When you go to a Seattle Mariners game at Safeco Field next season, you will see something new -- the field itself.

For the first time since the stadium opened in 1999, the entire playing surface is being replaced. The Mariners say that with the exception of the replacement of the infield and foul territory grass before the 2012 season, the playing surface is mostly the same as it was when the stadium opened 18 years ago.

The current grass will be shaved down to its roots. Sand will be excavated, followed by leveling of the subsurface and installation of new infield dirt and new turf.

The Mariners say the new turf will be a mixture of sand, peat and other amendments to help maintain moisture and airflow. Just as it was with the original turf, the grass will come from Country Green Turf Farms near Olympia.

The infield will be replaced with about 260 tons of clay from Salt Lake City.

The project began Thursday and is expected to last through October, but the pitcher's mound won't be installed until March.

Safeco Field's turf is currently the oldest in Major League Baseball, according to the Mariners. As the turf has been patched up over the years with thin layers of sand, the field elevation has been raised. This project will lower the elevation by about four inches.

2018 will be the final season the stadium is called Safeco Field. The insurance company and the Mariners announced earlier this year that the naming rights agreement will not be extended. The new name of Safeco Field for 2019 has not yet been announced.