ATTLEBORO - Low level radioactive pollution is not expected to hamper plans to build a replica of Fenway Park's famous left field wall at the Finberg Field recreation complex, a health official said Friday.

However, officials will be careful because the soil at the complex is known to be clean only to a depth of three feet and footings needed for the fence are supposed to be four feet deep, said health agent Jim Mooney.

"We'll take a cautious approach, like with anything else we do over there," he said.

An alternative is to change the plans so that three-foot footings are acceptable, Mooney said.

Recreation officials announced a plan Thursday to build a likeness of Fenway's "Green Monster" at Cooney Field, which is part of the Finberg youth baseball complex. The fence will be 92 feet long and vary in height from eight feet to four feet. Plans call for the digging of 23 four-foot deep holes for footings. The site was cleaned by state's Department of Environmental Protection more than two decades ago and is safe to play on. It was filled with clean material to a depth of three feet.

Finberg, located at the intersection of Park and Bishop streets, was once a dump where low-level radioactive materials used in watches and clock dials were deposited. High concentrations of nickel were also found there.

Most of the pollutants were found in the back portion of the parcel, which is now paved. However, there were pockets of the radioactive material found in the playing areas.

The pollutants would only be dangerous if they're ingested, said Mooney.

If the city needs to dig four feet down it may have to hire an environmental professional to monitor excavation and disposal of the dirt, Mooney said. Filling the holes with concrete footings and posts will end any potential danger, he said.

GEORGE W. RHODES can be reached at 508-236-0432 or at grhodes@thesunchronicle.com.