The Port Arthur City Council on Tuesday amended its Tax Increment Reinvestment Zone to accommodate massive private investment — perhaps as much as $150 million — when Motiva moves its offices into historic buildings downtown.

Changes in the TIRZ, which was first adopted five years ago, will generate some $16 million for the city to improve utilities and infrastructure, demolition and environmental abatement and streetscaping in an area that encompasses 309 acres bounded by Houston Avenue to the west, Rev. Ransom Howard and Seventh Avenue to the north, Lake Charles Avenue to the east and the Port Arthur ship channel.

“You get to guide this downtown area to an era that people would never imagine,” said attorney Art Pertile, who presented the revised TIRZ. “No one else gets to do this.”

“Port Arthur is open for business,” said Mayor Derrick Freeman, “$150 million is about ready to come to our downtown.”

Investment downtown started with the purchase by Motiva of two historic buildings at the intersection of Austin Avenue and Fifth Streets: The Federal Building, built in 1912 and listed on the National Register of Historic Places; and the six-story Adams Building, completed in 1926 and for generations a major office building for professionals in the city.

Motiva is expected to close the deal on the buildings on or around May 15. The plan is to move some 500 office employees into the buildings after abating and renovating the buildings within three years. Many of those professional and office workers will come from Motiva Enterprise’s site on Savannah Avenue; some additional jobs may be generated, Motiva officials said.

Motiva may also seek additional office space downtown.

Later Tuesday, city councilmembers revealed that Motiva had purchased the Hotel Sabine downtown.

The city expects that restaurant, retail and perhaps some presence of financial institutions and a pharmacy also will move into the area to support and accommodate the Motiva workforce. The site is just a couple of blocks from City Hall.

In presenting the amended TIRZ, Pertile said the TIRZ does not represent a new tax, but does reflect the increases in property values in that area expected to come with the new business development. Those raised property values will generate a budget of $16,685,100 for the city, money that will be used to encourage development with substantial infrastructure upgrades. That money will be used roughly in this way:

• $4.55 million for utilities
• $5 million for streetscaping
• $4 million for zone operation and administration
• $2.530 million for financing bonds
• About a half-million for demolition and environmental abatement.
• About $200,000 for attorney fees.

“We hope the zone will expand,” Pertile said.

In fact, Motiva had been weighing purchasing additional downtown property, including the empty 10-story Hotel Sabine, built in 1929 and empty since the 1980s. At least some consideration has been made for transforming that hotel into some sort of facility for short-term residence needs for people working with or at Motiva. Other considerations are for moving some retail into the building.

Parking is also a consideration downtown, and several lots may be secured for employee parking.

“Let’s do this,” said Mayor Pro Tem Thomas Kinlaw, who chairs the TIRZ board. The City Council OK’d the amended document unanimously.