Federal officials are laying more groundwork to begin construction on President Donald Trump’s planned 250-foot-tall triumphal arch, sharing additional documents that detail the project’s scope and an aggressive timetable for potentially completing work before Trump’s term ends.

According to National Park Service documents posted this month, the administration envisions 20 hours per day of construction on the arch, year-round, in hopes of completing the project within two to three years. Construction experts said that timeline — which would involve two 10-hour daily shifts — is unusually aggressive for a nonemergency project.

The arch also would be built with concrete clad in granite, unlike the nearby Lincoln Memorial and other monuments that were constructed with natural stone like marble and limestone — another way to expedite its construction, experts said.

“He’s obviously in a hurry to try to get this all done before he leaves office,” said Matthew Bell, a University of Maryland architecture professor, commenting on the timeline and materials. “Most of the major monuments in D.C. are stone.”

The Park Service said the project would require large cranes, including one that may be 320 feet tall and another that could be as high as 300 feet. The planned site for the arch is on a flight path to nearby Reagan National Airport, where planes can sometimes fly at around 500 feet of altitude, raising concerns about safety.

The Federal Aviation Administration has said it is reviewing whether the arch’s planned height would present risks to airplanes transiting the area, concluding in a preliminary report last week that the arch would need red blinking lights to alert planes at night. An FAA spokesperson said Tuesday that the agency was still conducting a full study on the project.

FAA, Transportation and Interior Department spokespeople did not respond to questions about whether the additional height of the cranes would pose further risk.

The White House declined to comment on the Park Service documents. Officials said they planned to begin construction as soon as all approvals are received.

“The Triumphal Arch in Memorial Circle is going to be one of the most iconic landmarks not only in Washington, D.C., but throughout the world,” Davis Ingle, a White House spokesman, said in a statement.

Trump has insisted that the 250-foot-tall arch be built to mark America’s 250th anniversary, and two federal panels led by Trump allies have rushed the project through reviews. The arch would be erected at Memorial Circle, a traffic roundabout near Arlington National Cemetery that is tucked inside Washington’s boundaries, and it would represent the president’s most significant change to Washington’s skyline.

The administration is not planning to seek authorization for the project from Congress, drawing rebukes from Democrats who say the president continues to flout long-established laws and norms. Trump has also demolished the White House East Wing to clear space for his planned ballroom, decided unilaterally to renovate the Lincoln Memorial’s Reflecting Pool, and undertaken other construction projects without going through the usual legally required reviews or seeking approval from Congress.

“Running through all these incidents is an inexplicable disregard for legal process,” Sen. Richard Blumenthal (D-Connecticut), the top Democrat on the Senate’s permanent subcommittee for investigations, wrote in a letter Tuesday to Park Service leaders.

Blumenthal asked for the Park Service to explain and justify its use of urgent procedures, including no-bid contracts, to complete Trump’s projects; to share its internal records on the arch, the Reflecting Pool and other work driven by the president; and to provide a full list of projects underway or under consideration on Park Service land in the D.C. area. The letter was shared with The Washington Post.

Some construction and design firms have declined to work on the arch, worried that they could not meet the administration’s aggressive timeline and wary of the risks of participating in the controversial project, according to two people who spoke on the condition of anonymity to describe internal deliberations around the project.

Fifty-two percent of Americans are against the planned arch, compared with 21 percent who favor it, according to a Washington Post-ABC-Ipsos poll conducted in April.

The project is also the subject of a lawsuit brought by several military veterans who say the towering structure would alter their visiting experience to nearby Arlington National Cemetery. Lawyers for Public Citizen, a watchdog group that is representing the military veterans, have urged a federal judge to halt the project.

“With every passing day, Defendants’ arch moves closer to construction,” Public Citizen lawyers argued in a filing to U.S. District Judge Tanya Sue Chutkan last week.

Trump administration lawyers have argued that the project should not be halted because it has not officially begun. Administration officials have also said they will provide at least 14 days’ notice before beginning construction of the arch.

The Park Service last week opened a 10-day comment period for the public to weigh in on the arch project. The comment period, which the agency and administration officials have not publicized on their communications channels, according to a Post review, is a legally required step before beginning construction.

The Park Service has acknowledged the potentially adverse effects of the arch on Arlington National Cemetery and other nearby monuments — “all of which derive significance in part from their planned visual, commemorative, and spatial relationships across the Potomac River and through the monumental core,” one report concluded.

The Interior Department last month awarded a contract to Otak Inc., a Portland, Oregon-based architectural firm, to perform compliance-related work related to the arch project. Otak declined to answer questions about the contract and its involvement in the project, referring comment to the Trump administration.

The project has already received approval from the Commission of Fine Arts, which reviews designs for major federal projects. A second panel, the National Capital Planning Commission, is expected to approve the project as soon as next month.

Will Scharf, the Trump-appointed chairman of the National Capital Planning Commission, also said last week he believed a federal law limiting the height of construction in Washington should not apply to the arch. The law restricts most construction in Washington to a maximum height of 130 feet.

Meanwhile, Trump officials have declined to include a half-dozen historic preservation and advocacy groups, such as the National Trust for Historic Preservation and the Cultural Landscape Foundation, in a federally required process to consider the arch’s potential effects on historic properties. All of the excluded organizations, which have historically offered input on past federal projects, have sued the Trump administration over the president’s planned ballroom, his Reflecting Pool and other initiatives.

“Each of these organizations brings subject area expertise that could be helpful,” Charles Birnbaum, the president of the Cultural Landscape Foundation, wrote in a letter Monday to the Park Service, asking to participate in the process. The letter was shared with The Post.