The National Building Museum’s popular summer “The Beach” installation is coming to a close on Monday. But luckily for D.C. residents, the 750,000 plastic tennis-sized balls will be staying in city bounds, finding a new home in the Dupont Underground space.

Now, the challenge is crafting how to transport these 750,000 balls from Point A to Point B.

Dupont Underground — the long-abandoned trolley platforms under Dupont Circle that is in the process of being converted into a massive community arts and events space — is calling for volunteers to move these balls on Monday and Tuesday next week.

The balls need to be packed into 1,400 boxes already at the National Building Museum. Once they arrive at Dupont Circle, there is no unloading dock, and they need to be carried downstairs to the underground space. The balls will be donated to Dupont Underground through a partnership with the National Building Museum.

“I said without a moment of hesitation that we will take [these balls] because it is an immediate opportunity [to engage the space,]” said Braulio Agnese, the managing director of Dupont Underground. “It was a gift from heaven.”

The balls, however, will no longer be used to recreate an indoor beach. In the next few months, Dupont Underground is planning to call on artists to enter a design competition in which they use the balls to create an on-site installation. It’s still unclear exactly when Dupont Underground will open, but Agnese said he’s pushing for mid-fall. This competition would be part of the space’s inaugural programming.

“The public has been enjoying the balls in one kind of form,” Agnese said. “And here’s an opportunity to take them to put a challenge to designers to say, ‘How will you repurpose them to give a completely different experience?'”

For those interested, there are number of volunteer opportunities to help move the balls. At 4:30 p.m. Monday, Dupont Underground is looking for 25 people to each carry one box of balls from the National Building Museum to Dupont Underground via Metro’s Red Line and then pour the balls into the underground space. This is the symbolic, public arts portion of the move.

More practically, Dupont Underground is looking for people on Monday afternoon to help pack the balls into boxes and load them into trucks. Bookstore Movers is donating two trucks to the cause, and the One Love Massive art firm will be donating a bus. Split, a D.C.-based ride-sharing app, will help to transport volunteers from the museum to Dupont for free. Once they get to Dupont, volunteers are needed to walk the boxes downstairs.

Volunteers are also needed to help with the move on Tuesday.

Here is a full list of the volunteer times. (Note: You do not need a ticket to volunteer, and anyone is welcome to help.)