New details of Avista Development’s proposed Catalyst Project, slated for development in the University District, show a larger project than what was first publicly revealed.

The entire project is expected to have four mixed-use commercial and residential buildings with nearly 685,000 square feet of gross floor area, according to a recently published legal notice.

In March, Avista said the initial phase of the Catalyst Project, to be located at 601 E. Riverside, just east of the future, southern landing for the University District Gateway Bridge, would include a 140,000-square-foot building with six above-ground stories and a basement.

The Catalyst Project is expected to occupy 5 acres of land. The most recent public notice says the development eventually will include a multistory parking garage. Approximately 250 to 300 parking spaces will be added due to the project.

The construction phase will require 2,500 cubic yards of fill and will involve grading the entire site.

Five buildings constructed between 1939 and 1952 with a total of 47,400 square feet of floor space have been demolished, or are in the process of being demolished, to make room for the Catalyst Project area, Avista’s application to the city of Spokane shows.

The project is subject to a state-required environmental review, and Avista has filed a State Environmental Policy Act (SEPA) application for the property.

The application says currently the site is a mixture of commercial and light industrial that includes automotive repair, dry cleaners, and light manufacturing. Historical land use there includes auto wrecking and an asphalt paving company.

Latisha Hill, Avista’s senior vice president of development, says Avista Corp. and affiliate Avista Development still are in the early process of developing the north side of the 500 and 600 blocks of east Sprague Avenue.

Avista had initially indicated that it expected groundbreaking on the Catalyst site to coincide somewhat with the beginning of construction on the pedestrian bridge last summer. However, Hill says Avista Development’s efforts on the Catalyst Project were slowed over the summer when officials discovered two Avista properties on the site required the removal of underground tanks from the premises. In all, Avista removed six underground tanks, Hill says.

“We spent summer cleaning all the parcels, and it literally gave us an opportunity to begin cleaning from the ground up,” she says.

As for the Catalyst Project’s potential tenants, Hill adds, “We still don’t have a major announcement to make at this point. Right now, we expect to keep moving and plowing through the initial phase.”

Hill declines to identify the development partners during the predevelopment stage of the Catalyst Project.

Planned uses for the initial building include laboratories, offices, classrooms, study areas, and some storage, the application says.

The SEPA application says an estimated 1,200 students and faculty would reside or work in the completed project.

“For the purposes of this project, the mixed land uses could potentially include office, multi-family residential, coffee shop buildings intermixed with the primary land use of classrooms and higher education-type buildings,” the application says.

A site plan with the application shows a similarly sized building in a future phase just east of the initial project. The buildings would overlook the BNSF Railway Co. tracks, which run along the south edge of the Washington State University Spokane campus.

The Catalyst Project would balance development near the south landing with planned development near the north landing of the University District Gateway Bridge, Hill says.

The 450-foot-long, 120-foot-high bridge will serve as a highly visible connection between the University District and the East Sprague Avenue neighborhood.

The 770-acre U District, just east of downtown, includes Gonzaga University and the Spokane campuses of Washington State University and Eastern Washington University. The University of Washington, Whitworth University, and Community Colleges of Spokane also have programs based within the U District.

Avista had owned about an acre of land within the Catalyst Project area since 2008. The company had originally intended to develop it for an electrical substation there.

In 2016, Avista Development purchased an additional 3.8 acres in three transactions totaling $3.6 million, Spokane County Assessor’s records show.

Avista Development plans to ask the city to vacate undeveloped portions of east Riverside Avenue and north Sheridan Street right of way within the Catalyst Project area, the application says.

In July, Avista announced it’s being acquired by Toronto-based utility Hydro One for $5.3 billion U.S. The transaction, according to the two companies, is designed to allow Avista to maintain its corporate identity here.