WASHINGTON — Construction crews working on a new helipad at the White House have taken apart the massive granite seal that would serve as the new landing spot for Marine One, signaling potential delays in the project. The White House said it’s continuing to make improvements as part of efforts to best match the needs of the building and its grounds. “Thanks to President Trump, the White House has never looked better, and it will only continue to get better under his leadership.” But their use has been limited because their exhaust vents aim heat downward, posing a risk to the South Lawn grass. He has also noted that the landing pad could be used for other White House events, such as press conferences.