Carroll County officials say they were surprised to learn two months ago that the state had declared in 1988 that it was illegal for builders to bury stumps and other construction debris at new house sites.
"The practice, whether it was right or wrong, was that they wereallowed to bury debris as long as it wasn't in an easement or septic area," said Ralph Green, head of the county permits and inspections office.
Some county homeowners have spent hundreds of dollars to fill sinkholes that developed in their yards as stumps and other wood debris gradually decayed.
Some builders have also borne the expense of returning to old subdivisions to fill sinkholes that occurred years after developments were completed.
A truckload of fill dirt in Carroll County sells for about $75.
State officials say they haven't cited any local builders because they didn't know tree stumps were still being buried in Carroll County.
"We can't cite anyone if we don't know about it," said Maryland Department of the Environment spokeswoman Sandra Palmer.
"If [homeowners] complained to the county and it stopped there, we'd have no way of knowing about it."
The county water resource bureau has logged 300 reports of sink holes in the past four years. Staff members traced most of the holes to the action of underground water dissolving carbonate rock.
But 52 reports, about one-sixth of the total, were tentatively or positively traced to buried construction debris.
Geologists say it usually takes five to 10 years for wood to decay underground.
James E. Slater Jr., county environmental services administrator, reported that he had advised the county staff last month to stop allowing builders to bury construction debris.
He took the action after an Environmental Affairs Advisory Board (EAAB) committee, formed to study limits on debris that can be buried at house construction sites, learned from the Department of the Environment that the state had banned all such burying.
Mr. Slater said the practice "is kind of a hangover from years ago and, quite frankly, it was wrong."
Catherine M. Rappe, head of the county water resource management bureau, said she doesn't know how many builders still bury stumps.
"We know it's still going on. We don't know to what extent," she said.
Kevin E. Dayhoff, an EAAB member who chaired the buried debris committee, said he believes only a few builders still bury stumps.
Banning construction debris burials is a good idea for safety and environmental reasons, Mr. Dayhoff said. But he faulted the Department of the Environment for its handling of the ban.
"My problem with the state is this: They tell you what you can't do. They should tell you what you can do," Mr. Dayhoff said.
He said he has been working with county personnel on other ways builders can dispose of stumps.
Edward Dexter, chief of the Department of the Environment's solid waste compliance division, said stumps can be ground into mulch or taken to a landfill designated to accept them.
Nonbiodegradable debris such as concrete blocks must go to a rubble landfill.
The department interpreted a state law regulating landfills to mean that builders burying debris on house sites are operating landfills without a permit.