A rock quarry on Oahu is going to be mined for longer than previously permitted and look different upon closure under a final regulatory decision made Wednesday.

The state Land Use Commission voted unanimously to extend a special operating permit by 15 years, to 2047 from 2032, for the roughly 200-acre hillside quarry in Makakilo owned by Grace Pacific LLC.

Other approvals granted by the commission will allow Grace to shift where excavation can occur to access higher quality rock without increasing the total area mined, and permit a planned asphalt plant and a fairly new concrete production facility to run 24 hours a day on-site. The concrete plant was also confirmed as a previously approved use on the property.

Grace sought the approvals in an application filed last year to amend its existing permit tied to the quarry established by a predecessor in 1973 on Puu Makakilo, a hill zoned for agriculture and previously used for livestock grazing when sugar cane filled the landscape in adjacent areas that later became suburban parts of Oahu’s “second city” of Kapolei.

The company, which is the largest paving contractor in the state and supplies aggregate and concrete for construction projects, said its requested changes were critical for the local construction industry and could reduce costs for customers including the city. The Makakilo quarry is one of three rock quarries on Oahu.

“Without this quarry, Hawaii and Oahu in particular would be in a very negative supply state for our aggregate needs,” Calvert Chipchase, an attorney representing Grace, told commissioners.

Chipchase said without some of the requested changes, Grace, which was sold in November by Hawaii real estate investment firm Alexander &Baldwin Inc. to local construction firm Nan Inc. for $57.5 million, would have to import rock from the mainland or Canada at higher costs.

Earlier this year, Dawn Takeuchi Apuna, director of the city Department of Planning and Permitting, recommended approval of Grace’s application. So did the Honolulu Planning Commission after a public hearing.

The LUC considered those recommendations as well as input from the public, Grace, DPP and the state Office of Planning and Sustainable Development.

During the commission’s hearing, the biggest issue debated was what the face of the excavated hillside, which is visible from parts of the Ewa Plain and the H-1 freeway, should look like when operations cease.

The Office of Planning wanted Grace to stick to a prior commitment it made in 2008 for the final grading of the excavated rock face to be a landscaped slope. This commitment, according to the agency, addressed community concerns about aesthetics of the hillside scar.

Grace instead proposed leaving four or five benches, or stair-like cuts each spanning about 15 feet, in the remaining face that Chipchase said would be covered naturally over time by vegetation.

Katia Balassiano, land use division administrator at the Office of Planning, asked the commission to make the previous final grading plan a condition for the other changes sought.

“We do understand that a commitment to a regrading plan that has more gentle slopes on which grass and vegetation would grow is more costly,” she said. “However, we believe that it is closer to the intention of what had been reached back in 2008 and what we think the community is interested in. …”

Chipchase said that since 2008 Grace concluded that a stepped face would allow more efficient and safe quarry operations while also resulting in a more stable final facade with better rainwater drainage and less erosion. The new final grading plan, he noted, was endorsed by DPP and the Planning Commission.

Another idea, suggested by the Makakilo-Kapolei­-Honokai Hale Neighborhood Board, was to produce an artistic stone relief carving on the excavated face.

Kioni Dudley, a vice chair of the board, told the commission about a resolution the board passed to seek such a carving reflecting Native Hawaiian culture, an idea that has been conveyed to Grace to replace what the board calls an “eyesore.”

“Our people want to see that unsightly wall beautified,” Dudley said, adding that it could also serve as a visitor attraction.

State Sen. Mike Gabbard (D, Kapolei-Makakilo-Kalaeloa) expressed support for the carving idea in written testimony to the commission.

Chipchase said the type of rock on the wall face would not be suitable for a Mount Rushmore type of carving.

“It’s not an idea that we would accept or ask you to implement,” he told the commission.

Other issues that area community members have raised in relation to quarry operations include noise, dust and vibrations from rock blasting.

Daryl Tacey told the commission in written testimony that the quarry work is no longer tolerable and has damaged thousands of homes that have been developed around the site over the past 50 years.

“Shut this down and move it to a location away from the Second City as it has no benefit to the residents of Makakilo or Kapolei,” Tacey wrote.

Chipchase said there are no property damage risks and that Grace mitigates dust and noise, which are subject to regulatory compliance.

Grace’s application received much support from construction trade organizations.

Commission Chair Dan Giovanni called the quarry a critical and needed industrial enterprise, and said in his view Grace’s revised final grading plan was reasonable.

One commission member, Ku‘ikeokalani Kamakea-ʻOhelo, was excused, and another, Ken Hayashida, recused himself over a conflict connected with the city. Grace’s application was approved 7-0.