Mystic — Lynn McDonnell etched her daughter’s name and the words “Peace,” “Love” and “Aloha” in wet cement on Thursday near the playground along the Mystic River being built to celebrate Grace McDonnell’s life.

Then she and her husband, Chris McDonnell, pressed starfish and oyster-shaped shells into the cement because their daughter loved the water.

“Thank you so much,” Lynn McDonnell told dozens of volunteers gathered around them as a brisk wind blew sand off the beach. Grace, 7, was one of the 20 first-graders who died in the December 2012 shootings at Sandy Hook Elementary School in Newtown.

The McDonnells chose Williams Beach behind the Mystic YMCA because Grace loved the beach and because it was in Mystic that Chris McDonnell proposed to his wife.

Nate Wheeler, 15, a volunteer from Stonington High School, said he wanted to help.

“It wasn’t even my family and I was still pretty emotional,” he said.

Dylan Schlapfer, 17, of Robert E. Fitch High School in Groton, said, “All the starfish and the shells, it hit the heart because it just shows how much they loved her.”

More than 150 volunteers had arrived by 7 a.m. Thursday to help install the playground equipment, said William Lavin, founder of the “Where Angels Play Foundation,” which is building playgrounds to commemorate each of the 20 children and six adults killed at the school.

The truck that holds the playground equipment was delayed on its way from Atlanta, so crews raked, landscaped and did other preparation work.

Grace’s older brother, Jack, broke ground with a shovel, was given a tool belt and will serve as foreman, Lavin said.

“He will be our boss,” he said.

The New Jersey Firefighters Mutual Benevolent Association began building playgrounds after Hurricane Katrina, then organized again after Sandy Hook as the “Sandy Ground Project: Where Angels Play,” to build 26 more playgrounds in Connecticut, New York and New Jersey. Grace’s playground will be number 19.

“The major theme is peace and grace, to live gracefully, as she did,” said Lavin. “... The idea of all these playgrounds is to have these angels watch over the angels that are still with us.”

The playground will incorporate some of Grace’s own artwork into the vinyl panels. She loved to draw and paint.

A ribbon-cutting is scheduled for 11 a.m. Sunday.

Firefighters from New London, Mystic, Fairfield, Bridgeport, Milford, Stratford and Torrington arrived to help Thursday, along with the crew from New Jersey.

Students from Stonington and Fitch raked, painted and cleared rocks out of the sand.

Megan Wilkins, 17, a volunteer from Stonington, said her family lived in Newtown for many years before moving to Stonington. Though Wilkins was still young when they moved, she recognized all the places and people interviewed after the tragedy. She helped organize a fundraiser to make snowflakes to decorate the new Sandy Hook school, and felt helping at the playground was also important.

“I think it’s only right that we give back to a community that was so good to us,” she said.

Local businesses including Mystic Drawbridge Ice Cream, Mystic Market, the Steak Loft Restaurant, the Voodoo Grill, The Mystic Boathouse and The Captain Daniel Packer Inne Restaurant & Pub donated food for lunch for the volunteers. Still more businesses offered help with dinner.

Bob Brower, who handles logistics for the foundation, said he expected the playground equipment to reach Mystic later Thursday. It takes seven to eight hours to install, and crews planned to rubberize the cement today and Saturday, Brower said.

The equipment, painted pink and purple — Grace’s favorite colors — could arrive as late as 9 p.m., volunteers said. But they planned to work through the night to install it if necessary, they said.

The group also built a playground called Emilie’s Shady Spot to honor victim Emilie Parker at Riverside Park in New London. It opened in November.

Lavin said the premise of the foundation is to “pay it forward” so that one community raises the money and provides the volunteers to build a playground in the next.

It’s working, he said. Proceeds raised in New London and other communities are helping build Grace’s playground in Mystic and will be used for future playgrounds.

The foundation has also heard from other communities affected by tragedy, such as Boston, about building playgrounds there, he said.

Odessa Glaza, 17, a student at Fitch, said the message of “paying it forward” is compelling.

“I think it’s just one message of how a community can be a powerful element in recovery and healing,” she said.

d.straszheim@theday.com