. San Francisco's preseason schedule is expected to feature home games in the second and third weeks.

Offices will begin to house 49ers staff in the new stadium in April, though the team is working with the city to make sure the fire alarms and other safety mechanisms are fully operation.

"They can take their safety gear off at their desks but it will still be an active construction site," Hill said. "We've got a good three months of moving people over."

He said there are still concession areas to complete, and the 49ers' locker room and training area are still taking shape.

"Think about it like it's a house where the walls and roof are up," Hill said. "It looks like you could almost move furniture in and have an event next week."

The Bandera Bermuda grass is slated to arrive in late March with installation set to begin as soon as April 1. It is being grown at a sod farm outside Livingston in California's Central Valley.

"It's something hearty and will rebound," Hill said of the natural grass.

All club levels look out to the field in one direction and the surrounding area in another. It's 35 rows up to the first club seating area, while Row 1 of the stadium is about 10 feet off the field. With the addition of temporary seating in the northwest and southwest plaza areas, Levi's Stadium will go from approximately 68,000 to 73,000 for the 2016 Super Bowl.

Guido, who worked to open the Dallas Cowboys' AT&T Stadium from 2007-09, figures it will take two to three weeks to train 1,000 in the guest services staff who will work throughout a stadium spanning 1.8 million square feet.

For players, it will be cozy around team headquarters and they won't have to walk far on game day. The current locker room will serve as a changing station of sorts for players coming off the practice field before heading to the film room or meetings.

"Thirteen feet, closest point facility to the stadium," offered 49ers President Paraag Marathe.

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AP NFL website: www.pro32.ap.org