Route 31 sinkhole studied

May 29, 1994|By Donna E. Boller | Donna E. Boller,Sun Staff Writer

The State Highway Administration is studying geologists' recommendations to excavate and shore up the sinkhole on Route 31 that swallowed Robert W. Knight's van in March, fatally injuring the 24-year-old Taneytown man.

The SHA also may excavate a smaller sinkhole that has caused road settling on Route 31 about 600 feet east of the accident site, said Douglas R. Rose, the SHA's district engineer.

Mr. Rose said that he cannot give details about the project until he studies the SHA geologists' and soil specialists' recommendations, and that he does not know when the work could begin.

Meanwhile, he said, the administration's assessment is that the road is safe to travel.

"It appears to be perfectly safe, except for a little settlement," he said. He said settlement is common to new roadbeds.

A. David Martin, chief of the SHA's engineering and geology division, recommended excavating the sinkholes, finding the places in underlying rock where soil is washing away and filling those gaps with concrete. Work crews then would replace the subsurface soil with rock and concrete.

The idea is to allow water to seep through the concrete, but to block soil from washing away under the road and causing the road to sink, Mr. Martin explained.

The procedure is patterned on undergirding that the SHA did on a sinkhole on Falls Road, Mr. Martin said. The 8-foot-wide hole appeared in the road 1,000 feet south of the Baltimore Beltway in March 1991.

Mr. Martin said the Falls Road work has been successful, as measured by the absence of any sinkholes in the area since the undergirding.

The two roads are underlain by similar rock, the Cockeysville marble formation under Falls Road and the Wakefield marble formation under Route 31.

State highway officials also have mapped all the areas where state roads cross areas underlain by carbonate rock for an overall program to identify possible sinkhole problem sites, Mr. Martin said.

The program involves seven counties, from Baltimore County west to Garrett.

Mr. Martin said Washington County has the largest quantity of limestone underlying roads. He ranked Carroll third in the state for limestone under roads.

He said SHA geologists plan to check the roads' sinkhole and patching histories with district engineers, then test areas "where we think we have hot spots."

He did not have a cost estimate for undergirding the Route 31 sinkholes. The Falls Road work cost about $125,000, and the Carroll sinkhole was bigger, he said.

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