A small private school in upper Northwest Washington wants to turn part of the Hearst Playground into a regulation baseball diamond for its spring baseball season and Babe Ruth League games and practices.

The Maret School, on Cathedral Avenue NW, is proposing to build the $20,000 facility on what is now a Recreation and Parks Department softball field south of the school at 37th and Quebec streets NW.

Maret leaders said they assumed the offer would be applauded by residents in Ward 3, where there are no public ball diamonds, a waiting list at the two private ones and a lively Little League program ready to graduate hundreds of potential Babe Ruth players, who play on bigger, regulation-size diamonds.

The school also has promised to maintain the diamond.

"The Maret School is willing to make a gift to the District," said Sam Dunn, a Maret School trustee with two teenage sons who play ball. "There are almost 2,000 kids playing Little League baseball in Northwest Washington, but as they get older and graduate to the Babe Ruth League, they need larger baseball fields to play on."

However, weeks after the plan was unveiled at a Advisory Neighborhood Commission meeting, a group of residents, citing concerns about noise and traffic, other Hearst sports programs and some beloved trees, are mounting a campaign to halt the plan. Girding for a fight, they have enlisted the help of activist Joel Odum, the Tenleytown activist who led the neighborhood battle to block a baseball field at Friendship playground a few years ago.

The friction is typical of efforts around the District to provide more playing fields. Available open space is often so coveted that neighbors resist devoting it to facilities that might increase traffic, parking problems and noise.

A developer's offer last spring to turn a portion of Chevy Chase Playground into a $50,000 lighted Little League field drew volleys of opposition that persisted until the developer withdrew.

"But there just aren't enough fields for kids to play on," said George Bullock, founder of the Capital Babe Ruth League. "And in the future the problem will double and triple."

Many opposition leaders are longtime residents.

"This is a multiple-use park. It's not an athletic field," said Roger Meyers, who has lived in the neighborhood about 20 years. "It's a place where we come to walk our dogs, play pickup Frisbee games and come and watch the sunset."

"This is an outrageous appropriation of public land for private use," said John Belcher, who has lived in the neighborhood for 25 years. "We are talking about environmental damage."

The baseball diamond proposed would be 100 feet longer than the current softball field, and would require skinning the grass to put down composition clay, building bleachers and putting up a retaining wall.

Planners say construction would require cutting about five sycamores from an embankment of 50 trees, but it would not affect the two rows of ornamental oaks that line the park's perimeter.

Parents and coaches have rushed to support the proposal.

"Baseball is on the rise in Washington," said Bryan Lighthouser, who played ball on the field when he was a student at Phoebe Hearst School. "And there are no baseball diamonds these kids can play on around here."

A field at St. Albans School for Boys and another at Sidwell Friends School are booked solid, said George Bullock, founder of the Capital Babe Ruth League, and alternative Recreation and Parks Department diamonds are far away and in poor repair.

Meanwhile, Little League programs in Ward 3 have grown dramatically, said Ann Kane, president of the Capital City Little League, because more families with young children have moved there. And about 60 percent of Little League players at age 13 want to go on to Babe Ruth League, Bullock said.

"It brings a sense of community to parents. It's something to do {with their children} in this fast-track city," said Kane.

The Maret School, the Babe Ruth League and the Police Boys and Girls Club have said they would share the estimated $1,500 annual cost of maintenance. Arthur Fawcett, head of the recreation department's Office of Policy, said this transfer of upkeep would be a relief for the city.

But Odum said the city's budget woes bring pressure for agreements of this type. "That's the fault of this city. They say: 'You're going to pay for it? You can have it.' "

Fawcett said traffic certainly would increase, but that Hearst has ample street space for parking. The noise would be minimal, he said, because Hearst "is much better buffered from people's houses than many other playgrounds."

But Fawcett also said the city will not make a decision until the ANC has made its recommendation. ANC leaders say they will hear the community out at a meeting Nov. 26.

"With all this community dissent, we don't dare jump the gun and make a decision," said ANC chairwoman Patricia Wamsley.