CHICAGO (WLS) -- Dozens of local ComEd workers came back home Monday night after spending a month in Puerto Rico.Among them were Mark Graham and his team, who rebuilt a playground that was destroyed by Hurricane Maria. Before heading back to Chicago, they bought a swing set, a trampoline, a playhouse and countless balls and hula hoops for a kindergarten who had been without a play area for the last six months."Seeing the joy on those kids faces along with their incredible teacher Mrs. Vanessa when we revealed our work was truly PRICELESS," Graham wrote on Facebook. "Spending time here and seeing the people of PR and how they have kept a truly positive attitude through all of the devastation and hearing all the thank you's , you guys are angels' was life-changing for me. Thank you to the thousands of linemen, mechanics and support personnel from across our country who helped rebuild Puerto Rico."The 72 workers were helping to restore power. Crews say some homes in Puerto Rico could be without power for more than a year."It's really bad down there. We felt kind of bad we didn't have enough time. We wanted to stay longer," said ComEd Overhead Crew Leader Jason Orta. "Neighbors are still helping neighbors. You have people who lost everything and they're happy and still doing what they need to do."ComEd said their workers helped restore power to more than 7,000 residents while they worked in mountainous terrain.A second wave of ComEd employees flew to Puerto Rico Monday to continue the relief efforts.