Morning Call: September 25, 2004

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For the first time, a state official Friday publicly blamed a Stockertown quarry for contributing to a rash of sinkholes that has disrupted traffic and damaged private property in parts of Northampton County for four years.

But Gary Hoffman, deputy secretary of operations for the state Department of Transportation, stopped short of blaming Hercules Cement Co. for a sinkhole that damaged a northbound Route 33 bridge in January and led to its $3.5 million replacement as well as the state's decision to replace the southbound bridge.

Hoffman said it was PennDOT's fault the northbound bridge over the Bushkill Creek failed because the state did not take into account the region's porous geology when the span was built in the 1970s.

"We know that the quarry is unquestionably a contributor," Hoffman told residents and government officials at Memorial Library of Nazareth and Vicinity. "But to say it is 50 percent, 60 percent of the problem or 90 percent of the problem, I think none of us can say that."

Hercules officials did not attend the meeting, which elected officials called to brief residents on an 8-month-old joint state and federal probe into the sinkholes and a new plan to slow sinkhole development in and around the Bushkill.

Joe Pospisil, Hercules' vice president of manufacturing, could not be reached. However, he has said there is no proof that the 98- year-old company is responsible because sinkholes form naturally in limestone-rich regions. Two other Nazareth area quarries -- Essroc

Italcementi Group and Eastern Industries Inc. -- have made the same argument.

The sinkhole plan, which residents oppose and is being reviewed by the state Department of Environmental Protection and U.S. Army Corps of Engineers, calls for Hercules and PennDOT to jointly line 850 feet of the creek, up to the state-owned land around the Route 33 bridges, with a synthetic material.

The state hopes the plastic membrane, which Hercules has a separate permit to use at two other stream locations farther north, will stop creek water from draining into the ground and causing sinkholes. The lining would then reduce the amount of creek water flowing underground through sinkholes and into the quarry.

Hoffman said he knows the lining won't solve the overall sinkhole problem, but it's the best short-term solution to protect the bridges. He added the lining would help protect the creek if the Corps receives federal approval and local or state assistance to line more of the stream bed.

However, he said, if the joint plan is approved, PennDOT would not begin its share of the work if studies show the lining would have a detrimental effect on residents downstream of Route 33.

In not blaming Hercules for the sinkhole under the Route 33 bridge, Hoffman said sinkholes have been opening in the area for generations.

"Those bridges should have been on deep foundations to begin with, but that is literally water down the hole now," Hoffman said. "There were probably sinkholes developing out there before the quarry. There's going to be sinkholes developing if the quarry went away."

Studies have shown that quarries can cause sinkholes when they pump groundwater out of their pits. The pumping creates a massive underground funnel called the "cone of depression" or "zone of influence." Groundwater is sucked up through the cone, which then buckles the surface above until a hole opens.

Based on Hercules' own groundwater studies, which DEP uses as its official records, the quarry's cone is believed to cover 2.2 square miles, stopping on the east side of the northbound Route 33 bridge. The studies estimate Hercules' cone will grow an additional 1.3 square miles when the quarry, now 300 to 330 feet deep, uses DEP's March 2003 approval to mine deeper.

Although state officials previously acknowledged the size of Hercules' cone, no one said Hercules has contributed to the sinkholes, which began opening in 2000 when a Palmer Township family was forced from their home and the small Stockertown-Tatamy bridge was swallowed.

DEP mining inspector Mike Menghini said Friday that although the state granted Hercules' a "conditional approval" to mine an additional 150 feet, the agency is now having second thoughts.

"We are not comfortable with them going deeper. We want them to go laterally," Menghini said. "We could stop [the permit] if it shows an effect they cannot remediate, but then they can appeal that."

Steve Esack