WASHINGTON — Arlington National Cemetery leaders are working on what could be one of the largest expansions in decades, warning that without more burial space the nation’s iconic military burial ground would run out of new grave sites within a dozen years.
Workers just finished construction on a giant structure that can hold tens of thousands of cremated remains; cemetery officials hope to begin a controversial 27-acre expansion this fall; and they will soon start designing a 38-acre addition around the Air Force Memorial near the Pentagon.
The expansion plans are part of a whirlwind of modernization put in place since investigators revealed widespread problems several years ago.
The changes, including digitized records that allow cemetery visitors to look up burial sites online, have transformed internal operations and the visitor experience at the cemetery, which dates to the Civil War.
But one project, which officials say would beautify the area and add more than 27,000 interment sites for veterans on the northern side of the grounds, has drawn opposition.
Critics say the Millennium Project, as the 27-acre expansion is called, does not fit the historic site, would damage a stream, and raze hundreds of trees in place since the Civil War. Some ask whether it would make more sense to begin planning for the inevitable — the day when the cemetery will be full.
It is no small question for a place that attracts more than 4 million visitors a year, with graves that span US history, including Revolutionary War soldiers, US presidents, Abner Doubleday, Oliver Wendell Holmes Jr., Joe Louis, Pierre L’Enfant, and many thousands of others who served the country.
‘‘I love Arlington. But it’s not big enough for all future wars,’’ said Representative Jim Cooper, Democrat of Tennessee, a member of the House Armed Services Committee.