Workers with earth-moving equipment appeared last month at the 38-acre BoRit site on Maple Street near Butler Pike, where industrial fragments of asbestos were discarded in heaps until the 1960s.

Crews under contract with the Environmental Protection Agency cleared brush and smoothed part of the land into an access road for later work on creek banks.

But the work so incensed some community residents that they are poised to challenge the EPA during a meeting tomorrow.

"I believe that action was a hazard," said Sharon McCormick, cofounder of the 26-person BoRit Citizens Advisory Group, created to give the EPA feedback on matters involving the site.

"This is really a serious problem. This is really serious stuff."

Citizens said they believed the EPA violated its guidelines by not warning them of the impending work at the site, and by failing to disclose what it would mean to the public's health and safety.

Eduardo Rovira Jr., BoRit on-site coordinator for the EPA, denied those claims. Rovira said that notice was sent to the advisory group's cochairs by e-mail, and that it was incumbent on them to tell others.

Co-chair Robert B. Adams said he doesn't remember an e-mail. He recalled Rovira saying in an offhand way that minor work might occur soon. "I didn't feel like I needed to tell anybody about it," Adams said.

Asbestos fibers have been linked to various lung cancers in humans, but the level of exposure that is dangerous is a sticking point between the citizens and the EPA. The citizens have asked that scientists take a fresh look at air-sampling data.

EPA officials insisted that the public was safe because air sampling done during disturbance of the soil on July 10 and 11 had showed that only one asbestos fiber had migrated from the site, which is bounded by Maple Street, a McDonald's restaurant, Wissahickon Creek, and Chestnut Avenue.

"All other results, including the ones located along the McDonald's back parking lot, were non-detect for asbestos," Rovira said.

Citizens worried aloud about the welfare of workmen who didn't wear protective gear, including respirators, while engaged in activities that could cause asbestos to become airborne.

The EPA said crews were safe because exposure levels were low and the earth-movers in which they worked were pressurized. But on July 28, after seeing a July 15 photo of a worker walking at the site without protective gear, the EPA reversed its stance.

"To be on the safe side, we have decided that during field activities, any contractor working inside the fence will wear Level C [hard hat, Tyvek suits, safety shoes and respirator]," Rovira said on the EPA's BoRit Web site, www.epaosc.netBoRit.

The two sides held a conference call Friday. They'll meet at 6:30 p.m. tomorrow in the Fellowship Hall at First Presbyterian Church, 4 S. Ridge Ave., Ambler. The session is open to the public.

The site has a rich history. From the late 1800s to 1933, it was owned by Keasbey & Mattison Co., which made milk of magnesia.

One night in 1886, the story goes, owner Dr. Royal Mattison spilled the liquid on a hot stove and didn't clean it all up. By morning it had hardened, and asbestos was born, according to a 1988 government document.

After 1933, a series of manufacturers dumped industrial slurry, and asbestos pipe, tile and shingles on the waste pile.

By the 1980s, the pile had become "a public health risk," because of the presence of exposed asbestos, said a July 14, 2008, document from the U.S. Department of Health and Human Services. Asbestos fragments were poking through the soil and the vegetation that was meant to act as a cover.

In 2004, developer Kane Core Inc., of Skippack, bought six acres where the pile sits. Owners David F. Kane and Mark Marino hoped to cap the dump with cement and build a 17-story condominium complex above it.

But the plan, criticized as dangerous and not in keeping with the borough's character, caused such a public outcry that Kane Core withdrew it in October 2005.

"It's disappointing, what has happened," Kane said at the time. He couldn't be reached for comment last week.

The site is in limbo. According to Xspand, of Morristown, N.J., which handles real estate tax liens for Montgomery County, Kane Core Inc. owes $19,758.57 on the property. The figure includes unpaid taxes, interest and fees for the years 2004 through 2007 that are owed to the county, Wissahickon School District, and Ambler Borough.

The parcel had been scheduled for tax sale April 16. But Montgomery County Solicitor Barry Miller said the Pennsylvania Department of Environmental Protection asked the county not to hinder "efforts to remedy the contamination at the site."

"As a result of that letter, we pulled it off the block," Miller said.